Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 281802 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 202 PM EDT SAT MAY 28 2016 .SYNOPSIS... High pressure stays overhead today into tonight. A tropical depression arrives to the South Carolina coast by Sunday morning then stays situated along the Carolina coast through midweek. && .NEAR TERM /THROUGH TONIGHT/... As of 1145 am EDT Saturday... Morning RNK/GSO soundings verify that we are in subsidence zone, with strong cap and large dewpoint depressions in excess of 40 degrees above the inversion. Aside for some fair weather cu, it should be a nice afternoon. For this afternoon, forecast area will remain in a subsidence zone between the tropical depression off the southeast coast, and the storm system moving across the upper midwest. We may see a shower or two possibly pop up in the WV mountains, but not really seeing enough evidence in the models to add pops. Expect to see mostly sunny skies as temperatures warm into the upper 70s to lower 80s west to mid 80s east. Tonight, the tropical system moves toward the South Carolina coastline. Models showing increasing clouds and allow for showers to basically move in from the southeast after midnight at least as far west as the southern Blue Ridge in VA and NC east toward Southside Virginia. We should stay dry across the northwester CWA tonight, with only slight chance across the New River Valley and near Lynchburg. With clouds increasing lows will stay elevated in the 60s across most of the region, though some upper 50s possible in the mountains. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... As of 430 AM EDT Saturday... T.D. #2 will be the main focus through the first part of this period. Leading edge of associated moisture will reach the southeast part of the CWA around daybreak Sunday...then spread north-northnortheast through the day. Limited instability...but deep tropical moisture and upslope flow along the Blue Ridge should support likely to categorical pops...with mostly chance pops west of the Blue Ridge not directly in the path of the tropical system. Several of the models suggest that it will be mainly the upper-level feature as opposed to the surface feature with the tropical system that will track northwest into our region...with the surface low remaining closer to the coast throughout the lifecycle. Instability is limited with abundant cloud cover...thus have only included isold thunder for now. Better thunder threat may be around the western periphery of the tropical system where the pops are lower but the air mass will likely tend to be slightly more unstable. With respect to rainfall...looking at less than an inch west of the Blue Ridge to around an inch to the east...with locally higher amounts. WPC rainfall seems a little high given the track of the deeper moisture and higher PWATS closer to the coast. Am not overly concerned about flooding issues...especially since the heavier rainfall will be east of the Blue Ridge/Piedmont areas. The main area to watch for flooding would be along the Blue Ridge in the Meadows of Dan area northeast toward Bedford and Amherst counties. Sunday will be muggy in the tropical air mass with min temps well above normal in the 60s...but max temps will be a little cooler...mainly in the 70s. For Monday...the upper-level feature associated with the tropical system has moved northeast of the region...fairly well agreed to by all of the models. Even the GFS...which for multiple consecutive previous days indicated that the tropical system/upper low would drift into western SC/NC and stall for several days next week...has come on board with the other models in lifting the feature quickly to the northeast by Monday. Tropical associated rainfall Monday should be limited to the northeast part of the CWA...with isold-sct diurnal convection mainly across the mountains. Much of the CWA could actually come under subsidence by Monday afternoon/evening...inhibiting precipitation. Tuesday will see the region under weak high pressure and little if any dynamic support. Expect just isold-sct diurnal convection...most favored across the mountains. The main upper- level support will remain across the central/western U.S. in association with a persistent upper-level trough. Temperatures Monday and Tuesday will be warmer and well above normal with lows in the 50s mountains and 60s elsewhere...with highs in the 70s mountains and 80s elsewhere. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 445 PM EDT Saturday... Quite a bit of change from previous days as Wednesday and Thursday the region is left under weak high pressure aloft and limited dynamics. The air mass will be very warm and humid...which will support scattered diurnal convection...most numerous across the mountains. By late Thursday...and especially into Friday...scattered to numerous convection can be expected as the Midwest trough finally moves into the region and taps into the deep tropical moisture present across the region. Any threat for flooding and/or severe weather would likely be on Friday. Temperatures will be above normal through the period and it will be humid...with lows mainly in the 60s and highs in the 80s. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... As of 200 PM EDT Saturday... Main concern next 24 hours will be movement of tropical system along the southeast atlantic coast and potential for impact to mid atlantic. Attm, it appears VFR will persist through at least the first 12 hours of the valid TAF period, which means little or no weather concerns through midnight tonight. Meanwhile, moisture will be advancing northwest form the South Carolina Coast...rain and multiple cloud layers moving into North Carolina tonight, then north and northwest into VA early Sunday. Models put primary focus for MVFR/low cigs/rain along and east of the Blue Ridge on Sunday with little impact in the west. Attm, all models keep deeper tropical moisture confined to areas east of the Appalachian Divide, so this will put KBLF-KLWB on the western periphery of the cloud shield and best chance from maintaining VFR. Mid/High clouds will thicken from the southeast overnight in advance of T.D. No. 2. However...most of the rain will not reach the Piedmont counties until after daybreak...but have introduced -RA into KDAN around 10Z and -DZ into KROA by 11Z. Cigs/vsbys will remain VFR through 12Z...and the mid/high clouds should prevent fog development at KBCB and KLWB Sunday morning. EXTENDED DISCUSSION... Low confidence on flight category for Monday-Thursday. Models indicate low pressure will stall over the eastern mid-atlantic and linger through mid week. Our forecast area will be on the western periphery of this feature which suggests best flight conditions will be over and west of the Blue Ridge. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...PM/WP SHORT TERM...RAB LONG TERM...DS/RAB AVIATION...PM is the U.S. government's official web portal to all federal, state and local government web resources and services.