Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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597 FXUS61 KRNK 051356 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 956 AM EDT Fri Jul 5 2024 .SYNOPSIS... High pressure offshore will continue to keep muggy conditions around through tonight, with heat indices exceeding 100 degrees in the Piedmont. A front is going to reach Ohio/TN Valleys this afternoon and several impulse will lead to scattered to numerous thunderstorms. This front will pass across the Mid-Atlantic by Saturday night into early Sunday. Spotty showers and thunderstorms will remain in the forecast for early next week as an upper level trough develops over the central United States. && .NEAR TERM /THROUGH TONIGHT/... As of 945 AM EDT Friday... Key Messages: 1) Heat Advisory remains in effect this afternoon/evening for our foothill and piedmont including Roanoke/Lexington, VA. 2) Strong to severe storms possible this afternoon with the main threat being damaging winds. Greater chances in the mountains. Expect an unstable/humid airmass this afternoon. With plenty of sunshine this morning, SBCAPEs are forecast to reach 2000-3000 J/kg by mid afternoon across southern VA into NC. There is a convective system moving across central KY into Mid TN this morning with an associated MCV. This piece of energy should reach our mountains by mid afternoon and push into the piedmont by later in the afternoon. Enough instability and high pwats to bring a damaging wind threat for any storms that form or move in this afternoon. Majority of convective allowing models have storms arriving in our mountains between noon-2pm, then better chances will be in the 3pm-9pm time frame. Better coverage still looks across our mountains of SW VA/southern WV into NC, with less in the piedmont. No changes to heat headlines. Previous discussion... A blocking high stretched from the central Atlantic and into Africa, and was keeping low pressure in the western Atlantic from progressing east. This in turn has resulted in slow movement of the weather pattern affecting much of the eastern CONUS. Within this broad trough, additional bands of PVA arriving today will provide lift for convection. Surface low pressure and associated fronts will near from the west but not cross until sometime Saturday, but we still have a lee trough in the area today to provide some focus. Showers and thunderstorms will develop over the southern Blue Ridge and also arrive from the west around late morning to noon. Instability will be a little better than yesterday, and shear will also be improved. Shear will be marginal and likely not enough for supercells, but we should see good coverage of multicells producing heavy rain and also some instances of damaging winds this afternoon and evening. Today will be slightly hotter and a bit more humid in spots compared to yesterday, but overall pretty similar. Current dew points were in the upper 60s to lower 70s, and southerly winds today will keep transporting Gulf of Mexico moisture to the Blue Ridge where it will interact with a lee trough. The 04/12Z and 05/00Z RNK soundings both had PWATs of 1.72", and this number beat the old record of 1.71" for that date set in 2013. NAEFS situational awareness table as well as the ECMWF Extreme Forecast Index and Shift of Tails point towards continued anomalous warmth and humidity today. PWATs will likely top 2.20" for parts of the Piedmont, and almost 2" for the mountains. Temperatures top out in the mid 80s to low 90s for the mountains, and the mid to upper 90s for the Piedmont. Lynchburg and Roanoke will be closest to meeting or exceeding their daily high records; see Climate section below. A Heat Advisory has been expanded slightly, and is now in effect for parts of north and north central NC, the Roanoke area, and parts of Southside VA and the Piedmont, based on calculated heat indices as high as 109. Please use caution if working or spending time outside, drink plenty of water, and do not leave children or animals unattended in cars. Overnight, shower and storm coverage gradually shrinks to just include the western mountains, as a cold front finally arrives on our doorstep. from the northwest overnight. Expect another humid and warm night, with widespread fog, some of it dense. Confidence in the near term is high. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 200 AM EDT Friday... Key Messages: 1. Good chances for storms producing heavy downpours with a slow moving frontal passage Saturday. 2. Temperatures cool off a bit this weekend. A cold front will be located over the foothills Saturday morning with convection starting by noon. This front will continue its slow track across the area, moving over the piedmont in the evening. With ample moisture and modest instabilities, strong storms with heavy downpours are possible towards Southside VA and northwest NC piedmont. By Sunday morning, this front should be in the coastal piedmont where it will stall and washout. High temperatures Saturday will range from the low to mid 80s across the mountains and low 90s in the foothills and piedmont. Mostly dry weather is expected Sunday which will have temperatures a few degrees warmer than Saturday. && .LONG TERM /TUESDAY THROUGH THURSDAY/... As of 210 AM EDT Friday... Key Messages: 1. Warmer than normal temperatures with daily storms early next week. 2. Trending cooler and possibly drier by mid week. An upper level disturbance will approach the Carolina coast Monday, bring Atlantic moisture into the area. Diurnal/orographically driven showers and thunderstorms are expected during the afternoon and evening, mainly along and east of the Blue Ridge. Models have a cold front moving across the region Tuesday afternoon into Tuesday night. High pressure builds in behind the front, keeping most of the area dry going into next weekend. It is still summer, so can not rule out a few hit and miss thunderstorms Thursday and Friday afternoon. Warmer than normal temperatures expected Monday into Wednesday. Near normal temperatures possible Thursday and Friday. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... As of 950 AM EDT Friday... Mainly VFR through this afternoon, except when any storms move over a TAF site. Best chance of TSRA noon-2pm along the southern Blue Ridge and BLF, then expanding east to the remainder of the TAF sites by 22z, though less coverage in the piedmont (DAN/LYH). Coverage will be more expansive south of a BLF-ROA line. Tonight, SHRA/TSRA will continue to affect mainly BLF and LWB as a front nears. Expect another night of widespread fog and stratus, as low as LIFR. Average confidence in the above forecast. AVIATION OUTLOOK... Saturday and Saturday night, a front will cross the area, bringing additional SHRA/TSRA/fog with possible MVFR or lower conditions. Sunday, the remaining SHRA/TSRA will only affect DAN and perhaps LYH, but fog is expected in locations where it rained Saturday, and some of this may be dense. For Monday, the probability for scattered SHRA/TSRA/MVFR conditions will be mainly confined to the afternoon and evening. On Tuesday and Tuesday night, another front arrives from the west, spreading SHRA/TSRA to the entire area, along with reductions in conditions. && .CLIMATE... As of 300 AM EDT Friday... Record highs and warmest lows temperatures for July 5th. Friday 07/05/2024 Site MaxT Year HiMin Year KBLF 93 1948 71 1969 KDAN 103 1919 76 1926 KLYH 98 2012 75 1900 KROA 100 1999 76 2012 KRNK 94 1930 78 1949 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Heat Advisory until 8 PM EDT this evening for VAZ022>024- 032>035-043>047-058-059. NC...Heat Advisory until 8 PM EDT this evening for NCZ003>006-020. WV...None. && $$ SYNOPSIS...NF/SH/WP NEAR TERM...SH/WP SHORT TERM...RCS LONG TERM...RCS/WP AVIATION...NF/SH CLIMATE...RCS/SH