Storms should affect the area tomorrow afternoon, and while the storms won't be as intense or anywhere near as widespread as Friday's storms, scattered storms are expected, and some of these could become strong or severe, producing small hail and gusty winds, with at least a 15% risk of severe weather expected at this time. Tomorrow morning's update will include a severe weather risk map.
Sunday, July 31, 2011
Storms should affect the area tomorrow afternoon, and while the storms won't be as intense or anywhere near as widespread as Friday's storms, scattered storms are expected, and some of these could become strong or severe, producing small hail and gusty winds, with at least a 15% risk of severe weather expected at this time. Tomorrow morning's update will include a severe weather risk map.
Saturday, July 30, 2011
Friday, July 29, 2011
**Forecast graphics will be posted with each update. Click on the images to view them in a larger size.**
7:45 PM: Most of the storms have ended across the area, but there is still some activity east of NYC. There is a strong storm near Bronx moving SE, towards northern Nassau. Another severe storm producing heavy rain and strong wind gusts is near central Nassau moving east, towards western Suffolk, and there is a strong thunderstorm with heavy rain affecting JFK airport.
This is the last storm update for tonight. Due to the storm updates, no discussion on the upcoming weather will be posted tonight. Instead, the typical evening update will be posted tomorrow morning, with updates to the 5-Day Forecast, Tropics page, Long Range Outlooks, and the Storm Summary pages during the rest of the day tomorrow.
7:20 PM: Warning: A severe thunderstorm capable of producing small hail and strong wind gusts up to 60 mph is currently over Union city, and will enter central/southern Manhattan (34th street and further south) within the next 10 minutes. This storm will then enter Queens within the next 15 minutes.
6:50 PM: **Tornado Warning is still in effect for Westchester county.**
The severe storm capable of producing a tornado is currently near Port Chester, NY, and is moving southeast. Some weakening of this cell is expected as it moves through the Long Island sound into a more stable air mass, but rotation may still persist once it crosses the sound. Places that will be affected by this cell within the next 1/2 hour are NE Nassau and NW Suffulk counties. Towns/cities in these areas include Bayville, Oyster Bay, Syosset, and Huntington.
Looking across the rest of the area, there is a heavy thunderstorm in central Bergen county moving east, towards southern Westchester. Another strong storm in eastern Morris county is moving ESE, towards Clifton and Fort Lee, later on moving into northern Manhattan. There is another strong storm near northwestern Passaic moving ESE, towards northern Bergen county. The last storm recently formed in eastern Union county, and is moving towards Staten Island and Brooklyn.
6:15 PM: **Tornado Warning is in effect for Westchester county.**
Widespread severe storms are currently affecting the area, with some of them producing rotation. The most intense storm is near Ossining, NY, and is moving SE. Places directly in the path of this possible tornado include White Plains and Port Chester.
Another severe storm with weak rotation is near the border of Sussex/Orange counties and is moving ESE, right along the border. This storm will affect places along the NY/NJ border over the next 1/2 hour. A severe storm in southern Sussex county capable of producing gusty winds and small hail is moving ESE as well, and will affect northern Morris, East Passaic, and southern Bergen counties.
4:00 PM: Storms Starting To Fire Up
Since this morning, the western half of the area began to destabilize with some clearing in the cloud cover. Most places west of NYC are seeing partly to mostly cloudy skies, with mostly cloudy skies in NYC and cloudy skies in Long Island/S CT, where temperatures are much colder, in the lower to mid 70s in southern Connecticut and the mid 70s to lower 80s in Long Island. While Long Island/S CT are under a stable air mass, places from NYC and further west are seeing more instability, with lift index values between -4 and -7, CAPE between 1000-2500, and bulk shear between 40-50 knots. Lower lift index values support a higher severe weather risk, and higher CAPE/bulk shear support a better severe weather risk.
The parameters above support at least a 30% risk of severe weather, where severe storms would be capable of producing strong to damaging wind gusts, hail, heavy rainfall, and an isolated tornado or two. As we have seen many times, however, the parameters alone don't determine if we see severe weather or not, as it is possible that severe storms just north or south of the area prevent storms from developing/persisting over the area.
Possible Storm Scenarios: As of now, we are seeing a severe storm in northeastern Pennsylvania moving ESE, which would take it into Orage and Rockland counties, and an area of strong thunderstorms in east central PA, moving towards places directly west and south of NYC. Every short range model showed this storm where it is now, then forming a line of severe storms extending further south, resulting in a widespread area of severe thunderstorms moving through most of northern NJ, SE NY and NYC between 6-10 PM tonight, producing heavy rainfall, strong wind gusts, smaill hail, and an isolated tornado.
The scenario mentioned above is a reasonable solution. It is possible, however, that storms fail to form south of the NE PA cell, and northern New Jersey/NYC would stay dry, missing today's storms. At this time, looking at the latest radar, there is no indication of additional storms forming in between the isolated cells near Allentown and the severe cell in northern PA, and that area will be monitored over the next 1-2 hours as it will determine whether NYC/N NJ see severe storms or only isolated storm activity.
11:00 AM: Severe Storms This Evening
The area is currenly seeing mainly cloudy skies after a round of showers and thunderstorms moved through northern NJ/NYC last night, bringing rainfall amounts up to 1/4 inch. This is just the first round of today's storms, as more widespread severe weather will affect the region, including the area, this evening. With the last widespread rain event, on July 25, the warm front was stuck to the west of the area, keeping us stuck with cloudy skies and non-severe rain and thunder. Today's scenario is different, however, as the warm front has already passed NYC, and is currently near central New England. As a result, today will bring more instability and a bigger risk of severe weather.
