Alert archive / Alabama / Flash Flood Warnings in 1999

Flash Flood Warning 37, NWS Mobile, AL

August 20, 1999Choctaw County, Washington County, Alabama

NWS Mobile, AL issued this flash flood warning at Aug 20, 1999, 9:11 PM CDT for Choctaw County, Washington County, Alabama. It was in force for 79 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
Aug 20, 1999, 9:11 PM CDT (02:11 UTC)
Expired
Aug 20, 1999, 10:30 PM CDT
In force
79 min
Issued by
NWS Mobile, AL
Area
Whole counties

Counties Choctaw County, AL, Washington County, AL

The radar

The Mobile radar (KMOB), 115 km from the middle of the area, began a volume at 02:13 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 00:00Z, 2.2 hours before the alert went out and 213 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 1999-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 206 joules per kilogram.LCLLFCEL10008507005003002001001 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, Birmingham, AL at 00:00Z on 1999-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 9 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
206 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
2676 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
9 m²/s²
0-3 km storm-relative helicity
-33 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Mobile, AL wrote its last area forecast discussion before this flash flood warning went out at Aug 20, 8:25 PM CDT, 46 minutes earlier.

Area forecast discussion, Aug 20, 8:25 PM CDT, 46 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
825 PM CDT FRI AUG 20 1999

LATEST SFC ANALYSIS SHOWS WEAK FRONTAL BOUNDARY NEAR AN ATL TO MGM
TO MEI LINE WITH LTL MOVEMENT SWD.  INITIAL CONVECTION THAT FIRED
EARLIER OVER THE NE PORTIONS OF THE CWA HAVE PUSHED SWD AND ARE NOW
DISSIPATING OVER THE NW FL COUNTIES.  LATEST RADAR SHOWS ANOTHER BKN
LINE OF TSTMS DEVELOPING ALONG THE FRONT BUT MAINLY CONCENTRATED
ACRS CHOCTAW...S MARENGO...N CLARKE AND WILCOX COUNTIES WHERE THE
AIRMASS RMNS MORE UNSTABLE DUE TO LACK OF AFTN CONVECTION.  THESE
STORMS WERE MVG SSE NEAR 15 MPH.  WITH THE ERN PORTIONS OF THE CWA
BEING STABILIZED FROM EARLIER STORMS...BELIEVE THIS LATEST DEVELOPMNT
WILL RMN MOSTLY CONCENTRATED OVER THE MORE UNSTABLE NW-SW PORTIONS
OF THE CWA.  WILL TWEAK POPS BACK REMAINDER TNGT WITH HIGHER POPS
WARRANTED OVER THE WRN SECTIONS.  WILL DROP MENTION OF SVR AS THREAT
CONTINUES TO LESSON AND THIS TREND SHUD CONTINUE RMNDR TNGT.

HAVE TWEAKED WNDS SLIGHTLY WITH VARIABLE WINDS LIKELY TO DOMINATE
WITH INFLUENCE OF APPROACHING TROF.  OTHERWISE...TEMPS ON TRACK.

NOTE...WITH STALLING FRONT ACRS FA...WOULD HAVE LIKED TO SEE AT
LEAST SLIGHT CHC POPS ACRS NRN SECTIONS AND CHC POPS ALONG COASTAL
SECTIONS FOR SAT.  BUT UP TO MIDNIGHT SHIFT TO ADJUST 2ND PERIOD.

OVER THE COASTAL WATERS...WEAK COOL FRONT WILL STALL NEAR THE COAST
ON SAT WITH SW WINDS AND SCT CONVECTION PREVAILING JUST OUT
AHEAD.

FCSTID=39

MOB UU 073/092 071/090 070 3932-
PNS UU 074/092 073/092 073 39221
DTS UU 076/090 076/089 077 39221
GZH UU 071/094 068/092 067 3921-
61A UU 070/093 067/092 067 3931-
2RO UU 069/093 066/092 067 3931-=

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 7:58 PM CDTSevere Thunderstorm WarningMOBClarke, Wilcox62 min
Aug 20, 9:11 PM CDTSevere Thunderstorm WarningMOBChoctaw, Washington79 min

Nearby

Flash Flood Warnings in Alabama, 1999Every flash flood warning in 1999

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.