Area Forecast Discussion
Issued by NWS Sterling, VA

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237 FXUS61 KLWX 302000 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 300 PM EST Wed Nov 30 2016 .SYNOPSIS... Low pressure over the upper Great Lakes will track into eastern Canada tonight. An associated cold front will push through the Mid Atlantic late tonight. High pressure will return to the region Friday and Saturday. Low pressure will track to the west of the region Sunday night. High pressure returns Monday into Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Nearly vertically stacked low currently located across the upper midwest...with associated cold front draped across the Ohio River Valley. These features will shift eastward through the rest of today as the low begins to fill. As this embedded shortwave will round the base of the upper low and eject out across the Mid-Atlantic. Showers have mostly pushed north of the area as warm front lifted north into PA...though, pre-frontal precipitation is beginning to re-enter the SW/W portions of the CWA. Most precipitation should be confined west of the Blue Ridge through the afternoon...with just isolated showers elsewhere. Guidance is in fairly good agreement in depicting a line (or broken line) of showers congealing across west of the Blue Ridge this afternoon and then pushing east across the I-95 corridor after 6 PM. High shear low CAPE scenario...with very strong shear (EBS values AOA 45 kts) and MUCAPE AOB 400 J/KG...could lead to a few isolated strong wind gusts (with best chances across S MD). Main question remains how much instability will be present when activity crosses any one location. Generally another half inch (with locally higher amounts) of rain possible with the activity. Cold front moves east across the area near midnight...with additional light rain showers along/near it. Front (and any showers) move east of the area by 4 AM. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Drying out Thursday (though some upslope snow showers are possible along the Allegheny Front)...with high temperatures in the 50s and gusty westerly winds under mostly sunny skies. High pressure builds into the area from the SW Friday with dry weather (outside of light upslope snow) and temperatures near normal. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... High pressure will keep dry conditions Saturday into part of Sunday as it drifts east from the Ohio Valley. High temperatures will be in the 40s for most of our CWA...30s at higher elevations. A shortwave trough in the upper levels could bring a chance of showers for late Sunday into early Monday... with additional precipitation into Monday afternoon on the Allegheny Front. Confidence is low after this, as guidance disagree on timing and location for a surface low to lift from the Gulf States...increasing the chance of precipitation to our region for Tuesday into Wednesday. High temperatures will be in the 40s and 50s...and low temperatures in the 30s mainly....with 20s at higher elevations which could see some type of frozen precipitation, and some 40s near the Bay. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... Challenging TAF period continues...with constantly changing conditions at many of the terminals. Most sites should remain AOA IFR (though some brief LIFR periods are possible)...due to low cigs/vis...until cold front cross terminals late tonight. Additionally, some risk for gusty showers later this afternoon/evening with a possibility of some isolated thunder, particularly southeast of DC. Cold front crosses the area after midnight tonight with a shift to west winds. Gusts in 25 kt range Friday and Saturday with VFR conds. Dry conditions expected for Saturday into part of Sunday with high pressure dominating weather conditions...therefore VFR conditions expected. Late on Sunday into Monday, an upper level disturbance could bring showers to the terminals, allowing for conditions to become sub-VFR. && .MARINE... SCA continues through Thursday with strong winds off the surface. For the remainder of today...gusty showers and perhaps an isolated thunderstorm may trigger Special Marine Warnings, particularly this evening. A cold front crosses the area tonight with a shift to west winds after midnight. West winds mix down through Thursday with gusts around 25-30 knots across the waters. SCA through Thursday for now...and is likely again both Friday and Saturday. Dry conditions expected for Saturday into part of Sunday with high pressure dominating weather conditions.Late on Sunday into Monday, an upper level disturbance could bring showers over the waters. Gusty winds possible a small craft advisory could be possible for this day. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EST Thursday for ANZ530>543. && $$ SYNOPSIS...MSE NEAR TERM...MSE SHORT TERM...MSE LONG TERM...IMR AVIATION...IMR/MSE MARINE...IMR/MSE is the U.S. government's official web portal to all federal, state and local government web resources and services.