Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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064 FXUS61 KRNK 041438 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1038 AM EDT Tue Jun 4 2024 .SYNOPSIS... High pressure will cover the western Atlantic and southeast United States today. A cold front approaches Wednesday bringing better coverage of showers and thunderstorms to the area. The front will move across region Thursday. A brief break in the wet weather pattern is expected behind the front on Friday and Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 1030 AM EDT Tuesday... Key Messages: 1. Warm and humid. 2. Scattered afternoon and evening showers and thunderstorms. Morning soundings support SBCAPE ranging from 1500 j/kg over the mountains to 2500 j/kg over the piedmont...enough buoyancy for scattered afternoon and evening showers and thunderstorms. Mean wind ranges from 5-8 mph out of the southwest...so expecting slow cell movement...and not surprising since upper level ridge is directly overhead. For this afternoon, our area will be under an upper ridge, although the axis should begin to shift east allowing a weak upper level impulse to head toward the southern Appalachians with it traversing into the Blue Ridge of VA overnight. Airmass will have average pwats running 1.2 to 1.5 inches this afternoon, so with a weak steering flow, storms could be slow moving and some will likely produce heavy downpours. Interacting outflows look to give the greater concentration of storms from the NC mountains up the Blue Ridge toward Roanoke, where will have high chance, then lower pops west and east of the Blue Ridge to isolated in the piedmont and across the mountains of SE WV. Low confidence on coverage as high-res models are showing some wide variance in where the concentration will be highest, but blend has it along the Blue Ridge. Should see a decrease in coverage this evening into the overnight but do not see radar becoming rain free, as showers could linger into dawn Wednesday as shortwave ridge breaks down as front approaches. After any fog lifts this morning look for sunshine to give way to building cumulus with a mix of clouds and sun in the afternoon. High temps will run around 5 degrees above normal with mid to upper 80s east to mid 70s to lower 80s across the mountains. Continued mild Tue night with lower to mid 60s areawide. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... As of 200 AM EDT Tuesday... Key Messages: 1. Showers and thunderstorms through midweek. 2. Moderate to heavy rain may lead to localized flooding Wednesday. 3. Warmer than normal temperatures through Thursday, cooler Friday. Slight ridging aloft ahead of an approaching upper trough will be over the eastern US through the middle of the week, allowing for warmer temperatures to continue. The trough, centered over south central Canada, will become more negatively tilted through the midweek, and its associated cold front will reach the central Appalachians and Mid Atlantic by late Wednesday into Thursday. Thunderstorms are possible along and ahead of this front, with the greatest chances over the western mountains Wednesday afternoon and evening. An upper shortwave rounds the base of the trough late Wednesday, which will provide additional support aloft for showers and thunderstorms. Above normal precipitable water values indicate potential for locally heavy rain, which leads to a marginal risk of flooding from excessive rainfall Wednesday. Ample moisture and modest instability will increase chances for and coverage of thunderstorms Wednesday into Thursday. The surface front will cross the area Thursday, which will bring an end to the showers and storms, though some showers could linger in the mountains through the day. Friday looks to be dry, but breezy given the decent cold air advection behind the front. Cooler and drier air works its way into the region following the frontal passage, so temperatures will drop a few degrees for Friday and heading into the weekend. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 200 AM EDT Tuesday... Key Messages: 1. Cooler temperatures through the weekend. 2. Chances for afternoon showers and storms continue through Sunday. The mid level trough will be situated over southern Canada and the eastern US through the weekend, with a few shortwaves rotating through the trough, keeping chances for showers and possible storms each afternoon and evening in the forecast, especially over the mountains. Some long range models are showing a surface low and cold front developing in the south central Plains by late Saturday, reaching the Mid Atlantic by Sunday, bringing another round of heavy rain and possible storms. However, with considerable differences in the models with the evolution of the upper trough over southern Canada, there is uncertainty in the forecast for the beginning of the work week. That being said, there is potential for unsettled weather to continue into Monday. Temperatures will be on the cooler side through the weekend, near to a few degrees below normal, following the passage of the cold front during the week, and dewpoints will drop a few degrees as well. By the beginning of the work week, temperatures will start gradually warming to near normal. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... As of 1030 AM EDT Tuesday... Expect cloud build-ups through early afternoon with development of widely scattered showers/storms, favoring both mountains and piedmont, but with little organization. Due to the slow movement, coverage, and timing of storms, forecast confidence is too low to include in the TAFs. Overall should be VFR with a light southeast wind. Fog will likely form late tonight with MVFR to IFR at most sites, highest confidence for LWB to get fog. EXTENDED AVIATION OUTLOOK... Morning fog is possible in mountain valleys Wednesday. Greater likelihood of flight restrictions/MVFR (or lower) on Wednesday and Thursday with showers and thunderstorms ahead of a cold front. Friday is expected to be drier and a better probability of VFR conditions behind the front. A few showers possible Sat in the mountains but mainly VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS/WP NEAR TERM...PM/WP SHORT TERM...AS LONG TERM...AS AVIATION...SH/WP