This Afternoon: While the area is currently under mainly cloudy skies, clearing in the cloud cover is expected around 12-2 PM, with mostly to partly sunny skies from NYC and further west. With the warm front still stuck in the eastern parts of the area, however, most of Long Island and southern Connecticut will see mostly cloudy to cloudy skies. With the break in the cloud cover, temperatures west of NYC will quickly warm up into the upper 80s to lower 90s, and a few mid 90s may be possible in NE NJ. Combined with the humidity, as dew points will be in the lower 70s, the heat index will reach the 96-100 degree range in NYC later this afternoon.
Evening / Overnight: The cold front will then approach the area overnight, bringing more widespread storms. The most widespread storms should stay in New York, where heavy rain and thunderstorms are expected, but as there will be instability in the area, there is a better risk of severe storms. Thunderstorms should start to form in SE NY/NE Pennsylvania late this afternoon, and move into the area in the evening hours, between 6 PM and 11 PM. These storms will be capable of producing strong wind gusts, small hail, and heavy rainfall with localized flash flooding possible. Stay tuned for storm updates this afternoon and evening.
Thursday, July 28, 2011
Reminder: For information about Tropical Storm Don, please refer to the "Tropics" page. Updates on Don are being posted twice a day.
Tomorrow's Storm Risk:
Tomorrow will bring a slight risk of severe weather. A warm front currently over Pennsylvania will cross the area tomorrow morning, bringing more instability into the area by the afternoon and evening hours. Most of the storms tomorrow evening are likely to stay to the north of the area, but some storms are expected to affect the area as well, especially from NYC and further north. Any storm that reaches the area will be capable of becoming severe. It is possible, however, that the severe weather may need to be shifted further north and away from NYC, and more information on tomorrow's severe weather risk will be posted tomorrow morning.
- Warmth will continue from Friday and beyond. Little change is expected in the conditions, as temperatures stay in the upper 80s to mid 90s from NYC and further west and in the mid to upper 80s in Long Island/S CT with partly sunny skies from Saturday through next Wednesday/Thursday, when the next cold front should reach the region, bringing a risk of thunderstorms late next week along with slightly cooler temperatures.
Wednesday, July 27, 2011
A warmer air mass will start to move into the area tomorrow. As a result, temperatures will warm up, reaching the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and mostly in the mid 80s further east due to a south wind.
There is the potential for a MCS (Mesoscale Convective System) to move into the area tomorrow night. Forecasting MCS type events can be very difficult, but the potential is there for one to affect the region, and if one does reach the area, it would be capable of bringing heavy rain and gusty winds. More information on this will be posted tomorrow.
Afterwards, Friday will bring warmer temperatures along with more humidity, with temperatures reaching the upper 80s to lower 90s from NYC and further west, with the heat index reaching the upper 90s. The potential is there for strong thunderstorms to affect the area in the evening and overnight hours. Stay tuned for more information on the potential strong storms for Friday.
Tuesday, July 26, 2011
- The 5-Day Forecast page was not updated, but the forecast has not changed since yesterday and is still valid.
- The Tropics page is still updated daily, twice a day, unless there is an active tropical cyclone approaching the US, when updates will be posted more frequently. The current activity graphic on the right side of the blog is updated twice a day as well. Tonight's update now has a 60% risk of development for Invest 90L, which will move into the Gulf of Mexico tomorrow.
- With a slightly cooler air mass moving in, tomorrow will slightly cool down, with most of the area in the mid to upper 80s for highs. Thursday will warm up with temperatures in the mid 80s to lower 90s across the area, with the warmest temperatures in the immediate NYC area where widespread lower 90s are expected.
- Friday will be hotter, with temperatures in the lower to mid 90s from NYC and further west and mid 80s to lower 90s east of NYC. Along with dew points in the lower 70s, the heat index values will likely reach 100 degrees, and a heat advisory will likely be issued tomorrow morning for Friday. Regarding the storm potential, the latest models are showing almost no precipitation on Friday, but with the given set up, I kept a risk of potentially strong storms in the forecast for Friday.
- Friday will start a heat wave which will last through early-mid next week. Temperatures through the weekend will stay in the upper 80s to mid 90s from NYC and further west, and the mid to upper 80s east of NYC. Temperatures are likely to slightly warm up around early next week ahead of a potential cold front by early-mid next week.
8:45 PM: The storm in New York City has intensified, and is currently a strong thunderstorm covering NW Brooklyn and Queens. This storm will produce heavy rain and gusty winds as it continues to move ESE, affecting the rest of Brooklyn and Queens, later on reaching Long Beach and southern Nassau county.
8:25 PM: The storms in southeastern New York earlier this afternoon ended up going through northern Westchester county into SW Connecticut. While these storms are no longer present, there are four storms cells over northern New Jersey, all of them moving towards the same direction in a line, targeting the same area from Sussex to West Passaic to northern Bergen with heavy rain and thunderstorms over the next 1-2 hours. These storms are not severe, but there is a strong cell near Franklin, NJ, which is expected to follow the path of the other storms as well. There is also an area of heavy rain near Patterson which will move ESE, towards Manhattan, within the next 1/2 hour.
Most of the area is dry, but there are some more storms in SW Connecticut. There are two small yet heavy thunderstorms near Danbury, CT, and there is a large heavy cell just north of Bridgeport, CT, moving ESE and offshore into the Long Island Sound.
