Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 141126 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 726 AM EDT Mon Aug 14 2017 .SYNOPSIS... An upper level disturbance through the area today. A frontal boundary will stay south of us into Tuesday, the shift away and dissipate into Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 245 AM EDT Monday... Convection continues to linger over the NC foothills/western piedmont earl this morning due in part to increased southeast flow into the mountains leading to convergence, and increased theta-e ridging. High-res models showing this area moving slowly east northeast toward southside VA through dawn, while keeping some lingering back over the same area. Some reports have come in of 2-6 inches of rain in the foothills. Given how this will move out, will stick with flood advisories for now, with no flood watches anticipated. For today, thinking is models may be underdone somewhat into the rainfall expansion, and feel that the Blue Ridge, from Roanoke south, and west to the WV will have a decent shot of rain showers and some thunder through the day. This will be aided by southeast flow into the mountains, combined with an upper vort moving out of TN into the Blue Ridge by 18z, then east of the area by this evening, as well as lift over the stalled frontal boundary in the Carolinas. There is another wave at 5h progged to move out of the TN Valley and cross the southern Appalachians this evening, which will keep a decent rain chance over our southern counties from the VA/NC border south through at least midnight. Once this wave passes, appears just some lingering showers through dawn Tuesday. Similar to previous forecast, kept high temp below mos, as think skies stay bkn/ovc most of the day, with a east-southeast wind. Highs will be mainly in the 70s across the area, but could surpass 80 over the Mountain Empire outside the wedge and possibly southeast of Danville and Yadkinville. Not much change in the airmass tonight, so lows still in the mid 60s to lower 70s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 245 AM EDT Monday... What ever is left of the wedge will erode through the day Tuesday as a weak upper level trough tracks over the south-central Appalachains. This trough will take advantage of afternoon heat (highs in the 80s) and abundant moisture (dew points in the mid 60s to low 70s) to produce afternoon showers and thunderstorms. Low level convergence is best along the VA/NC border south, therefore have the highest PoPs. A few storms could become strong or severe in this area however, our primarily concern is flooding from heavy downpours and slow moving storms in a PWAT environment of nearly 2 inches. Climatology does not favor widespread flooding this time of year. This convection will move into central North Carolina during the evening with high pressure building in from the west. Partial clearing is possible Tuesday night which could lead to fog forming in low lying areas. High pressure should remain dominate Wednesday but could see a few pulse storms firing along the Blue Ridge in the afternoon. These storms may drift east over the foothills before fading in the evening. Fog will be possible overnight in areas that see rain during the afternoon. Temperatures will warm above normal Wednesday with readings in the 80s, possible lower 90s across Southside VA. Dew points will also increase into the upper 60s to mid 70s. && .LONG TERM /THURSDAY 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. 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 /11Z MONDAY THROUGH FRIDAY/...
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As of 715 AM EDT Monday... Wedge in place with southeast flow will keep cigs in the MVFR to at times IFR range this morning, with lowest cigs along the Blue Ridge. For taf sites, appears mainly MVFR. Two areas of showers this morning, one from ROA-LYH, and scattered southward toward INT. Another area near LWB and points west. Will maintain VCSH most of the time with some tempo groups this morning to account for radar/high res trends. Overall rainfall will be light- moderate and can drop vsbys to 3-4sm. As of the this discussion, not too impressed with thunder chances, given extent of clouds, but some instability is possible, especially outside the wedge toward BLF. At the moment will keep VCTS out of the tafs. Better coverage of showers will be along/west of the Blue Ridge today, then from MKJ-TNB east to DAN tonight. Cigs overall should mainly stay MVFR though periods of IFR/VFR are possible. Late tonight models show less shower coverage and could see MVFR to IFR fog at most sites. Extended Aviation Discussion... Surface high pressure moves east Tuesday, but with weak wedge still in place could see lingering sub VFR cigs into midday Tuesday over BLF/LWB. Wed-Fri will have more instability and scattered to numerous showers, with thunderstorms and MVFR ceilings and visibilities possible during the afternoon and evening. Thursday-Friday appear a little more active than Wednesday.
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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/WP NEAR TERM...WP SHORT TERM...RCS LONG TERM...NF AVIATION...AMS/DS/WP EQUIPMENT...RAB/WERT

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