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
761 FXUS64 KHUN 311035 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 435 AM CST Fri Jan 31 2025 ...New NEAR TERM, SHORT TERM, LONG TERM... .NEAR TERM... (Today) Issued at 435 AM CST Fri Jan 31 2025 A mid-level cyclone currently resides across central MO, with a broad belt of 80-90 knot SW flow aloft in place across the TN Valley within the gradient between the low and subtropical high centered across the Greater Antilles/southeastern Bahamas. In the lower-levels, a gradually deepening area of low pressure will lift northeastward across MO and into west-central IL by 12Z, with an extensive band of light-moderate rain and embedded thunderstorms progressing slowly eastward through our region in advance of a surface trough axis that will eventually veer moderately strong southerly flow to the south-southwest. Although dewpoints have recovered into the m-u 50s, SPC mesoanalysis data suggests that MUCAPE remains in the 100-200 J/kg range at most, and with a 55-65 knot SSW low-level jet predicted to veer and subside by sunrise, we are not expecting any organization to the convective elements within the broader band of precipitation. Over the course of the day, the previously mentioned mid-level cyclone will open into a positively-tilted trough and shift slowly east-northeastward into the Upper OH Valley, as the related surface low tracks eastward into central PA. This configuration will result in a slower progression of the initial precipitation band across our region, with it now predicted to spread slowly eastward and out of the region between 18-21Z. However, solutions from the 0Z HREF and global models all suggest that redevelopment of showers and thunderstorms will occur by mid-afternoon across a broad region from central KY southwestward into the Mid-South region. This will occur as deep-layer ascent strengthens ahead of the approaching shortwave trough, and as temps rise into the l-m 60s, steepening low-level lapse rates in the wake of morning precipitation. Although CAPE may be a bit higher, ensemble data still suggests 100-200 J/kg at most, with lightning the greatest concern. && .SHORT TERM... (Tonight through Sunday night) Issued at 435 AM CST Fri Jan 31 2025 Late afternoon showers and thunderstorms will likely continue beyond 0Z this evening, but should spread east-southeastward with time and exit the region by 3Z as the initiating mid-level trough translates further eastward and away from the region. A cold front will veer low-level flow to the NNW for most of the CWFA by Midnight, with widespread postfrontal stratus clouds expected to blanket the region during the early morning hours on Saturday. With the incoming airmass Canadian in origin, temperatures will likely fall into the lower 40s by sunrise (although this could be a few degrees warmer due to the presence of low clouds). Data from the most recent suite of global models suggests that an unamplified westerly flow aloft will set up across the TN Valley from Saturday-Sunday night, while light SE return flow gradually develops from Saturday afternoon-Saturday evening as a high pressure cell shifts southeastward across New England and a northern stream trough (dropping southward along the Pacific Coast of British Columbia) induces development of a surface low in the lee of the northern Rockies. Although periods of enhanced cloud cover may occur on Saturday/Saturday night, conditions will remain dry and mild with highs returning to the l-m 60s Sunday (after only reaching the m-u 50s Saturday) and lows remaining in the l-m 40s. && .LONG TERM... (Monday through Thursday) Issued at 435 AM CST Fri Jan 31 2025 In the extended portion of the forecast, present indications are that zonal flow aloft will persist across the local forecast area for much of the new work week, as our region will remain located along the northern rim of a strong subtropical ridge centered well to our southeast. Light-moderate southerly low-level flow will continue at the surface, to the south of a developing warm front that will extend eastward into the OH Valley from a new area of low pressure across the southern High Plains. This, coupled with a west-southwesterly low-level jet of 20-25 knots, will result in warm afternoon temps in the l-m 70s, with lows increasing as well (into the u50s-l60s by Wednesday/Thursday mornings). As dewpoints finally begin to increase into the u50s-l60s by Tuesday night, low stratus clouds will become more common across the region, with a few showers/thunderstorms possible as well. However, we have kept POPs ~20% through Wednesday night and increased them to ~30-40% on Thursday (at which time moisture may begin to pool across the region ahead of a stronger cold front dropping southeastward through the Mid-MS Valley). && .AVIATION... (06Z TAFS) Issued at 1151 PM CST Thu Jan 30 2025 VFR conditions are expected at both terminals through 7-8Z. LLWS is expected at the start of the TAF period at both terminals where around 2000 feet winds will increase to around 45 knots from the SSW. More persistent MVFR or lower CIG/VSBY restrictions are expected as widespread rain and maybe a few -TSRA move into the terminals after 07Z to 08Z with continuing LLWS around 45 knots from the SSW. Around 15Z at KMSL (maybe a tad sooner), expect precipitation to end, though MVFR CIGS will linger. -RA may persist at bit longer at KHSV into the early afternoon hours before ending with lingering MVFR CIGS continuing. A PROB30 group was included for possible redevelopment in the late afternoon hours of a few showers. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...70/DD SHORT TERM...70/DD LONG TERM...70/DD AVIATION...KTW