Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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
44
45
46
47
48
49
50
814 FXUS64 KHUN 042322 AAA AFDHUN Area Forecast Discussion...UPDATED National Weather Service Huntsville AL 622 PM CDT Sat May 4 2024 ...New AVIATION... .NEAR TERM... (Tonight) Issued at 319 PM CDT Sat May 4 2024 Some isolated to scattered showers or thunderstorms could end up diving SSE from our southern middle Tennessee counties into portions of northeastern Alabama through 7 or 8 PM. However, coverage should be on the low side (30-40%) at best. Although some instability (1000-2000 J/KG is in place in this area, lapse rates and DCAPE is very meager. With no shear in place, only expect typical garden variety of thunderstorms producing heavy rainfall and some lightning. Expect this activity to become very isolated after 9 PM and mainly occur near the AL/GA border. Winds will be fairly light 2 to 6 mph much of the night. Expect mostly clear skies much of the rest of the evening into the overnight hours. This should allow some fog formation, but winds should be just high enough to kept it isolated in nature. Decent radiational cooling conditions should allow temperatures to drop to or just above dewpoint values though. Thus, expect lows to end up between 60 and 65 degrees in most locations. && .SHORT TERM... (Sunday through Tuesday) Issued at 319 PM CDT Sat May 4 2024 As a stronger disturbance moves north-northeast from northeastern Texas and central Oklahoma late Saturday night into Sunday morning, a warm front ahead of it moves northeast into northern Arkansas by the mid-afternoon hours. Models form robust convection along this warm front. However, most models only develop this convection as far east as Mississippi through the afternoon hours. This is a good thing given the sounding parameters further east into northern Alabama. This will likely keep any severe thunderstorm activity to the west of the area through the afternoon hours. Models do push this warm front further north into northwestern Alabama between 7 and 9 PM. However, models really drop off instability these storms have to work with during that timeframe. Shear continues to be too weak to support any severe weather. Gusty winds, frequent lightning, and heavy rainfall could occur as this weakening convection moves into the area and across northern Alabama and southern middle Tennessee overnight. If this activity along this warm front moves in sooner than expected, then a severe downburst or large hail threat might materialize. However, this is not expected as mentioned before. Models weaken this upper level disturbance and have it move more to the east Monday into Monday night. Not expecting as widespread or strong thunderstorm activity this far south, with the main energy with this disturbance remaining more over northern Tennessee into the Ohio Valley. However, high chance to likely chances of showers and thunderstorms should still remain in the forecast through the day on Monday. A drier pattern with zonal flow aloft is in place Monday night through Wednesday. Very strong warm air advection develops ahead of a strong cold front that develops over the central CONUS on Tuesday. 925 mb temperatures between 23 and 26 degrees are advected into the area ahead of the developing cold front well to our west. This should allow temperatures to climb into the mid to upper 80s during this period in the afternoon, despite some isolated to scattered showers and thunderstorms. We could see some highs around 90 degrees on Wednesday, but kept things a tad cooler for now. These isolated to scattered showers or thunderstorms should remain fairly unorganized, given low shear value and lack of drier air aloft. && .LONG TERM... (Wednesday night through Saturday) Issued at 319 PM CDT Sat May 4 2024 The more reasonable scenario for Wednesday evening into Thursday continues to look like an MCS ahead of that stronger cold front reaching our region by Wednesday evening. In this case, redevelopment of thunderstorms would occur along the path of the surface low (across MO) early Wednesday afternoon that could potentially grow upscale into a larger and more significant MCS that would move through our region late Wednesday night/early Thursday morning. This convective system would be entering an environment of even stronger deep-layer shear (with WSW flow aloft of 45-50 knots) and moderate-high levels of instability driven by surface dewpoints in the lower 70s beneath a plume of steep lapse rates aloft. Thus, a notable risk of severe thunderstorms producing large hail and damaging winds may materialize during this timeframe. A third and final round of storms may occur on Thursday night/Friday morning prior to the eventual passage of a cold front that should bring a drier/cooler airmass into the region by next weekend. && .AVIATION... (00Z TAFS) Issued at 622 PM CDT Sat May 4 2024 Low chances (15-25%) of showers/storms will persist through this evening, then diminish for the overnight period. Patchy fog is possible at the terminals, with forecast MVFR conditions at HSV and IFR at MSL later tonight; however, this will be reassessed at the next TAF issuance for any potential of patchy, dense fog. Confidence was too low to include in the TAFs at this time. Any fog will then lift and dissipate through 14Z, with low to medium (30-50%) chances of showers/storms to follow Sunday afternoon. Winds will decrease to be light and variable tonight, then become southwesterly at around 5 knots or so on Sunday. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....KTW LONG TERM....KTW AVIATION...26