Vencore Weather
26Jan/15Mon

6:00 AM | ****Major nor’easter produces some accumulating snow around here, but dramatically worse to our northeast****

6-Day Forecast

Today

Snow or a mix of rain and snow will change to snow early today, snow will become steadier and heavier as the day progresses, breezy, cold, highs in the middle 30’s early

Tonight

Periods of snow, windy, very cold, blowing and drifting will occur, lows in the lower 20’s

Tuesday

Periods of snow early, windy, quite cold, total snow accumulations of 3-6 inches likely with the lesser amounts to the west (e.g., Virginia suburbs west of DC) and the higher amounts on the north and east side (e.g., PG, Montgomery Counties), upper 20’s

Tuesday Night

Partly cloudy, brutal cold, middle teens

Wednesday

Partly sunny, very cold, upper 20’s

Thursday

Becoming cloudy, cold, snow in the afternoon and at night, mid 30’s

Friday

Mostly cloudy, cold, maybe some lingering snow early, mid-to-upper 30’s

Saturday

Partly sunny, cold, mid 30’s

Discussion

The potential exists for an historic nor'easter in the region from New York City/New Jersey-to-Boston. This will be a two-part event with the first part lasting into early afternoon associated with a “clipper” type of system. Snow this morning will be sporadic and can even be mixed with rain for a bit longer, temperatures are generally still above freezing limiting accumulations to small amounts. Then, once this system reaches the western Atlantic Ocean later today, the combination of the relatively warm ocean water, a powerful upper-level jet streak and an influx of brutally cold Arctic air from the northwest will cause it to explode off of the Northeast US coastline. As the mid-day and afternoon progress, the snow will become steadier and heavier with the brunt of the storm occurring here from later today into early Tuesday. There will be some blowing and drifting of snow later tonight and on Tuesday as winds crank up out of the northeast. The snow later during the brunt of the storm will be of the dry, fluffy variety.

The worst impact of the storm will be in northern and eastern sections of the DC metro region. Snowfall accumulations by the time the storm winds down late tomorrow could range somewhat widely across the area with western sections such as near Dulles Airport experiencing only a few inches inches and areas to the north and east (Montgomery, PG Counties) experiencing as much as 6 inches or so. One last point, the overall weather pattern looks absolutely frigid for the foreseeable future – perhaps right through February -and there will be multiple snow threats with the next one arriving late Thursday into Friday. The cold shot that arrives in about a week could bring record-breaking cold into the Northeast US as we begin the month of February.

Video

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25Jan/15Sun

10:00 AM | *****Major disruptive snowstorm potential from Philly-to-Boston later Monday into Tuesday; DC area in the game as well and gets accumulating snow*****

wv-l

Discussion

Overview
The potential exists for an historic nor'easter; especially, in the region from New York City/New Jersey-to-Boston. If you have some bare ground on your lawn, you may want to take a good look at it now as it will likely not be visible after today for many, many weeks. There will be accumulating snow over the next 48 hours in the Mid-Atlantic region and it will be subtantial in many areas. In addition, there will be multiple bitter cold Arctic air outbreaks during the next few weeks which will make sure that the snow sticks around for a long, long time. This will be a two-part event with the first part associated with a "clipper" from later tonight into tomorrow afternoon and in this time period any snow that falls can be mixed with rain primarily south of the PA/MD border. Then, energy from this system will feed into a coastal low which will develop explosively later tomorrow and tomorrow night as it heads to the northeast from the Carolina coastline producing snow (no more mixing issues) in the I-95 corridor.

“Clipper” type system Sunday night into Monday afternoon
An Arctic front slides through the region today setting the stage for the development of a major coastal storm during the next 48 hours. A “clipper” type of system now over the Mississippi Valley (water vapor image) is moving east-to-southeast today and it will reach the coastal waters of the western Atlantic Ocean by later Monday. Snow will move into the I-95 corridor region tonight, perhaps mixed with rain south of the PA/MD border. Precipitation will become all snow by tomorrow morning and continue into the afternoon. By this time, there can be a few inches of snow in the DC and Philly metro regions with lesser amounts to the north near New York City. The main action, however, begins late tomorrow and early tomorrow night; especially, from Philly and points to the north and east.

Explosive nor’easter Monday night into Tuesday
Once this system reaches the western Atlantic Ocean later tomorrow, the combination of the relatively warm ocean water, a powerful upper-level jet streak (below), and an influx of brutally cold Arctic air from the northwest will cause it to explode off of the Northeast US coastline from later Monday into Tuesday. As a result, snow will intensify by tomorrow night in the I-95 corridor region from Philly northeastward and perhaps even all the way down to the DC metro region. This snow will be of the dry, fluffy variety - not like the wet snow that fell Friday night. This could turn into an all-out blizzard by tomorrow night and Tuesday from Philly northeastward with heavy snow, strong winds and bitter cold. Blizzard conditions are likely in coastal areas from New Jersey northeastward to the New England coastline.

By the time Tuesday morning rolls around, there can be up to 6 inches or more of new snow in DC, a foot or more in Philly region, and 20-30 inches likely from NYC-to-Boston where it looks likely that this storm will be talked about for a long time. One last point, the overall weather pattern looks absolutely frigid for the foreseeable future – perhaps right through February - and there will be multiple snow threats with the next one arriving late Thursday into Friday. The cold shot early next week as we begin the month February could be record-breaking in the Northeast US.

