textproduct: Huntsville

KEY MESSAGES

Updated at 1050 PM CDT Fri Apr 17 2026

- There is a high (80-90%) chance for showers and thunderstorms this afternoon and evening. A few storms could produce gusty winds and small hail.

- A cool/dry airmass will overspread the region Sunday and Sunday night. This will be followed by a dry conditions and a gradual warming trend Monday-Thursday.

- Chances for showers and thunderstorms will begin to increase on Friday.

NEAR TERM

(Rest of Today and Tonight) Issued at 1050 AM CDT Sat Apr 18 2026

Earlier cloud cover around daybreak has thinned and broken up near and east of the I-65 corridor. This is allowing for some heating due to insolation as well as warm air advection current. RAP13 seems to be catching onto this trend well with 13Z RH forecast parameters at various mandatory levels.

Further west, deeper cloud cover is more entrenched. Dewpoint depressions are likely too large for precipitation to be reaching the ground, despite some rainfall returns aloft. However, between now and 1 PM, expect some of this could reach the ground as surface dewpoints increase ahead of the front. Mid level lapse rates are very steep, but the elevated mixed layer is very warm forming a very robust cap seen in 7 AM sounding data from both Nashville, TN and Birmingham, AL. This will likely be the impeding factor for severe thunderstorm development, despite ample shear that is in place and that should continue to increase into the evening hours ahead of the approaching cold front.

Current surface temperatures are in the 76 to 78 degree range in most areas. The exception to this is in far western portions of NW Alabama which has experienced thicker and more persistent cloud cover. Some additional breaks in cloud cover could linger into portions of NW Alabama through the morning hours, before stronger forcing at 700 mb and 500 mb push into that area ahead of the approaching frontal boundary. Temperatures should be warmest near and east of the I-65 corridor, climbing into the 76 to 85 degree range in some areas. Overall, lowered highs a tad though.

Given that model guidance is holding onto very strong mid level * lapse rates (7.5 to 8.0 degrees/km) through 4 or 5 PM this afternoon, some strong thunderstorms could develop early this afternoon as the stronger 700 mb and 500 mb forcing ahead of the front pushes into NW Alabama and further east. Would expect best instability to be near and east of the I-65 corridor this afternoon, given the more persistent breaks in cloud cover expected there today. Guidance does show some surface based and elevated CAPE between 300 and 800 J/KG this afternoon. Dewpoints may increase enough right ahead of the front for close to 1000 J/KG of SBCAPE to develop in portions of NW Alabama and slightly further east. The main results of this combination of factors would likely be some scattered strong storms producing small hail and gusty winds given expected mid-level lapse rates, just enough instability, and strong forcing through about 5 PM.

As we move into the early evening hours, the mid level lapse rates become much less robust and the wet-bulb zero heights climb above 10,000 feet. This would likely lessen the small hail risk, but increasing shear will likely keep a very low threat for small hail and gusty winds to 50 mph or so in the cards into the evening hours.

We need the rainfall. PWATs increase to between 1.5 and 1.7 inches, late this afternoon and evening. Given some strong/concentrated 700 mb forcing is shown in most guidance and some more scattered areas of stronger 500 mb forcing shown, we should get some solid rainfall out of this. Hopefully we get a solid half of an inch to an inch across the area. The strength of the 700 mb forcing and thermodynamic profile look like that is a good possibility. The strongest forcing pushes southeast into the area around 4 PM (NW AL) and exits the area (NE AL) just after midnight. This will be the most concentrated/persistent period of rainfall and thunderstorms. As noted earlier, the overlap of better mid-lapse rates, strong shear, and better instability should be in the early/mid afternoon period. This would be the period of more likely strongest thunderstorm activity.

SHORT TERM

(Sunday through Tuesday) Issued at 1050 AM CDT Sat Apr 18 2026

This front as noted in earlier section is a quick moving boundary. This should usher in some much drier and colder air behind it overnight. Through advection of much drier/cooler air, temperatures should drop into the 40 to 45 degree range by daybreak on Sunday. With the cool start on Sunday, highs will be at least 5 to 10 degrees below normal (maybe a bit more in higher elevations), only climbing into the 60 to 70 degree range in most locations.

A pretty chilly night is in store Sunday night, as light winds and clear skies should allow lows to drop to between 39 and 45 degrees (5 to 10 degree below normal).

As we move into Monday and Monday night, upper level ridging begins to re-establish itself over the desert southwest. Over the Tennessee Valley area, northwest flow aloft will still be in place, but begin to modify. This northwest flow aloft will keep highs near or slight below normal. Highs on Monday look to climb back into the upper 60s to around 75 degrees. Lows should warm a bit into the mid to upper 40s by Tuesday morning. During the day on Tuesday, highs should rebound back into the mid 70s to lower 80s (near or above normal values).

LONG TERM

(Tuesday night through Saturday) Issued at 1050 AM CDT Sat Apr 18 2026

During this period the upper ridge will shift east and over the Tennessee Valley. Unfortunately, very dry weather is expected Sunday though the beginning of next week at least, likely through the end of the week. Highs will continue to warm up into the 80s as the upper ridge builds more over the area towards the middle/end of next week. Lows should warm into the 50s and lower 60s.

Next weekend looks a bit more unsettled with the possibility of much more needed rainfall, but maybe some more robust thunderstorm activity.

AVIATION

(00Z TAFS) Issued at 557 PM CDT Sat Apr 18 2026

A broken area of TSRA is currently moving through the TN Valley. The line has already passed MSL, thus no thunder has been included in the TAF, rather just lingering low MVFR ceilings and visibilities. The area of stronger TSRA will likely be impacting HSV at the start of the period. A tempo group has been included to account for lowering of ceilings and visibilities as the strongest storms move through. Heaviest rain and storms look to move out of the area by 6Z with low MVFR clouds lingering behind the front. Winds will shift to the north and aid in clearing skies around sunrise. Clear skies will prevail through the day tomorrow with gusty from the north being the only lingering impact.

HUN WATCHES/WARNINGS/ADVISORIES

AL...None. TN...None.