Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 210528 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 128 AM EDT Wed Sep 21 2016 .SYNOPSIS... An upper low combined with the remnants of former Tropical Storm Julia will meander about eastern North Carolina and South Carolina through late week before finally shifting out into the Atlantic ocean. This will keep fairly unsettled conditions east of the Blue Ridge over the next several days, less so in western areas. High pressure will gradually build in from the west during the later half of the week. A backdoor cold front drops south through the area later Saturday followed by cooler high pressure Sunday into Monday. && .NEAR TERM /THROUGH TODAY/... As of 945 PM EDT Tuesday... Have trimmed back probability of precipitation to southeast of Danville for late this evening with a slight chance of rain gradually spreading to a Farmville to Yadkinville line by morning. An upper level low over the southeastern states is expected to pull the remnants of Julia back south into the North Carolina coastal piedmont tonight. Some models move remnants into South Carolina, some into the the interior portion of North Carolina. Subsidence and dry air intrusion in the northwest quadrant of this system will keep the northwest counties of the forecast area dry. Temperatures tonight will remain mild across the piedmont where thick clouds blanket the area. Elsewhere, clear skies will lead to some river valley fog, but mixing should deter widespread dense fog from forming. Opposite trend for daytime temperatures with cooler than normal conditions expected across the piedmont with thick cloud cover. Elsewhere, at or above normal temperatures under partly cloudy skies. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 309 PM EDT Tuesday... Closed low over the Southeast coast will interact with the post tropical remnants of Julia during the period. The challenge in the weather forecast is the degree to which the richer moisture on the northern side of this system gets advected into parts of our region. Isolated to scattered showers are possible Wednesday night across southern portions of the forecast area. Low temperatures Wednesday night will range from the mid 50s in the mountains to the mid 60s in the Piedmont. The trend of the ecmwf is further east with low and starting to weaken in more of an open wave feature similar to GFS. In any case, the unsettled weather with scattered convection may continue Thursday into Thursday night across the south and southeast portion of forecast area. Higher confidence in drier weather under sunshine across the north on Thursday. High temperatures Thursday afternoon will vary from the lower 70s in the southern mountains to around 80 degrees in the Piedmont. Clear to partly cloudy conditions will prevail Thursday night with readings from the mid 50s in the west to the mid 60s in the east. By Friday into Friday night, the closed low will transition into an open wave and progress further eastward into the Atlantic ocean. Drier air will push into our area and push all the precipitation out of the area. High temperatures on Friday will climb into the mid 70s in the west to the mid 80s in the east. The combination of light winds and low level moisture under a mostly clear skies will result in areas of river and mountain valley fog Friday night into Saturday morning. Low temperatures Friday night will general be from the mid 50s in the west to the mid 60s in the east. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 130 PM EDT TUESDAY... Strong upper ridging centered along the Mississippi River to start the weekend will gradually get pinched back to the southwest as a rather high amplitude troughing regime develops over the northeast U.S. by early next week. This will allow increasing northwest flow aloft to take shape across the region between the departing 500 mb ridging and eventual upper level low pressure over New England. Within this setup should a rather strong backdoor cold front drop south through the area later Saturday followed by cooler high pressure Sunday into Monday. This before yet another cold front arrives from the northwest on Tuesday with the next stronger mid level shortwave. However deeper moisture looks quite limited with both frontal passages given a dry west/northwest flow aloft so only including slight shower pops later Saturday west and again Tuesday. Low level flow turning more east/northeast behind the initial boundary, per the developing wedge could allow for a slight uptick in shower coverage southern sections Saturday night, although iffy for much more than clouds/sprinkles at this point per lower amplitude/drier ensembles. Should see high enough heights ahead of the weekend front to keep warm temps in place Saturday with highs mostly in the upper 70s to mid 80s. Subsequent rounds of decent cool advection look to arrive with each frontal passage into late Tuesday with potential for Sunday into Monday to remain quite cool if clouds are more widespread. This timing continues to vary between solutions as each may be too strong, although thinking highs mostly 70s Sunday-Tuesday, with 50s for lows and possible 40s valleys Monday morning with high pressure overhead. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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As of 120 AM EDT Wednesday... MVFR ceilings are approaching KDAN from the east and forecast soundings suggest by 09z that ceilings will be around 1500 ft. LYH should also be dropping to around 3000 ft by 09z. Elsewhere ceilings stay VFR. Across the mountain taf sites, fog may become an issue again, but not as much as last night per drying that took place today. Still expect some periods of LIFR to IFR at BCB/LWB around 9-12z. The upper low will continue to stay near the coast of NC Wednesday with a few showers stretching toward DAN but more times will be dry so not impact taf sites yet. The MVFR ceilings should lift by mid morning with gradient picking up, so gusty winds will be possible as far west as BCB, mainly in the 15 to 25 kt range at best. Winds should subside by 22-00z with VFR continuing through 06z/Thu. Extended aviation discussion... Thursday and Friday, outside of late night/early morning fog/low clouds, expect mainly VFR conditions. The slight chance of showers will remain just east of KLYH and KDAN through Thursday night. GFS/ECMWF have been consistent in filling and lifting out the low to the northeast on Friday. A back-door cold front will come through the Mid-Atlantic region on Saturday. High pressure will build in for Sunday. The chance of precipitation or any sub VFR conditions will increase through the day Sunday and into Sunday night.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RAB NEAR TERM...AMS/RCS SHORT TERM...KK LONG TERM...JH AVIATION...AMS/RCS/WP is the U.S. government's official web portal to all federal, state and local government web resources and services.