Alert archive / Alabama / Flash Flood Warnings in 2021

Flash Flood Warning 38, NWS Huntsville, AL

September 18, 2021Limestone County, Morgan County, Alabama

NWS Huntsville, AL issued this flash flood warning at Sep 18, 2021, 5:11 PM CDT for Limestone County, Morgan County, Alabama. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Sep 18, 2021, 5:11 PM CDT (22:11 UTC)
Expired: Sep 18, 2021, 8:15 PM CDT
In force: 3 hr
Issued by: NWS Huntsville, AL
Area: Storm-based polygon
Flood severity: None

Counties Limestone County, AL, Morgan County, AL

The radar

The Northeast Alabama radar (KHTX), 90 km from the middle of the area, began a volume at 22:11 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.

What was reported inside it

Time	Report	Where	Remark
Sep 18, 6:00 PM CDT	FLASH FLOOD	Decatur, AL	LEE ST. IN FRONT OF COURTHOUSE UNDER WATER, PARTS OF CHURCH ST NE UNDER WATER AND INVOLVING BUSINESSES. FIRE AND POLICE CURRENTLY ASSISTING MOTORIST.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 12:00Z, 10.2 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: 1085 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 648 m above ground
0-6 km bulk shear: 7 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: 51 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

706 
WGUS54 KHUN 182211
FFWHUN
ALC083-103-190115-
/O.NEW.KHUN.FF.W.0038.210918T2211Z-210919T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Huntsville AL
511 PM CDT Sat Sep 18 2021

The National Weather Service in Huntsville has issued a

* Flash Flood Warning for...
  Southeastern Limestone County in north central Alabama...
  Northwestern Morgan County in north central Alabama...

* Until 815 PM CDT.

* At 511 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Decatur, Madison, Athens, Hartselle, Priceville, Trinity, Tanner, 
  Somerville, Mooresville, Belle Mina, Basham, French Mill and 
  Capshaw.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3473 8714 3479 8708 3478 8679 3448 8679
      3448 8711 3469 8710

FLASH FLOOD...RADAR INDICATED

$$

25

2 follow-up statements

443 
WGUS74 KHUN 182306
FFSHUN

Flash Flood Statement
National Weather Service Huntsville AL
606 PM CDT Sat Sep 18 2021

ALC083-103-190115-
/O.CON.KHUN.FF.W.0038.000000T0000Z-210919T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Limestone AL-Morgan AL-
606 PM CDT Sat Sep 18 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM CDT THIS 
EVENING FOR SOUTHEASTERN LIMESTONE AND NORTHWESTERN MORGAN 
COUNTIES...

At 606 PM CDT, emergency management reported flash flooding within 
the Decatur area. Flash flooding is ongoing or expected to begin 
shortly elsewhere in Limestone and Morgan counties.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Emergency management reported several roads within the
         Decatur area are under water and 911 is responding to
         stranded motorists.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Decatur, Madison, Athens, Hartselle, Priceville, Trinity, Tanner, 
  Somerville, Mooresville, Belle Mina, Basham, French Mill and 
  Capshaw.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3473 8714 3479 8708 3478 8679 3448 8679
      3448 8711 3469 8710

FLASH FLOOD...OBSERVED

$$

25

736 
WGUS74 KHUN 190115
FFSHUN

Flash Flood Statement
National Weather Service Huntsville AL
815 PM CDT Sat Sep 18 2021

ALC083-103-190125-
/O.EXP.KHUN.FF.W.0038.000000T0000Z-210919T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Limestone AL-Morgan AL-
815 PM CDT Sat Sep 18 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR SOUTHEASTERN LIMESTONE AND 
NORTHWESTERN MORGAN COUNTIES...

The heavy rain has ended. Please continue to heed remaining road 
closures.

A Flash Flood Watch remains in effect until 700 PM CDT Sunday for 
portions of Alabama and southern middle Tennessee.

LAT...LON 3473 8714 3479 8708 3478 8679 3448 8679
      3448 8711 3469 8710

$$

25

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 17, 7:59 PM CDT	Areal Flood Warning	HUN	Lauderdale	116 min
Sep 18, 2:24 AM CDT	Flash Flood Watch	HUN	Colbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more	65 hr
Sep 18, 3:51 PM CDT	Flash Flood Warning	HUN	Limestone	3 hr
Sep 18, 6:53 PM CDT	Areal Flood Warning	HUN	Limestone, Morgan	6 hr

Nearby

Flash Flood Warnings in Alabama, 2021 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.