3:30 PM: Yesterday's update mentioned the potential for isolated activity today north of NYC, with most of the storms staying well north of NYC. With a low pressure moving through northern New York, widespread strong to severe thunderstorms have developed this afternoon in New York and are moving southeast, with a particular area of severe storms in east central New York intensifying as it is moving towards western Massachusetts/NW Connecticut. Meanwhile, a few strong thunderstorms in formed northeastern Pennsylvania, which are currently moving towards the western half of the area.
Most of the activity is to the north of the area, but two storms are approaching the northwestern parts of the area. The first storm is approaching Monticello, NY, which will move into NW Orange county in the next 3/4 hour, producing heavy rainfall and gusty winds. The second storm is near Scranton, PA, and is moving towards Sussex county, NJ. This storm is weaker than the storms further north, and is expected to begin weakening by the time that it reaches Sussex county.
The parameters in the area are supportive of severe weather, with decent lift index/CAPE values. The best lapse rates, however, are to the north of the area, and there is nothing to spark widespread storm development in the area. As a result, the best risk of strong thunderstorms this afternoon will be in interior SE NY, focusing over Orange/Rockland/Putnam counties in NY. The rest of the area can expect to see partly to mostly cloudy skies with dry conditions. If necessary, storm updates will be posted, otherwise the next update will be posted tonight.
Monday, July 25, 2011
10 AM: Some Storms Today, Severe Weather Stays West
Yesterday, a cold front moved through the area, bringing scattered thunderstorms especially in northern New Jersey. This cold front brought an end to the heat wave which has brought record temperatures into the region, and the front is now to the south of the area, which will help keep temperatures below the 90 degree mark today. A weak low pressure will move towards the Northeast, bringing another cold front through with thunderstorms affecting the region, but the NYC area will likely be spared from the majority of the action today.
Today's Set Up: The cold front is stuck to the south of the area as of this morning, and the warm front associated with the low pressure is currently near central Pennsylvania. The front will continue to move east for now, but there is a high pressure off the coast which will make it more difficult for the warm front to move east as it reaches the area. As a result, it is expected to remain near or just west of NYC through this evening, keeping an onshore SE wind in the area resulting in a stable air mass, while places further west become more unstable. Later tonight, the warm front is expected to move through, but it will be quickly followed by the cold front, keeping the area under a stable air mass.
We have seen this type of scenario happen several times throughout the spring. Not all cases were the same, but in most of them, we ended up seeing storms further west, towards Pennsylvania, weakening and later dissipating as they moved through NJ towards NYC. This is the same scenario that most of the models are showing for today as well, with most of the thunderstorms staying in Pennsylvania, and some models fail to bring any rain to NYC. This does not mean that the area will not see any rain, but the stable air mass will cause any storm that enters the area to begin weakening as it approaches NYC.
Today's Outlook: Instability further west today will cause strong to locally severe thunderstorms to form to our west, towards central Pennsylvania, New York and Virginia. These storms will then move east towards the more stable air mass over the area. Some storms are expected to move into northern NJ this afternoon evening, but as they do so, they will lose their severe characteristics. Despite this, they will still be capable of producing heavy rainfall in northern NJ and interior SE NY. As these storms continue to move towards the coast, they should rapidly collapse by the time that they reach and pass NYC. As a result, the best risk of storms today is to the west of NYC, where locally heavy rainfall is possible, and Long Island/southern Connecticut are expected to stay mainly dry other than some isolated shower/thunderstorm activity tonight. Storm updates will be posted this afternoon and evening if necessary.
Sunday, July 24, 2011
**Click on the images to the left of each update to view them in a larger size.**
2:45 PM: As the cold front is moving through the region, heavy but non-severe thunderstorms are affecting portions of the area. The main storm is currently near northern Warren county and is moving SE, producing heavy rainfall, gusty winds and potentially small hail. Another heavy thunderstorm is in central Westchester county and is moving towards the SE, but this storm is weakening, and will affect eastern Nassau/western Suffulk counties within the next 1/2 to 1 hour with light rain and thunder.
Otherwise, there are a few other heavy thunderstorms in northern New Jersey moving SE as well, especially in Sussex and West Passaic. The storm in Sussex has a narrow band of light to moderate rain stretching eastwards towards western Bergen county, and is moving SE along with the storm. This will result in at least some rain across most of northern New Jersey.
Saturday, July 23, 2011
- A detailed summary of last week's observations and forecast verification
- Tonight's post, which will discuss Monday's potential storms and the next surge of heat for late next week
- Updated Tropics and Weather Alerts pages
Friday, July 22, 2011
Across the area, today was one of the hottest days ever recorded in the New York City area, and across parts of the area and the region, even broke all time heat records. Newark, NJ reached an all time record high of 108 degrees, which produced a heat index well into the 110s when combined with dew points in the upper 60s to lower 70s. In addition to Newark's record, Bridgeport in Connecticut tied their all time record high of 103 degrees. Central Park's 104 degree high temperature is their 2nd warmest temperature on record, and Teterboro's 104 degrees is two degrees below the all time high temperature of 106 degrees. Below are the high temperatures today across the area, from the National Weather Service:
104 degrees - LaGuardia Airport
103 degrees - JFK
100 degrees - Islip (Long Island)
98 degrees - Montauk (Long Island)
108 degrees - Newark (Essex)
104 degrees - Teterboro (Bergen)
103 degrees - Caldwell (Essex)
100 degrees - Morristown (Morris)
99 degrees - Sussex (Sussex)
103 degrees - Bridgeport
101 degrees - New Haven
95 degrees - New London
Even though the temperatures were already hot enough, the humidity made the heat even worse. When Newark reached 108 degrees, the humidity resulted in a heat index of 117 degrees. Heat indices in the 110s were observed across most of the immediate NYC area due to dew points in the 70s combined with very hot temperatures. During July 2010, the area also observed a heat wave early in the month with similar temperatures, but during that heat wave, the humidity was not as significant as it was with this heat wave. The heat index values observed with this current heat wave are abnormally high and are quite rare for the NYC area.
