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
754 FXUS64 KHUN 170855 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 355 AM CDT Fri May 17 2024 ...New NEAR TERM, SHORT TERM, LONG TERM... .NEAR TERM... (Today) Issued at 255 AM CDT Fri May 17 2024 An area of low pressure continue to move ESE along a warm front draped just south of the northern Gulf of Mexico. This feature has brought very severe thunderstorm activity to southern Texas and Louisiana/Mississippi very early this morning. However, the strongest activity seems to be shifting more offshore into the Gulf of Mexico over the last few hours. Further north of the low pressure center, a large shield of light to moderate rain with some embedded isolated elevated storms continue to move northeast into the area. In most areas, surface dewpoint depressions are less than 5 degrees. So the expect light to moderate rain being produced by isentropic lift will overspread northern Alabama and southern middle Tennessee over the next hour or so. Based on area temperatures and dewpoints, lows will likely be able to drop into the lower to mid 60s. Most guidance keeps light to moderate rainfall and maybe a few elevated thunderstorms in the forecast this morning, before most of it moves northeast or southeast of the area by the early/mid afternoon hours. This morning rainfall and lingering cloud cover should keep highs noticeably cooler with highs only reaching the lower to mid 70s in most locations (a few upper 60s possible in higher elevations). Most guidance moves an upper level low over NE Texas/eastern Oklahoma ENE along a very slow moving front into central/northern Arkansas late this afternoon into the early evening hours. This should be the focusing mechanism for another round of showers and thunderstorms over those areas mostly to our west. && .SHORT TERM... (Tonight through Monday) Issued at 255 AM CDT Fri May 17 2024 Whether this area of showers and thunderstorms can maintain itself or strengthen as the front moves into NW Alabama later this evening is a big question mark. Shear is very weak (15 to 25 knots) in most guidance. CAPE is not overly impressive, but does climb to between 500 and 1200 J/KG later today in guidance. Given the weak shear and worked over atmosphere, despite the front moving into NW Alabama and southern middle Tennessee, not expecting precipitation coverage to be much. However, during the day on Saturday, as the front moves further southeast into the area, daytime heating should allow for an area of showers and thunderstorms should reform along the front. Again shear will be very weak. Instability won`t be overly impressive either (mainly 500 to 1000 J/KG). Thus, not expecting any severe thunderstorm activity. However an area of showers and thunderstorms will likely develop. The weak cold front and upper level trough axis associated with it move southeast into southern Alabama and Georgia late Saturday night in all guidance. Returning sunshine and some warm air advection should allow highs to climb back into the upper 70s. By Sunday morning, expect a dry forecast west of the I-65 corridor, as an amplified upper ridge begins building east into the area. Lows will be slightly cooler, but not alot with temperatures in the 60 to 64 degree range as you wake up. However, with a weak upper low just to our east of southeast along the front, a low chance (20-30%) of showers cannot be ruled out. The very strong upper level ridge working into the area combined with returning sunshine should allow temperatures to climb into the lower to mid 80s. This upper level ridging only become more amplified Sunday night into Monday morning. An upper level disturbance moves well north of the area on the NW side of the upper ridge towards the Ohio Valley into Monday morning. The overall pattern doesn`t change much though into Monday. Lows shouldn`t change much, but highs will likely warm a bit more into the mid 80s in most locations on Monday with dry weather firmly in place. && .LONG TERM... (Monday night through Thursday) Issued at 255 AM CDT Fri May 17 2024 Dry and warm conditions will continue into Tuesday, and thanks to a flow rounding a surface ridge along the east coast. After a mild night with lows in the lower 60s, highs on Monday should rise into the mid 80s under mostly sunny skies. This trend should continue on Tuesday with highs nearing 90 degrees in a few places. Lows in the mid 60s Mon night should range in the upper 60s to near 70 Tue night. A storm system forecast to form over the Rockies and adjacent High Plains over the weekend will head to the NE, reaching the Great Lakes on Wednesday. A cold front trailing south of it will move across the area on Wed. Moisture convergence and lift preceding it will return medium chances (30-50%) of showers and thunderstorms beginning Tue night. Unsettled weather with scattered showers and thunderstorms will remain in the forecast into Thursday. Overall storm strength should remain "general" with a risk of strong outflow wind gusts, heavy downpours, and sudden and/or frequent lightning. Even with more clouds and rain chances, high temperatures on Wed/Thu should range in the mid/upper 80s, and lows in the 60s. && .AVIATION... (06Z TAFS) Issued at 1147 PM CDT Thu May 16 2024 There have been no significant changes to previous aviation forecast reasoning, as lgt RA (and perhaps a couple of embedded TSRA) along the northern periphery of a Gulf Coast MCS will begin to spread northeastward into northern AL by 7-8Z. However, this will occur with only minor reductions to vsby and cigs. In the wake of the initial round of light precipitation (which should progressively spread northeastward and out of the region btwn 14-18Z), additional storms may develop along a trailing outflow boundary extending from northern LA into west central AL, but with low confidence in impacts as far north as MSL/HSV, we will not include this scenario in the current TAFs. A more likely scenario is that widespread low stratus clouds will develop by late morning and persist for the rest of the period, with occasional lgt SHRA possible as well. Sfc winds (initially from the SE at speeds less than 5 kts) will shift to SSE and strengthen to 5-10 kts prior to sunrise. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....KTW LONG TERM....RSB AVIATION...70