Alert archive / Alabama / Flash Flood Warnings in 2011

Flash Flood Warning 20, NWS Mobile, AL

April 20, 2011Monroe County, Alabama

NWS Mobile, AL issued this flash flood warning at Apr 20, 2011, 2:36 PM CDT for Monroe County, Alabama. It was in force for 74 min. 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, 2:36 PM CDT (19:36 UTC)
Expired
Apr 20, 2011, 3:50 PM CDT
In force
74 min
Issued by
NWS Mobile, AL
Area
Storm-based polygon
Flood severity
None

County Monroe County, AL

The radar

The Mobile radar (KMOB), 120 km from the middle of the area, began a volume at 19:37 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 nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 7.6 hours before the alert went out and 200 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 12:00Z on 2011-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2075 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 12:00Z on 2011-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.193958Sfc1 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
2075 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
550 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
151 m²/s²
0-3 km storm-relative helicity
166 m²/s²
Significant tornado parameter
1.3
Supercell composite
7.5

Open this sounding in Storm Lab

The text

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

150 
WGUS54 KMOB 201936
FFWMOB
ALC099-202230-
/O.NEW.KMOB.FF.W.0020.110420T1936Z-110420T2230Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTH CENTRAL MONROE COUNTY IN SOUTH CENTRAL ALABAMA...
  THIS INCLUDES THE CITY OF FRISCO CITY...

* UNTIL 530 PM CDT

* AT 233 PM CDT...NATIONAL WEATHER SERVICE RADAR INDICATED VERY HEAVY
  RAIN FROM A THUNDERSTORM NEAR FRISCO CITY...MOVING VERY SLOWLY TO  
  THE EAST NORTHEAST AT 5 MPH.

* THE THUNDERSTORM PRODUCING VERY HEAVY RAIN WILL BE NEAR...
  FRISCO CITY BY 300 PM CDT...
  EXCEL BY 340 PM CDT...

ADDITIONAL RAINFALL AMOUNTS OF THREE TO FOUR INCHES OF RAINFALL ARE 
POSSIBLE IN THE WARNED AREA. DRIVERS AND RESIDENTS ALONG STATE ROAD 
21 JUST SOUTH OF FRISCO CITY SHOULD BE ON ALERT TO POSSIBLE FLOODING.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

LAT...LON 3153 8730 3145 8725 3132 8738 3143 8754

$$

JC
1 follow-up statement
879 
WGUS74 KMOB 202050
FFSMOB

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOBILE AL
350 PM CDT WED APR 20 2011

ALC099-202058-
/O.CAN.KMOB.FF.W.0020.000000T0000Z-110420T2230Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONROE AL-
350 PM CDT WED APR 20 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR SOUTH CENTRAL
MONROE COUNTY...

THUNDERSTORMS HAVE DISSIPATED...ENDING THE THREAT OF FLASH FLOODING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM CDT
WEDNESDAY EVENING FOR SOUTHWESTERN ALABAMA.

LAT...LON 3153 8730 3145 8725 3132 8738 3143 8754

$$

10

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; radar from the NEXRAD Level II archive.