Today brought the worst of this heat wave. Tomorrow, unfortunately, won't bring any significant improvements as the heat and humidity continue with the only difference being slightly lower temperatures and humidity. Sunday will bring relief in the form of a cold front, which will be followed by much cooler temperatures on Monday along with the risk of thunderstorms. This cool down is only brief, however, as another heat wave is possible once again late next week.
Temperatures are still very warm across most of the area, and as of 9 PM, temperatures were in the mid 80s inland, lower to upper 90s in the immediate NYC area, and in the upper 80s to lower 90s east of NYC. Temperatures will continue to gradually drop overnight, reaching the mid 70s inland, upper 70s to mid 80s in the immediate NYC area, and the mid 70s to lower 80s in Long Island and southern Connecticut. With the humidity still in place, the heat index value will stay high, dropping into the upper 80s at the lowest in NYC/Newark. There is the potential that if low temperatures end up in the mid to upper 80s in NYC/Newark, these locations could break the record for the highest minimum temperature.
Tomorrow's Outlook: Heat Continues
Tomorrow will bring only minor improvements as the heat and humidity continue across the area. Temperatures at 850 mb, which were near 24 degrees celsius today, will slightly lower tomorrow to around 22 degrees celsius. As a result, high temperatures will be slightly lower as well, reaching the mid to upper 90s inland, lower to mid 100s across most of the immediate NYC area with a west wind. With a WSW wind in Long Island/southern CT, however, temperatures will be lower than those of today, reaching the mid 90s in southern Connecticut and the mid to upper 90s in Long Island, except for the immediate southern coast which should stay in the lower 90s.
Dew points will be slightly lower as well, reaching the upper 60s to lower 70s across the area. This will result in slightly lower but still dangerous heat index values across the area, which are expected to end up near 100 degrees inland, 105 degrees in the immediate NYC area, and 95-100 degrees in Long Island/southern Connecticut.
***As of 2:51 PM on Friday, July 22, 2011, Newark in New Jersey reached an all time record high temperature of 108 degrees. The previous all time record was 105 degrees, recorded on August 9, 2001.***
The rest of the area is recording very hot temperatures as well, with 103 degrees in Teterboro and Central Park, and 101 degrees at the JFK airport. Temperatures will continue to rise over the next 1-2 hours before becoming steady and starting to gradually drop, and other locations may tie or break their all time records as well. Heat indices will remain at dangerously high levels, in the 110 to 120 degree range. Stay tuned for more updates on the heat over the next several hours.
Sunday, July 17, 2011
Note: This blog is going on a weather related trip over the next week. The next update, along with some comments on the trip, will be posted on Saturday, July 23.
A massive ridge is currently centered over the central United States, bringing extreme heat to that region. Some of the heat from this ridge is spreading towards the region, which is bringing temperatures into the 90s. Meanwhile, a storm in Canada will bring a cold front through tomorrow, bringing a risk of severe weather. Behind this front, temperatures will slightly cool down, but by late next week, temperatures will warm up even more, potentially reaching the 100 degree mark in parts of the area.
The outlook for today has not changed since yesterday. Mostly to partly sunny skies are still expected, with highs in the upper 80s to lower 90s from NYC and further west, and the mid 80s across most of Long Island and southern Connecticut.
Monday: Severe Storms Possible
A cold front will move through the region on Monday, bringing a risk of strong to severe thunderstorms. Unlike most of the outbreaks we've seen in the region this summer, however, this set up is more favorable for severe weather. In addition to supportive lift index and CAPE values, bulk shear is also modeled to be supportive, between 35 and 45 knots. We had some cases where there was favorable bulk shear this summer which did not end up over the areas which saw severe weather, but in this case, the supportive area of bulk shear is expected to end up over the same region expected to see thunderstorms, which is already a sign of a better chance of severe thunderstorms. Lapse rates are expected to be supportive as well.
With the factors above in place, there is at least a 15% risk of severe weather across most of the area. The best risk of severe thunderstorms is expected to end up in southern New England and parts of southern New York State, which includes the northern parts of the area. These places have the most supportive parameters, and at this time, I placed a low-end 30% risk in those areas. Thunderstorms across the area will be capable of producing gusty winds, heavy rainfall, and small hail.
Medium Range Heat Wave: 100s Possible
Behind this cold front, temperatures will only slightly cool down. Tomorrow will bring lower to mid 90s from NYC and further west, and Tuesday will bring upper 80s to lower 90s from NYC and further west. Mid to upper 80s are expected as well in Long Island and southern Connecticut. Wednesday will bring similar temperatures to those of Tuesday.
Things will change by Thursday, however. The large ridge currently over the central US will shift eastwards, so that the focus of the heat will be further east as well, closer to the area than we've seen most of this summer. A strong cold air mass in SE Canada will attempt to drop southeast towards the region, but at least early in this time frame, will only make it as far south as northern New England, allowing the excessive heat to spread into the NYC area.
