Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 201909 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 309 PM EDT Tue Sep 20 2016 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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As of 309 PM EDT Tuesday... 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. Depending on where this tropical features goes will determine if a band of showers moves across Southside and/or to the Blue Ridge late tonight and tomorrow. For this package, we will keep 30-40 PoPs across Southside Virginia and northern North Carolina. Subsidence and dry air intrusion in the northwest quadrant of this system will keep others dry. Temperatures tonight will remain mild across the piedmont where thick clouds blanket the area. Elsewhere, clear skies may lead to some 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.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
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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.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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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.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/... As of 140 PM EDT Tuesday... Weather through the TAF valid period will be driven largely by remnants of T.S. Julia and a stalled frontal boundary along the coast. This will result in a strengthening northeast flow and even low end gusts across the Piedmont this afternoon. This will also keep low-end VFR clouds across the piedmont, moreso towards KDAN. Areas across the foothills and west of the Blue Ridge will see scattered fair weather cumulus through the rest of today. Outer bands of light rain may creep toward Danville tonight with the best chance toward sunrise based on 12z model data. Western valleys will likely see a repeat of the dense ground fog after 06Z Wed, although confidence in this occurring is not as high as it was this morning. Extended aviation discussion... Wednesday through Friday, outside of late night/early morning fog/low clouds, expect mainly VFR conditions with the caveat to this being any lingering slight chance of showers from Julia per GFS/ECMWF, mainly affecting areas east of the Blue Ridge. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RAB NEAR TERM...RCS SHORT TERM...KK LONG TERM...JH AVIATION...RCS

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