250mb_jet_streak

Filed under: NYC, PHL, WMA Comments Off
24Jan/15Sat

11:45 AM | **Snow tomorrow night and Monday from a system that will then explode off the Northeast US coastline…more accumulating snow possible here Monday night/Tuesday along with brutal cold air…as far as the longer-term is concerned – buckle up for that as well!**

Discussion

Sunday night/Monday
As today’s coastal storm affects wind down along the I-95 corridor, another storm is already taking shape upstream. A “clipper” type of system is dropping southeastward today into the Northern Plains and it will reach the coastal waters of the western Atlantic Ocean by later Monday. Snow will move into the I-95 corridor region tomorrow night and continue on Monday with a big impact likely on the Monday morning commute along with possible school closings. This snow will be of the dry, fluffy variety - not like the wet snow that fell last night. Preliminary snowfall estimates by later Monday afternoon are as follows: DC region 3-6 inches, Philly region 3-6 inches, NYC region 2-4 inches.

Monday night/Tuesday
Once this system reaches the western Atlantic Ocean later Monday, the combination of the relatively warm ocean water and an influx of brutally cold Arctic air from the northwest will cause it to explode off the Northeast US coastline from late Monday into Tuesday. As a result, more accumulating snow could fall in the I-95 corridor on Monday night and Tuesday and it could be substantial. New England is quite likely to get walloped by an all-out wind-blown blizzard on Monday night and Tuesday and the I-95 corridor region from DC-to-Philly-to-NYC is going to be a close call. Brutal cold air reaches our region Monday night and it’ll last for much of the week. In fact, the overall weather pattern looks absolutely frigid for the foreseeable future – perhaps right through February -and there will be multiple snow threats.

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23Jan/15Fri

10:00 AM | ****Unfolding weather pattern to bring significant snow and brutal cold to the Mid-Atlantic region during the next few weeks and perhaps right through the month of February****

Discussion

Overview
Some winters in the Mid-Atlantic region never bring significant snow. Some winters never feature the brutal cold that winter can offer. It is quite likely that we’ll get to experience both significant snow and brutal cold here in the Mid-Atlantic region during the next few weeks and that type of pattern with snow and cold could actually last right through the month of February. There will be numerous snow threats along the way beginning with the one from this evening into Saturday and then a second from Sunday night into Monday. In addition, brutal cold air outbreaks are likely to make numerous visits here as well during the next couple of weeks with the first one to arrive by Tuesday of next week. In fact, low temperatures by Wednesday morning could be sub-zero in many parts of the Northeast US and single digits in the I-95 corridor region from DC-to-Philly-to-NYC.

An especially interesting and scary-looking time period will be as we end January and begin February. Not only are there signs for a major coastal storm around February 1st (Super Bowl Sunday) or so, but brutal cold is likely to follow during the first few days of February that could bring temperatures to near zero again in many places across the Northeast US (see forecast map below for 2-meter temperature anomalies in the 5-day period from 2/2 to 2/7).

Feb_cold
[GFS 2-meter temperature anomaly forecast map for 5-day period of 2/2-2/7; map courtesy Weather Bell Analytics at weatherbell.com]

Temperatures and the connection to the 500 millibar height anomaly pattern
One week ago we discussed the likelihood for strong ridging to develop along the west coast of North America as we progress into the latter part of January. Indeed, the forecast map (below) from yesterday’s 12Z GFS Ensemble run for February 1st continues to insist on strong ridging (oranges) along the west coasts of Canada and the US and this type of upper air pattern usually leads to multiple Arctic air mass incursions into the northern US from northern Canada. In fact, this forecast map suggests that the upper-level winds at 500 millibars – which tend to follow the height anomaly lines - could actually bring air directly from the North Pole into the northeastern US by the beginning of February.

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[GFS Ensemble height anomaly forecast map for February 1st; courtesy Penn State eWall]

Short-term snow threats
Tonight/Saturday
Precipitation from an intensifying coastal storm should reach the DC metro region early this evening (5pm or so), the Philly region between 9pm – 11pm, and NYC between 1 and 3am. The main thumping of snow from this system will be on its front end before a changeover takes place to freezing rain and sleet and perhaps even to plain rain from the cities to the coast. This event is likely to end in the DC metro region by early tomorrow afternoon, late afternoon in Philly and early evening in NYC. Snow and ice accumulation estimates are as follows:

1-3 inches in the northern and western suburbs of the District; lesser amounts in DC and points south and east
3-6 inches in the Philly and NYC metro regions and in their northern and western suburbs; lesser amounts to the south and east

Sunday night/Monday
Another system will drop southeastward across the Great Lakes region late Sunday in much the same manner as some of the recent “clippers”. This system, however, has more potential than those as it will intensify in the Mid-Atlantic region on Monday, tap into some coastal moisture, and will have a cold air mass in place as it arrives. As a result, snow is likely to be the dominate precipitation type with this system on Sunday night and Monday and anywhere from several inches of snow are possible from DC-to-Philly-to-NYC. There is quite likely to be a significant disruption with the Monday morning commute due to the snowfall.

Buckle up, it’s going to be a wild ride.

Video

Filed under: Climate Info, NYC, PHL, WMA Comments Off