Alert archive / Alabama / Severe Thunderstorm Warnings in 2006

Severe Thunderstorm Warning 91, NWS Huntsville, AL

April 21, 2006Madison County, Alabama

NWS Huntsville, AL issued this severe thunderstorm warning at Apr 21, 2006, 6:34 AM CDT for Madison County, Alabama. It was in force for 41 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Apr 21, 2006, 6:34 AM CDT (11:34 UTC)
Expired
Apr 21, 2006, 7:15 AM CDT
In force
41 min
Issued by
NWS Huntsville, AL
Area
Counties, with a storm outline in the text

County Madison County, AL

The radar

The Northeast Alabama radar (KHTX), 46 km from the middle of the area, began a volume at 11:35 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 00:00Z, 11.6 hours before the alert went out and 152 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.

Skew-T log-pSkew-T log-p diagram, Nashville Metro, TN at 00:00Z on 2006-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 135 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 00:00Z on 2006-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 7 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
135 J/kg
Mixed-layer CIN
-81 J/kg
Mixed-layer LCL
1065 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
7 m²/s²
0-3 km storm-relative helicity
-5 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning 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 severe thunderstorm warning went out at Apr 21, 2:50 AM CDT, 3 hours 44 minutes earlier.

Area forecast discussion, Apr 21, 2:50 AM CDT, 3 hours 44 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
250 AM CDT FRI APR 21 2006

.DISCUSSION...
ANOTHER FAIRLY BUSY NIGHT HERE AT THE HUN WITH MORE SVR STORMS
DEVELOPING EVERYWHERE AROUND US. ATMOSPHERE OVER THE CWFA ITSELF WAS
SLIGHTLY MORE STABLE THANKS TO EARLIER CONVECTION...BUT DEVELOPING
STORMS CLOSER TO I-20 INDICATES THAT WE ARE DESTABILIZING WITH TIME.
MAIN AREA OF STORMS IS FIRING ALONG A PREFRONTAL TROUGH FEATURE
EXTENDING BACK TO NEAR VICKSBURG MS...WHILE THE REAL COLD FRONT IS
STILL WELL TO THE NW...JUST NOW MAKING ITS WAY INTO CENTRAL ARKANSAS.

FOCUS CONTINUES TO BE ON SHORT-TERM CONVECTION. NASA WRF HAS AGAIN
DONE A FAIRLY GOOD JOB AND REMAINS THE PREFERRED MODEL...WITH 12KM
NAM LOOKING REASONABLE AS WELL.

PREFRONTAL TROUGH WILL CONTINUE TO FOCUS CONVECTION NEAR THE CWFA
TODAY...AND IS NOT EXPECTED TO SHIFT SIGNIFICANTLY TODAY. WHILE MUCH
OF THE AIR MASS HAS STABILIZED THIS A.M....EXPECT IT TO DESTABILIZE
AGAIN TODAY IN ADVANCE OF THE MAIN SHORTWAVE. MOST FAVORABLE AREA
FOR PCPN TODAY WILL BE IN NWRN AL AND SRN MID TN NEAR THE TROUGH...
AND WILL DEPICT THIS IN THE POP GRIDS...TAPERING FROM CATEGORICAL TO
LIKELY. UNFORTUNATELY THERE IS NO REST FOR THE WEARY WITH NEW MODEL
RUNS SHOWING A SLOWER PROGRESSION WITH THE SYSTEM...AND WILL GO WITH
WIDESPREAD CATEGORICAL POPS TONIGHT.

AS MENTIONED...DONT EXPECT STABILITY TO BE MUCH OF AN ISSUE...BUT
STORM TYPE/HAZARDS WILL BE. WIND FIELDS LOOK MORE IMPRESSIVE THIS
TIME AROUND WITH IMPROVING DEEP LAYER SHEAR INDICATING BETTER
SUPERCELL POTENTIAL...BUT LOW-LEVEL SHEAR DOES NOT INCREASE TO
MATCH. THING TO WATCH WILL BE DEVELOPMENT OF WAVES ALONG THE FRONT
WHICH WOULD BACK THE WINDS LOCALLY AND ENHANCE LLVL SHEAR...AS BEST
INDICATED BY LATE AFTN/EARLY EVE 12KM NAM SOUNDINGS. IN ADDITION TO
THE SVR TSRA THREAT...FLOODING IS A CONCERN...WITH ABUNDANT MOISTURE
REFLECTED BY PWS OF 1.4 TO 1.6 INCHES IN ALL THE MODELS...AND THE
EXPECTED SLOWER MOTION OF THE SYSTEM. BELIEVE MOST OF THE AREA WILL
BE ABLE TO HANDLE A HVY RAIN EVENT GIVEN VERY DRY CONDITIONS IN
RECENT WEEKS...WITH THE EXCEPTION OF SRN AND ERN ZONES WHERE
ACTIVITY HAS BEEN TRAINING AND REDEVELOPING EACH AFTN. WILL ISSUE A
FLASH FLOOD WATCH FOR THOSE AREAS FROM 21-09Z...AND MENTION HVY RAIN
POTENTIAL IN THE ZFP ELSEWHERE. DEPENDING ON RADAR TRENDS/TRAINING
POTENTIAL...THIS WATCH MAY HAVE TO BE EXPANDED BY THE DAY SHIFT.

