Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 140531 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 131 AM EDT Mon Aug 14 2017 .SYNOPSIS... A stationary front was stalled south of our region, extending from Arkansas eastward into the Carolinas. Surface pressure will progress from the Great Lakes region into Pennsylvania by tomorrow, with an associated ridge axis extending south along the lee of the Appalachians. An upper level disturbance will head eastward through Tennessee tomorrow near the stalled front, with its associated moisture impacting our region with increased chances of showers and storms, especially across western and southern sections of the area. && .NEAR TERM /THROUGH TODAY/... As of 245 PM EDT Sunday... Moisture is continuing to slowly creep back into the southern and southwestern sections of the area this afternoon. Some isolated showers have developed across parts of the Northern Mountains of North Carolina and Mountain Empire region of southwest Virginia. Additional development in similar areas is expected to continue into early this evening, along with the potential development eastward along the NC/VA border. As the night progresses, coverage of these showers will decrease through the early morning hours of Monday. Towards sunrise Monday, look for showers to increase again, especially across the southwestern sections of the area as an upper level disturbance in Tennessee makes progress towards our region, riding along the north side of the aforementioned stationary front. While this is occurring, we expect a lee side ridge of high pressure to nose south from its parent high pressure system heading eastward through Pennsylvania into New England. With this nose in place, and rain falling into it during the course of the day Monday, we are expecting plenty of cloud cover and temperatures on the cool side. Have favored temperatures a few degrees below the cooler MET MOS numbers. Guidance forecast instability factors suggest there may be enough instability along the edge of this wedge to allow for isolated thunderstorms across western and southern sections of the area by the afternoon. The disturbance over Tennessee will be overhead or on our western doorstep around peak heating of the day, and thus have bumped precipitation chances higher across the western sections. Low temperatures tonight are expected to range from around 60 to the mid 60s across the mountains with mid 60s to near 70 across the Piedmont. High temperatures on Monday are forecast in the low to mid 70s across the Piedmont. Across the mountains mid 60s to around 70 will be common. The exception will the area between roughly Bluefield, WV to Richlands and Marion, VA. This area will be just outside the influence of the wedge and have the potential of having high temperature in the mid to upper 70s. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... As of 200 PM EDT Sunday... For Monday evening, will be keeping an eye on a thunderstorm complex approaching from the west. Weather forecast models appear somewhat split as to where these storms will track, with the NAM and others suggesting these storms drift into our western Virginia/NW North Carolina counties, while the GFS/Canadian indicating these storms will mainly pass to the south. Have therefore left higher rain chances in our North Carolina counties for late Monday evening based on the uncertainty in the track of the storms. Weak high pressure will shift across the mid Atlantic and lower New England states on Tuesday, bringing somewhat drier air to the northern half of the forecast area. As such, have higher rain chances confined south of Highway 460, locations closer to the stalled front and therefore with greater moisture. That stated, the lack of any organized disturbance moving across our area will keep convection widely scattered and driven by daytime heating. Coverage of rainfall will diminish quickly toward sunset with the loss of daytime heating. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 1130 AM EDT Sunday... Looking into the second half of the week, believe most of the shower and thunderstorm activity will be hit-and-miss variety, driven by daytime heating, as the weather forecast models do not indicate any highly organized disturbances moving our way. Models are hinting at a cool front approaching from the northwest by week`s end, which may bring greater coverage of rainfall, however given the weak push from high pressure behind the front, it remains uncertain how far south this front will progress. For Wednesday, held temperatures a degree or two below the guidance consensus as generally southeasterly windflow continues to draw cooler Atlantic moisture into the central Appalachians. Temperatures enter a modest warming trend towards the end of the workweek as a weak warm front lifts across the region, allowing surface winds to shift more southwesterly, tapping more humid air from the Gulf of Mexico. Temperatures may be a degree or two cooler next weekend, depending on the amount of cloud cover associated with the cold front approaching the mid Atlantic. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 125 AM EDT Monday... Cloud cover will be extensive this morning and on thru this taf period. Wedge setup will keep cigs in the MVFR or lower range at times, especially as we head into later this morning. Models keep best threat of showers across the mountains and confidence still not high enough to put more than VCSH in. At times, cigs/vsbys could drop to IFR, especially BCB/BLF/LWB. Extended Aviation Discussion... Surface high pressure moves east Monday night and on Tuesday a warm front moves north through the region. Wed-Fri will have more instability and scattered to numerous showers, with thunderstorms and MVFR ceilings and visibilities possible during the afternoon and evening.
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&& .EQUIPMENT... As of 755 PM EDT Saturday Aug 12th... KFCX doppler radar will continue to be down for the rest of the month due to a failing bull gear. It will only be operational during this time frame for brief periods if an imminent significant widespread severe weather and/or hydrologic event occurs. Operating the system for any amount of time until the bull gear is replaced risks a catastrophic failure that would further extend system downtime. From the 17th through the 27th the radar will most likely be down completely as the repairs are expected to be made during this period. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS NEAR TERM...DS SHORT TERM...NF LONG TERM...NF AVIATION...AMS/DS/WP EQUIPMENT...RAB/WERT

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