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
823 FXUS61 KRNK 282356 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 756 PM EDT Fri Jun 28 2024 .SYNOPSIS... A warm frontal boundary will lift into the area overnight bringing widespread clouds. High pressure will shift northeast off the New England coast Saturday, setting the stage for showers and storms mainly for the mountains Saturday afternoon. A cold front pushes through late Sunday. && .NEAR TERM /THROUGH SATURDAY/... As of 735 PM EDT Friday... Key Messages: 1) Warm front overnight will bring widespread stratus. 2) Stratus lingers until mid morning. 3) Chance of convection for western and northern sections tomorrow afternoon and evening, but severe threat looks low. No showers have been able to sustain themselves this afternoon and evening in our forecast area, due to capping and drier air above 700mb. ESE winds were helping to bring moisture to the Piedmont this evening, and expect this moisture increase to continue as a warm front lifts north into the area. We may see a sprinkle or two overnight, but in general we will see mainly low stratus, some ~800ft, especially after 2 AM. Low stratus hangs around through 10 AM or so before beginning to scatter out and lift. A pre-frontal trough will arrive in the afternoon and will bring isolated to scattered showers and storms to the area, mainly west of I-77 and north of I-81. Severe storms look unlikely here, with less than 20 kts of flow at 500mb, 0-6km shear of 10 knots or less, and tall skinny CAPE. The stronger activity will be to our north. That said, slow storm motions, high PWATs, and deep warm cloud depths will increase the chance for moderate rain leading to flooding. As of 200 PM EDT Friday... Key Messages: 1) Upslope scattered showers/few storms through Friday night. 2) More rounds of scattered showers Saturday Shower activity has been sparse today so far, but high res models remain insistent that there will be scattered pockets of precipitation later this afternoon and evening. They won`t be particularly heavy or well organized. Moisture advection from a high to our northeast will cause a mostly upslope event along the mountains of southwest VA and northwest NC. As for Saturday, a broad but deepening upper trough becomes more centrally placed over the eastern CONUS/Mid-Atlantic. This accompanies an approaching front from Canada/Great Lakes. Storms will be better organized than Friday, and there is a marginal risk for severe storms mainly north of the I-64 corridor. Temperatures will be above normal, and with the aforementioned moisture advection heat indices in the Piedmont and Southside VA could approach 100 degrees. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 130 PM EDT Friday... Key Messages: 1. Hot and Humid Sunday, cooler and drier by Monday. 2. Showers and storms on Sunday, with locally heavy rainfall possible. 3. Primary threat is damaging wind. A strong upper level trough will track eastward over the Great Lakes and into the northeastern US through the weekend, and into the Atlantic by the beginning of the work week. The associated surface frontal system will move through the upper Midwest and Great Lakes region, with the cold front reaching the western border of the forecast area late Saturday morning, crossing the area through Sunday. Showers and storms from Saturday may linger overnight into Sunday, which could impact the day`s high temperatures, depending on the coverage of residual cloud cover during the morning hours. This will also play into the potential for severe weather later during Sunday afternoon and evening, as cloud cover could limit diurnal destabilization. That being said, the front will provide a better forcing mechanism for storm development, and increased deep layer shear could lead to better storm organization, thus increasing the potential for storms to become severe. The primary threat with any of these storms would be strong and damaging winds, with high DCAPE forecast, and moderate to locally heavy rainfall is still possible, with above normal precipitable water, indicating plenty of atmospheric moisture available. Timing of the frontal passage itself will also influence the potential for severe storms; if it coincides with the peak diurnal heating, then severe potential is greater. Another factor that could influence the possibility of severe storms is the duration of prefrontal showers and storms that could linger overnight Saturday into Sunday. Behind the front, cooler and drier air works into the region as high pressure builds over the northeast. Temperatures will fall closer to seasonal normals, but the biggest difference will be felt with the drier air, and thus lack of humidity. The surface high will keep the weather quiet Monday and Tuesday, making for a pleasant start to the work week, after a hot and humid day on Sunday. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 130 PM EDT Friday... Key Messages: 1. Increasing temperature and humidity through the period. 2. Showers and storms possible Wednesday into Thursday. 3. Hot and humid weather possible for Independence Day. Surface high pressure will remain situated over the region through Tuesday, keeping the weather dry and quiet. By midweek, an upper ridge starts to build over the southeastern states, increasing 500mb heights over the area, and temperatures will start trending warmer. Southwesterly flow ahead of an approaching cold front will start to advect moisture into the area, increasing the humidity through the middle of the week as well. The combination of increasing temperature and humidity will cause heat indices to rise to the upper 90s to near 100 in the VA Southside and NC Piedmont around Independence Day. The return flow around the high could spark showers and thunderstorms over the southern Blue Ridge, however, coverage is uncertain at this time, given differences in the long range deterministic models. The previously mentioned cold front will slowly approach the Ohio Valley Thursday, keeping shower and storm chances in the forecast Wednesday afternoon through Thursday into Friday, as the region remains in the warm sector until the frontal passage. At this time, the front looks to orient more west to east, and stall across the Ohio Valley and Mid Atlantic, which would continue shower chances through the end of the work week, but with this being at the end of the forecast period, details are uncertain, and thus forecast confidence is lower late in the week. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... As of 710 PM EDT Friday... Ceilings will lower to MVFR/IFR 07-09Z at all terminals as a warm front moves through. We may get a sprinkle or spot of drizzle overnight, but for the most part kept ceilings above 1 kft, except for DAN which looks to have the better easterly flow. However, LYH, ROA, and BCB will also flirt with sub-IFR for a few hours. Ceilings improve after 14-16Z, scattering out and/or lifting for a few hours before afternoon convection begins. Expect TSRA to be isolated, but included -TSRA at BCB, ROA, BLF,LWB and where neighborhood probabilities are higher for at least VCTS/CB for a few hours Sunday afternoon/evening. Confidence in the above scenario is moderate. EXTENDED AVIATION OUTLOOK... A greater coverage of showers/thunderstorms and associated MVFR flight conditions are possible Sunday morning as a cold front nears, then the highest chances moves to the Piedmont in the afternoon, possibly affecting LYH and DAN. Monday and Tuesday appear to be VFR as high pressure works in from the north. On Wednesday there is a chance of -TSRA in the mountains as a warm front and pre-frontal trough nears. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...VFJ/WP NEAR TERM...SH/VFJ/WP SHORT TERM...AS LONG TERM...AS AVIATION...SH