Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 240507 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 107 AM EDT Sun Jun 24 2018 .SYNOPSIS... Low pressure aloft will pass north of the region Sunday into Sunday night allowing a weak surface boundary to shift south across the area by Monday. High pressure aloft will build over the eastern U.S. during the later half of the week resulting in hotter and humid conditions along with the threat of diurnally driven showers and storms. && .NEAR TERM /THROUGH TODAY/... As of 945 PM EDT Saturday... No major updates with this forecast adjustment. Have only tweaked hourly temperatures and dew points to reflect the latest conditions and expected trends through midnight. Also, made minor adjustments to the sky cover to reflect even less coverage prior to the arrival of the activity currently making gradual progress eastward through far southwest Virginia. As of 645 PM EDT Saturday... Very little remains in the way of showers across the region. This trend should continue as we approach sunset and the loss of the daytime heating. Additional showers will be possible later this evening as a disturbance moves into eastern Tennessee. The western quarter of the region may see isolated to scattered showers after midnight through daybreak Sunday. As of 300 PM EDT Saturday... Water-vapor imagery shows a mid-level trough over the Ohio Valley rotating eastward towards the Mid-Atlantic region this afternoon into tonight. The upper low will lift out across the northeast U.S. by Monday. SPC Mesoscale analysis at 18z showed that CAPEs have rebounded top 1k to 2k J/Kg east of the Blue Ridge. Lis this afternoon vary from minus one to minus three across eastern half of our Forecast area. The HRRR and HiResW-ARW-east showed scattered showers and thunderstorms developing this afternoon and moving east across our region into tonight. The latest day one convective outlook keeps a marginal threat of severe weather across eastern portions of forecast area. There is a small window for an isolated pulse severe thunderstorm in the east. However, the best instability will be pooled across the coastal plain to our south and east. With the loss of solar heating this evening expected scattered convection to diminish and tapper off into tonight. Once again expect areas of low clouds and fog to form overnight into Sunday morning. Low temperatures tonight will range from around 60 degrees in the mountains to around 70 degrees in the piedmont. Quasi-zonal mid-level height regime will govern conditions aloft across the East. Airmass should become moderately unstable which should lead to the development of scattered showers and thunderstorms Sunday afternoon. A couple of weak shortwave rotating across our area should enhance thunderstorms formation. SPC does have the far western portion of the CWA in a 5%/Marginal Risk of severe weather on day two convective outlook, which seems reasonable. High temperatures on Sunday will vary from the lower 70s in the northwest mountains to the lower 90s in the piedmont. /Confidence Levels/ Temperatures...High Precipitation Chances... medium Winds...Medium && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... As of 200 PM EDT Saturday... Sunday afternoon and evening thunderstorms will gradually fade away overnight as a weak front tracks across the region Sunday night into Monday. Stable air behind the front will keep thunderstorms chances low Monday, while temperatures will again warm above normal. Temperatures Monday will range from the low to mid 80s west of the Blue Ridge to near 90 east. North to northeasterly flow Monday night into Tuesday will bring a brief break from the heat as a wedge of high pressure skirts over the Mid Atlantic states and south-central Appalachains. Temperatures will range from the mid 70s to lower 80s west and low to mid 80s east. The wedge will slowly erode over the mountains during the day Tuesday as a cold front approaches from the west. Areas outside of the wedge may see a few thunderstorms develop in the afternoon, then fade during the evening hours. Areas that typically erode outside of the wedge first are the Mountain Empire of southwest Virginia west to the Bluefield-Richlands area. Greenbrier Valley may also come out of the wedge late Tuesday, depending on if the front is still over the Midwest or in the Ohio Valley. As the front continues to approach the area Tuesday night, the wedge will erode over the mountains, but remain entrenched across the foothills and piedmont counties into Wednesday morning. /Confidence Levels/ Temperatures - High Precipitation Chances - Medium Thunderstorm Chances - High && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 220 PM EDT Saturday... The GFS is quick to remove the wedge Wednesday morning, while the ECM hangs on to it over the piedmont into the early afternoon. In either case, scattered showers and thunderstorms will form over the area as the wedge erodes, it is just a timing issue. As the front tracks over the region Wednesday, more numerous showers and thunderstorms will over take the area. The front stalls over the piedmont overnight which may keep lingering showers in the area into the early morning hours Thursday. The front is expected to move east during the day Thursday with only an isolated chance for afternoon thunderstorms in the afternoon. Temperatures Wednesday and Thursday will run close to normal levels. A heat dome of high pressure over the southern Plains early in the week will move over the East Coast next weekend. Temperatures will once again run warmer than normal, ranging from the mid 80s to lower 90s across the mountains and mid to upper 90s east. Scattered thunderstorms are also expected to develop each afternoon and evening. /Confidence Levels/ Temperatures - Medium to High Precipitation Chances - Low to Medium Thunderstorm Chances - Low to Medium && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... As of 115 AM EDT Sunday... Another round of showers with a weak impulse aloft approaching from the west will likely affect the KBLF-KLWB vicinity in the next hour before heading east and fading upon crossing the Blue Ridge. Therefore will include either a VCSH or TEMPO mention across the western sites to start. This may also cause ceilings to fall to below VFR levels espcly in the wake of the showers at KBLF with overall VFR expected from the Blue Ridge east. Patchy IFR/MVFR fog is possible late tonight into early Sunday morning in the mountain and river valleys. During Sunday, look for showers and storms to increase across the entire region, especially in the afternoon, as low instability increases once again thanks to surface heating and an upper level disturbance will approach from the Ohio Valley. Coverage remains highly uncertain with guidance showing differing locations of where more organized clusters may reside. Since appears the mountains again likely have the best shot at a shra/tsra included another VCTS or VCSH mention this afternoon with west/northwest flow likely making for less coverage out east where will leave out mention. Otherwise will be on the breezy side with westerly flow at 10-18 kts with gusts to 25 kts possible. .Extended Aviation Discussion... A cold front may linger near southern sections Sunday night into Monday with added showers/storms possible as another wave rides down the boundary on Monday. This likely to result in periods of MVFR southern sites with VFR across the north. Should finally see the front get far enough south for mostly VFR conditions Tuesday. Isolated to scattered MVFR showers and thunderstorms are possible by Wednesday with more isolated nature to convection Thursday when should be back to mainly VFR. && .EQUIPMENT... As of 338 PM EDT Saturday... The NOAA weather radio transmitter in Hinton, West Virginia that is WXM72 and broadcasting at a frequency of 162.425 MHz is off the air. Parts are on order to repair the transmitter, but there is no known time of restoration. We apologize for any inconvenience. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/KK NEAR TERM...DS/KK SHORT TERM...RCS LONG TERM...RCS AVIATION...DS/JH/KK/NF EQUIPMENT...

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