Forecast for the Tri-State Area: Temperatures on Thursday will begin to warm up, reaching the lower to potentially mid 90s inland, mid 90s across most of the immediate NYC area, and with a southwest wind, Long Island and southern Connecticut should reach the mid 80s to lower 90s. Humidity will begin to slightly increase as well, allowing the heat index to reach the upper 90s in the immediate NYC area.
Friday is likely to be the hottest day of this heat wave, though Saturday could bring similar conditions as well. 850 mb temperatures are modeled to be in the 21-24c range, similar to what we saw with the July 2010 heat wave. Mainly dry conditions are expected along with mostly/partly sunny skies and a WSW wind. Unless there is a significant change with the expected set up, the conditions above are capable of bringing the hottest day of the year across the area. High temperatures are likely to reach the mid to upper 90s inland, upper 90s to potentially lower 100s across most of the immediate NYC area, and Long Island/southern Connecticut are likely to end up in the upper 80s to mid 90s, though upper 90s could be possible closer to NYC in the warmest case scenario. Humidity is expected as well, with dew points modeled to be near the upper 60s to lower 70s. This would bring the heat index into the mid-upper 100s in the immediate NYC area.
Forecast Uncertainty: The forecast for Friday is not 100% certain yet, but based on the set up for this time frame and the agreement between the models and model ensembles regarding the intensity and placement of the heat, there is a relatively high probability that Friday ends up bringing conditions similar to those mentioned above. There is the possibility that the heat ends up being slightly weaker than expected or that the back door cold front drops south of the expectation, which would result in cooler temperatures than the above, but even in these scenarios, Friday is likely to end up as a hot and humid day.
Beyond Friday, there is increasing uncertainty regarding another cold front, as the GFS has the heat lasting through early next week, the ECMWF brings a weak back door cold front through which slightly cools down temperatures, and the GGEM brings a stronger cold front through with temperatures returning into the 80s. At this time, I am siding with a scenario closer to that of the ECMWF, where temperatures cool down into at least the upper 80s to mid 90s on Saturday or Sunday, followed by another warm up by early next week. There is more uncertainty, however, and the confidence level in the forecast decreases beyond Saturday. With the next update, either late on Friday or on Saturday morning, I will discuss what the forecast is from that point and beyond.
Saturday, July 16, 2011
With the high pressure previously over the region sliding offshore, a much warmer air mass is spreading into the region, with temperatures warming up as well, reaching the upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and the lower to mid 80s in Long Island and southern Connecticut. Today ended up slightly warmer than expected in the immediate NYC area, though the forecast for Long Island and southern Connecticut verified.
As a warmer air mass continues to spread into the region, temperatures will continue to warm up, reaching the lower 90s over a more widespread area tomorrow. A cold front will move through on Monday, bringing a risk of strong thunderstorms along with increased heat and humidity, with temperatures reaching the mid 90s in parts of the immediate NYC area. Temperatures will slightly cool down on Tuesday/Wednesday, but by the late week, a massive ridge in the central US will spread towards the region, bringing the potential for the hottest temperatures of the year.
Warmth will continue to spread into the region tomorrow, with the result being slightly warmer temperatures than those of today. A southwest wind is expected along with partly sunny skies, which will result in temperatures reaching the upper 80s to lower 90s from NYC and further west. Widespread mid 80s are expected in Long Island and southern Connecticut, with lower 80s near the immediate coast and upper 80s closer to NYC.
Monday - Wednesday: Stormy, Then Slightly Cooler
As a cold front approaches the area on Monday, the heat and humidity will only get worse, with temperatures reaching the lower to mid 90s from NYC and further west, though temperatures will be cooler further east, reaching the mid to upper 80s across most of Long Island and southern Connecticut. Combined with dew points near 70 degrees, the heat index may reach the upper 90s in parts of the immediate NYC area.
Along with the cold front comes a risk of thunderstorms. At this time, it appears that this front may bring a better risk of rainfall than most of the previous fronts we've seen so far this month, and the parameters on the models are supportive of at least some severe weather, though the best risk of severe thunderstorms will likely stay to the north of the area. Precipitation amounts are more uncertain, and while locally heavy rainfall amounts are possible, widespread heavy rainfall amounts are not expected. The latest operational NAM runs are showing a widespread 1-2 inch area, but is a wet outlier, compared to the other models and the parallel NAM runs as well. More information on Monday's storms will be posted with an update tomorrow morning.
By Tuesday and Wednesday, a slightly cooler air mass will move in as a high pressure moves into the region. Temperatures will not significantly cool down, but at least upper 80s to lower 90s are expected across the area on Tuesday. Wednesday will bring upper 80s to lower 90s from NYC and further west, but slightly cooler temperatures further east, reaching the mid to upper 80s across most of Long Island/southern Connecticut except for the immediate coast.
Longer Range: Tomorrow morning's update will discuss the longer range in more details, including potential scenario graphics.
Friday, July 15, 2011
With the high pressure sliding offshore, winds will turn more towards the SSW/southwest during the weekend, allowing the warmth to slowly build in. A massive ridge is currently centered over the central United States, with widespread 500 mb heights over 594 dm expected, a clear signal for extreme heat. As we have seen most of this summer, the ridge has focused over the central US while a short lasting surge of heat spreads into the region, and at least for this weekend, this will be the case once again.
