textproduct: Huntsville

KEY MESSAGES

Updated at 1025 PM CDT Tue Jun 30 2026

- An Extreme Heat Warning remains in effect for all of northern AL and southern Middle TN through 7PM Wednesday due to a combination of afternoon temperatures in the mid-upper 90s and heat indices up to 114F. A Heat Advisory remains in effect from 7PM Wednesday through 7PM Thursday.

- Low to medium (20-40%) afternoon/evening thunderstorm chances exist region-wide Wednesday through Saturday. Conditions will be favorable for damaging winds, frequent lightning, and perhaps small hail particularly on Wednesday and Thursday.

NEAR TERM

(Rest of Tonight and Wednesday) Issued at 1025 PM CDT Tue Jun 30 2026

A tranquil night is forecast tonight, with little to no cloud cover and calm winds. Even with these conditions, dew point depressions are a bit high for widespread fog formation. But, there is a low chance of some patchy fog in sheltered valleys and near bodies of water. Expect lows to be warm, merely dropping into the mid to upper 70s.

The stout upper ridge will persist into Wednesday, but begin to flatten slightly by the late afternoon and evening. Surface high pressure will also maintain its hold over the Appalachians and down through the north-central Gulf coast. Overall, the dangerously hot conditions are forecast to continue through Wednesday, with highs reaching the mid to upper 90s. With elevated moisture, heat indices are expected to reach between 106-114 degrees. A Major to Extreme (Level 3 and 4 of 4) NWS HeatRisk remains, along with WBGTs in the upper 80s to around 90 degrees. Therefore, the Extreme Heat Warning remains in effect through 7PM Wednesday. Make sure to take precautions for the dangerous heat! Wear light-colored, loose-fitting clothing, stay hydrated, and take frequent breaks in the shade if you work outside or have outdoor activities! Look before you lock - never leave people or pets in vehicles!

In addition, a few subtle, upper shortwaves look to move over the Southeast and may provide enough lift for afternoon and evening thunderstorms (20-40%). These may dampen the heat a bit, but exactly where these will set up is uncertain. This is because we are anticipating these to be the usual, summertime pop-up thunderstorms/downbursts. Therefore, not everyone will see rain/storms, but it is still important to remain weather aware.

Taking a look at some of the thermodynamic parameters that, if met or exceeded, would point to higher risk of downbursts, there are many signs that indicate Wednesday is likely to be a severe downburst day. Model soundings show lapse rates from the surface to 3 km around 8 deg C/km, along with a theta e difference of at least 40K. In addition, there is plenty of moisture, with moist mid levels via the model sounding profile, PWATs around 2 inches, and mean mixing ratios around 18 g/kg. With these hot conditions, instability will be abundant as well. DCAPE values look to reach around 1000 J/kg with MLCAPE greater than 4000 J/kg when looking at RAP soundings. Lastly, WINDEX (an index that could indicate how strong downburst winds could be) values shown by guidance is generally between 65-80 knots or so. With all this being said, the thresholds for each of these parameters for significant downbursts are met and/or exceeded. This coincides with a Marginal Risk of severe storms outlooked by the Storm Prediction Center for much of north Alabama and southern middle Tennessee.

Ultimately, damaging winds will be the main threat with any downbursts on Wednesday, but frequent lightning, brief downpours, and perhaps some small hail will also be threats. Stay weather aware and have a safe place to go if warnings are issued for your area!

SHORT TERM

(Wednesday Night through Friday Night) Issued at 1025 PM CDT Tue Jun 30 2026

The aforementioned upper pattern (upper ridge) will generally persist through Thursday, but gradually shift over the eastern seaboard and further flatten on Friday. Ripples of subtle upper shortwaves are shown by guidance to continue over the Southeast during this time as well. However, the surface high pressure over the Appalachians down into the north-central Gulf coast will persist. Therefore, hot conditions will continue Thursday and Friday, but perhaps not quite to Extreme Heat Warning level (but Heat Advisory level). Highs in the mid to upper 90s will continue (with lows in the 70s), with heat indices in the 100-110 degree range. NWS HeatRisk remains in the Major to Extreme categories and forecast WBGTs continue to reach the upper 80s to around 90 degrees. Therefore, while the current Heat Advisory is in effect through 7PM Thursday, would not be surprised if this is extended further through at least Friday. Continue practicing heat safety and stay weather aware if you have outdoor activities!

With the loss of daytime heating, expecting the thunderstorm activity to wane through Wednesday evening, with no rain overnight. This diurnal pattern, with afternoon/evening thunderstorms will then be the norm through late week. In addition, the downburst risk will remain high on Thursday, as the parameters mentioned in the Near Term are nearly identical in value. This coincides with a Marginal Risk of severe storms outlooked by the Storm Prediction Center for all of north Alabama and southern middle Tennessee. These downburst parameter values decrease somewhat for Friday, resulting in a continued risk, just perhaps not for high-end downbursts. This will be monitored. Overall, damaging winds will be the main threat with any downbursts Thursday and Friday, with frequent lightning, brief downpours, and some small hail also threats. Stay weather aware!

LONG TERM

(Saturday through Tuesday) Issued at 1025 PM CDT Tue Jun 30 2026

Bottom line up front, major to extreme heat concerns will persist into the holiday weekend as the region remains under a ridge of high pressure.

We have already been in the thick of the heatwave this week but let's continue to review heat safety: This holiday weekend you need to ensure that you and your family, friends, and pets are staying safe from the heat. Know the signs of heat illness, heat exhaustion can lead to heat stroke. Hydrate with water, wear light colored clothing, seek shade or take breaks indoors, NEVER leave pets or people in vehicles, check in on young children and the elderly. More safety info can be found on our social media and website.

This weekend, the center of the ridge will shift a little eastward, but it will continue to dominate the TN Valley and the region. Saturday/July 4th, trends will be monitored closely to see if another heat product needs to be issued as highs will be in the low to mid 90s with nearly everyone feeling a heat index of 100 and some spots reaching a heat index of 105. Diurnal convection will persist with low chances (20-40%) in the afternoon and evening hours.

A shortwave will move across the Midwest on Sunday and through the OH Valley on Tuesday. It will create a sfc low that will tote a cold front with it. This will bring an increased chances of showers and thunderstorms. Look for medium chances on Sunday (40-60%), then medium to high chances on Monday (50-70%) and Tuesday (60-80%) as the front approaches the TN Valley. Widespread organized storms are not anticipated as there will be very weak to no wind shear, however forecast soundings show a good amount of CAPE, high PWATS, and good low level lapse rates. Therefore, there will be a heavy rain and wind risk with some of the storms. With the increase in cloud cover and rainfall chances, we will see a decrease in temps, with highs in the lower 90s on Sunday and in the upper 80s by Tuesday. Lows will remain anchored in the lower 70s.

AVIATION

(06Z TAFS) Issued at 1150 PM CDT Tue Jun 30 2026

VFR conditions will be the predominant flight category at each terminal through the period. A low chance of TSRA is forecast this afternoon and have added PROB30 to account for this at both terminals between 20-00z. Should a TSRA impact either terminal, localized IFR/MVFR conditions may occur.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Extreme Heat Warning until 7 PM CDT Wednesday for ALZ001>010-016.

Heat Advisory from 7 PM Wednesday to 7 PM CDT Thursday for ALZ001>010-016.

TN...Extreme Heat Warning until 7 PM CDT Wednesday for TNZ076-096-097.

Heat Advisory from 7 PM Wednesday to 7 PM CDT Thursday for TNZ076-096-097.