![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
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
381 FXUS64 KHUN 161408 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 908 AM CDT Fri Aug 16 2024 ...New NEAR TERM... .NEAR TERM... (Rest of Today) Issued at 908 AM CDT Fri Aug 16 2024 An active day of weather across the Tennessee Valley is on tap, with both excessive heat impacts and strong/severe storms in the forecast. Ahead of a surface cold front, warm moist air is pooling over the Tennessee Valley with the combination of high temperatures in the mid to upper 90s and dewpoints in the mid 70s creating heat index values of between 105-109 degrees. A Heat Advisory is in effect from 11 AM to 5 PM today for areas along and west of I-65. This slow- moving cold front will approach the region later this afternoon, serving as a forcing mechanism for clusters of showers and thunderstorms. Sufficient heating the morning hours should create a moderately unstable environment in the afternoon with SBCAPE values around 2000-3000 J/kg in an uncapped environment. Additionally, soundings show quite a bit of dry air at the mid- levels with a pronounced inverted-v profile. Thus, think there will be a threat for microbursts with the strongest cells as well as damaging straight- line wind bursts in any line segments that can develop. This will be very mesoscale driven, but timing looks to be mainly this afternoon, with convection waning by early this evening. && .SHORT TERM... (Tonight through Saturday night) Issued at 357 AM CDT Fri Aug 16 2024 This activity will likely push east of the area after 9 or 10 PM and dissipate. The highest and better chance of showers and strongest thunderstorms looks to be near and east of the I-65 corridor into southern middle Tennessee. Temperatures will still be rather warm when you wake up on Saturday morning (68-73 degrees) given expected cloud cover. Highs look like they will be hard pressed to climb above the 90 to 94 degree range. This should keep heat index values at bay. They could briefly hit 105 degrees for an hour, but not long enough to entertain another Heat Advisory yet. The actual cold front associated with this storm system doesn`t really move much on Saturday. Additional disturbances move either ESE or SE along the front Saturday into Saturday night. Just how they move will have a big impact on the forecast on Saturday. For now, going with the clustering of most guidance, which moves another disturbance east from southwestern Missouri into the area on Saturday. This appears like it could be more widespread coverage of showers and thunderstorms on Saturday afternoon into Saturday night in northwestern Alabama. Shear will be strong with more widespread shear of 35 to 40 knots shown in most models over the area. However, due to more prevalent cloud cover with showers/convection likely starting a bit sooner by the late morning/early afternoon, instability and lapse rates don`t look as good as on Friday. Despite this, there will still be enough instability (1000-2000 J/KG) for at least marginally severe storms to occur. Main threat again will be damaging winds, frequent lighting, and heavy rainfall. && .LONG TERM... (Sunday through Thursday) Issued at 357 AM CDT Fri Aug 16 2024 Consensus guidance from the 16/00Z suite of global models suggests that a mid-level longwave trough will become established across eastern North America early in the period, with moderately strong NNW flow aloft predicted to remain in place across the TN Valley through the middle of next week. At the surface, an area of low pressure will shift east-northeastward across southern Quebec and into western New England on Sunday/Sunday night, with the trailing cold front expected to cross the CWFA at some point Sunday afternoon. Thus, a low-medium (20-40%) chance for showers and a few thunderstorms has been maintained in the grids through late Sunday morning. Although some wrap-around stratus clouds may impact the northeastern portion of the region on Sunday night/Monday (in the wake of the departing cyclone), probabilities for any light rain showers or sprinkles remain very low (5-10%). Light-moderate N-NE flow will advect a cooler/drier continental airmass southward early next week, with highs falling into the m-u 80s for most of the region beginning Monday, and lows dropping into the u50s-l60s Tuesday morning (and perhaps m-u 50s Wednesday morning). Present indications are that low- level ESE flow will return Wednesday night as a subtle surface trough retrogrades westward across the region, and this will allow for a minor increase in both low-level moisture and chances for showers on Thursday. && .AVIATION... (12Z TAFS) Issued at 653 AM CDT Fri Aug 16 2024 VCTS was included at KMSL from 14Z for isolated to scattered showers or thunderstorms that may come close to the terminal. A better chance of -TSRA is expected at KHSV later this afternoon. Thus, a tempo group was left in for that terminal for MVFR CIGS/VSBYS due to -TSRA activity. Winds should be light and variable by the evening hours. Patchy fog was included at KHSV, since a better chance of rain is expected there. Otherwise, VFR conditions are expected. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory from 11 AM this morning to 5 PM CDT this afternoon for ALZ001>007-016. TN...Heat Advisory from 11 AM this morning to 5 PM CDT this afternoon for TNZ096. && $$ NEAR TERM...AMP.24 SHORT TERM....KTW LONG TERM....70 AVIATION...KTW