Warmer 850 mb temperatures will spread into the region, which will allow surface temperatures to warm up as well, reaching the mid to upper 80s from NYC and further west on Saturday and lower to mid 80s further east. Sunday will bring even warmer temperatures, with more widespread upper 80s from NYC and further west, and a few lower 90s are expected in the immediate NYC area, especially in NE NJ.
Monday - Wednesday: Cold Front Moves Through, Severe Storms?
So far this summer, the area has been mostly spared from major widespread severe weather outbreaks. We are not looking at a widespread major severe weather outbreak for Monday, but the risk of thunderstorms is higher than what we have recently seen. A cold front will approach the area on Monday, bringing warmer temperatures, reaching the lower to mid 90s in the immediate NYC area, but along with the heat comes a risk of severe thunderstorms. The latest models are showing high precipitable water values, decent LI/CAPE values, and supportive lapse rates as well, factors which are all supportive of severe weather. The best risk of severe weather should be in the Northeast, to the north of the area, but some thunderstorms are expected in the area as well, and the latest modeled parameters support at least a low risk of severe weather in the area. Stay tuned for more information on Monday's severe weather risk.
The intensity of the cold front is the main question at this time. The ECMWF once again fails to bring any significant cool down with the front, while the GGEM brings a significant cool down for the middle of next week. Both solutions are likely extremes, and the most reasonable and least extreme solution at this time is the GFS, which shows a slight cool down for the middle of next week with temperatures cooling down into the mid to upper 80s across most of the area for Tuesday and Wednesday. At this time, I went along with a solution close to that of the GFS, with widespread mid to upper 80s behind the cold front on Tuesday, and a few lower 90s cannot be ruled out. Wednesday will bring slightly cooler temperatures.
Thursday And Beyond: Big Heat Possible
As previously mentioned, the center of the ridge for now will focus over the central US. It is possible, however, that this changes by late next week. Behind Wednesday's brief cool down, there is a general model consensus for the center of the ridge to shift east, taking it closer to the area, and allowing more heat to make it into the region. Each model handles this differently, with some of them showing the possibility that a back door cold front drops through the Northeast during the peak of the heat, but should the heat spread in with no back door cold front, this has the potential to match, if not pass the hottest temperatures of the June 6-8 heat wave, when Teterboro in Bergen county (NE New Jersey) reached 100 degrees. The ECMWF is the hottest model, showing 850 mb temperatures which support high temperatures easily reaching the 100s, but was not used for today's update especially when considering that it tends to have a warm bias with heat waves and is currently the most extreme solution.
This is still in the medium range and is subject to change, but at this time, given the potential set up during this time frame, temperatures are likely to significantly warm up around Thursday/Friday, and if no back door cold front comes through, the heat should last through next weekend. Temperatures may be capable of surging well into the 90s with this type of set up, and parts of the region may even reach the 100s. Stay tuned for more information on the potential heat wave with tonight's update.
Thursday, July 14, 2011
Wednesday, July 13, 2011
As mentioned above, today brought unexpected storms into the area with cooler temperatures than expected. Tomorrow through the weekend will be dry, however, as a high pressure moves over the area, which will prevent rain from affecting the area and keep mainly sunny skies in place. This high pressure will bring seasonable temperatures as well, peaking in the upper 70s to mid 80s across the area.
With the high pressure exiting the region by Sunday, more cloud cover will return, and as the wind begins to shift more towards the south/SW, hotter temperatures will return, with 90s returning into the immediate NYC area for Monday and Tuesday before the next cold front comes through. Unlike the more recent cases, however, it is possible that the cold front may have less of an influence than previous scenarios we've seen, and if this scenario verifies, excessive heat may affect the area by late next week.
Tuesday, July 12, 2011
Monday, July 11, 2011
Tomorrow will bring partly sunny skies to the area with a WSW wind turning WNW and 850 mb temperatures near 18-20 degrees celsius. The factors above support temperatures reaching the lower to mid 90s across northern NJ, SE NY, and NYC, and if mostly sunny skies continue through the afternoon and evening hours with no storms, temperatures may even reach the upper 90s in parts of NE NJ. With the wind direction coming mostly from the west, little sea breeze is expected in Long Island and southern Connecticut, with temperatures reaching the lower 90s across most of Long Island and southern Connecticut except for the immediate coast.
The cold front will move through tomorrow in the evening hours, but at this time, it appears that a relatively dry frontal passage is the more likely scenario. Isolated thunderstorms are possible in the afternoon hours, and any storm that develops may become strong or potentially severe, but the severe weather risk for tomorrow is low.
Wednesday And Beyond: Sunny, Dry, Seasonably Mild
Behind tomorrow's cold front, a stretch of pleasant weather will begin as a high pressure sticks around the region through the late week and the weekend, with mainly sunny skies and temperatures in the upper 70s to mid 80s from Thursday through Sunday, with the exception of Wednesday which should bring temperatures into the mid to upper 80s across most of the area with a few lower 90s possible in the immediate NYC area. Overnight lows will also be chilly, dropping into the 50s north and west of NYC and in southern Connecticut.
By early next week, unsettled weather begins to return into the region. Another potentially massive ridge in the central US once again appears to fail to bring a major heat wave in the area, with the worst of the heat staying to the west of the region, but temperatures will begin to warm up as the high pressure exits the region, bringing more of a SSW wind, and some of the heat in the central US spreads into the region, potentially bringing temperatures into the 90s for parts of the area around early-mid next week, which is also when the next chance of rain will be for the area. Stay tuned for more information on the longer range.
