Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 241751 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 151 PM EDT Fri Mar 24 2017 .SYNOPSIS... High pressure off the coast will establish a warmer and more moist southerly flow across the Appalachians and central mid Atlantic region into the weekend. A slow moving cold front will enter from the west on Sunday with a chance for showers and possibly a thunderstorm. Our weather then looks to remain unsettled through next week as a series of disturbances move across the central and southern part of the country, keeping a chance for showers and thunderstorms in our forecast through Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 100 PM EDT Friday... The wedge has eroded over parts of SE WV this morning. A warm front in northwesterly flow continues to track across the Mid Atlantic region. With all this taking place, an isolated shower or two may track across western Greenbrier this afternoon. As of 345 AM EDT Friday... It`s looking like a quiet end to the workweek as an upper level ridge is the dominant weather feature over the Appalachians, though there will be a fair amount of cloud cover around. At the surface, high pressure along the middle Atlantic coast will continue to push offshore today. Satellite imagery shows some lower clouds extending back from the NC mountains toward the Gulf coast, guidance supports return flow around the high drawing these clouds up into the region this afternoon along and east of the Blue Ridge into Southside. Additionally, a short wave will swing through the Ohio valley along a warm front on the rim of the upper ridge. This is generating some shower/storms well off to our northwest, but expect some showers to brush by to our north today with lower clouds extending southward into the region. Quiet weather then continues tonight as the ridge axis crosses the region and high pressure at the surface remains parked off the mid Atlantic coast. With a deepening southerly flow, temperatures will moderate considerably from readings yesterday with highs about 10 degrees warmer which will be above normal for late March. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 400 AM EDT Friday... A very active, highly kinematic, westerly flow will be in place across the U.S. with the Pacific wide open. A parade of vigorous upper-level low pressure areas will march from west to east across the U.S. through the period. At least four such significant systems are noted during the 7-day period beginning Sunday. Saturday will bring one last day of dry weather to the area as an upper ridge briefly moves across the area and temporarily blocks the upstream system in the central U.S. A warm front will continue to lift northward through the northern portions of the Mid-Atlantic into NY and New England. The surface high that has been providing us with the cool weather the last few days will move to our southeast. The region will be solidly in the warm sector with southerly to southwesterly surface flow. 850mb temps will soar into the double digits allowing surface temps to warm well into the 60s west to the 70s Piedmont. These readings are about 10-15 degrees above normal for late March. By Sunday, the first of the Pacific system will arrive. Models are in general agreement on the details. Timing is faster than has been indicated in recent days with this system now arriving in the western part of the CWA Sunday morning and then into the Piedmont by Sunday afternoon. The faster arrival of these system also heralds better dynamics as well. Models are in pretty good agreement on a near solid line of showers and thunderstorms translating from the TN valley into western VA. The risk of severe weather with this system appears low as instability is meager at best with capes below 500 J/kg. Have included a slight chance of thunder western areas, but left as showers east of the Blue Ridge at this time. Rainfall amounts are expected to range from 1/2 to 3/4 inch west of the Blue Ridge to 1/4 to 1/2 inch east of the Blue Ridge. Temperatures will remain warm Sunday, but the clouds and precipitation will keep readings on the order of 5-7 degrees cooler than Saturday. The clouds, southerly flow, and warm, Gulf air in place will keep overnight minimums very balmy, well into the 50s most areas. On Monday, the first upper low will lift northward toward the Great Lakes and weaken as yet another upper-low follows quickly on its heels moving out of the Central Plains. This system promises to be somewhat more progressive and transition into an open wave as it moves into the eastern U.S Tuesday. This leaves the CWA in an unseasonably warm, humid air mass Monday between systems with little in the way of dynamics or forcing, yet with lots of clouds and high RH. Any breaks in the sun could trigger isolated pop up showers and thus have left in chance pops west to slight chance pops east with no thunder. Temperatures will be warm Monday with lows in the 50s and highs mostly in the 70s, except 60s western mountains. && .LONG TERM /TUESDAY THROUGH THURSDAY/... As of 142 PM EDT Friday... Active pattern this period. Upper-level low pressure system will arrive in our region early Tuesday. Dynamics are marginally favorable for thunderstorms, but if line of convection moves in sooner, lack of thermodynamics will limit thunder threat. High temperatures are expected to be in the 60s to lower 70s. Wednesday should be dry with upper ridge building again. Thursday, still dry as upper low slowly edges eastward over the southern plains keeping us under warm ridge, although could start see mid/upper level moisture working in from the southwest. High pressure nosing in from the northeast may keep it cooler, so kept highs in the 60s. Friday, the upper low pushes northeast toward the midwest with strong high situated over the mid atlantic coast. Will start seeing warm advection precip arriving late Thursday night with front not moving into the area until later Friday. By then dynamics weaken over the north. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 140 PM EDT Friday... High pressure along the Mid-Atlantic coast will continue to push offshore today allowing winds to come around to the south and southwest. A barrier jet is situated over the piedmont (LYH- DAN) this afternoon and will result in breezy and gusty winds (15-20G25kt) into this evening. Extensive mid and high clouds this morning are becoming scattered as temperatures warm and mixing increases. The southerly winds will allow low level moisture to increase resulting in increased potential for MVFR ceilings overnight/early Saturday along and south of the VA/NC border. Otherwise, ceilings should remain VFR for most areas through the TAF period. Some patchy valley fog is possible overnight but confidence is low. Extended Aviation Discussion... Moisture continues to increase over the weekend ahead of an upper-level low pressure area moving northeast from the southern plains. Precipitation is not expected until Sunday when sub-VFR conditions become more of a possibility. Otherwise looking at overall VFR to start the weekend with most lower cigs remaining west of the area until later Sunday at this point. Periods of unsettled weather will continue into the first half of next week as a series of upper-level lows track from west to east across the U.S. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...MBS/RCS SHORT TERM...RAB LONG TERM...RAB/WP AVIATION...RCS

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