Alert archive / Alabama / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 11, NWS Birmingham, AL

February 11, 2009Cherokee County, Alabama

NWS Birmingham, AL issued this severe thunderstorm warning at Feb 11, 2009, 3:09 PM CST for Cherokee County, Alabama. It was in force for 25 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: Feb 11, 2009, 3:09 PM CST (21:09 UTC)
Expired: Feb 11, 2009, 3:34 PM CST
In force: 25 min
Issued by: NWS Birmingham, AL
Area: Storm-based polygon

County Cherokee County, AL

The radar

The Northeast Alabama radar (KHTX), 95 km from the middle of the area, began a volume at 21:09 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
Feb 11, 11:10 AM CST	Tornado Watch	SPC	6 hr

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 9.2 hours before the alert went out and 136 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 841 m above ground
0-6 km bulk shear: 66 kt
0-1 km storm-relative helicity: 330 m²/s²
0-3 km storm-relative helicity: 366 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 Birmingham, AL wrote its last area forecast discussion before this severe thunderstorm warning went out at Feb 11, 10:19 AM CST, 4 hours 50 minutes earlier.

Area forecast discussion, Feb 11, 10:19 AM CST, 4 hours 50 minutes before

AREA FORECAST DISCUSSION...CORRECTED ISSUANCE TIME
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1019 AM CST WED FEB 11 2009

.UPDATE...MESOSCALE UPDATE.

&&

.DISCUSSION...

WATCHING CLOSELY AS MESOSCALE SITUATION EVOLVES THIS MORNING. AS
EXPECTED...MAIN LIMITING FACTOR/CONCERN FOR TODAY WILL BE
INSTABILITY. ENVIRONMENTAL WINDS ARE RATHER STOUT...50 KNOTS AT
ABOUT 2.5KFT ABOVE THE DECK...AND IT WILL NOT TAKE MUCH TO GET THIS
MOMENTUM DOWN TO THE SURFACE. BASED ON LATEST MSAS ANALYSIS AND
RUC13 FORECAST...CONCUR WITH SWOMCD REGARDING LOCATION OF BEST
INSTABILITY ACROSS THE SOUTHERN TIER OF CENTRAL ALABAMA. A FEW
BREAKS IN THE CLOUDS SHOWING UP IN THE VISIBLE SATELLITE ACROSS THIS
AREA...WITH TEMPS NOW RISING INTO THE 70 DEGREE RANGE AND DEWPOINTS
CREEPING UPWARD WELL INTO THE LOWER 60S. INFLUX OF COOLER AND DRIER
AIR IN THE MID LEVELS SHOULD ENHANCE CONVECTIVE POTENTIAL. AS THE
LINE MOVES INTO THE GRADUALLY DESTABILIZING ENVIRONMENT...WILL HAVE
TO WATCH CLOSELY FOR INTENSIFICATION. WHILE BRIEF SPINUPS CAN NOT BE
RULED OUT WITH THE LINE...STRONG WINDS SHOULD BE THE PRIMARY CONCERN
ACROSS THE NORTH. STILL HAVE CONCERNS THAT MORE ISOLATED CELLS IN
THE SOUTH MAY HAVE A BETTER SHOT AT A TORNADO AS CAPES AND SHEAR
CONTINUE TO CLIMB.

HAZARDOUS WEATHER OUTLOOK BEING UPDATED TO REFLECT LATEST THINKING
ON TIMING.

JD/81

&&

.AVIATION...12Z TAF DISCUSSION.

LOW CLOUDS WITH BASES NEAR 1500 FEET HAVE DEVELOPED OVER CENTRAL
ALABAMA THE PAST FEW HOURS AND EXPECT THEM TO PERSIST THROUGH
SUNRISE. SOUTHERLY WINDS WILL INCREASE TO 10-15 KNOTS BY SUNRISE.

AFTER SUNRISE...SOUTHERLY SURFACE WINDS WILL INCREASE TO NEAR 20
KNOTS BY 15Z DUE TO TIGHTENING PRESSURE GRADIENT AHEAD OF SURFACE
FRONT...WITH GUSTS TO 30 KNOTS. EXPECT LINE OF SHOWERS AND TSTMS TO
REACH TCL BY 17Z AND I-65 CORRIDOR BY 18Z...AND NEAR ANB AND MGM
BETWEEN 21 AND 22Z.  SVR STORMS POSSIBLE ACROSS ALL OF CENTRAL
ALABAMA DUE TO HIGH SHEAR AND A SQUALL LINE MOVING FROM EAST TO
WEST.  RAIN SHOULD BE MOSTLY EAST OF ALABAMA BY 00Z WITH CLEARING
ABOUT 2 HOURS AFTER FRONTAL PASSAGE.

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY NORTHERN HALF UNTIL 6 PM WEDNESDAY.
LAKE WIND ADVISORY SOUTHERN HALF UNTIL 6 PM WEDNESDAY.

&&

50

Hazardous weather outlook, Feb 11, 3:00 PM CST, 9 minutes before

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In the hours before

Local storm report, Feb 11, 2:14 PM CST, 55 minutes before

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Local storm report, Feb 11, 2:15 PM CST, 54 minutes before

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Local storm report, Feb 11, 2:16 PM CST, 53 minutes before

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Local storm report, Feb 11, 2:38 PM CST, 31 minutes before

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Local storm report, Feb 11, 2:45 PM CST, 24 minutes before

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Local storm report, Feb 11, 2:59 PM CST, 10 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Feb 11, 11:11 AM CST	Severe Thunderstorm Warning	BMX	Marion, Winston	34 min
Feb 11, 1:04 PM CST	Severe Thunderstorm Warning	BMX	Blount, Jefferson, St. Clair	26 min
Feb 11, 1:41 PM CST	Severe Thunderstorm Warning	BMX	Blount, Etowah, St. Clair	34 min

Nearby

Severe Thunderstorm Warnings in Alabama, 2009 Every severe thunderstorm warning in 2009

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.