Vencore Weather
26Nov/14Wed

7:00 AM | **The first significant snow event of the season**

6-Day Forecast

Today

Rain this morning will mix with sleet and then change to all snow during the mid-to-late afternoon, breezy, noticeably colder than yesterday, highs near 40 degrees this morning and then slowly falling through the day

Tonight

Snow through much of the evening, possibly mixed with rain at times; otherwise, remaining mostly cloudy, breezy and cold, lows near 30 degrees; watch for continuing slick spots on the roads late tonight

Thursday

Mostly cloudy, breezy, cold, maybe a snow shower or two, near 40 degrees

Thursday Night

Mostly cloudy, cold, upper 20’s

Friday

Mostly sunny, cold, mid-to-upper 30’s

Saturday

Partly sunny, still cold, near 40 degrees

Sunday

Partly sunny, not as cold, upper 40’s

Monday

Partly sunny, cool, near 50 degrees

Discussion

The first significant snow event of the season is now getting underway in parts of the Mid-Atlantic region. Low pressure will intensify rapidly today as it tracks quickly northeastward along the coastline. This major storm is expected to pass just east of Long island early tonight and then should reach Nova Scotia by early Thursday. The rain/snow line will drop from the northwest to the southeast over the next several hours resulting in a gradual changeover of the precipitation to all snow by later today. The mid-to-late afternoon and evening will feature primarily snow and it will be of the heavy and wet variety. Don't be surprised if there is some "thundersnow" as well later today given the quick intensification of the storm. The snow ends later this evening and Thanksgiving Day will remain on the cold side. Accumulations for this event should end up on the order of 3-6 inches in and around the NYC metro region, 6-10 inches in the northern and western suburbs and 2-4 inches across Long Island. One final word of caution, given the combination of rain this morning which will be followed by heavy, wet snow later today in the N and W suburbs, there can be some downed tree limbs due to the excessive weight and perhaps even some power outages.

Video

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25Nov/14Tue

1:00 PM | **An update on tomorrow’s first significant snow event of the season**

NAM_snowfall
[High-resolution snowfall estimate forecast map from NAM model; courtesy NOAA]

Discussion

Overview
All systems go for the first significant snow event of the season in much of the Mid-Atlantic region. Snowfall estimates (see below) in the region from DC-to-Philly-to-NYC have not changed with the latest model guidance; however, the timing of the event has speeded up by a couple of hours. As a result, the precipitation will likely begin in the pre-dawn hours in many areas along the I-95 region between DC and Philly and will end in all locations a bit sooner tomorrow evening.

Details
Low pressure is developing today over the eastern Gulf of Mexico and it will intensify rapidly on Wednesday as it tracks quickly northeastward along the east coast. The low is expected to pass just east of Long Island on Wednesday evening before reaching Nova Scotia by Thursday morning. This storm will have a big impact on the interior Mid-Atlantic region on Wednesday with more snow to the north and west and less to the south and east. The map (above) shows snowfall estimates from the high-resolution version of the NAM computer forecast model and it clearly shows the higher amounts to the north and west and the lesser amounts to the south and east. The rain/snow line will be dropping from the northwest to the southeast tomorrow morning in the region near I-95. Precipitation will likely be in the form of all snow by early afternoon along I-95 and points to the north and west. Sleet can get involved as well on Wednesday during the transition period from rain to snow. Elevation will also play an important role with higher elevation locations to the north and west changing quicker to snow compared with nearby lower elevation locations.

Travel
As far as travel is concerned, precipitation from this coastal storm will begin in the pre-dawn hours in many locations so “beating it” will be somewhat difficult given its quick movement. However, there will be a time period during the initial changeover to snow in which the snow will melt on the roadways given the warmth of recent days. In general, the worst driving conditions are likely to occur from the mid-day hours through the afternoon and then into the early evening before winding down. The snow will wind down from southwest-to-northeast later tomorrow (late afternoon in DC, early evening in Philly, late evening in NYC).

