Alert archive / Florida / Flood Watches in 2021

Flood Watch 4, NWS Melbourne, FL

December 20, 2021Volusia County, Florida

NWS Melbourne, FL issued this flood watch at Dec 20, 2021, 9:21 AM EST for Volusia County, Florida. It took effect at Dec 20, 2021, 2:00 PM EST. It was in force for 14 hr.

The area

The counties it named.

The facts

Issued
Dec 20, 2021, 9:21 AM EST (14:21 UTC)
In effect from
Dec 20, 2021, 2:00 PM EST
Expired
Dec 21, 2021, 4:00 AM EST
In force
14 hr
Issued by
NWS Melbourne, FL
Flood severity
None

County Volusia County, FL

The radar

The Melbourne radar (KMLB), 116 km from the middle of the area, began a volume at 14:23 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, 2.4 hours before the alert went out and 91 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, Cape Canaveral, FL at 12:00Z on 2021-12-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 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, Cape Canaveral, FL at 12:00Z on 2021-12-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -6 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
1 J/kg
Mixed-layer CIN
-68 J/kg
Mixed-layer LCL
736 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
-6 m²/s²
0-3 km storm-relative helicity
34 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

550 
WGUS62 KMLB 201421
FFAMLB

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Melbourne FL
921 AM EST Mon Dec 20 2021

.Persistent heavy showers and storms may produce locally heavy 
rainfall across portions of coastal Volusia, Brevard, and Indian 
River counties beginning this afternoon through the overnight hours. 
Rainfall amounts of 3 to 4 inches are possible with locally higher 
amounts of up to 6 inches.

FLZ047-054-141-147-210900-
/O.NEW.KMLB.FA.A.0004.211220T1900Z-211221T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Southern Brevard-Indian River-Coastal Volusia-Northern Brevard-
Including the cities of Vero Beach, Rockledge, Daytona Beach, 
Titusville, Melbourne, Palm Bay, New Smyrna Beach, Ormond Beach, 
Sebastian, and Cocoa
921 AM EST Mon Dec 20 2021

...FLOOD WATCH IN EFFECT FROM 2 PM EST THIS AFTERNOON THROUGH LATE 
TONIGHT...

* WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...A portion of east central Florida, including the following 
  areas, Coastal Volusia, Indian River, Northern Brevard and 
  Southern Brevard.

* WHEN...From 2 PM EST this afternoon through late tonight.

* IMPACTS...Excessive runoff may result in flooding of creeks, 
  streams, and other low-lying and flood-prone locations. Flooding 
  may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

KN

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 20, 3:53 AM ESTBeach Hazards StatementMLBVolusia15 hr
Dec 20, 3:10 PM ESTAreal Flood AdvisoryMLBBrevard4 hr
Dec 20, 4:32 PM ESTAreal Flood AdvisoryMLBBrevard88 min

Nearby

Flood Watches in Florida, 2021Every flood watch 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.