Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
838 FXUS61 KRNK 301901 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 301 PM EDT Sun Jun 30 2024 .SYNOPSIS... A cold front will move across the mid-atlantic region, with scattered showers and thunderstorms through this evening. Less humid air arrives Monday, along with cooler temperatures, fair weather persisting into Tuesday. Temperatures start to heat up again by the 4th of July. && .NEAR TERM /THROUGH MONDAY/... As of 300 PM EDT Sunday... Key Message: 1) Hot and humid with scattered showers/storms through this evening. 2) Cooler and less humid Monday. Steamy airmass covers entire forecast area with dewpoints in the 70s. Its uncomfortable to say the least... HVAC units having to work a little harder to remove the moisture from the air. This entire airmass is getting compressed ahead of an approaching cold front...regional PWAT values AOA 2 inches. Weather focus through this evening will be on the potential for showers and thunderstorms. The airmass certainly supports them, but there are limitations. The morning RNK and GSO soundings indicated westerly winds both surface and aloft. Westerlies over the mountains tend to suppress deep convection due to downward motion lee off the ridges, but since there is no capping inversion, think we will see at least some scattered activity over the mountains until sunset. Better convergence is expected over the piedmont where the westerlies over the mountains meet the southwesterly winds over the piedmont. This lee trof or convergent area should provide the better focus for deep convection with main severe threat from Highway 29 east toward the coast. Another area to watch is a mesoscale convective vortex (MCV) that is moving east-southeast along the KY/TN border. The models do not seem to be picking up on this feature very well, but experience would support clustering of deep convection underneath and in advance of this feature as it moves east- southeast through the NC High Country and Carolinas. That said, will maintain at least chance pops for scattered showers across the entire CWA but likely pops or numerous showers and thunderstorms for the VA/NC piedmont, and across the southwest mountains (Mount Rogers) of VA and into the NC High Country. Whether any of this becomes severe will be highly dependent on buoyancy and organization. Wind profiles are unidirectional with little or no directional shear. This would imply a predominantly multicellular storm mode. The high PWATs suggest thunderstorm cores will be very rain efficient with water loading resulting in some healthier downdraft winds. Forecast SBCAPE of 2000 g/kg is respectable...so would think damaging isolated severe gusts would be the modus operandi for the stronger storm cells through this evening. By in large today will be the best chance for getting any rain (and that is not saying much). Once the front comes through tonight, pops go way down until later in the week. Until the front clears the area, humidity levels will remain elevated. Temperatures will also remain quite warm (hot actually) with oppressive dewpoints. Expectation is for a wholesale change in airmass overnight with a much more pleasant day Monday. Dewpoints are expected to fall at least 20 degrees...falling into the 50s for Monday! Temperatures will also come down...a pleasant way to start the first day of July. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 200 PM EDT Sunday... Key Messages: 1: Heat ramps up heading towards Independence Day The first half of next week will be characterized by surface high pressure an intensifying subtropical ridge growing out of the southern plains and covering most of eastern and southern CONUS. This will result in daily increases in temperature as well as dewpoint. Highs on Monday will grow from the mid 80s/ upper 70s, and become 80s and low 90s by Wednesday July 3. Summer will make its presence known. All of this ridging and high pressure will keep skies clear and prevent shower formation, so shade and remaining indoors will be the only reprieve from the heat. This period of high temperatures and no cloud cover will only serve to worsen the abnormally dry and moderate drought conditions we`re experiencing in the region. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 230 PM EDT Sunday... Key Messages: 1: Independence Day hot with potential for storms 2: Unsettled second half of the week Independence Day (Thursday) will likely be the hottest day of the week, and even the hottest of the season so far. Highs east of the Blue Ridge will be well into the 90s. Heat indices towards central VA and Southside VA will likely exceed 100F for a few hours in the afternoon Thursday and Friday. At the same time a front looks to finally break through the ridging over the southern CONUS, bringing the next shot of showers and storms since this weekend. Following the ridge weakening and surface high pressure being displaced, several waves with indeterminate timing will keep showers and storms in the forecast from Thursday on through the weekend. Timing of showers will be monitored closely as we forecast for holiday activities. Confidence is increasing for stormy conditions on Independence Day to potentially disrupt activities. After Independence Day, temperatures could moderate a bit, but still expecting temperatures and heat indices well above normal. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... As of 300 PM EDT Sunday... Scattered showers/storms to persist through sunset, then expect clearing. Greatest coverage is expected south of I-64. A wind shift will take place later this evening. A cold front over the Ohio Valley will cross the mountains, winds ahead of the front are out of the WSW. Expect them to shift to the north overnight...then out of the northeast for Monday. A wholesale change in airmass is expected for Monday...featuring cooler temperatures, lower humidity, and clear skies. Confidence in the above scenario is moderate to high. EXTENDED AVIATION OUTLOOK... Monday-Wednesday appear to be VFR as high pressure works in from the north. Could be some fog Monday night in the river valleys and for areas that received significant rainfall. Storm chances increase by Thursday ahead of a front so sub-VFR possible. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...VFJ LONG TERM...VFJ AVIATION...PM