Alert archive / Alabama / Flash Flood Watches in 2009

Flash Flood Watch 16, NWS Birmingham, AL

September 18, 200939 counties in Alabama

NWS Birmingham, AL issued this flash flood watch at Sep 18, 2009, 5:02 AM CDT for 39 counties in Alabama. It took effect at Sep 18, 2009, 7:00 AM CDT. It was in force for 5 days.

The area

The counties it named.

The facts

Issued: Sep 18, 2009, 5:02 AM CDT (10:02 UTC)
In effect from: Sep 18, 2009, 7:00 AM CDT
Expired: Sep 23, 2009, 6:00 AM CDT
In force: 5 days
Issued by: NWS Birmingham, AL
Flood severity: None

All 39 counties

Autauga County, AL, Barbour County, AL, Bibb County, AL, Blount County, AL, Bullock County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Etowah County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lamar County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Marion County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Pike County, AL, Randolph County, AL, Russell County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL

The radar

The Birmingham radar (KBMX), 22 km from the middle of the area, began a volume at 10:02 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, 10.0 hours before the alert went out and 23 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: 572 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 549 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 61 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Birmingham, AL wrote its last area forecast discussion before this flash flood watch went out at Sep 18, 4:54 AM CDT, 8 minutes earlier.

Area forecast discussion, Sep 18, 4:54 AM CDT, 8 minutes before

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Hazardous weather outlook, Sep 17, 11:21 PM CDT, 5 hours 41 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1121 PM CDT THU SEP 17 2009

ALZ011>015-017>050-190430-
MARION-LAMAR-FAYETTE-WINSTON-WALKER-BLOUNT-ETOWAH-CALHOUN-
CHEROKEE-CLEBURNE-PICKENS-TUSCALOOSA-JEFFERSON-SHELBY-ST. CLAIR-
TALLADEGA-CLAY-RANDOLPH-SUMTER-GREENE-HALE-PERRY-BIBB-CHILTON-
COOSA-TALLAPOOSA-CHAMBERS-MARENGO-DALLAS-AUTAUGA-LOWNDES-ELMORE-
MONTGOMERY-MACON-BULLOCK-LEE-RUSSELL-PIKE-BARBOUR-
1121 PM CDT THU SEP 17 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...TONIGHT.

SCATTERED SHOWERS AND A FEW THUNDERSTORMS COULD STILL PRODUCE
LOCALIZED HEAVY RAIN WHICH COULD LEAD TO ADDITIONAL FLOODING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

PERIODS OF RAIN...HEAVY AT TIMES...WILL CONTINUE FRIDAY. SEVERAL
DAYS OF RAINFALL WILL SATURATE SOILS...INCREASING THE THREAT OF
FLASH FLOODING.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT IS NOT
EXPECTED AT THIS TIME.

In the hours before

Local storm report, Sep 18, 12:44 AM CDT, 4 hours 18 minutes before

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Local storm report, Sep 18, 1:37 AM CDT, 3 hours 25 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 17, 7:23 PM CDT	Areal Flood Advisory	BMX	St. Clair	112 min
Sep 17, 8:06 PM CDT	Flash Flood Warning	BMX	Jefferson, St. Clair	3 hr
Sep 17, 9:26 PM CDT	Flash Flood Warning	BMX	Jefferson, St. Clair, Shelby	3 hr
Sep 18, 12:33 AM CDT	Flash Flood Warning	BMX	Jefferson, St. Clair, Shelby	5 hr
Sep 18, 2:57 AM CDT	Areal Flood Advisory	BMX	Jefferson, Shelby	2 hr
Sep 18, 6:48 AM CDT	River Flood Warning	BMX	Bibb, Jefferson, Shelby	14 hr
Sep 18, 3:55 PM CDT	Areal Flood Advisory	BMX	Marengo	2 hr
Sep 18, 5:41 PM CDT	Areal Flood Advisory	BMX	Lowndes	2 hr
Sep 18, 5:54 PM CDT	Areal Flood Advisory	BMX	Perry	2 hr
Sep 18, 6:29 PM CDT	Areal Flood Advisory	BMX	Tuscaloosa	2 hr

Nearby

Flash Flood Watches in Alabama, 2009 Every flash flood 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.