Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 270802 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 402 AM EDT Sat May 27 2017 .SYNOPSIS...High pressure overhead this morning will move offshore later today. A wave of low pressure will move across the area this afternoon or evening pushing a weak front south of the area late tonight. A stronger cold front will move through the area Monday. High pressure will return to the area mid next week. && .NEAR TERM /THROUGH TONIGHT/...Weakening t-storm complex over OH early this morning is associated with a low pressure system over Indiana. Weakening showers will move across the area mainly after daybreak, but will be insignificant. The low pres center will continue to move east across the area this afternoon or this evening and will set up a warm front across the southern half of the fcst area. NSSL WRF-ARW and instability fcst fields from different models indicate the area from Augusta county south and east through Charlottesville will be the prime area for strong potentially severe convective development later this afternoon and early this evening. Damaging winds and large hail appear to be the main threat. 0-6km flow around 30kt should keep storms moving with flash flooding risk low despite saturated soils and potential training convection. The low pres system and associated front will push south of the area later tonight with showers ending. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...Sunday will likely start out quiet, but with plenty of low clouds. Low pressure will be tracking from the mid-MS valley to southwest Ontario by late Sunday night. A sfc trof will establish across the area during the afternoon with PWATs increasing over 1.5 inches. Widespread convection appears likely Sun afternoon and evening with potential for flash flooding especially west of the Blue Ridge given saturated soils. Convection begins to weaken and shift east late Sun night due to loss heating and sfc trof shifting east. Convection could redevelop east of the Blue Ridge Mon afternoon with actual frontal passage. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Upper level low pressure will be slowly moving across Ontario and Quebec during the Tuesday through Thursday time frame. While overall flow will be from the SW to W aloft, there will still be opportunities for shortwave troughs to dive through the area. It does appear there will be two additional boundaries following Monday`s front that will drop southeast through the middle of the week. The second (likely late Wednesday or Thursday looks to be the stronger of the two in terms of airmass change. While this pattern is a little unsettled, rain chances should be scattered and instability for thunderstorms limited. Ensemble spread increases toward the end of the weak regarding the upper air pattern and evolution of the closed low. However, there should be a dry period at some point as surface high pressure builds into the area behind the cold front. Above normal temperatures on Tuesday will decrease through the remainder of the week behind the frontal passages. Highs will settle into the 70s with lows in the 50s, which is near normal. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...VFR conditions today, but with morning showers. KCHO terminal will be the most vulnerable to t-storms today with brief MVFR/IFR conditions possible. Widespread convection Sun evening with flying restrictions likely. Overall Tuesday and Wednesday should be VFR, but there could be some scattered showers and perhaps a thunderstorm as weak fronts move through the area. && .MARINE...Gradient winds below SCA, but winds and waves higher near t-storms. Winds are forecast to remain below SCA criteria Tuesday and Wednesday, although a cold front on Wednesday could lead to slightly higher winds. && .TIDES/COASTAL FLOODING...Minor coastal flooding expected at Straits Point for the next several high tide cycles. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Coastal Flood Advisory until 6 AM EDT early this morning for MDZ017. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...LFR NEAR TERM...LFR SHORT TERM...LFR LONG TERM...ADS AVIATION...ADS/LFR MARINE...ADS/LFR TIDES/COASTAL FLOODING...LFR is the U.S. government's official web portal to all federal, state and local government web resources and services.