Alert archive / Alabama / Heat Advisories in 2021
Heat Advisory 5, NWS Huntsville, AL
NWS Huntsville, AL issued this heat advisory at Jul 29, 2021, 1:27 PM CDT for 11 counties in Alabama; Franklin County, Lincoln County, Moore County, Tennessee. It took effect at Jul 30, 2021, 12:00 PM CDT. It was in force for 7 hr.
The area
The counties it named.
The facts
- Issued
- Jul 29, 2021, 1:27 PM CDT (18:27 UTC)
- In effect from
- Jul 30, 2021, 12:00 PM CDT
- Expired
- Jul 30, 2021, 7:00 PM CDT
- In force
- 7 hr
- Issued by
- NWS Huntsville, AL
Counties Colbert County, AL, Cullman County, AL, DeKalb County, AL, Franklin County, AL, Jackson County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Franklin County, TN, Lincoln County, TN, Moore County, TN
The radar
The Northeast Alabama radar (KHTX), 69 km from the middle of the area, began a volume at 18:31 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, 6.5 hours before the alert went out and 159 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
- 853 J/kg
- Mixed-layer CIN
- -170 J/kg
- Mixed-layer LCL
- 1220 m above ground
- 0-6 km bulk shear
- 7 kt
- 0-1 km storm-relative helicity
- 64 m²/s²
- 0-3 km storm-relative helicity
- 86 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 Jul 29, 1:24 PM CDT, 3 minutes earlier.
Area forecast discussion, Jul 29, 1:24 PM CDT, 3 minutes before
Area Forecast Discussion
National Weather Service Huntsville AL
124 PM CDT Thu Jul 29 2021
.NEAR TERM...(Tonight)
Issued at 123 PM CDT Thu Jul 29 2021
Other than a few high clouds, a mostly clear sky is expected again
tonight. River/lake valley fog is again expected late tonight,
especially in southern TN and northeast AL, where lows could dip into
the upper 60s in spots. Some of these areas dropped into the middle
60s this morning.
.SHORT TERM...(Friday through Saturday)
Issued at 123 PM CDT Thu Jul 29 2021
A Heat Advisory will run from Noon - 7 PM on Friday, mainly for
counties along and west of a Lynchburg-Huntsville-Cullman line, where
heat index values may reach 105+, at least for an hour or two.
The other factor tomorrow will be a cold front dropping south into
middle and eastern TN during the afternoon hours. This may produce a
few thunderstorms that will trickle into southern middle TN and north
Alabama during the afternoon hours. Forecast soundings are weakly to
un-capped during peak heating, and with a possible MCV dropping
southeast, will carry a slight chance into the early evening as well.
The TN valley will be on the southern periphery of a broad northwest
flow at 5h across the northeastern quadrant of the CONUS on Saturday.
It will be another hot and humid day, but it is less certain heat
index values will reach 105+, so have held off on another advisory
just yet. Diurnally generated afternoon thunderstorms are a
possibility again.
.LONG TERM...(Saturday night through Wednesday)
Issued at 123 PM CDT Thu Jul 29 2021
A trough then digs into the southeast by Sunday into Monday. This
brings a secondary cold front through the region. In advance of and
along the front, clusters of showers and thunderstorms are expected.
One or more clusters/small MCS will drop southeast with the front
late Saturday night into Sunday. Bulk shear values will increase to
20-30kt, so a couple of strong to severe storms cannot be ruled out.
The front will be slow to drop southeast and will keep high chance to
likely PoPs into Monday, before shifting south of the area on
Tuesday. The widespread clouds and numerous showers and thunderstorms
will keep temperatures in the lower to middle 80s on Monday.
Temperatures will warm into the upper 80s Tuesday and Wednesday, with
lows in the 60s, as a 5h trough/upper low remains entrenched over
the eastern CONUS next week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1124 AM CDT Thu Jul 29 2021
VFR flight weather conditions are forecast during a majority of the
period. Patchy BR/FG is possible along the TN River, and have
included a TEMPO period of BR and MVFR at KMSL from 10-13Z.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT this evening for ALZ001>007-016.
Heat Advisory from noon to 7 PM CDT Friday for ALZ001>007-016.
TN...Heat Advisory until 7 PM CDT this evening for TNZ096.
Heat Advisory from noon to 7 PM CDT Friday for TNZ076-096.
&&
NEAR TERM...17
SHORT TERM...17
LONG TERM...17
AVIATION...17
For more information please visit our website
at weather.gov/huntsville.Hazardous weather outlook, Jul 29, 7:53 AM CDT, 5 hours 34 minutes before
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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.