Sunday, July 10, 2011
A warm air mass currently over the central US will begin to spread towards the region, with 850 mb temperatures expected to reach 18 degrees celsius over the area. With mostly sunny skies and a southwest wind, this will bring temperatures into the upper 80s to lower 90s from NYC and further west. Due to the southwest wind, temperatures will be more variable east of NYC, ranging from the lower 80s near the southern/eastern sections of Long Island to the lower 90s in southern Connecticut away from the immediate coast. Parts of western Long Island may also reach the lower 90s.
Tuesday - Friday: Hot And Stormy, Then Sunny And Dry
The peak of the heat is expected to arrive on Tuesday, when 850 mb temperatures will be near 20 degrees celsius along with WSW winds. The cold front will also be moving through the region on Tuesday, however, bringing a risk of thunderstorms to the region, and the amount of cloud cover and storms near the area will determine how hot temperatures get across the area. If the area sees partly sunny skies with isolated storms, high temperatures should reach the mid 90s in the immediate NYC area with the heat index reaching the lower 100s. If the area sees mostly cloudy skies with widespread storms, however, temperatures will end up lower, peaking in the lower 90s at most in the immediate NYC area.
At this time, I am leaning towards the warmer scenario, expecting mid 90s in NE NJ and lower 90s for most locations west of NYC, with scattered thunderstorms. Storms that develop on Tuesday may end up becoming strong, producing gusty winds. Stay tuned for more information on Tuesday's heat and potential storms.
Behind Tuesday's cold front, a high pressure will move into the region, providing the area with sunny skies and cooler temperatures from Wednesday through Saturday. Wednesday will still be warm, with upper 80s in NE NJ, but Thursday through Saturday will bring high temperatures in the upper 70s to mid 80s across the area. Temperatures will begin to warm up by Sunday/Monday.
Saturday, July 9, 2011
With the low pressure out of the region, currently moving towards Newfoundland, today ended up with warmer temperatures than those of yesterday but without any significant heat, as temperatures reached the mid 80s inland and the mid to upper 80s in the immediate NYC area, Long Island, and southern Connecticut. Tomorrow will bring similar temperatures, but a brief yet intense heat spell will affect the area on Monday and Tuesday, with the potential for temperatures to reach the 95-100 degree range in parts of the immediate NYC area on Tuesday along with a risk of strong thunderstorms.
Tomorrow will be another nice day across the area. With a high pressure still over the region, mainly sunny skies will continue through tomorrow with a light south wind expected. High temperatures will be slightly warmer than those of today, reaching the mid to upper 80s inland, upper 80s to lower 90s across most of the immediate NYC area except for coastal sections of NYC, and the lower to mid 80s across most of Long Island and southern Connecticut, with the warmest temperatures away from the immediate coast.
Monday - Tuesday: Hot, Humid, And Stormy
Over the last week, the potential was mentioned for a surge of heat early this week that could bring temperatures into the lower to potentially mid 90s. Yesterday's storm, which is currently moving towards Newfoundland, will fail to prevent this heat from reaching the region, with its only impact on the area being slightly delaying the entrance of the heat. As we have been under the same pattern through most of the summer, this surge of heat will be short lasting as well, as a storm moving from west to east in southern Canada will already bring a cold front through on Tuesday, but despite the short duration of the heat, hot temperatures are expected, which could end up close to those of the early June heat wave.
As previously mentioned, a weak low pressure is expected to move from west to east through southern Canada, ending up north of the Great Lakes on Monday and north of Maine on Tuesday. As this is a weak storm, most of the heat will shift towards the east as well without significantly weakening. The June 6-8 heat wave set up was also similar to this set up in some ways, as there was also a weak low pressure in southern Canada moving from west to east, allowing the heat to spread into the region without any significant moderation. With the heat moving into the region, Monday will bring warmer temperatures, reaching the upper 80s to mid 90s from NYC and further west along with partly sunny skies. An isolated thunderstorm cannot be ruled out west of NYC in the afternoon, but no significant storms are expected on Monday at this time.
The cold front will move through the area on Tuesday. With the previous update, there was some uncertainty with the exact timing, and as a result, I went conservative with the temperature outlook. With the latest expected scenario, however, it appears that the timing and cloud cover will be supportive enough to allow temperatures to rise into the 90s across parts of, if not most of the area. Lower to mid 90s are expected from NYC and further west on Tuesday, and a few upper 90s cannot be ruled out in parts of NE NJ should the warmer case scenario verify. Humid conditions are expected as well, and the heat index could reach the upper 90s to near 100 degrees on Tuesday. Scattered thunderstorms are possible once again in the afternoon and evening hours, with the potential for strong to severe thunderstorms as well.
Mid-Late Week: Sunny, Dry And Colder
A trough will move into the region behind Tuesday's cold front, bringing a relief from the brief heat spell. While Wednesday should still be very warm, with mid to upper 80s across most of the area with a west/WNW wind expected, the rest of the week will be colder as a high pressure moves over the region, bringing a cooler air mass along with sunny skies. Low temperatures on Wednesday night are expected to drop into the 50s away from NYC and the coastal areas, with sunny skies and highs in the upper 70s to mid 80s expected on Thursday. Similar conditions are expected for Friday as well.
By next weekend, another large ridge in the central US should begin to spread towards the region. The worst of the heat could stay to the west of the region once again as it has done so far this summer, but hot temperatures are likely to return into the region once again by the weekend, and temperatures may return into the 90s in parts of the area by the weekend or early next week. Stay tuned for more information on the longer range.
