Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 252020 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 420 PM EDT WED MAY 25 2016 .SYNOPSIS... High pressure is centered just off the southeast Atlantic Coast. This feature will remain nearly stationary through the end of the week, clockwise flow around the high resulting in a warm southwest wind. Increasing moisture from the southwest will result in increasing cloudiness along with scattered showers and a few thunderstorms. an area of low pressure is forecast to develop over the Bahamas Friday. This feature is expected to impact the beaches along the southeast Atlantic coast this weekend. && .NEAR TERM /THROUGH THURSDAY NIGHT/... As of 330 PM EDT Wednesday... Cu field this afternoon pretty much tells us where there is low level moisture and where there isn`t, satellite pix indicating moisture mainly west of the Appalachian divide. As such, any shower threat this evening and overnight will be mainly confined to areas west of the blue ridge, and primarily west of I-77 where deeper moisture will have a chance to make inroads during the overnight. per regional radars...Deeper moisture is advancing across the OH/TN valleys...showers and thunderstorms ongoing from western TN northeast into KY. This activity is progged to move east northeast overnight...but advancing slow enough not to impact areas east of the Appalachians. High pressure is currently building just off the southeast Atlantic Coast, clockwise flow around the high resulting in a warm southwest wind from the Gulf Coast into the Tennessee and Ohio Valleys. This southwest wind flow is also advecting moist air northward with dewpoints in the 60s. A broad upper level trof of low pressure resides over the western U.S. and a short wave has ejected from this trof, this disturbance currently moving northeast through the mid-upper MS Valley. It is the tail end of this short wave that is associated with the area of showers/storms over wrn TN/KY. Models show this short wave moving down stream and weakening with time as it encounters the building upper level ridge over the southeast and mid-atlantic regions. Never the less, this increase in moisture and lift will be enough to contribute to widely scattered shower and thunderstorm formation Thursday. Since dynamics are waning, the thunderstorms are not expected to be severe. With the influx of warmer air, high temperatures Thursday will reach the middle and upper 80s east of the Blue Ridge with upper 70s and lower 80s elsewhere. Lows tonight and again Thursday night will generally be in the upper 50s to lower 60s. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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As of 400 PM EDT Wednesday... Synoptic pattern will continue to feature an upper level trough in the southwestern U.S. with a ridge of high pressure over the east, the primary surface high still centered along the southeast Atlantic Coast. Southwest flow will provide warmth and moisture to the forecast area, daytime heating allowing for pop-up showers/storms, but lack of dynamic support leading to little or no organization. Net result is a summertime sort of pattern with shower threat mainly tied to the peak heating part of the day. Models are in agreement that an area of low pressure will develop in the vicinity of the Bahamas on Friday, with potential impact to the beaches along the southeast Atlantic Coast this weekend. For the central Appalachians we should escape any influence through at least Saturday.
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As of 410 PM EDT Wednesday... Forecast challenge this period will hinge on track of the area of tropical low pressure along the southeast Atlantic Coast. The upper flow will remain quite stagnant 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 most models suggest, although there are notable differences in the distance it will track inland, it will likely linger for several days with non-existent steering currents and blocked upper flow. The upper high to the north could keep the system lingering in place for several days. Rainfall may become a concern depending on how far inland the system tracks. 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. Max temps will remain mostly in the 70s mountains and 80s elsewhere, with lows mainly in the 60s. Have not made any drastic changes to the extended QPF as there is still considerable uncertainty in exactly how much precipitation we will see.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... As of 200 PM EDT Wednesday... Generally VFR conditions expected through the TAF valid period...with a few exceptions...mainly in the form of late night/early morning fog in some of the mountain valleys...and in the vcnty of any shower activity. Main focus for shower activity this evening will be west of Interstate 77 in addition to isolated thunderstorms. Focusing mechanism is a short wave ejecting from a broad upper low over the southwestern U.S. Best coverage of showers this evening will be over the OH/TN valleys with little or no impact to areas east of the Appalachians. As the short wave moves northeast there will be a better opportunity for showers and a few storms to develop across areas east of the Appalachians Thursday afternoon. Until then...VFR. 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...PM NEAR TERM...PM SHORT TERM...PM LONG TERM...PM/RAB AVIATION...PM is the U.S. government's official web portal to all federal, state and local government web resources and services.