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10-Day Outlook: Cold with SNOW!

Josh Larson @ 3:30 PM

Most Recent Update: 3:30pm, Feb 9th

This weekend's MAJOR SNOWSTORM is coming into better focus and the team has been evaluating the latest model guidance all morning. We now feel pretty confident predicting at least 2-4" of snowfall for the immediate DC metro area. It also appears that most locations will see all snow, though some mixing of sleet or rain may occur well to the south and east of the immediate area. See the "Snow Lover's Crystal Ball" below for more details on this approaching winter storm. And remember to say tuned to throughout the weekend for the latest updates.

Today's Forecast

Another winter-like day today, with mostly sunny and breezy conditions on tap. Expect high temperatures to remain in the upper 30s in most locations. Clear and very cold tonight with overnight lows ranging from the upper teens to the mid 20s.

Pattern Overview

Last week's outlook highlighted that we'd be locked into much more wintry pattern (featuring a strong "trough-east/ridge-west") pattern by this time; indeed, temperatures are finally at below-normal values and we look to hold the current wintry pattern for at least the next week.

While some of the models hint that our cold air may break down somewhat by the middle of next week, it's my opinion, based on an evaluation of some of the major atmospheric patterns influcening the jet stream -- namely the NAO and EPO -- that we're not likely to see a return to above-normal temperatures (other than, perhaps, very briefly) over the next 10 days.

Temperatures over the next 5 days will average some 5-10 degrees below normal, and temperatures over the following five days should like average near or slightly below normal. Temperatures thereafter are certainly open to debate, but I think they'll probably continue to stay near or somewhat below normal.

But the big weather story is undoubtably this weekend's snowstorm -- our first since mid December...

Snow Lover's Crystal Ball

Next Chance of Accumulating Snow: Saturday, Feb. 11
Probability: 66%
Potential Impact:

Commentary: Most models have come into agreement to support at least a moderate snowfall for the DC metro area from mid-day Saturday through Sunday morning. Snow will likely develop between 8am and 1pm Saturday and will continue into Sunday morning. The heaviest snow will likely fall Saturday evening into the early morning hours Sunday. It appears likely that enough cold air will be present that most everything that falls should be in the form of snow -- expect well to the south and east where some mixing with sleet and rain may take place. Current thinking suggests a high probability of at least 2-4", with the potential for for considerably more, especially north and west of town.

Updated Snowfall Probabilities:
< 1" --> 15% chance
1-3" --> 20% chance
3-6" --> 30% chance
6-10" --> 20% chance
> 10" --> 15% chance

The next 5 days (Feb 9-13)

Forecast highs/lows: 38/24 (normal = 45/29)
Forecast precip: above normal

After today's sunny weather with highs in the upper 30s, Friday will feature more in the way of cloud cover, as well as slightly milder temperatures. Expect a partly sunny morning with a mostly cloudy afternoon; high temperatures will probably make it into the lower 40s. Friday night will feature mostly cloudy skies ahead of the approaching storm system; lows will be in the mid to upper 20s. Saturday will feature overcast skies, breezy conditions and snow likely developing by mid-day. Highs will range from the low to mid 30s, with overnight lows in the mid 20s. Snow will continue heavy overnight Saturday and may linger into the morning hours Sunday. Sunday afternoon will feature stray snow showers with windy conditions. Highs will be in the mid 30s, with very chilly overnight lows from the teens to the low 20s. Monday will feature partly cloudy and blustery conditions with scattered snow showers; highs will be in the 30s with overnight lows in 20s.

The next 5 days (Feb 14-18)

Forecast highs/lows: 44/29 (normal = 47/30)
Forecast precip: near normal

The forecast for the following 5 days is much more uncertain due to fairly significant model disagreement. It is an unanswered question whether a ridge over the Southeast US will build westward and expand, which could lead to moderating (even above-normal) temperatures. However, it is my contention that cold air, especially at the low levels, will continue to bleed south into our area from southeastern Canada. Couple that with the potential for snow on the ground -- which tends to lead to cooler than forecast temperatures due to its high albedo -- and I think our temperatures will remain at near to slightly below normal levels. For the most part from 40-45 for highs with overnight lows in the 20s. Precipitation is possible mid-week, though it is unclear whether it will be in the form of rain or snow.

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