Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 260828 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 428 AM EDT THU MAY 26 2016 .SYNOPSIS... High pressure staying off the coast through Friday with typical summer like weather impacting us increasing humidity. This weekend, a potential tropical low may arrive toward the South Carolina coast and linger in the general area into early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 350 am EDT Thursday... Moisture to continue to increase today with a weak upper trough moving across. Should see an increase in cloud cover with a threat for showers and storms more in the afternoon and into the evening. Still coverage to stay more scattered. Will see a few showers this morning across the mountains. Looks like activity will wane after dusk with most places dry after midnight. Highs today will range from the upper 70s to lower 80s mountains, to the mid to upper 80s east. Tonight will maintain persistence with lows in the lower to mid 60s. Fog may be an issue where it rains this afternoon and evening as well as in the river valleys. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 400 am EDT Thursday... Broad...weak upper ridging will be over the region Friday into Saturday...with a broad and highly diffluent upper low across the western and central U.S. A deep conveyor belt of Gulf moisture will be tracking northward through the southern and central Plains through the period with a continued active severe convective pattern there. For our region...steering currents will be weak and dynamics fairly non-existent. The disturbance that will result in increased diurnal convection Thursday...will have moved into New England by Friday...leaving little triggering mechanism to work with Friday. However...a very moist summerlike atmosphere will be present across the region with PWATS in around 1.5 inch. Scattered convection should develop...especially across the Alleghanys and western mountains in association with differential heating. Areas east of the Blue Ridge should continue to see the least chance for convection...owing to subsidence along the western periphery of a developing tropical system across the Bahamas. The remainder of the forecast period continues to hinge heavily on the track...intensity...and duration of a tropical system developing across the Bahamas. The GFS remains very aggressive with this system...tracking what appears to be a true...tropical warm core system northwest and inland toward northwest NC. PWATS approach 2.0 inches...well above normal values...per the GFS. Meanwhile...most of the other models keep the core of the system near or just off the SC/NC coast...but do depict tropical moisture spiraling inland away from the core into our region by Sunday. The GFS solution would bring heavy rain into the CWA and arouse flooding concerns...while the other models suggest much less potential...barring a predecessor rain event (PRE). Will need to watch closely...but the consensus among most models is for scattered to numerous showers/thunderstorms by Sunday across the region...especially east of the Blue Ridge...requiring at least high chance pops for now. It will not be widespread continuous rain event...but largely diurnally driven. Humidity levels will definitely be on the increase through the period and overall it will feel very muggy and summerlike with mild to warm nights and warm/humid days. Looks for lows mainly in the 60s with highs in the 80s...70s mountains. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 415 am EDT Thursday... Forecast challenge through the period will continue to depend on the track of an area of tropical low pressure across the southeast states. As noted above...the GFS brings this system well inland into the GA/SC/NC region and leaves it lingering across the region through the period thanks to a stagnant upper atmospheric pattern with an upper high to our north and a broad upper low continuing in the western U.S. Therefore...if the tropical system does drift into the GA/SC/NC area as the GFS suggests...it will likely linger for several days with non-existent steering currents and blocked upper flow. Rainfall may become a concern as a result. The ECMWF continues to paint the least ominous solution, keeping the bulk of the precipitation and higher PWATS closer to the coast. At a minimum, we can expect scattered diurnal convection with warm/humid conditions through the period. Chance to high chance pops are in order through the entire period. Max temps will remain mostly in the 70s mountains and 80s elsewhere, with lows mainly in the 60s. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... As of 140 AM EDT Thursday... Generally VFR conditions expected through the TAF valid period...with a few exceptions...mainly in the form of early morning fog in some of the mountain valleys/BCB/LWB. Expect some mid and high cloud debris from showers and thunderstorms well to the west of the region. Medium confidence that this cloud cover will not be enough to hamper fog formation. A short wave ejecting from a broad upper low over the southwest United States moves northeast Thursday, bringing a better opportunity for showers and a few storms to over the mountains and across areas east of the Appalachians Thursday afternoon. MVFR ceilings and visibilities are likely in any of these storms. Coverage will be limited enough to just have VCTS in the TAFs for now. Extended discussion... Wind flow through Friday will be out of the southwest with the weather pattern more reflective of summer conditions, primarily VFR except for widely scattered afternoon and evening showers during the peak heating part of the day. Nightime fog also possible in the mountain valleys, but mainly after midnight up until an hour or two after daybreak. Potential wind flow change is advertised by the models this weekend per development of a storm system off the southeast Atlantic Coast. Models differ quite a bit on timing and movement of this feature so low confidence forecast beyond Saturday attm. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...RAB LONG TERM...PM/RAB AVIATION...AMS/PM/WP

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