Alert archive / Alabama / Tornado Watches in 2009

Tornado Watch 237

May 4, 200911 counties in Alabama; George County, Greene County, Mississippi

The Storm Prediction Center issued this tornado watch at May 4, 2009, 2:34 AM CDT for 11 counties in Alabama; George County, Greene County, Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: May 4, 2009, 2:34 AM CDT (07:34 UTC)
Expired: May 4, 2009, 7:34 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

Counties Baldwin County, AL, Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Escambia County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Wilcox County, AL, George County, MS, Greene County, MS

The radar

The Mobile radar (KMOB), 86 km from the middle of the area, began a volume at 07:36 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
May 4, 3:00 AM CDT	Severe Thunderstorm Warning	MOB	Mobile, Washington	45 min
May 4, 3:40 AM CDT	Severe Thunderstorm Warning	MOB	Baldwin, Clarke, Mobile, Monroe, Washington	65 min
May 4, 3:57 AM CDT	Flash Flood Warning	MOB	Greene	2 hr
May 4, 4:09 AM CDT	Severe Thunderstorm Warning	MOB	Washington	51 min
May 4, 4:29 AM CDT	Severe Thunderstorm Warning	MOB	Mobile, Washington	61 min
May 4, 4:50 AM CDT	Severe Thunderstorm Warning	MOB	Monroe	55 min
May 4, 5:02 AM CDT	Tornado Warning	MOB	Monroe	28 min
May 4, 5:19 AM CDT	Flash Flood Warning	MOB	Washington	41 min
May 4, 6:07 AM CDT	Severe Thunderstorm Warning	MOB	Conecuh	53 min
May 4, 6:11 AM CDT	Severe Thunderstorm Warning	MOB	Baldwin, Escambia, Monroe	16 min
May 4, 6:34 AM CDT	Severe Thunderstorm Warning	MOB	Mobile	41 min
May 4, 6:55 AM CDT	Flash Flood Warning	MOB	Clarke, Mobile, Washington	3 hr
May 4, 7:30 AM CDT	Severe Thunderstorm Warning	MOB	Choctaw, Clarke, Wilcox	60 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 7.6 hours before the alert went out and 224 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: 332 J/kg
Mixed-layer CIN: -105 J/kg
Mixed-layer LCL: 1021 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 169 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

928 
WWUS20 KWNS 040732
SEL7  
SPC WW 040732
ALZ000-FLZ000-MSZ000-041300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 237
NWS STORM PREDICTION CENTER NORMAN OK
235 AM CDT MON MAY 4 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       SOUTHERN ALABAMA
       WESTERN FLORIDA PANHANDLE
       FAR SOUTHEAST MISSISSIPPI

EFFECTIVE THIS MONDAY MORNING FROM 235 AM UNTIL 800 AM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 40 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTHWEST OF MOBILE
ALABAMA TO 45 MILES NORTH NORTHEAST OF CRESTVIEW FLORIDA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU7).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...CLUSTER OF ELEVATED SUPERCELLS NEAR THE SRN MS/AL
BORDER AT 07Z SHOULD PERSIST/INCREASE AS THEY MOVE NEAR
MOIST/UNSTABLE GULF AIR RESIDING SOUTH OF SURFACE FRONT EXTENDING
W-E JUST NORTH OF THE COAST.  SHEAR REMAINS MORE THAN ADEQUATE FOR
SUPERCELLS...AND COULD SUPPORT AN ISOLATED TORNADO OR TWO EARLY THIS
MORNING NEAR THE FRONT. THREATS OF LARGE HAIL AND ISOLATED DAMAGING
WINDS ARE ALSO EXPECTED.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 27025.


...EVANS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 4, 1:30 AM CDT	Mesoscale Discussion	SPC	Barbour, Bullock, Butler, Choctaw, Clarke, Coffee and 13 more	3 hr
May 4, 2:12 AM CDT	Mesoscale Discussion	SPC	Baldwin, Coffee, Covington, Dale, Escambia, Geneva and 2 more	93 min
May 4, 4:58 AM CDT	Mesoscale Discussion	SPC	Baldwin, Barbour, Butler, Clarke, Coffee, Conecuh and 10 more	2 hr
May 4, 7:33 AM CDT	Tornado Watch	SPC	Baldwin, Butler, Coffee, Conecuh, Covington, Crenshaw and 6 more	6 hr
May 4, 10:38 AM CDT	Mesoscale Discussion	SPC	Barbour, Dale, Geneva, Henry, Houston	67 min
May 4, 1:34 PM CDT	Mesoscale Discussion	SPC	Baldwin, Coffee, Conecuh, Covington, Dale, Escambia and 2 more	56 min
May 4, 3:24 PM CDT	Mesoscale Discussion	SPC	Bibb, Chilton, Choctaw, Clarke, Clay, Coosa and 7 more	66 min

Nearby

Tornado Watches in Alabama, 2009 Tornado Watches in Mississippi, 2009 Every tornado watch 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.