Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 241823 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 223 PM EDT Mon Jul 24 2017 .SYNOPSIS... A weak cold front will slide southeast through the area tonight before stalling over the Carolinas Tuesday into Wednesday. High pressure builds north of the region behind the front bringing a return to more seasonal temperatures later tonight through mid or late week. Another cold front approaches from the northwest on Friday and works slowly through the area by the weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 210 PM EDT Monday... Convection continues at a minimum this afternoon as the region remains in a somewhat drier westerly flow between the exiting surface trough to the east and the cold front along the Ohio River. This front should finally slide southeast and across the region later this evening as the upper trough to the north swings by to the northeast. Latest guidance still showing some degree of at least shallow convection just ahead of the boundary with the Nam quite agressive, while other solutions only show widely scattered coverage within the instability axis along our northwest slopes. Since some potential for a band of broken convection to move into the northwest sections, have included low to isolated pops later this afternoon into early evening for locations mainly west of the New River Valley. Otherwise should see clearing take shape overnight as the front sags to the south allowing for a bit more comfortable air to advect into the mountains where expect lows well into the 60s. Moisture may linger across the south/east so kept lows mainly upper 60s to lower 70s there. Also despite good drying today, appears some fog/stratus development possible espcly valleys given heavy rain from last night and better radiational cooling west tonight. High pressure builds in from the north on Tuesday with weak northerly flow resulting in enough dry advection to limit most convection to across far southern sections at best. This seen via model lowering of PWATS from north to south and axis of deeper moisture well to the south closer to the residual surface front. Therefore reduced pops to slight chance mainly across northwest NC where perhaps enough low level moisture/instability may linger to pop a shower or two but iffy. Otherwise enough subsidence for overall mostly sunny skies and not quite as hot/humid with highs low/mid 80s mountains to 87-92 east of the Blue Ridge. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 1245 PM EDT Monday... Little change in the weather pattern and no synoptic scale forcing Wednesday and Thursday. Will keep minimal probability of precipitation, mainly in southern Virginia and northern North Carolina each afternoon and evening. Persistence combined with bias corrected MET/MAV guidance will be reasonable for daily highs and lows. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 1245 PM EDT Monday... Upper pattern amplifies starting on Friday with the upper ridge over the western United States slightly retrograding and a trof digging in the east. An upper low may eventually close off somewhere over the Tennessee Valley or Mid Atlantic region by Sunday or Monday. This closed low solution was not supported by a majority of the extended guidance. Probability of showers and thunderstorms will increase on Friday and Saturday with some vorticity advection and lowering heights. Air mass ahead of the trough stays in the +16 to +20 range for temperatures at 850MB and will be a little cooler on Sunday and Monday. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 1245 PM EDT Monday... Overall conditions have returned to VFR across the region with only KBLF holding onto some lower MVFR cigs under upslope flow. Expect those lower cigs to finally scatter out shortly resulting in mainly cumulus VFR cigs beneath some high clouds above into early this evening. Cant totally rule out isolated convection developing mainly west of the KBLF-KLWB corridor after mid afternoon with an isolated storm or two possible around KDAN. However given uncertainty will leave out any mention with best potential over the western sites late this afternoon. Winds will be turning more west/northwest through the rest of the afternoon with speeds mainly 5-15 kts except for a few gusts above 20 kts over the ridges. Weak front drops southeast through the area overnight with any lingering convection over the west fading this evening. Looks like enough of a threat to include a VCSH mention perhaps at KLWB or KBLF early this evening but quite iffy in whether or not any shra/tsra to the west will actually make it to any of the terminals. Otherwise expecting VFR under clearing this evening before possibly seeing some filling in of low clouds/fog across parts of the mountains, and espcly around KBLF given continued weak upslope flow. Also appears with slightly lower dewpoints that temperatures fall enough to help develop dense fog across the valleys. Thus including a IFR/LIFR mention at KLWB late as well as brief MVFR to IFR late at KBCB/KLYH and perhaps KBLF. Any sub-VFR due to low clouds/fog will gradually improve Tuesday morning as drier air mixes out low level moisture under high pressure. Convective chances again appear quite low Tuesday afternoon with any threat mainly south of the taf locations so running with overall VFR under cumulus/cirrus for now. Aviation Extended Discussion... A frontal boundary should stall to the south, with high pressure wedging southward on Wednesday. Overall VFR but with flow turning more east, this could bring some MVFR/IFR ceilings, which should quickly dissipate by Thursday. Any convection also likely to remain isolated and south of the taf sites again later Wednesday. Next best threat for showers and storms arrives with another front Friday with perhaps some of this coverage lingering over southern/western sections into Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/WP

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