Alert archive / Alabama / Flash Flood Warnings in 2011

Flash Flood Warning 21, NWS Huntsville, AL

April 20, 2011Colbert County, Lauderdale County, Alabama

NWS Huntsville, AL issued this flash flood warning at Apr 20, 2011, 10:47 PM CDT for Colbert County, Lauderdale County, Alabama. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Apr 20, 2011, 10:47 PM CDT (03:47 UTC)
Expired
Apr 21, 2011, 1:26 AM CDT
In force
3 hr
Issued by
NWS Huntsville, AL
Area
Storm-based polygon
Flood severity
None

Counties Colbert County, AL, Lauderdale County, AL

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 00:00Z, 3.8 hours before the alert went out and 172 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 2011-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2011-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -10 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
920 m above ground
0-6 km bulk shear
58 kt
0-1 km storm-relative helicity
-10 m²/s²
0-3 km storm-relative helicity
72 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

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

839 
WGUS54 KHUN 210347
FFWHUN
ALC033-077-210930-
/O.NEW.KHUN.FF.W.0021.110421T0347Z-110421T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1047 PM CDT WED APR 20 2011

THE NATIONAL WEATHER SERVICE IN HUNTSVILLE HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  COLBERT COUNTY IN NORTHWEST ALABAMA...
  LAUDERDALE COUNTY IN NORTHWEST ALABAMA...

* UNTIL 430 AM CDT

* AT 1042 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED  
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS          
  NORTHWEST ALABAMA. ONE TO TWO INCHES OF RAIN HAS                   
  ALREADY OCCURRED...AND AN ADDITIONAL ONE TO TWO INCHES ARE         
  POSSIBLE OVER THE NEXT SEVERAL HOURS.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  FLORENCE...MUSCLE SHOALS...SHEFFIELD...TUSCUMBIA...
  UNDERWOOD-PETERSVILLE...CHEROKEE...KILLEN...LEIGHTON...LEXINGTON...
  LITTLEVILLE AND ROGERSVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. DO
NOT ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND TO
ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN
WATER BEGINS RISING.

&&

LAT...LON 3500 8721 3480 8723 3478 8727 3475 8726
      3475 8729 3481 8735 3480 8741 3471 8743
      3470 8745 3466 8744 3465 8748 3457 8752
      3458 8814 3489 8810 3492 8814 3501 8819

$$

CA
1 follow-up statement
424 
WGUS74 KHUN 210626
FFSHUN

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
126 AM CDT THU APR 21 2011

ALC033-077-210639-
/O.CAN.KHUN.FF.W.0021.000000T0000Z-110421T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LAUDERDALE AL-COLBERT AL-
126 AM CDT THU APR 21 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR COLBERT AND
LAUDERDALE COUNTIES IS CANCELLED...

MODERATE RAINFALL HAS ENDED ACROSS THE WARNING AREA.  RAINFALL 
AMOUNTS OF THREE QUARTERS TO ONE AND ONE HALF INCHES HAVE BEEN 
REPORTED...BUT NO FLOODING HAS BEEN REPORTED.  AREA CREEKS AND 
STREAMS MAY STILL EXPERIENCE WITHIN BANK RISES OVERNIGHT.

IF FLOODING HAS BEEN OBSERVED...PLEASE REPORT IT TO YOUR LOCAL LAW 
ENFORCEMENT AGENCY.

LAT...LON 3500 8721 3480 8723 3478 8727 3475 8726
      3475 8729 3481 8735 3480 8741 3471 8743
      3470 8745 3466 8744 3465 8748 3457 8752
      3458 8814 3489 8810 3492 8814 3501 8819

$$

KULA

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 20, 9:06 PM CDTSpecial Weather StatementHUNFranklin39 min
Apr 20, 9:30 PM CDTFlash Flood WarningHUNFranklin, Lawrence6 hr
Apr 20, 9:47 PM CDTSpecial Weather StatementHUNLawrence43 min
Apr 20, 10:25 PM CDTSevere Thunderstorm WarningHUNCullman50 min
Apr 20, 10:31 PM CDTSpecial Weather StatementHUNLimestone44 min
Apr 20, 11:21 PM CDTFlash Flood WarningHUNCullman3 hr
Apr 20, 11:25 PM CDTSevere Thunderstorm WarningHUNCullman, Marshall, Morgan50 min
Apr 20, 11:29 PM CDTSpecial Weather StatementHUNJackson31 min
Apr 21, 12:09 AM CDTSpecial Weather StatementHUNDeKalb51 min
Apr 21, 12:19 AM CDTSevere Thunderstorm WarningHUNDeKalb41 min

Nearby

Flash Flood Warnings in Alabama, 2011Every flash flood warning in 2011

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.