Alert archive / Alabama / Heat Advisories in 2021
Heat Advisory 8, NWS Huntsville, AL
NWS Huntsville, AL issued this heat advisory at Aug 10, 2021, 12:46 PM CDT for 9 counties in Alabama; Lincoln County, Moore County, Tennessee. It took effect at Aug 12, 2021, 11:00 AM CDT. It was in force for .
The area
The counties it named.
The facts
- Issued
- Aug 10, 2021, 12:46 PM CDT (17:46 UTC)
- In effect from
- Aug 12, 2021, 11:00 AM CDT
- Expired
- Aug 12, 2021, 2:24 AM CDT
- In force
- Issued by
- NWS Huntsville, AL
Counties Colbert County, AL, Cullman County, AL, Franklin County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Lincoln County, TN, Moore County, TN
The radar
The Northeast Alabama radar (KHTX), 89 km from the middle of the area, began a volume at 17:48 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Nashville Metro, TN (KBNA), launched 12:00Z, 5.8 hours before the alert went out and 165 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1950 J/kg
- Mixed-layer CIN
- -27 J/kg
- Mixed-layer LCL
- 904 m above ground
- 0-6 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- 51 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this heat advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Huntsville, AL wrote its last area forecast discussion before this heat advisory went out at Aug 10, 12:00 PM CDT, 46 minutes earlier.
Area forecast discussion, Aug 10, 12:00 PM CDT, 46 minutes before
Area Forecast Discussion National Weather Service Huntsville AL 1200 PM CDT Tue Aug 10 2021 .UPDATE... For 18Z TAFS. && .NEAR TERM...(Rest of Today) Issued at 920 AM CDT Tue Aug 10 2021 Temperatures are warming quickly this morning with most locations already in the low to mid 80s under sunny skies. Broad low amplitude ridging features aloft with a shortwave trough to the north across the Northern Plains. Temperatures will continue to warm today into the upper 80s to mid 90s with dewpoints in the low to mid 70s. This will lead to heat indices in the 100-105 degree range for most areas this afternoon. Locations from Huntsville westward could briefly touch heat indices of 105 with heat advisories in effect to the west in Mississippi and west Tennessee. Will forgo a heat advisory at this time but will continue to monitor the latest temperature and dewpoint trends throughout the day. With these temperatures and dewpoints, SBCAPE values will climb to around 3000 J/Kg. However, there is no real lifting mechanism to speak of with weak flow and broad ridging aloft. Latest model guidance puts the forecast area in a relative PW minimum area with values near 2 inches to the north and south. The latest CAMs, especially the HRRR, do not indicate much more than isolated coverage at best this afternoon. Additionally, visible satellite imagery is clear across the area with no cumulus development so far. Due to these factors, lowered PoPs for the update to around 20-30%. .SHORT TERM...(Tonight through Thursday) Issued at 147 AM CDT Tue Aug 10 2021 A semi-persistence forecast holds through Thursday with hot and muggy conditions and mainly afternoon thunderstorms. Heat Index values should remain mainly below Advisory levels, but it will be close and this may change. Dew points will be in the lower to middle 70s once again with highs back in the lower to middle 90s (expect upper 80s atop the higher plateaus/mountains). Mainly afternoon and evening thunderstorm chances will continue, with isolated to scattered coverage expected at this point. Mesoscale outflow boundaries may play a role here in later forecast updates during the next couple of days. .LONG TERM...(Thursday night through Monday) Issued at 147 AM CDT Tue Aug 10 2021 A pretty typical summer pattern will persist through the end of the week, as a Bermuda high helps reinforce a warm and moist airmass over the Southeast. Daily chances for showers and thunderstorms will continue through the entire extended period, as several smaller disturbances move through the area, The weekend forecast becomes a bit tricky for two reasons. One, a cold front is expected to move south through the lower OH River Valley, and could aid in generating more widespread activity Saturday and Sunday. Two, we will now have our eyes on Potential Tropical Cyclone Six as its track will likely determine the southward extend of the cold front. Have capped PoPs at chance through the extended, but could see having to increase them over the weekend in future forecast updates. Temperatures will stay fairly close to normal for mid-August, with highs in the upper 80s/lower 90s each day and lows in the upper 60s/lower 70s. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1200 PM CDT Tue Aug 10 2021 VFR conditions currently across the terminals and these conditions are forecast to continue throughout the TAF cycle. Showers are starting to develop in the hot and humid summer airmass this afternoon. Expect these to continue to grow with VCTS at HSV through 00z. Lower confidence at MSL and have kept the forecast dry there. Dry conditions are forecast overnight with light winds. Winds will generally be from the south to southwest throughout the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && NEAR TERM...MA SHORT TERM...17 LONG TERM...25 AVIATION...MA For more information please visit our website at weather.gov/huntsville.
Hazardous weather outlook, Aug 10, 2:11 AM CDT, 10 hours 35 minutes before
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</html>The office that day
Everything else NWS Huntsville, AL issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 10, 12:46 PM CDT | Heat Advisory | HUN | Colbert, Cullman, Franklin, Lauderdale, Lawrence, Limestone and 3 more | 30 hr |
| Aug 10, 3:46 PM CDT | Special Weather Statement | HUN | Jackson | 29 min |
| Aug 10, 4:14 PM CDT | Special Weather Statement | HUN | Jackson | 31 min |
| Aug 10, 5:20 PM CDT | Special Weather Statement | HUN | DeKalb | 40 min |
| Aug 10, 5:58 PM CDT | Special Weather Statement | HUN | DeKalb | 32 min |
Nearby
Heat Advisories in Alabama, 2021Heat Advisories in Tennessee, 2021Every heat advisory in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.