Alert archive / Alabama / Flash Flood Warnings in 2009

Flash Flood Warning 72, NWS Huntsville, AL

September 17, 2009Lauderdale County, Alabama

NWS Huntsville, AL issued this flash flood warning at Sep 17, 2009, 7:17 AM CDT for Lauderdale County, Alabama. It was in force for 5 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: Sep 17, 2009, 7:17 AM CDT (12:17 UTC)
Expired: Sep 17, 2009, 12:15 PM CDT
In force: 5 hr
Issued by: NWS Huntsville, AL
Area: Storm-based polygon
Flood severity: None

County Lauderdale County, AL

The radar

The Columbus AFB radar (KGWX), 128 km from the middle of the area, began a volume at 12:18 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, 0.3 hours before the alert went out and 167 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: 1026 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 455 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 71 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 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 Sep 17, 6:45 AM CDT, 32 minutes earlier.

Area forecast discussion, Sep 17, 6:45 AM CDT, 32 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
645 AM CDT THU SEP 17 2009

.UPDATE...FOR 12Z TAFS/AVIATION DISCUSSION
&&

.AVIATION...SHRA...ALONG WITH A FEW EMBEDDED TSTMS...ARE XPCTED TO
BE OFF AND ON THROUGH 00Z FRI AS AN AREA OF LOW PRESSURE OVER SE TX
GRADUALLY BEGINS TO MOVE TOWARD THE NE. MVFR CONDITIONS ARE
GENERALLY XPCTED TO PREVAIL ALTHOUGH BRIEF IFR/LIFR CONDITIONS ARE
POSSIBLE...ESPECIALLY FOR TERMINALS IN AND NEAR CONVECTIVE ACTIVITY.
&&

.DISCUSSION...THE SHOWERS THAT AFFECTED PARTS OF NW ALABAMA HAVE FOR
THE MOST PART FADED. A LOOK AT METARS AND MESOSITE OBSERVATIONS THUS
FAR SHOW UPWARDS OF 1.2 INCHES OF RAIN OVER THIS REGION. HOWEVER
THERE OBVIOUSLY WERE HIGHER AMOUNTS...WHICH WILL BE NOTED LATER
TODAY ON OUR DAILY TEMPS/PRECIP REPORT COMING OUT AROUND 10 AM...
HUNOSOHUN OR SXUS54 KHUN PRODUCT. AS OF THE PRESENT...A BAND OF
SHOWERS CONTINUED ALONG THE TN/AL BORDER FROM EAST OF SAVANNAH TO
NORTH OF MERIDIANVILLE. OTHER SHOWERS WERE AFFECTING DEKALB COUNTY
AND APPROACHING SOUTHERN CULLMAN COUNTY.

FORECAST WISE...NOT MANY CHANGES IN THE BIG PICTURE PATTERN FOR THE
SHORTER TERM THROUGH SATURDAY. PESKY LOW PRESSURE WILL REMAIN ACROSS
THE TX/LA REGION INTO FRIDAY. A SOUTHERLY FLOW EAST OF THE LOW WILL
CONTINUE TO FEED RICH GULF MOISTURE OVER THE TENNESSEE VALLEY. THUS
VERY GOOD/LIKELY CHANCES OF MORE SHOWERS AND EMBEDDED T-STORM WILL
CONTINUE. WITH PRECIP WATER AMOUNTS RANGING FROM 1.7 TO OVER 2
INCHES PER NAM/GFS BUFFER SOUNDINGS...THERE WILL BE A RISK FOR
LOCALLY HEAVY AMOUNTS OF RAINFALL. GIVEN THE FLOODING THAT AFFECTED
NW ALABAMA WED EVENING...HAVE DECIDED TO ISSUE A FLASH FLOOD WATCH
FOR THEM FOR TODAY. ADDITIONAL HEAVY RAINFALL PLUS A WET GROUND WILL
CAUSE MORE RUNOFF/FLOODING PROBLEMS.

THE LOW SHOULD FINALLY WEAKEN AND MOVE ACROSS MS/AL DURING LATE
SATURDAY. THE 00Z GFS/ECMWF WERE RATHER SIMILAR WITH BIG PICTURE QPF
COVERAGE/AMOUNTS THEN...HOWEVER THE EUROPEAN WAS A TAD WETTER.

FURTHER OUT...RAIN CHANCES SHOULD DROP IN TO THE CHANCE RANGE FOR
THE REST OF THE WEEKEND AND FIRST PART OF THE NEXT WORK WEEK.
RESIDUAL MOISTURE/INSTABILITY APPARENTLY WILL NOT BE TO QUICK TO
DEPART...DESPITE THE LOW BECOMING MORE DIFFUSE WITH TIME...SO
CHANCES FOR SHOWERS CONTINUE.

A COLD FRONT PASSAGE IS A POSSIBILITY IN ABOUT A WEEK. BOTH THE
GFS/ECMWF HINT AT A FRONT NEARING THE AREA DURING THE WED/THU TIME
FRAME. THE GFS WAS WEAKER AND DISPLACED SOMEWHAT FURTHER NORTH THAN
THE MORE AGGRESSIVE ECMWF. THESE MODELS OVER THE PAST WEEK OR SO
HAVE REPEATEDLY ADVERTISED SOMETHING LIKE THIS FURTHER OUT. GIVEN
THE UNCERTAINTY IN WHEN/IF A FRONT ARRIVES IS PROBLEMATIC...SO HAVE
MADE THE LAST TWO PERIODS PARTLY CLOUDY WITH A SLIGHT CHANCE OF
CONVECTION. FOR WHAT IT IS WORTH...ASTRONOMICAL AUTUMN ARRIVES NEXT
TUES AFTERNOON.
&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR THE FOLLOWING
ZONES: COLBERT...FRANKLIN AL...LAUDERDALE...LAWRENCE.

TN...NONE.
&&

UPDATE...09
DISCUSSION..RSB

Hazardous weather outlook, Sep 17, 6:03 AM CDT, 1 hour 14 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 16, 7:36 PM CDT	Flash Flood Warning	HUN	Colbert, Franklin, Lauderdale, Lawrence	4 hr
Sep 17, 3:50 AM CDT	Flash Flood Watch	HUN	Colbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more	6 days
Sep 17, 7:53 AM CDT	Flash Flood Warning	HUN	Lauderdale	3 hr
Sep 17, 11:29 AM CDT	Flash Flood Warning	HUN	Colbert, Lauderdale	3 hr
Sep 17, 11:48 AM CDT	Flash Flood Warning	HUN	Lauderdale	3 hr
Sep 17, 2:29 PM CDT	Areal Flood Warning	HUN	Lauderdale	4 hr

Nearby

Flash Flood Warnings in Alabama, 2009 Every flash flood warning 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.