FRONT SHOULD FINALLY MOVE THROUGH THE AREA EARLY SATURDAY MORNING...
AGAIN A BIT SLOWER THAN DEPICTED BY PAST MODEL RUNS. WILL HANG ONTO
20/30 POPS EAST OF I-65 SAT MORNING TO ALLOW FOR LINGERING SHRA.
SUBSTANTIAL DRYING BEHIND THE SYSTEM SHOULD MEAN A MOSTLY SUNNY AFTN
FOR MOST EVERYONE WITH MORE PLEASANT AND MORE SEASONABLE TEMPS. WENT
WITH A COMPROMISE FOR MAX TEMPS SAT...TRENDING TOWARDS WARMER
NUMBERS WEST WHERE SUN SHOULD LAST THE LONGEST.

QUIET WX WILL BE SOMEWHAT SHORT-LIVED AS A CLIPPER SYSTEM RIDES SEWD
THROUGH THE NW FLOW. WINDS WILL SHIFT TO THE W THEN SW SAT NIGHT AND
SUN AHEAD OF THIS FRONT...NEVER REALLY ALLOWING FOR GOOD RADIATIONAL
COOLING IN THE PROCESS...AND RESTARTING WAA FOR SUNDAY. COMPROMISE
VALUES LOOK GOOD FOR BOTH PDS...DISCARDING THE OUTLIER NAM NUMBERS.
WHILE THE 12KM NAM TRIES TO GENERATE LT QPF JUST TO OUR NW SUNDAY...
MODEL SOUNDINGS SHOW THE LOWEST 10KFT TO BE FAR TOO DRY FOR ANYTHING
TO REACH THE SFC...AND WILL NOT INCLUDE A MENTION OF PCPN ATTM.

LEFT THE EXTENDED ALONE WITH MORE PRESSING ISSUES IN THE SHORT TERM.
&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    78  56  77  54 /  80 100  20  10
SHOALS        77  56  76  54 /  90  80  10  10
CULLMAN       79  57  75  53 /  70 100  10  10
FAYETTEVILLE  77  55  77  53 /  90 100  20  10
FORT PAYNE    80  58  74  50 /  70 100  30  10
&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...FLASH FLOOD WATCH FROM 4 PM FRIDAY TO 4 AM SATURDAY FOR THE
     FOLLOWING ZONES: CULLMAN...DE KALB...AND MARSHALL.
TN...NONE.
&&

BCC
Hazardous weather outlook, Apr 21, 5:00 AM CDT, 1 hour 34 minutes before
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In the hours before

Special weather statement, Apr 21, 5:06 AM CDT, 1 hour 28 minutes before
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Special weather statement, Apr 21, 5:30 AM CDT, 1 hour 4 minutes before
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Special weather statement, Apr 21, 5:48 AM CDT, 46 minutes before
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Special weather statement, Apr 21, 5:59 AM CDT, 35 minutes before
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Local storm report, Apr 21, 6:20 AM CDT, 14 minutes before
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Special weather statement, Apr 21, 6:30 AM CDT, 4 minutes before
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The office that day

Everything else NWS Huntsville, AL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 20, 7:36 PM CDTSevere Thunderstorm WarningHUNJackson39 min
Apr 20, 7:44 PM CDTSevere Thunderstorm WarningHUNMadison31 min
Apr 21, 12:49 AM CDTSevere Thunderstorm WarningHUNLimestone41 min
Apr 21, 2:43 AM CDTSevere Thunderstorm WarningHUNCullman62 min
Apr 21, 3:10 AM CDTSevere Thunderstorm WarningHUNMarshall53 min
Apr 21, 3:43 AM CDTSevere Thunderstorm WarningHUNJackson33 min
Apr 21, 4:00 AM CDTFlash Flood WatchHUNCullman, DeKalb, Marshall21 hr
Apr 21, 4:43 AM CDTSevere Thunderstorm WarningHUNMarshall27 min
Apr 21, 5:02 AM CDTSevere Thunderstorm WarningHUNJackson43 min
Apr 21, 5:09 AM CDTSevere Thunderstorm WarningHUNMadison21 min
Apr 21, 5:37 AM CDTSevere Thunderstorm WarningHUNMorgan38 min
Apr 21, 6:15 AM CDTSevere Thunderstorm WarningHUNMorgan45 min
Apr 21, 6:21 AM CDTSevere Thunderstorm WarningHUNMorgan39 min
Apr 21, 7:01 AM CDTSevere Thunderstorm WarningHUNLimestone29 min
Apr 21, 3:18 PM CDTSevere Thunderstorm WarningHUNJackson18 min
Apr 21, 3:20 PM CDTSevere Thunderstorm WarningHUNJackson, Madison40 min
Apr 21, 3:26 PM CDTSevere Thunderstorm WarningHUNDeKalb49 min
Apr 21, 3:55 PM CDTSevere Thunderstorm WarningHUNJackson35 min
Apr 21, 4:15 PM CDTSevere Thunderstorm WarningHUNDeKalb15 min
Apr 21, 4:30 PM CDTSevere Thunderstorm WarningHUNJackson15 min
Apr 21, 5:36 PM CDTSevere Thunderstorm WarningHUNMarshall24 min
Apr 21, 6:40 PM CDTSevere Thunderstorm WarningHUNDeKalb35 min
Apr 20, 8:04 PM CDTSevere Thunderstorm WarningHUNFranklin35 min

Nearby

Severe Thunderstorm Warnings in Alabama, 2006Every severe thunderstorm warning in 2006

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.