Oct 22

Oct 22, 2014 Brief Update

Forecast Update:

Tonight’s forecast discussion is an update from yesterday’s discussion. The next full analysis will be posted on Thursday evening.

rad_10.22gfs_10.22

From left to right, the latest available surface analysis and radar composite from the NWS Weather Prediction Center (WPC), and the initialized GFS 500 hPa heights and vorticity from NCEP Model Analyses & Guidance; both are valid at 1800 UTC Wednesday (2:00 PM Wednesday EDT).

nerad25Since yesterday’s update, the upper level trough has cut off with a closed upper level low, while the surface low pressure redeveloped offshore and deepened to near 1003 hPa southeast of New Jersey. As the low developed last night, heavy thunderstorms persisted over northeast NJ, coastal NYC and western Long Island, where rain totals locally exceeded 1 inch with flash flooding and localized hail yesterday evening. A more organized band of heavy rain developed this morning over eastern New Jersey, shifting offshore throughout most of the day before reorganizing and retrograding west throughout the evening and early overnight hours as the surface low deepened along with increased upper level forcing over the area. The latest regional radar imagery from the Pennsylvania State University e-Wall, posted to the left, depicts the moderate rain bands covering the majority of the area; the latest radar estimates depict storm total rainfall since yesterday morning around 1/2 to 1 inch for most location, locally up to 2 inches over the same locations which observed heavy thunderstorms yesterday evening.

Occasional rain bands will continue to rotate through the area tonight with another 1/4 to 1/2 inch of rain expected, locally higher, before gradually decreasing in intensity and coverage area on Thursday as the low pressure occludes and the stronger forcing and low level jet shift northeast towards New England and Maine. Isolated showers will continue through Thursday afternoon and Friday with otherwise mainly cloudy skies and temperatures slowly rising into the low to mid 50s on Thursday and the upper 50s to low 60s on Friday. The windy conditions will continue, however, with the wind shifting to the northwest and continuing through Saturday, when a mostly dry frontal passage will usher in a brief cool down on Sunday followed by a quick warming trend next week. Tomorrow’s forecast discussion will analyze the longer range in more detail.

Oct 21

Oct 21, 2014: Cloudy, Rainy Through Friday

Forecast Highlights:

gfs_namer_042_850_temp_mslp_precipA developing coastal low off the coast will deepen before stalling off the coast of Long Island by Thursday, providing the area with a stretch of cloudy skies, breezy northerly winds and occasional showers through Friday with rain totals generally amounting to 3/4 to 1.5 inch. Cloud cover will begin to decrease by Saturday, but with a secondary frontal passage on Saturday night briefly reinforcing the cloud cover and wind before a brief warm up early next week.

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Oct 20

Oct 20, 2014 Brief Update

Forecast Update:

Tonight’s forecast discussion is an update from yesterday’s discussion. The next full analysis will be posted on Tuesday evening.

rad_10.20gfs_10.20

From left to right, the latest available surface analysis and radar composite from the NWS Weather Prediction Center (WPC), and the initialized GFS 500 hPa heights and vorticity from NCEP Model Analyses & Guidance; both are valid at 1800 UTC Monday (2:00 PM Monday EDT).

Since yesterday’s update, the shortwave trough over the Midwest has progressed into Indiana, continuing to amplify due to strong ridging to its west. Analyzing the last 4-8 model runs, the most noticeable change in the model guidance has been to correct for a stronger, sharper and farther south shortwave trough than previously forecast, which results in stronger forcing tonight into Wednesday and would lead to a more widespread coverage area of scattered showers over Pennsylvania and New York state than initially expected. The outlook remains unchanged for the area through Wednesday evening, with scattered showers late tonight and into Wednesday amounting to less than 1/4 inch.

