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
41
42
43
314 FXUS61 KRNK 221825 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 225 PM EDT Sun Sep 22 2024 .SYNOPSIS... A weak cold front will sink southward across the Piedmont today, bringing a north-northeasterly wind shift to the lower Mid-Atlantic. Another cold front will approach slowly from the west tonight into Monday, bringing rounds of on-and-off shower activity to region through much of the coming workweek. A return of high pressure will bring drier conditions for the end of the week. && .NEAR TERM /THROUGH MONDAY/... As of 200 PM EDT Sunday... Key Messages: 1) First day of fall living up to its name! 2) Clouds increase tonight after sunset, with showers moving in from the west towards morning. 3) Periods of showers and storms throughout Monday, mainly for the mountains. A backdoor front was in the process of sinking south across the eastern part of the forecast area, allowing cooler and drier air to filter in from the north. This could be seen in the visible satellite imagery this afternoon, as stratus remained socked in over eastern and central VA, east of a Buena Vista to Lynchburg to Danville line. Temperatures there were in the low to mid 70s, while to the west temperatures were in the low 80s to mid 80s under full sunshine. Aloft, troughing over the western Atlantic will continue to drift east, allowing weak ridging to shift east as well. This will put the Mid Atlantic region right in the path of a stream of upper level energy in due westerly flow, and will help fuel showers and thunderstorms throughout the day Monday, at least for part of the area. CAMs seem to show a first wave of showers developing mainly between 5 and 9 AM over the western mountains. To the east, wedging high pressure will support dense fog and stratus, and less convection. Overnight lows will be in the upper 50s to mid 60s. After a brief break in the rain and perhaps some partial clearing in the late morning to early afternoon hours, another stronger area of showers and storms will arrive ahead of a cold front. This area of storms will arrive in a semi-linear fashion, and again will impact the mountains and foothills most. Moderate to heavy rain leading to flooding looks to be the main concern. An isolated damaging wind gust is possible, but any significant severe weather is not likely due to morning clouds, stratus, and overall lack of instability. Temperatures will reach the low to upper 70s, with cooler readings over the east. Confidence in the near term is moderate. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 200 PM EDT Sunday... Key Messages: 1: Daily showers and storms for the first half of the week A frontal system will begin to move into the OH River Valley from the plains, and lift a nearly stationary front in the Mid-Atlantic back to the north. Along with an incoming cold front to the west, this setup places us in the warm sector with significant southerly flow and moisture convergence. Looking at instability on Tuesday and Wednesday afternoon, CAPEs are generally between 500-1000J/kg, which are certainly high enough to force some convection and a few storms amongst the showers. The high levels of moisture and blanket of cloud cover will hold onto heat in the overnight periods, keeping overnight lows above normal, but preventing extensive surface heating during the day, and holding daytime highs around or just under normal in the mid to low 70s for most. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 130 PM EDT Sunday... Key Messages: 1) Showers and a few storms will be possible for Thursday, with precipitation chances decreasing for Friday into the weekend. 2) A potential tropical system in the Gulf of Mexico could bring impacts to our area next weekend, but confidence is currently low. An upper-level trough will move across the northern US later this week and move over the Ohio River Valley. This along with highs in the 70s to around 80 degrees will allow enough lift for showers and storms to occur across the area on Thursday. Friday will have similar conditions but increasing cloud cover will keep high temperatures in the low to mid 70s into the weekend. High pressure over New England builds and begins to wedge in across the CWA on Saturday. This will decrease rain chances, but heavy cloud cover with upslope flow will persist with a few showers still possible. Confidence in this forecast remains very low, as models are in disagreement over the timing and location of the upper-level trough previously mentioned. This trough will also play a very important factor in the timing and direction of a potential tropical disturbance in the Gulf of Mexico later this week. Models are inconsistent with each run, having the system track anywhere between the southern Ohio River Valley to along the East Coast. The GFS and ECMWF MSLP ensemble members generally have the system tracking into the southern Appalachians or just to the west into Tennessee, but each run has not been consistent to this point. Regardless, there is an increasing chance that a tropical system may head towards our CWA next weekend, but confidence remains low for any impacts that may occur. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 220 PM EDT Sunday... Stratus continues to affect areas east of LYH and DAN this afternoon, and stratus and fog are expected to build back west after dark, dropping most of the region into LIFR/IFR conditions after 23/05Z. MVFR conditions return to BLF and LWB for a change by mid morning tomorrow, as showers enter the area. SHRA/isolated TSRA will be possible for mainly the mountains through 18Z. To the east, showers will be possible later, but thunderstorms are less likely there due to MVFR stratus lingering. Winds will be light and variable overnight, becoming westerly and 5 to 10 kts for the mountains, and SSE 5 to 10 kts or so for the piedmont. EXTENDED AVIATION OUTLOOK... LIFR/IFR stratus and fog are expected again Monday night into Tuesday morning. Daily chance of showers, thunderstorms, and lingering sub-VFR conditions continue Monday afternoon through at least the week as several systems affect the region. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...NF/SH NEAR TERM...SH SHORT TERM...VFJ LONG TERM...JCB AVIATION...NF/SH