Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 251108 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 708 AM EDT Tue Jul 25 2017 .SYNOPSIS... A weak cold front will stretch the NC west into Tennessee today then gets pushed further south tonight by high pressure building in from the northeast. Another cold front approaches from the northwest Thursday into Friday exiting to our southeast by Saturday morning. && .NEAR TERM /THROUGH TONIGHT/... As of 320 AM EDT Tuesday... Have a little fog/low clouds banked up across southern WV into the Mountain Empire where an inverted sfc trough lingers. Expect these clouds/fog to erode after 8-10am. High pressure will bring drier airmass/dewpoints to much of the region today, with models showing deeper moisture shunted south of our forecast area. Still enough of a gradient plus some return flow and inverted trough along the southern Appalachians to maybe generate isolated storms across the NC High Country possibly moving into the NC foothills this afternoon. Otherwise enough subsidence for overall mostly sunny skies with highs low/mid 80s mountains to upper 80s to around 90 east of the Blue Ridge. Any convection weakens and shifts out of our ares this evening with skies staying generally clear. High pressure will be over New England late Tuesday night so some return flow may still generate lower stratus/fog along the southern Appalachians, but overall confidence is low and another day of drying should limit this. Lows running close to normal with upper 50s to lower 60s mountains, to mid to upper 60s east of the Blue Ridge, but including Roanoke- Lexington. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 330 AM EDT Tuesday... High pressure over New York Wednesday morning will slide east in the Atlantic ocean Wednesday night into Thursday. Some weak orographic lift may combine with solar heating to create isolated to scattered diurnal showers and thunderstorms mainly along the southern Blue Ridge. High temperatures Wednesday will range from the the mid 70s in the mountains to the mid 80s in the piedmont. Any convection will taper off quickly Wednesday evening with loss of solar heating. Under partly cloudy skies, low temperatures Wednesday night will vary from around 60 degrees in the west to near 70 degrees in the east. Low pressure with a trailing cold front will move east across the Ohio Valley Thursday into Thursday night. The timing looks a little faster than yesterday. Thus, increased pops on Thursday and bring likely into the western mountains Thursday night. High temperatures on Thursday will climb to around 80 degrees in the mountains to about 90 degrees in the Piedmont. SPC has placed most of the forecast area in a slight risk for severe weather Thursday afternoon into Thursday evening. The main threat is for fast moving bands with damaging winds. Also, any thunderstorm could produce locally heavy rains. With clouds and rain, low temperatures Thursday night will generally be in the mid 60s in the mountains to the lower 70s in the Piedmont. && .LONG TERM /FRIDAY 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 /11Z TUESDAY THROUGH SATURDAY/... As of 702 AM EDT Tuesday... Only area with sub-VFR conditions is BLF and cigs are starting to rise to MVFR. Should be VFR by 14z, with all sites staying VFR through the period thanks to high pressure working southward from the Great Lakes into New York. Any storms this afternoon will be isolated and stay confined to the mountains south of HLX-VJI. Winds are going to be light, from the northwest most of the period. Fog threat late tonight expected to be light, so kept it out of the tafs for now, with best chance of fog in the typical spots like LWB. If enough of an east wind arrives, fog forming over the Greenbrier River could push into LWB after 09z. Aviation Extended Discussion... Should stay VFR under high pressure into Wednesday though some sct-bkn VFR cigs possible in the mountains (BLF-LWB-BCB). Should start to see front approaching with better threat of showers/thunderstorms Thursday into Friday. Outside of storms expect VFR conditions, with possible late night fog by Friday morning. Saturday looks drier with northwest flow, but could see lingering low end VFR/high end MVFR ceilings in SE WV. && .EQUIPMENT... As of 345 AM EDT Tuesday... The temperature sensor on the observing equipment at Lynchburg has failed, therefore no temperature data will be available until technicians can replace the defective part later this week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/WP NEAR TERM...WP SHORT TERM...KK LONG TERM...AMS AVIATION...JH/RAB/WP EQUIPMENT...WP

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