Alert archive / Florida / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS Melbourne, FL

September 19, 2021Seminole County, Florida

NWS Melbourne, FL issued this flash flood warning at Sep 19, 2021, 6:07 PM EDT for Seminole County, Florida. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 19, 2021, 6:07 PM EDT (22:07 UTC)
Expired: Sep 19, 2021, 8:30 PM EDT
In force: 2 hr
Issued by: NWS Melbourne, FL
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Seminole County, FL

The radar

The Melbourne radar (KMLB), 97 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.

The nearest sounding before it

Cape Canaveral, FL (KXMR), launched 12:00Z, 10.1 hours before the alert went out and 85 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: 1110 J/kg
Mixed-layer CIN: -23 J/kg
Mixed-layer LCL: 850 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

004 
WGUS52 KMLB 192207
FFWMLB
FLC117-200030-
/O.NEW.KMLB.FF.W.0001.210919T2207Z-210920T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Melbourne FL
607 PM EDT Sun Sep 19 2021

The National Weather Service in Melbourne has issued a

* Flash Flood Warning for...
  Northwestern Seminole County in east central Florida...

* Until 830 PM EDT.

* At 607 PM EDT, Seminole County Emergency Management reported 
  thunderstorms producing heavy rain across the warned area. Between 
  3.5 and 5 inches of rain have fallen. Additional rainfall amounts 
  of 1 to 2 inches are possible in the warned area. Flash flooding 
  is ongoing, especially in the Sanford area where numerous roads 
  are closed, several water rescues have been needed, and water is 
  approaching homes in the area.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Emergency management reported.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Sanford, Lake Mary, Longwood, Sanford Airport, and Heathrow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 2869 8144 2871 8144 2874 8142 2878 8141
      2882 8142 2885 8138 2885 8136 2883 8131
      2883 8122 2881 8122 2879 8120 2879 8119
      2880 8118 2878 8118 2879 8114 2869 8114

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Rodriguez

2 follow-up statements

748 
WGUS72 KMLB 192259
FFSMLB

Flash Flood Statement
National Weather Service Melbourne FL
659 PM EDT Sun Sep 19 2021

FLC117-200030-
/O.CON.KMLB.FF.W.0001.000000T0000Z-210920T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Seminole FL-
659 PM EDT Sun Sep 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM EDT THIS 
EVENING FOR NORTHWESTERN SEMINOLE COUNTY...

At 659 PM EDT, Seminole County and City of Sanford Emergency 
Management report numerous roads are closed in the Sanford area due 
to high standing water. While the heaviest rain has ended, 
thunderstorms continue to produce moderate rainfall in the warned 
area. Between 4 and 5.5 inches of rain have fallen. Additional 
rainfall amounts of 0.5 to 1.5 inches are possible in the warned 
area. Flash flooding is already occurring.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Emergency management reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Sanford, Lake Mary, Longwood, Sanford Airport, Midway, and 
  Heathrow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 2869 8144 2871 8144 2874 8142 2878 8141
      2882 8142 2885 8138 2885 8136 2883 8131
      2883 8122 2881 8122 2879 8120 2879 8119
      2880 8118 2878 8118 2879 8114 2869 8114

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Rodriguez

764 
WGUS72 KMLB 200029
FFSMLB

Flash Flood Statement
National Weather Service Melbourne FL
829 PM EDT Sun Sep 19 2021

FLC117-200039-
/O.EXP.KMLB.FF.W.0001.000000T0000Z-210920T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Seminole FL-
829 PM EDT Sun Sep 19 2021

...FLASH FLOOD WARNING AT 830 PM EDT THIS EVENING FOR NORTHERN 
SEMINOLE COUNTY HAS BEEN REPLACED WITH A FLOOD WARNING...

The heavy rain has ended in Seminole County, however standing water 
remains an issue in many areas of the county, especially in Sanford. 
Please continue to heed remaining road closures.

LAT...LON 2869 8144 2871 8144 2874 8142 2878 8141
      2882 8142 2885 8138 2885 8136 2883 8131
      2883 8122 2881 8122 2879 8120 2879 8119
      2880 8118 2878 8118 2879 8114 2869 8114

$$

Rodriguez

The office that day

Everything else NWS Melbourne, FL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 19, 4:09 PM EDT	Areal Flood Advisory	MLB	Volusia	81 min
Sep 19, 4:26 PM EDT	Areal Flood Advisory	MLB	Volusia	64 min
Sep 19, 4:49 PM EDT	Special Weather Statement	MLB	Orange	26 min
Sep 19, 5:19 PM EDT	Areal Flood Advisory	MLB	Orange, Seminole, Volusia	116 min
Sep 19, 5:39 PM EDT	Areal Flood Warning	MLB	Seminole, Volusia	28 min
Sep 19, 6:14 PM EDT	Special Weather Statement	MLB	Osceola	31 min
Sep 19, 6:46 PM EDT	Areal Flood Advisory	MLB	Orange, Osceola	119 min

Nearby

Flash Flood Warnings in Florida, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.