Oct 26, 2011: Cold Spell Starts Tomorrow Night


– The 2010-11 preliminary winter outlook will be posted late tomorrow afternoon.

– Two polls have been opened; the first is for snow in the NYC tri-state area for this week, and the second is for the outlook for this weekend. Please vote your thoughts on these storms in the polls, with the first poll closing tomorrow night and the second one closing on Friday night.


With a weak wave of low pressure moving into the Northeast, today brought mostly cloudy skies and similar temperatures to those of yesterday, reaching the upper 50s to lower 60s inland and the lower to mid 60s across the rest of the area. Despite the mainly cloudy skies, no rain was observed across the area today as the precipitation stayed in the northern Northeast, where scattered showers fell and even some light snow was observed in some of the higher elevations.

A strong cold air mass currently over southern Canada will begin to move into the northeastern US tonight, and will be pushed into the region behind a wave of low pressure moving through the region tomorrow, bringing light to moderate snow across parts of the Northeast and a cold rain to the NYC area. Behind this wave of low pressure, several days of near to below freezing overnight lows are expected, with the first widespread frost and freeze of this fall taking place during this time frame other than a risk of showers for Saturday. The cold won’t last for a long period of time, however, as temperatures will begin to moderate towards the first week of November.

Tomorrow’s Outlook:

With the wave of low pressure moving into the region, the NYC area is expected to see occasional showers throughout the day, especially towards the evening, amounting to about 1/2 to 3/4 inch of rain with locally higher amounts possible. With the cold air mass slowly pushing south throughout the day, temperatures will steadily cool down, with the peak temperatures of the day expected to take place tonight with temperatures reaching the lower to upper 50s. During the day hours tomorrow, temperatures are expected to peak in the morning, reaching the mid to upper 40s inland, upper 40s to lower 50s in the immediate NYC area and southern CT, and in the lower to mid 50s in Long Island. Temperatures will continue to steadily cool down, and by 8 PM, will fall below the 40 degree mark across most of northern NJ, SE NY and southern CT.

Looking across the rest of the region, the wave of low pressure will be responsible for producing the first widespread snow event of this fall in the Northeast. The cold air mass is not a very strong one with the cold only coming in towards the end of the storm, meaning that significant accumulations are not expected in the Northeast, but a general 1 to 4 inches of snow are likely to fall in the higher elevations of the Northeast, especially towards western Massachusetts and the Catskills in NY. For the lower elevations of southern New England away from the immediate coast, rain is expected during the day tomorrow, which will likely mix with show showers tomorrow night as the storm begins to move offshore. Snow is unlikely in the NYC tri-state area, but the potential is there for some flakes to mix with the rain in parts of Sussex and Orange counties. Unless there is a significant change in the forecast, storm updates will not be posted tomorrow as the winter outlook will be posted.

Friday – Sunday: Widespread Frost/Freeze Expected; Update On Storm Potential

A strong air mass will move into the region behind the storm, and with clearing skies, cold temperatures are expected for tomorrow night, dropping into the upper 20s to lower 30s in NW NJ/Orange county, lower to mid 30s across the rest of SE NY, NE NJ and southern CT, mid 30s in Long Island, and upper 30s in NYC. Friday will bring more sunshine, with mostly sunny skies and high temperatures reaching the upper 40s to lower 50s across the area. Cold temperatures are expected again for Friday night, and with a high pressure providing mostly clear skies, low temperatures will be similar to those of Thursday night, bringing the first risk of a widespread frost and freeze across the area. Most places that have not seen their first frost yet will most likely have frost between Thursday night and Saturday night.

The biggest uncertainty for this weekend is for a storm potential on Saturday and Saturday night. This storm potential became the focus of attention for this weekend 2 days ago, when the majority of the models showed a significant nor’easter affecting the region, but yesterday’s models significantly backed away, with the ECMWF the only model holding on to the strong storm idea with the rest of the model guidance staying offshore. Today’s model runs trended back slightly to the west, with the GFS showing a light rain event, the UKMET showing a more significant storm, and the CMC trending slightly to the west. The ECMWF model, however, backed away from its solution of a big storm and went towards a solution closer to that of the GFS.

When looking at the latest model runs and considering that there are about 3 days left until the storm affects the region, it appears that the models may be reaching an agreement on the overall scenario for the storm, with a weak low pressure bringing light rain to coastal areas with the bulk of the storm staying offshore. Although this set up is supportive of a storm coming up the coast, there are many other variables that have to end up in the right positions in order for a significant nor’easter to affect the region. In addition, the storm is not expected to be very amplified, with almost every model showing a weak, broad area of low pressure near eastern North Carolina, when the scenearios that showed a big storm moving up the coast already had a stronger, more organized low pressure near eastern NC. It is very possible that we may see additional west adjustments on the models, but unless we see more noticeable changes with the set up towards more amplification, it is unlikely that the models trend towards anything more than light-moderate rain along the I-95 corridor.

Considering the latest trends and the set up, I am currently going with a scenario slightly to the west of the model consensus, expecting cloudy skies with light rain affecting the area, especially further east towards Long Island where moderate rain is possible. Chilly high temperatures are expected, likely reaching the mid 40s to lower 50s across the area. The rain would end by Saturday night as skies clear and temperatures drop again to near/below freezing levels. There is still uncertainty with the storm as the models are still having issues with handling the set up across the US, and the potential is there that we may either see a weak storm, in which case the area sees partly cloudy skies and highs in the lower to mid 50s, or we may see a stronger storm closer to the coast, in which case we would see moderate rain, likely mixing with wet snow north/west of NYC, with high temperatures in the lower to mid 40s. Stay tuned for more information on the potential weekend storm.

Next Week: Warming Up, Stormy Start To November?

The cold air mass will begin to weaken behind Saturday’s potential storm, but enough cold air will still be in place for a chilly Halloween, with high temperatures in the lower to mid 50s across most of the area for Monday along with partly sunny skies. Cloud cover will increase by Monday night, however, as a potential storm may approach the region. The latest models are showing the potential for a strong low pressure to affect the region on Tuesday and Wednesday, but with the cold air mass significantly weakening by that time, any precipitation will fall in the form of rain. There is uncertainty with the location of this storm, considering that the models still first have to nail down the weekend storm’s location, but the potential is there for rain to affect the area on both days, followed by warming temperatures for the second half of next week, potentially returning into the 60s. Stay tuned for more information on the longer range.

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