Alert archive / Alabama / Tornado Warnings in 2010

Tornado Warning 20, NWS Huntsville, AL

April 25, 2010DeKalb County, Alabama

NWS Huntsville, AL issued this tornado warning at Apr 25, 2010, 12:09 AM CDT for DeKalb County, Alabama. It was in force for 36 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 25, 2010, 12:09 AM CDT (05:09 UTC)
Expired: Apr 25, 2010, 12:45 AM CDT
In force: 36 min
Issued by: NWS Huntsville, AL
Area: Storm-based polygon

County DeKalb County, AL

The radar

The Northeast Alabama radar (KHTX), 58 km from the middle of the area, began a volume at 05:11 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 24, 7:11 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 5.2 hours before the alert went out and 168 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1231 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 483 m above ground
0-6 km bulk shear: 69 kt
0-1 km storm-relative helicity: 415 m²/s²
0-3 km storm-relative helicity: 438 m²/s²
Significant tornado parameter: 3.6
Supercell composite: 15.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this tornado 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 tornado warning went out at Apr 24, 7:25 PM CDT, 4 hours 44 minutes earlier.

Area forecast discussion, Apr 24, 7:25 PM CDT, 4 hours 44 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
725 PM CDT SAT APR 24 2010

.UPDATE...MESOSCALE UPDATE AND UPDATED AVIATION DISCUSSION.
&&

.DISCUSSION...
TORNADIC STORMS STILL CONTINUING IN OUR SOUTHEASTERN-MOST COUNTIES.
THE "FINAL BAND" OF ACTIVITY HAS DEVELOPED SLIGHTLY MORE SOUTHWARD
BUT STILL CONSISTS OF JUST SHOWERS AND CLOUDS AT THIS TIME. WATCH
SITUATION HAS CHANGED...SO LET ME EXPLAIN IT ALL HERE. WESTERN THREE
COUNTIES ARE OUT OF ALL WATCHES. DRIER AIR (EVEN DRIER THAN ALREADY
EXISTS) IS FILTERING IN. METRO HUNTSVILLE (INCLUDING LAWRENCE
COUNTY) REMAINS IN THE 9 PM EXPIRATION TIME WATCH...AND IF WE SEE NO
DEVELOPMENT ALONG THE "FINAL LINE"...WE WILL PROBABLY START LETTING
THOSE COUNTIES GO. NEW WATCHES HAVE BEEN ISSUED FOR THE COUNTIES TO
BE AFFECTED BY THE ONGOING STORMS...BOTH IN SRN TN AND IN NERN AL.
ALTHOUGH THOSE RUN OFFICIALLY UNTIL 2 AM...THEY WILL LIKELY BE
CANCELLED LONG BEFORE THAT.
&&

.AVIATION.../UPDATED FROM 00Z TAFS/
FINAL BAND WILL BE PUSHING THROUGH KMSL ALMOST ANYTIME. WILL REMOVE
THE TEMPO GROUP FOR STORMS AS SOON AS IT DOES AND INDICATE SKC.
EVENTUALLY PLAN TO DO THE SAME AT KHSV...BUT IT MAY BE MID/LATE
EVENING. AFTER THAT...VFR CONDITIONS ARE EXPECTED...THOUGH SOME
CONVECTIVE CLOUDS...BUT STILL VFR CEILINGS...ARE LIKELY TOMORROW
AFTERNOON.
&&

.PREV DISCUSSION...
STRONG/LOCALLY SVR CONVECTION CONTINUES ACROSS MUCH OF THE SE REGION
THIS AFTERNOON...UNDER A STRONGLY SHEARED ENVIRONMENT. THE DEGREE OF
SFC BASED INSTABILITY THOUGH...ALONG WITH A FAIRLY STRONG CAP BELOW
H7...LOOKS TO BE THE DECISIVE FACTORS WHETHER THIS CONVECTION HAS
TRENDED BETTER/MORE ORGANIZED. THE BRUNT OF THIS ACTIVITY THUS FAR
HAS REMAINED JUST BELOW SVR THRESHOLDS. WHILE THERE REMAINS SOME
UNCERTAINTY OVER HOW MUCH AIR MASS DESTABILIZATION IS ABLE TO
DEVELOP OVER THE NEXT FEW HRS...STRONG LL INFLOW COUPLED WITH A FEW
LINGERING HRS OF SFC BASED HEATING MAY STILL ALLOW FOR SOME
ORGANIZED SVR/TORNADIC STORMS ACROSS THE AREA...THROUGH THE
REMAINING AFTERNOON AND EARLY EVENING PERIODS. CURRENT TOR WATCH IN
EFFECT RUNS THROUGH 02Z SUN/9 PM CST. EVEN IF THE SVR WX/TORNADIC
THREAT FAILS TO MATERIALIZE...STRONG DIFFLUENT PATTERN IN PLACE
ALOFT WILL ALLOW FOR SOME TRAINING OF CONVECTIVE BANDS INTO THE
EVENINGS HRS...LEADING TO A LOCALIZED THREAT OF FLASH FLOODING.

