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
480 FXUS64 KHUN 010124 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 824 PM CDT Fri May 31 2024 ...New NEAR TERM... .NEAR TERM... (Tonight) Issued at 824 PM CDT Fri May 31 2024 Looking at the earlier 7 PM sounding from BMX, drier air is still in place below 700 mb. Very saturated above that level though through the remainder of the sounding. PWATS in that sounding were at 1.42 inches. The warm front to our south hasn`t moved much, but has inched northward slightly. It currently extends from between KEET and KTCL NNW through central Franklin county (AL) to Savanah (TN). An area of heavier showers and a few thunderstorms formed along it a few hours ago that produced a quick 0.25 to 0.80 inches of rainfall in those areas. Further east, dewpoint depressions (10 to 20 degrees still) are indicative of the airmass that was still in place in the BMX sounding. Thus, mainly we have had just cloud cover and virga in areas east of the warm front. This activity is much lighter now and the heavier precipitation is forming more southwest of this boundary currently. The majority of the stronger lift in the atmosphere right now is concentrated west of the area over central and northern Mississippi. Several models continue to show this stronger forcing remaining in central MS and that area of showers and embedded thunderstorms expanding and spreading more northerly than to the east over the next 3 to 5 hours. However, shortly after 1 AM, several models depict the upper low over eastern Kansas shifting slightly further east. As it does so, additional shortwaves moving along its southeast periphery make it far enough east so that the eastern portion of this area of showers and embedded thunderstorms makes it into northwestern Alabama in a more persistent manner. No shear is in place over the area and don`t expect any much of the night. There is some elevated instability present west of the I-65 corridor (around 500 to 1000 J/KG). So will likely see at least a few embedded thunderstorms continuing as that activity moves into NW Alabama after 1 AM. As this occurs, Corfidi vectors at and near the surface do oppose the mean flow, so some backbuilding of showers and thunderstorms looks like a possibility. With PWATS climbing to over 1.7 inches towards daybreak and the stronger forcing continuing to move further east into the Alabama, some ponding of water on roadways and possibly isolated flash flooding could occur. Shear does increase to around 30 to 35 knots at 7 AM. However, not expecting any surface based instability to be in place and only very meager elevated instability. Overall increased precipitation chances overnight, especially after 1 AM. Not expecting many thunderstorms, but a few elevated storms could occur. Also, raised low temperatures slightly (lower mid 60s west), but kept a decent gradient in far northeastern Alabama (58 to 62), with more SE flow expected much of the night (given the drier airmass in that location upstream). A more pronounced flash flooding/river flooding concern and a low end threat for severe weather may develop later in the day on Saturday. && .SHORT TERM... (Saturday through Monday) Issued at 313 PM CDT Fri May 31 2024 For the weekend and early next week, an unsettled pattern is forecast with chances for showers and thunderstorms in the picture. The ARW/FV3 and longer term models all indicated numerous to widespread showers and thunderstorms impacting the area on Saturday. With plenty of cloud cover and high rain chances, temperatures will trend cooler than today. Highs Sat should only warm in to the mid/upper 70s. The NBM`s low/mid 70s looked too cool so boosted them up a few degrees. The heaviest showers move more to the east Sat night with lesser rain chances expected Sunday. Rainfall totals over the area should range from 1/2" east to over 1.5" west. The higher amounts of rain over our western areas could run-off, resulting in a risk of flooding and flash flooding. The Weather Prediction Center has a slight risk for our western 2/3s of our area on Sat, main due to runoff from Fri night into Saturday morning rain totals. With more sun peeking through, high temperatures to start the new week should rise into the lower 80s. Convection chances appear to become more on a diurnal trend, with higher odds Monday afternoon. && .LONG TERM... (Monday night through Thursday) Issued at 219 AM CDT Fri May 31 2024 A shortwave across the TN Valley will start off the unsettled pattern that will persist through mid week. An upper level trough in the Northern Plains will develop a sfc low and associated cold front on Tuesday. Another shortwave will slide out ahead of this system to keep low chance (20-30%) of showers and storms in the forecast through Tuesday. The sfc low will remain up in the Great Lakes or just north of there, the cold front will push southeast into the region on Wednesday. We will see an uptick in the coverage of showers and storms (30-50%) before the front pushes through on Thursday. Not expecting severe storms at this time, but will monitor trends as we get closer to the event. Ahead of the front, daytime highs will start off in the lower 80s and climb to encroach 90 degrees by Wednesday with lows around 70 degrees. Behind the front, temps will only slightly improve. && .AVIATION... (00Z TAFS) Issued at 553 PM CDT Fri May 31 2024 A narrow line of showers continues to develop well southwest of the KMSL terminal at this hour. Expect this activity to mainly move NNW and not affect the terminal through 02Z. However, kept a PROB30 group in in case this activity expands far enough eastward during that period. Expect the bulk of rain and thunderstorms to move northeast into the KMSL terminal closer to 08Z and the KHSV terminal around 09Z, expect CIGS to drop to MVFR or lower around that timeframe. This should be a persistent and widespread area of RA and -TSRA. Southeast winds around 10 knots should increase early this evening and especially after midnight (sustained around 10 knots with gusts to 20 knots). A timeframe of 10Z to 14Z at the KMSL terminal and 12Z to 16Z was highlighted for heavier -TSRA for now. During this period, some IFR or lower CIGS or VSBYS could occur. Expect conditions to improve some after these tempo groups, when VSBYS or CIGS could become predominantly MVFR again. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....RSB LONG TERM....JMS AVIATION...KTW