Alert archive / Alabama / Flash Flood Warnings in 2011

Flash Flood Warning 36, NWS Birmingham, AL

July 21, 2011Jefferson County, Alabama

NWS Birmingham, AL issued this flash flood warning at Jul 21, 2011, 4:30 AM CDT for Jefferson County, Alabama. It was in force for 4 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 21, 2011, 4:30 AM CDT (09:30 UTC)
Expired
Jul 21, 2011, 8:30 AM CDT
In force
4 hr
Issued by
NWS Birmingham, AL
Area
Storm-based polygon
Flood severity
None

County Jefferson County, AL

The radar

The Birmingham radar (KBMX), 56 km from the middle of the area, began a volume at 09:32 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 was reported inside it

TimeReportWhereRemark
Jul 21, 5:17 AM CDTFLASH FLOOD2 Nne Center Point, ALA PORTION OF SWEENEY HOLLOW RD IS FLOODED AND COMPLETELY IMPASSABLE. FLOODING BEGAN AT APPROXIMATELY 517 AM.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 9.5 hours before the alert went out and 55 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, Birmingham, AL at 00:00Z on 2011-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 642 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 00:00Z on 2011-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 square meters per square second.1939Sfc1 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
642 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
994 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
101 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

015 
WGUS54 KBMX 210930
FFWBMX
ALC073-211330-
/O.NEW.KBMX.FF.W.0036.110721T0930Z-110721T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BIRMINGHAM AL
430 AM CDT THU JUL 21 2011

THE NATIONAL WEATHER SERVICE IN BIRMINGHAM HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHERN JEFFERSON COUNTY IN ALABAMA...

* UNTIL 830 AM CDT

* AT 427 AM CDT...NATIONAL WEATHER SERVICE INDICATED SLOW MOVING     
  THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE WARNED AREA.     
  ESTIMATED AMOUNTS OF TWO TO THREE INCHES HAVE BEEN OBSERVED        
  BY RADAR...WITH AN ADDITIONAL ONE TO TWO INCHES EXPECTED AS        
  THE STORMS CONTINUE TO MOVE OVER THE SAME AREA.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...     
  FULTONDALE...GARDENDALE...PINSON...TRUSSVILLE...ADAMSVILLE...
  BROOKSIDE...CARDIFF...CENTER POINT...CLAY...GRAYSVILLE...AND       
  WEST JEFFERSON.

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.

&&

TO REPORT SEVERE WEATHER...
CALL 1-800-856-0758.

LAT...LON 3374 8654 3372 8652 3366 8652 3362 8655
      3359 8688 3358 8717 3363 8713 3363 8709
      3366 8709 3366 8706 3372 8703 3377 8658
      3376 8655

$$

16
2 follow-up statements
067 
WGUS74 KBMX 211049
FFSBMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
549 AM CDT THU JUL 21 2011

ALC073-211330-
/O.CON.KBMX.FF.W.0036.000000T0000Z-110721T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
JEFFERSON AL-
549 AM CDT THU JUL 21 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR NORTHERN JEFFERSON
COUNTY UNTIL 830 AM CDT...

AT 544 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE WARNED AREA. 
RAINFALL HAS ESTIMATED AT 2 TO 3 INCHES OVER THE PAST TWO HOURS IN 
THE WARNED AREA. A REPORT OF JUST OVER 2 INCHES OF RAIN CAME FROM 
THE TRUSSVILLE AREA. FLASH FLOODING WAS ALSO REPORTED NORTH OF THE 
CENTER POINT AREA WITH THE ROADS IMPASSABLE.

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING 
INCLUDE...FULTONDALE...GARDENDALE...TRUSSVILLE...ADAMSVILLE...
BROOKSIDE...CARDIFF...CENTER POINT...CLAY...GRAYSVILLE...PINSON AND 
WEST JEFFERSON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3374 8654 3372 8652 3366 8652 3362 8655
      3359 8688 3358 8717 3363 8713 3363 8709
      3366 8709 3366 8706 3372 8703 3377 8658
      3376 8655

$$
677 
WGUS74 KBMX 211210
FFSBMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
710 AM CDT THU JUL 21 2011

ALC073-211330-
/O.CON.KBMX.FF.W.0036.000000T0000Z-110721T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
JEFFERSON AL-
710 AM CDT THU JUL 21 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR NORTHERN JEFFERSON
COUNTY UNTIL 830 AM CDT...

AT 707 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THUNDERSTORMS WITH VERY HEAVY RAINFALL EAST OF THE WARNED AREA. THIS 
STORM WILL SLIDE INTO THE WARNED AREA WITHIN THE NEXT HOUR. 
ADDITIONALLY SCATTERED SHOWERS AND THUNDERSTORMS MAY DEVELOP AHEAD 
OF THIS STORM AS WELL. RAINFALL OF 2 TO 3 INCHES HAVE FALLEN IN THE 
PAST 3 HOURS ACROSS NORTHERN JEFFERSON COUNTY...WITH A FEW AREAS 
RECEIVING LOCALIZED FLOODING.

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING 
INCLUDE...FULTONDALE...GARDENDALE...PINSON...TRUSSVILLE...
ADAMSVILLE...BROOKSIDE...CARDIFF...CENTER POINT...CLAY... 
GRAYSVILLE...AND WEST JEFFERSON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 3374 8654 3372 8652 3366 8652 3362 8655
      3359 8688 3358 8717 3363 8713 3363 8709
      3366 8709 3366 8706 3372 8703 3377 8658
      3376 8655

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 3:17 AM CDTAreal Flood AdvisoryBMXClay, Randolph, St. Clair, Shelby, Talladega118 min
Jul 21, 3:35 AM CDTFlash Flood WarningBMXClay, Talladega3 hr
Jul 21, 4:04 AM CDTAreal Flood AdvisoryBMXJefferson, St. Clair, Walker3 hr
Jul 21, 5:19 AM CDTAreal Flood AdvisoryBMXCalhoun, Clay, Cleburne, Randolph, Talladega116 min
Jul 21, 7:00 AM CDTAreal Flood AdvisoryBMXFayette, Lamar, Walker3 hr
Jul 21, 7:19 AM CDTFlash Flood WarningBMXSt. Clair3 hr
Jul 21, 8:06 AM CDTFlash Flood WarningBMXWalker3 hr
Jul 21, 8:46 AM CDTFlash Flood WarningBMXWalker3 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.