There has been relatively little change in the forecast positioning of the low as it becomes cut off on Wednesday and Thursday, with a period of light to moderate rain expected to affect the area on Tuesday night into Wednesday. The main change since yesterday’s update has been to include more rain over the area on Thursday as rain bands over New England wrap around to the west of the low, but with otherwise no significant changes in the forecast to note. The latest outlook is slightly wetter than yesterday’s forecast, with rain totals between 1/2 and 1 inch in northern NJ, and 1 to 2 inches over NYC, Long Island, southern CT and southeast NY. A more detailed analysis will be posted with Tuesday’s update.

Oct 19

Oct 19, 2014: Frost Tonight, Coastal Low This Week

Notice

Blog Notice: An update to the 8-Day Outlook is scheduled soon, with a separate forecast for every county in the forecast area, including one for each NYC borough. This update is on track to be completed during November.

Forecast Highlights:

f78_2A much colder air mass is currently positioned over the region, with temperatures having only peaked in the low to mid 50s this afternoon across most of the area. Areas of frost are possible tonight as temperatures fall into the 30s outside of NYC, but with increasing cloud cover and wind as a coastal low pressure stalls off the coast, with occasional showers expected between Thursday and Friday generally amounting to 1/2 to 1 inch.

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Oct 16

Oct 16, 2014: Cooler Pattern Upcoming

Forecast Highlights:

gfs_namer_150_850_temp_mslp_precip_2Following last night’s frontal passage, a gradual cooling trend is expected through the weekend, bringing a return to near to below average temperatures. A secondary cold front will pass through on Saturday, ushering in much colder temperatures for Sunday and Monday, followed by a potential coastal low pressure mid-late next week which may provide an extended period of clouds, wind and rain.

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Oct 14

Oct 14, 2014: Heavy Rain Expected on Thursday

Notice

The 8-Day Outlook has been updated as of tonight.

Forecast Highlights:

nam-hires_namer_042_sim_reflectivityA warm and humid air mass returned into the region as temperatures climbed into the mid to upper 70s today. Similar temperatures will continue on Wednesday before a cold front produces heavy rain and isolated thunderstorms on Thursday. A weak cool down will follow the cold front on Friday, but with a much stronger surge of cold air likely to bring high temperatures into the 50s range late in the weekend into early next week.

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Oct 12

Oct 12, 2014: Warmer, Rainy Next Week

Forecast Highlights:

gfs_namer_090_850_temp_mslp_precipFollowing the departure of yesterday’s light rain event, mostly sunny skies will continue today before clouds and temperatures increase early in the week, with high temperatures rebounding into the mid 70s again. A slow moving cold front will produce heavy rain on Wednesday night into Thursday, followed by a gradual cooling trend with another risk of showers next weekend.

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Oct 09

Oct 9, 2014: Rain on Friday, Next Week

Forecast Highlights:

gfs_namer_138_850_temp_mslp_precipA weak wave of low pressure will approach the region on Friday, producing a period of light to moderate rain overnight into Saturday morning as it gradually deepens to the east. Temperatures will quickly rebound into the 70s early next week ahead of the next strong frontal passage, with moderate to heavy rain likely on Tuesday night into Wednesday, followed by another transient cool down and warming trend.

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Oct 07

Oct 7, 2014: Heavy Storms Likely Tonight

Forecast Highlights:

hrrr_east-us_00645_sim_radarAn anomalously strong upper level low continues to spin over Ontario while drifting east, with a strong shortwave trough rotating through the northeast US tonight, providing sufficient forcing to result in a risk of heavy to locally strong thunderstorms tonight over the area. Behind the storm system, cooler temperatures will return through next weekend along with a risk of light rain on Friday ahead of the next widespread rain event next week.

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Oct 04

Oct 4, 2014: Cooler Temperatures Return

Forecast Highlights:

gfs_namer_036_500_vort_htA strong cold front is currently moving through the region, having produced moderate to heavy rain over parts of the area earlier today. A strong surge of cold air will follow, with temperatures struggling to pass 60 degrees on Sunday. Temperatures will slightly moderate early in the week with light rain on Tuesday night, followed by a gradual warming trend late in the week along with another light rain potential on Friday.

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