Summary of snowfall estimates

DC area:
1-3 inches in and around the District
3-6 inches in the N and W suburbs
Coating-1 inch just S and E of the District

Philly area:
2-4 inches in and around Philly
4-8 inches in the N and W suburbs
Coating-2 inches at the Jersey Shore

NYC area:
3-6 inches in and around the NYC metro region
6-10 inches in the N and W suburbs
2-4 inches across Long Island

wv
[Water vapor image showing lots of moisture along the east coast; courtesy NOAA]

Filed under: NYC, PHL, WMA Comments Off
25Nov/14Tue

7:00 AM | **First significant snow of the season on Wednesday**

6-Day Forecast

Today

Partly sunny, cooler than yesterday, highs in the mid 50’s

Tonight

Mostly cloudy, turning colder late, lows in the upper 30’s by morning

Wednesday

Rain developing in the morning, changing to snow from northwest-to-southeast during the afternoon hours, breezy, noticeably colder, highs near 40 degrees

Wednesday Night

Snow likely before midnight, breezy, cold, total accumulations by morning of 3-6 inches in and around the NYC metro region, 6-10 inches in the northern and western suburbs, 2-4 inches across western and central Long Island, lows near 30 degrees

Thursday

Mostly cloudy, a bit of a breeze, cold, maybe a snow shower or two, near 40 degrees

Friday

Mostly sunny, cold, mid-to-upper 30’s

Saturday

Partly sunny, still cold, near 40 degrees

Sunday

Partly sunny, milder, upper 40's

Discussion

The first significant snowfall of the season is on the way for the NYC metro area and much of the Mid-Atlantic region. Low pressure will develop over the eastern Gulf of Mexico later today and intensify as it tracks northeastward along the east coast on Wednesday. The low is expected to pass just east of New Jersey on Wednesday evening before reaching the New England coastal waters late Wednesday night. This coastal storm will have a big impact on the interior Mid-Atlantic region on Wednesday and Wednesday night resulting in rather typical fashion in this region of generating more snow to the north and west and less snow to the south and east.

Precipitation should overspread the region from the southwest around dawn. Precipitation should start off as rain or a mixture of rain and snow before changing to all snow from northwest-to-southeast during the afternoon hours. Snow is likely for most, or all, of the storm in places well to the northwest of here such as in the Hudson Valley region. The last area to change over to snow will be over Long Island and they can expect less snowfall (2-4 inches in western and central sections). Northerly winds are forecast to increase to 10 to 20 mph on Wednesday with gusts to 25 or 30 mph possible. The snow will be of the heavy, wet variety.

As far as road conditions are concerned, initially the snow will have trouble sticking thanks to the recent round of warm weather. The worst driving conditions are likely to occur during the late afternoon and especially tomorrow evening when the effectiveness of the sun diminishes and temperatures drop to near freezing. One other note, looking ahead, signs point to a break in the weather pattern as we begin December with above-normal temperatures quite likely for awhile.

Video

Filed under: NYC Comments Off
24Nov/14Mon

12:30 PM | *An update on the accumulating snow for Thanksgiving Eve*

GFS and GFSX
[12Z GFS forecast map for Wednesday afternoon]

Discussion

Overview
The first significant snowfall of the season is on the way for many parts of the Mid-Atlantic region. Low pressure will develop over the eastern Gulf of Mexico on Tuesday night and intensify as it tracks northeastward along the east coast on Wednesday. The low is expected to pass just east of New Jersey on Wednesday evening before reaching the New England coastal waters late Wednesday night. This coastal storm will have a big impact on the Mid-Atlantic region on Wednesday and Wednesday night resulting in rather typical fashion of generating more snow to the north and west and less snow to the south and east. Odds are against much accumulation of snow at or near the immediate coastline given the fact that the air mass will be only marginally cold for snow and there will be no blocking cold high pressure system to the north of here.

As far as travel is concerned, precipitation from this coastal storm will be an all-day affair in the region from DC-to-NYC, but the earlier in the day one can drive the least likely snow will become a problem. Roads will take awhile to become slippery given the warmth of today and the expected relative warmth of tomorrow. The worst driving conditions should occur from late Wednesday afternoon through Wednesday evening when the sun loses its effectiveness on the roads (yes, it has an effect even on overcast days). Of course, the best advice of all for those planning to travel would be to drive on Tuesday if at all possible.

Details
Precipitation should overspread the region from the southwest early Wednesday morning. Precipitation should be mainly rain during the daylight hours from I-95 to points south and east, and mainly snow well to the northwest (e.g., Hudson River Valley). As colder air gets drawn into the system, the rain-snow line will drop southeastward during the day and the precipitation should change to snow in the immediate I-95 corridor by later Wednesday and continue as snow Wednesday night. The last area to change over to snow will be across Long Island and they can expect the least amount of snow. Northerly winds are forecast to increase to 10 to 20 mph on Wednesday with gusts to 25 or 30 mph possible. The snow will be of the heavy, wet variety.

Preliminary snowfall estimates
3-6 inches of snow in the far northern and western suburbs (e.g. interior northern NJ),
1-3 inches of snow in the NYC metro region and immediate surroundings,
<1 inch across Long Island

Stay tuned, still some time to go before this event.

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