SVR WX/FLASH FLOODING THREAT SHOULD BEGIN TO TAPER OFF TOWARD THE E
AFTER MIDNIGHT AS THE COLD FRONT BEGINS TO SWEEP EWD THROUGH THE
FORECAST AREA. POTENT UPPER TROUGH/SHRTWV OVER THE MID PLAINS STATES
SHOULD BEGIN TO LIFT INTO THE OH VALLEY OVERNIGHT AND INTO SUN AS IT
DEAMPLIFIES...HELPING TO LIMIT FURTHER PRECIP CHANCES OTHER THAN
SOME ISOLATED SHOWERS. CONDITIONS THOUGH MAY BE SLOW TO CLR THROUGH
THE WEEKEND PERIOD AND INTO NEXT WEEK WITH THE AREA REMAINING UNDER
A SWLY FETCH REGIME. WEAK HIGH PRESSURE OUT OF THE PLAINS STATES
WILL EVENTUALLY BEGIN TO SETTLE INTO THE SE REGION PAST TUE...WITH
OVERALL TEMPS HOVERING NEAR SEASONAL TRENDS.

GOING PAST MID WEEK...HIGH PRESSURE WILL BEGIN TO SHIFT EWD TOWARD
THE SRN ATLANTIC BASIN ALLOWING FOR A GRADUAL WARMING TREND. THE
LATTER HALF OF THE GFS SOLUTION STILL POINTS TOWARD ANOTHER SFC
BOUNDARY MOVING INTO THE SE REGION FRI AND SAT. WILL AT LEAST
CONTINUE/MAINTAIN THE TREND OF RAIN CHANCES RETURNING TO THE
FORECAST HEADING INTO NEXT WEEKEND.
&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

DISCUSSION/AVIATION...JE/23
PREV DISCUSSION...09

Hazardous weather outlook, Apr 24, 9:37 PM CDT, 2 hours 32 minutes before

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In the hours before

Local storm report, Apr 24, 10:49 PM CDT, 1 hour 20 minutes before

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Special weather statement, Apr 24, 10:54 PM CDT, 1 hour 15 minutes before

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Local storm report, Apr 24, 10:55 PM CDT, 1 hour 14 minutes before

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Local storm report, Apr 24, 11:01 PM CDT, 1 hour 8 minutes before

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Local storm report, Apr 24, 11:08 PM CDT, 1 hour 1 minute before

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Special weather statement, Apr 24, 11:17 PM CDT, 52 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 24, 7:12 PM CDT	Tornado Warning	HUN	Cullman, Marshall, Morgan	33 min
Apr 24, 7:41 PM CDT	Tornado Warning	HUN	Madison, Marshall	34 min
Apr 24, 8:11 PM CDT	Tornado Warning	HUN	DeKalb, Jackson, Marshall	34 min
Apr 24, 8:36 PM CDT	Flash Flood Warning	HUN	Cullman	4 hr
Apr 24, 8:39 PM CDT	Special Weather Statement	HUN	Cullman	51 min
Apr 24, 8:53 PM CDT	Tornado Warning	HUN	Cullman	37 min
Apr 24, 9:35 PM CDT	Special Weather Statement	HUN	Marshall	40 min
Apr 24, 10:04 PM CDT	Special Weather Statement	HUN	Cullman	41 min
Apr 24, 10:08 PM CDT	Special Weather Statement	HUN	Marshall	37 min
Apr 24, 10:15 PM CDT	Tornado Warning	HUN	DeKalb, Marshall	30 min
Apr 24, 10:40 PM CDT	Tornado Warning	HUN	DeKalb	35 min
Apr 24, 10:48 PM CDT	Special Weather Statement	HUN	Marshall	27 min
Apr 24, 11:12 PM CDT	Tornado Warning	HUN	DeKalb	27 min
Apr 24, 11:17 PM CDT	Special Weather Statement	HUN	Marshall	43 min
Apr 24, 11:21 PM CDT	Tornado Warning	HUN	DeKalb	17 min
Apr 24, 11:42 PM CDT	Tornado Warning	HUN	DeKalb	33 min
Apr 24, 11:44 PM CDT	Flash Flood Warning	HUN	DeKalb	3 hr
Apr 25, 10:32 AM CDT	Areal Flood Warning	HUN	DeKalb	8 hr
Apr 24, 10:17 PM CDT	Special Weather Statement	HUN	Franklin	28 min
Apr 24, 10:54 PM CDT	Special Weather Statement	HUN	Franklin	66 min

Nearby

Tornado Warnings in Alabama, 2010 Every tornado warning in 2010 Tornadoes in 2010

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.