Alert archive / Alabama / Flash Flood Warnings in 2021

Flash Flood Warning 18, NWS Huntsville, AL

March 31, 2021DeKalb County, Jackson County, Marshall County, Alabama

NWS Huntsville, AL issued this flash flood warning at Mar 31, 2021, 9:41 AM CDT for DeKalb County, Jackson County, Marshall County, Alabama. It was in force for 119 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
Mar 31, 2021, 9:41 AM CDT (14:41 UTC)
Expired
Mar 31, 2021, 11:40 AM CDT
In force
119 min
Issued by
NWS Huntsville, AL
Area
Storm-based polygon
Flood severity
None

Counties DeKalb County, AL, Jackson County, AL, Marshall County, AL

The radar

The Northeast Alabama radar (KHTX), 65 km from the middle of the area, began a volume at 14:41 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, 2.7 hours before the alert went out and 152 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 2021-03-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 455 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 2021-03-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 273 square meters per square second.19395878Sfc1 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
455 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
527 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
273 m²/s²
0-3 km storm-relative helicity
283 m²/s²
Significant tornado parameter
0.6
Supercell composite
3.5

Open this sounding in Storm Lab

The text

As transmitted.

152 
WGUS54 KHUN 311441
FFWHUN
ALC049-071-095-311745-
/O.NEW.KHUN.FF.W.0018.210331T1441Z-210331T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Huntsville AL
941 AM CDT Wed Mar 31 2021

The National Weather Service in Huntsville has issued a

* Flash Flood Warning for...
  DeKalb County in northeastern Alabama...
  Southeastern Jackson County in northeastern Alabama...
  Marshall County in northeastern Alabama...

* Until 1245 PM CDT.

* At 941 AM CDT, emergency management reported thunderstorms 
  producing heavy rain across the warned area. Between 1 and 3 
  inches of rain have fallen. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Emergency management.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Albertville, Scottsboro, Fort Payne, Boaz, Guntersville, 
  Rainsville, Henagar, Crossville, Sylvania, Fyffe, Powell, 
  Geraldine, Section, Ider, Pisgah, Douglas, Valley Head, 
  Hammondville, Mentone and Dutton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3436 8647 3486 8558 3452 8551 3447 8558
      3444 8558 3436 8563 3426 8577 3424 8584
      3421 8584 3418 8619 3410 8630 3426 8645

FLASH FLOOD...OBSERVED

$$

McCoy
1 follow-up statement
705 
WGUS74 KHUN 311640
FFSHUN

Flash Flood Statement
National Weather Service Huntsville AL
1140 AM CDT Wed Mar 31 2021

ALC049-071-095-311650-
/O.CAN.KHUN.FF.W.0018.000000T0000Z-210331T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DeKalb AL-Jackson AL-Marshall AL-
1140 AM CDT Wed Mar 31 2021

...FLASH FLOOD WARNING IS CANCELLED FOR DEKALB, SOUTHEASTERN JACKSON 
AND MARSHALL COUNTIES...

This flash flood warning has been replaced with an Areal Flood 
Warning.  Even though the heavy rain has ended, flooding will 
continue to cause problems for the next several hours. Please 
continue to heed remaining road closures.

LAT...LON 3436 8647 3486 8558 3452 8551 3447 8558
      3444 8558 3436 8563 3426 8577 3424 8584
      3421 8584 3418 8619 3410 8630 3426 8645

$$

McCoy

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 31, 3:38 AM CDTSpecial Weather StatementHUNMarshall52 min
Mar 31, 3:56 AM CDTSpecial Weather StatementHUNMorgan49 min
Mar 31, 4:59 AM CDTAreal Flood WarningHUNJackson3 hr
Mar 31, 6:21 AM CDTAreal Flood WarningHUNCullman3 hr
Mar 31, 7:21 AM CDTFlash Flood WarningHUNCullman6 hr
Mar 31, 7:30 AM CDTFlash Flood WarningHUNJackson, Marshall4 hr
Mar 31, 7:36 AM CDTSpecial Weather StatementHUNCullman39 min
Mar 31, 8:49 AM CDTFlash Flood WarningHUNMadison, Marshall, Morgan3 hr
Mar 31, 11:35 AM CDTAreal Flood WarningHUNDeKalb, Jackson, Madison, Marshall, Morgan6 hr
Mar 31, 1:06 PM CDTAreal Flood WarningHUNCullman5 hr
Mar 31, 1:42 PM CDTRiver Flood WarningHUNMadison, Marshall, Morgan55 hr
Mar 31, 1:52 PM CDTFreeze WatchHUNColbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more13 hr
Mar 31, 1:52 PM CDTFreeze WarningHUNColbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more42 hr
Mar 31, 5:29 PM CDTAreal Flood WarningHUNDeKalb3 hr
Mar 31, 6:18 PM CDTAreal Flood WarningHUNCullman18 hr

Nearby

Flash Flood Warnings in Alabama, 2021Every flash flood warning in 2021

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.