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Mid-Atlantic

Winter Storm Threat: February 8-9 (Final Call)

I ended up going more bullish with the southern fringe of the different snow contours east of the mountains and across south-central Pennsylvania, otherwise my thoughts are pretty similar to yesterday.

20170208-09_final

Still looking at a fair amount of uncertainty regarding snow accumulation east of the mountains due to the very warm temperatures leading into this event. A good pasting of snow is expected once temperatures cool down early Thursday morning, but a 1-2 hour shift in either direction with the introduction of colder air could add or remove some 1-4″ of snow. That being said, once the changeover to snow is made, it will be snowing quite hard, and heavy snow can overcome marginal surface temperatures.

Winter Storm Threat: February 8-9 (Initial Call)

This time it’s the 40N crew that will cash in with this upcoming snow storm. After a very mild Wednesday along the East Coast, temperatures will come crashing down overnight as a disturbance develops over Virginia and tracks just south of Long Island.

20170208-09_initial

Ultimately, the strengthening and position of the surface low will have a large impact on how far north/south the 1″+ snow amounts end up. The snow will also be battling against a very warm antecedent air mass that will keep most spots as rain for at least the onset of precipitation. This means places like D.C. and Baltimore will struggle to change over to snow overnight. Heck, D.C. stands a risk of never changing over to snow at all Thursday morning if the more northern model solutions are correct.

As the initial storm system moves out Thursday morning and early afternoon, a second upper-level vort. max will slide through the Mid-Atlantic. This could trigger snow showers across more of the Mid-Atlantic Thursday afternoon and evening. Most places around/south of D.C. will still be too warm to see this light snow stick, but a little “snow TV” is better than nothing… I think?

Winter Storm Threat: January 6-7 (Final Call)

As the event is unfolding, time for a final update. A slight shift north and west, but overall similar thinking to yesterday’s forecast.

20170106-07_final

I think that there is a little more room for this to shift a bit further north and west compared to moving it south and east. The area of significant snowfall seems pretty locked in at this point, with concerns about mixing on the southern edge of the snow accumulation in the Carolinas.

Winter Storm Threat: January 6-7 (Initial Call)

A legit winter storm is finally coming to the southern Mid-Atlantic, but it probably won’t be a huge hit for D.C. residents as this suppressed storm system aims for areas south and east of I-95, instead of the usual jackpot areas.

20170106-07_initial

There is still a chance for this system to drift a bit more north and west, but for the past few days, forecast guidance has been pretty consistent in keeping any notable snowfall in the Southeast and in areas east of I-95 from Richmond, VA northward. Another concern is how much snow ends up falling over North Carolina, where some places will be battling with rain and a wintry mix before changing over to snow on the back end of the system. All-in-all, it looks like a solid hit for the more southern folks that get included in my snow forecast maps.

Winter Storm Threat: February 8-10 (Only/Final Call)

This storm has a complicated setup. You have multiple surface lows within a broader upper-level trough, marginal surface temperatures, and large discrepancies in QPF placement between the models.

Temperatures along and east of I-95 are the most uncertain, which are expected to be in the low-to-mid 30s through most of the event. Areas north and west of I-95 will start above freezing, and will cool to at or below freezing depending on how strong the snowfall rates are tonight.

Snowfall rates will be one of the most important factors in determining which areas see 4-8 inches, and which areas get 1-4 inches. The best rates are likely to be along the Maryland/Pennsylvania border into southern New Jersey.

20160208-09_MAsnow_final

The intensity of the initial coastal low, the secondary coastal low development, the strength of the low over the Great Lakes, and the timing of the strengthening and weakening of these lows are wreaking havoc on the QPF output on the various models.

I tried my best to offer a realistic compromise between the differences in QPF, while also accounting for the surface temperature and snowfall rate issues. I could definitely see a tighter gradient between accumulation amounts than what I have on the map.

Winter Storm Threat: January 22-24 (Final Call)

One final update before the frozen stuff starts to fall in the southwestern corner of my map. Made minor adjustments to the fringes in central/eastern North Carolina and up around NYC, with a slight expansion of the 18″+ contours.

20150122-24_MAsnow_final

Timing and impacts from this potential blizzard remain on track to what I said earlier today.

Winter Storm Threat: January 22-24 (Second Call)

The heavy snow in the core of the Mid-Atlantic remains on track, given the newest model data and latest trends. Two notable changes were made to the northern and southern fringes of the snow accumulation. General timing remains the same, with snow expected to start in the D.C. area between 3-6 p.m. Friday.

20150122-24_MAsnow_second

The northeastern edge of the snow accumulation was cut back as confidence increases in the storm track, leaving lower snow amounts across northeastern Pennsylvania into northern New Jersey. On the southern edge, western North Carolina into western Virginia and West Virginia saw snow increases due to better confidence in the QPF forecast and better temperature profiles. Further east, more warm air wrapping into the eastern side of the system made for lower snow forecasts across northeastern North Carolina, southeastern Virginia, and along the immediate Atlantic Coast.

Ice will also be an issue in the Southeast and in southwestern Virginia. Currently, areas in northern South Carolina and central North Carolina are forecast to receive 0.25-0.75″ of ice, according to the NWS.

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At the moment, the NWS also has Blizzard Watches posted from the greater D.C. region up through Philadelphia and into NYC and Long Island.

20160121_BlizzardWatchesNoon

I will be posting a final forecast update this evening.