Alert archive / Tennessee / Flash Flood Warnings in 2013

Flash Flood Warning 45, NWS Huntsville, AL

August 21, 2013Franklin County, Tennessee

NWS Huntsville, AL issued this flash flood warning at Aug 21, 2013, 9:46 AM CDT for Franklin County, Tennessee. 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 counties it named.

The facts

Issued: Aug 21, 2013, 9:46 AM CDT (14:46 UTC)
Expired: Aug 21, 2013, 12:45 PM CDT
In force: 3 hr
Issued by: NWS Huntsville, AL
Area: Storm-based polygon
Flood severity: None

County Franklin County, TN

The radar

The Northeast Alabama radar (KHTX), 25 km from the middle of the area, began a volume at 14:46 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

Nashville Metro, TN (KBNA), launched 12:00Z, 2.8 hours before the alert went out and 118 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: 2305 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 545 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 41 m²/s²
0-3 km storm-relative helicity: 116 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 4.8

Open this sounding in Storm Lab

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 Huntsville, AL wrote its last area forecast discussion before this flash flood warning went out at Aug 21, 6:45 AM CDT, 3 hours 1 minute earlier.

Area forecast discussion, Aug 21, 6:45 AM CDT, 3 hours 1 minute before

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Hazardous weather outlook, Aug 21, 4:30 AM CDT, 5 hours 16 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HUNTSVILLE AL
430 AM CDT WED AUG 21 2013

ALZ001>010-016-TNZ076-096-097-211815-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DEKALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
430 AM CDT WED AUG 21 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH ALABAMA AND PORTIONS
OF SOUTHERN MIDDLE TENNESSEE.

.DAY ONE...TODAY AND TONIGHT...

SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE TENNESSEE VALLEY
THROUGH THIS AFTERNOON. LOCALLY HEAVY RAINFALL...GUSTY WINDS...AND
FREQUENT LIGHTNING WILL ACCOMPANY THE STRONGER STORMS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY...

THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW.

A TRANSITION TO A MORE TYPICAL PATTERN OF ISOLATED AFTERNOON AND
EARLY EVENING STORMS IS EXPECTED THROUGH THE END OF THE WEEK.

A WARMING TREND...ALONG WITH RESIDUAL MOISTURE FROM RECENT
RAINFALL...WILL PRODUCE HEAT INDICES RISING ABOVE 100 DEGREES
ACROSS NORTHWEST ALABAMA DURING THURSDAY AFTERNOON.

.SPOTTER CALL TO ACTION STATEMENT...

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

CCC

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 11:23 AM CDT	Flash Flood Warning	HUN	Colbert, Lauderdale	3 hr
Aug 21, 5:32 PM CDT	Special Weather Statement	HUN	Marshall	43 min
Aug 21, 6:52 PM CDT	Special Weather Statement	HUN	Lawrence	23 min
Aug 21, 10:26 AM CDT	Special Weather Statement	HUN	Moore	49 min

Nearby

Flash Flood Warnings in Tennessee, 2013 Every flash flood warning in 2013

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.