textproduct: Huntsville

KEY MESSAGES

Updated at 1110 AM CDT Tue Sep 22 2026

- There is a low risk for strong to severe thunderstorms this afternoon across the southeastern half of the forecast area. Damaging wind gusts, small hail, and frequent lightning will be the main threats with this activity.

- A slightly cooler and drier airmass will begin to arrive on Wednesday night. Highs will fall back into the lower-mid 80s from Thursday-Monday, with lows in the mid 50s-lower 60s.

NEAR TERM

(Rest of Today and Tonight) Issued at 223 PM CDT Tue Sep 22 2026

There have been no significant changes to near term forecast reasoning since the update earlier this morning. Scattered thunderstorms (which initially developed in the vicinity of a stationary surface trough bisecting the CWFA) will continue to spread southeastward this afternoon. With SPC mesoanalysis indicating SBCAPE in the 2500-3000 J/kg range, strengthening W-NW flow aloft will support a minor degree of storm organization into multicell clusters, with locally damaging downburst winds and frequent lightning expected to be the primary convective impacts. Latest high-resolution model guidance still suggests that both storm coverage and intensity should decrease substantially between 23-1Z, followed by partial clearing this evening. However, a broken-overcast layer of low stratus clouds is likely to develop within the moist boundary layer airmass shortly after Midnight, and a few sprinkles of rain or low-topped showers may occur beneath this cloud deck. Overnight lows will be in the mid 60s.

Previous Discussion: A mid-level subtropical high will migrate slowly eastward across south TX over the course of the near term period, as a weak closed cyclone travels southeastward from eastern IA into IN. This configuration will force light W-NW flow aloft (10-20 knots) to gradually strengthen into the 25-35 knot range by the end of the period. At the surface, a trough of low pressure currently extends from the Arklamiss region northeastward through northwest AL/middle TN and into WV. This feature will provide the low-level lift for convective development within the seasonably moist and unstable airmass (featuring PWAT of 1.6-1.7" and MLCAPE of 1000-2000 J/kg) in an environment otherwise lacking synoptic scale forcing for ascent. With development of a few convective cells already in progress across central parts of the CWFA, we anticipate that storm coverage will continue to increase through day (peaking during the mid-afternoon and then beginning to diminish rapidly between 23-1Z). Given the current position/orientation of the boundary and a modest increase in steering flow throughout the day, cells should spread east- southeastward with time, with highest coverage anticipated across our southeastern forecast zones. With afternoon temperatures expected to range from the m-u 80s in the east to the l90s in the west, low-level lapse rates will remain sufficiently steep to support brief strong wind gusts (up to 40-50 MPH). However, parameters for severe downburst winds appear generally less favorable today (compared to yesterday).

Overnight, surface pressures will rise within a large anticyclone centered across southern Quebec. This will effectively result in a cold air damming scenario to the east of the central/southern Appalachians, and should force the low-level confluence axis (bisecting our forecast area) to remain nearly stationary. Although a few low-topped showers will be possible at times (particularly in the vicinity of the trough axis), both POPs and the risk for lightning/thunder will be very low due to nocturnal stabilization of the boundary layer. An abundance of low stratus clouds appears likely to evolve during the early morning hours Wednesday, and should keep overnight lows from falling below the m-u 60s.

SHORT TERM

(Wednesday through Thursday night) Issued at 1110 AM CDT Tue Sep 22 2026

Over the course of the short term period, a subtropical high (centered along the northwest Gulf Coast) is predicted to strengthen and amplify northward through the Great Plains, as a mid/upper-level cyclone tracks southeastward from IN to a position off the coast of NC/SC. As this occurs, winds aloft across the local area will progressively veer to N-NW and strengthen to 35-45 knots, with dry advection in the mid/upper-levels contributing to a rapid drop in atmospheric moisture content beginning late Wednesday afternoon. In the low-levels, the surface trough bisecting our CWFA will remain nearly stationary on Wednesday, but should begin to drift westward Wednesday night as the magnitude of cold air damming will be maximized across western VA/NC during this timeframe. The boundary will likely focus the development of convection once again from late Wednesday morning into the afternoon hours, and given the anticipated orientation of this feature and strengthening NW steering flow, highest coverage will be across the southeastern portion of the forecast area. In spite of stronger flow/shear, CAPE will limited as morning stratus clouds should be slow to mix out and will keep afternoon temps in the 85-90F range. Thus, the risk for strong downburst winds will be even lower (compared to today). Nevertheless, a few thunderstorms will be possible (particularly in the southeast). Due to expectations that the trough will begin drifting westward Wednesday night, a few low-topped showers will be possible region- wide during the overnight hours.

During the timeframe from Thursday-Thursday night, the surface trough will continue to advance northwestward and away from the region, with light E-SE flow at the surface advecting a cooler/drier airmass into the region from the ridge to our east. Thus, we expect rain chances to drop considerably during this period, with only a few showers possible (both in the vicinity of the trough and in the higher terrain to our northeast) Thursday afternoon. Temperatures will be notably cooler on Thursday afternoon, with highs ranging from the m-u 70s in the elevated terrain of northeast AL/southern Middle TN to the m80s in the west. Overnight lows will fall into the m50s-l60s by Friday morning.

LONG TERM

(Friday through Monday) Issued at 923 PM CDT Mon Sep 21 2026

A Fall-like weather pattern will persist through the long term period as the Tennessee Valley sits underneath northwest flow that will continue to usher in a cooler airmass. Dry conditions continue with afternoon highs in the low to mid 80s with overnight lows in the mid to upper 50s. As we head into next week, a weak mid level ridge begins to shift into the Southeast. This should warm temperatures up a few degrees into the mid to upper 80s. At the same time a shortwave is forecast to dig southeast across the Plains. This would bring a low chance of precip during the day on Monday. However, this is quite far out and at this time there is low confidence in this occurring. Therefore, kept the NBM very low chance (5-15%) of showers on Monday.

AVIATION

(18Z TAFS) Issued at 1242 PM CDT Tue Sep 22 2026

Scattered TSRA will continue to develop this aftn in the vicinity of a sfc trough (which will remain nearly stationary while bisecting the forecast area from SW-to-NE). This activity should spread southeastward with time, and PROB30 groups have been indicated at MSL/18-23Z and HSV/19-24Z. Lightning and brief strong wind gusts (up to 40 kts) may prompt issuance of AWWs during this timeframe, and heavy pcpn could also result in MVFR vsby reductions. Skies will partially clear as convection shifts further southeastward and dissipates btwn 23-1Z. However, low stratus clouds appear likely to develop shortly after Midnight and will provide MVFR cigs thru the end of the period. Prevailing sfc flow will remain light and from the NE.

HUN WATCHES/WARNINGS/ADVISORIES

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