Thursday, July 7, 2011
The area saw its fourth consecutive day of heat as temperatures surged into the upper 80s to lower 90s inland, lower to mid 90s in most of the immediate NYC area, and mostly in the mid 80s to lower 90s across Long Island and southern Connecticut. Earlier this afternoon, isolated thunderstorms formed in the southern half of New York City and moved east through southern Long Island, but otherwise, most of the area stayed dry.
Since my discussion three days ago about the potential for the models to trend towards adding a feature to block the heat from easily spreading in, the models trended towards a low pressure moving towards Nova Scotia/Newfoundland and Greenland during the weekend, shortening the heat to a 2 day time frame, around Monday and Tuesday. As the low pressure will develop near the region tomorrow, however, this trend put the area under the risk of locally heavy rainfall tomorrow and tomorrow night, with occasional showers and thunderstorms bringing the potential for rain totals locally as high as 1 to 2 inches of rain.
As previously mentioned, a low pressure will begin to develop near the region tomorrow, which will later on become a stronger storm moving towards Nova Scotia and Newfoundland. This low pressure will not be very organized yet tomorrow, but it will produce scattered showers and thunderstorms, which will be capable of producing locally heavy rain with precipitable water values near 2 inches. It is possible that some places in the tri-state area may fail to see rain, but at this time, the coverage area of the rain is expected to be widespread enough to affect at least most of the area. Due to the cloud cover and rain, tomorrow will bring cooler temperatures, peaking in the mid 70s to lower 80s across the area. Storm updates may be posted tomorrow in the morning and afternoon hours.
Weekend To Early Next Week: Warming Up
A few days ago, on July 4th, the models were expecting a transition to a positive NAO with a large surge of heat spreading into the region. My update that afternoon mentioned that the models have done the same for this week and ended up trending towards a negative NAO and a low pressure near the Davis Strait, keeping any heat surge relatively weak and preventing it from becoming sustained. We are seeing the models repeating this trend, as the latest consensus is there for the low pressure which will form near the region tomorrow to move towards Newfoundland and then towards Greenland. While it is unlikely to move into the Davis Strait as the last few storms in that region have done, a negative NAO will persist, and is expected to remain mostly negative or neutral through mid July.
With the storm moving into the Newfoundland/Greenland region, the entrance of the heat into the region will be delayed, with lower 90s expected to make an appearance in parts of the area on Monday and potentially Tuesday. Mid to upper 80s are expected from NYC and further west on Sunday, with parts of NE NJ potentially reaching the 90 degree mark. With a high pressure nearby, mostly sunny skies are expected for Sunday and Monday.
By Tuesday, a storm moving from west to east through southern Canada will bring an end to the short lasting surge of heat. The cold front will move through around Tuesday, and while the exact timing is still uncertain, there is the potential for thunderstorms with this cold front, especially around Monday night and potentially on Tuesday if the cold front slows down from the current expectation.
Longer Range: Cool Down, Then Warming Up
Behind the front, the pattern we are currently under will repeat itself once again, as the models have trended away from the original idea of a longer lasting heat spell lasting through next week and now show a trough moving into the region. This will not bring a much colder air mass, but temperatures are expected to cool down into at least the upper 70s to mid 80s through mid-late next week with mainly sunny skies. There are indications that the area may warm up once again by next weekend, but the specific details cannot be nailed down yet as this is still in the longer range. Stay tuned for more information on the longer range.
Due to technical difficulties, no update was posted last night. I am currently working on a detailed update which will be posted this afternoon, discussing widespread thunderstorms on Friday and Friday night, the return of hot temperatures on Monday and Tuesday early next week, and what may follow in the longer range.
Tuesday, July 5, 2011
Wednesday And Thursday: Heat Continues
A weak low pressure moving through the Northeast will help keep the heat in place through tomorrow and Thursday. Tomorrow will be the hottest day, with a warm southwest wind bringing temperatures into the upper 80s to lower 90s across most of the area with a few mid 90s in the immediate NYC area. Long Island will be the coolest spot, with high temperatures ranging from the lower 80s further south/east to the upper 80s further north/west and closer to NYC.
A cold front will move through the region, but unlike yesterday's expectation, the cold front is now expected to be mostly dry when it reaches the area. Isolated thunderstorms are expected, some of them producing locally heavy rainfall, but they will not be as widespread or as heavy as Sunday's storms. As a result, Thursday's temperatures were raised with less cloud cover in the forecast, with temperatures now expected to end up similar to those of Wednesday, if not slightly cooler.
Friday And Beyond: Slightly Cooler, Then Warm Again
Behind the cold front, a cooler air mass will move into the region for Friday and Saturday, bringing high temperatures into the upper 70s to mid 80s across the area for both days with mostly sunny skies and dry conditions, though an isolated thunderstorm cannot be ruled out for Friday especially south and east of NYC.
For Sunday through Tuesday, the models continue to show heat spreading into the region, but vary with the intensity and duration of the heat. As I mentioned in my post last night, a more likely scenario based on this summer's trend and pattern is one where the area slightly warms up for 2-3 days around early next week, likely somewhere in the upper 80s-mid 90s range, followed by a cold front with a cooler air mass briefly returning behind it. This is still in the longer range and could change, but at this time, this scenario is more likely than a prolonged heat wave with temperatures surging into the upper 90s. More information will be posted on this time frame as details become clearer.