Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 300757 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 357 AM EDT MON MAY 30 2016 .SYNOPSIS...
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Tropical depression Bonnie will stay near the South Carolina coast today into tonight, slowly working northeast to the North Carolina coast Tuesday. A cold front arriving from the west Friday will finally boot Bonnie out to sea.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 330 AM EDT Monday... Tropical depression Bonnie continues to track very slowly if at all between Charleston and Myrtle Beach. Water vapor satellite shows a plume of tropical moisture feeding into the NC coast then northward across the Virginia piedmont. Drier air is situated across the Appalachians with more moisture with a shortwave moving across the Ohio Valley. Early this morning a narrow band of showers had formed near I-77 in NC north along the Blue Ridge of Virginia. The 04z HRRR seemed to be picking up on this fairly well with subsequent 06z run also hitting the southern Blue Ridge into the NC foothills with best threat of showers this morning with isolated to scattered coverage to the east. At the same time fog was becoming dense where it had cleared along and west of the Blue Ridge from Fancy Gap north toward I-81 from Marion to Christiansburg. Think fog will be periodic based on in and out lower clouds and possible showers but enough coverage of lower visibilities to warrant a Special Wx Statement. For today, any fog will be diminishing by 9am. Following the HRRR into late morning and blending with the 00z GFS as it seemed to have a decent handle on synoptic features gives us isolate to scattered showers til lunchtime. Should see some sunshine enough to destablize the airmass. More thunder is expected this afternoon, but not expecting it to be widespread, as it will be dependent on how much sunshine occurs. This afternoon, thinking the better low level convergence stays near the Blue Ridge and the across the Piedmont roughly east of a LYH-DAN line and moreso east of our forecast area. Looking for high chance to even low likely pops along and either side of the Blue Ridge this afternoon and then east of South Boston to Charlotte Court House with low/scattered threat elsewhere. Given the flow from the sfc-7h mb will be mainly light from the NNE should see some heavy rain potential with slow moving storms and precipitable water values of 1.5". At the moment will not highlight this in the HWO as it will be isolated, but would not be surprised that a flood advisory or even a flash flood warning is issued later this afternoon for small scale area. With a little more sunshine or breaks expected went close to MAV guidance on highs with mainly upper 70s to lower 80s across a good deal of the region. Slightly cooler in the lower to mid 70s along the Southern Blue Ridge. Tonight, remnants of Bonnie still situated near the NC/SC coast. Models show deeper moisture well east of us but will still be in a tropical like airmass and think showers will linger all night, though coverage will lessen as will thunderstorm threat. Will go with isolated coverage most of the night and still looks like areas near the Blue Ridge may stay in more of a favorable low level convergence zone to keep isolated showers here through the overnight. Drier air will try to make it at least to the WV/VA border south toward the NC/TN border. This gradient will likely enhance fog potential with fog likely most areas overnight.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/...
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As of 210 AM EDT Monday... Tropical Depression Bonnie will continue to linger over the Carolinas through Thursday. While Bonnie is inland, she will continue to weaken, losing her closed circulation aloft. However, she will maintain and generate spiral bands of convection, especially during the afternoon, fading in the evening. These bands will likely move east over the piedmont, possibly making it to the Blue Ridge each afternoon. Even if these bands do not track that far east, afternoon heating and easterly upslope in a tropical air mass should be enough to generate scattered showers and an isolated thunderstorm along and west of the Blue Ridge Tuesday and Wednesday afternoon. By Thursday, a closed low is expected to move over the Great Lakes and its associated cold front will enter the Ohio Valley. This front will give Bonnie a nudge out to sea. This cold front and remaining tropical moisture will bring a good chance for widespread showers Thursday and Thursday night. Temperatures will continue to warm by a degree or two each day until the front moves east of the area Thursday night into Friday. Temperatures will generally warm into the upper 70s to lower 80s. Overnight lows will remain muggy and in the 60s.
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&& .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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As of 400 PM EDT Sunday... A cold front Friday will result in an increased threat for showers/storms...its passage bringing a less humid airmass to the region for the weekend. Until the frontal passage at the end of the week, temperatures, especially the overnight lows, will favor above normal readings. After the frontal passage, lower dewpoints and clearing skies will support lower nightime lows. Daytime highs are advertised to be close to normal.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/... As of 137 AM EDT Monday... Terminals will be tricky this morning as skies had cleared enough to allow fog to form and start to form. Any fog is contingent on how much low and mid deck forms and/or moves in. Have high enough confidence in the LWB/BCB terminals to put MVFR fog with tempo IFR to LIFR vsbys and/or cigs. Liked the overall solution of the GFS and 4z HRRR which paints some light showers near DAN this morning then develops some toward BCB/BLF after 08-10z. Further east there should be some breaks as well and with rainfall earlier fog will be a fair bet at LYH/DAN, and possibly ROA. Overall keeping them MVFR fog with possible IFR cigs. Expect some slow deterioration to any lower cigs this morning and will see a few showers around. As we head toward late morning into early afternoon look for more of a broken deck of cu/sc rising to high end MVFR then VFR. Nothing to focus where shra/storms form but looking at shotgun effect with all terminals possibly having at least a shower or tsra in the vicinity during the afternoon, so kept that in from previous taf issuance, but delayed based on the fact the heating will be delayed with low clouds to start the morning. Any showers will dissipate somewhat enough to take VCTS out of the Tafs by 00z/31. Fog will be possible moreso after the end of this taf cycle. EXTENDED DISCUSSION... There may be a repeat of tonight again Monday night into Tuesday morning. What remains of Bonnie appears to stay situated over the SC coast with our area staying just close enough to keep a few showers around at night then scattered storms during the afternoon again Tuesday. This looks to possibly play out again Tuesday night into Wednesday. Finally an stronger upper trough will kick what is left of Bonnie out to sea Thursday-Friday. Thursday may be our driest day with frontal showers and storms Thu night into Friday. Overall looking at possible MVFR to IFR at night through Thursday morning, with mainly VFR during the day except in showers/storms. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...RCS LONG TERM...PM AVIATION...WP

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