Alert archive / Florida / Flash Flood Warnings in 2021

Flash Flood Warning 6, NWS Jacksonville, FL

September 16, 2021Clay County, Duval County, Saint Johns County, Florida

NWS Jacksonville, FL issued this flash flood warning at Sep 16, 2021, 6:07 PM EDT for Clay County, Duval County, Saint Johns County, Florida. It was in force for 3 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 16, 2021, 6:07 PM EDT (22:07 UTC)
Expired
Sep 16, 2021, 9:15 PM EDT
In force
3 hr
Issued by
NWS Jacksonville, FL
Area
Storm-based polygon
Flood severity
None

Counties Clay County, FL, Duval County, FL, Saint Johns County, FL

The radar

The Jacksonville radar (KJAX), 16 km from the middle of the area, began a volume at 22:09 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

Jacksonville, FL (KJAX), launched 12:00Z, 10.1 hours before the alert went out and 18 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, Jacksonville, FL at 12:00Z on 2021-09-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1536 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, Jacksonville, FL at 12:00Z on 2021-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.1939Sfc1 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
1536 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
760 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
43 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

739 
WGUS52 KJAX 162207
FFWJAX
FLC019-031-109-170115-
/O.NEW.KJAX.FF.W.0006.210916T2207Z-210917T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Jacksonville FL
607 PM EDT Thu Sep 16 2021

The National Weather Service in Jacksonville has issued a

* Flash Flood Warning for...
  Northeastern Clay County in northeastern Florida...
  Central Duval County in northeastern Florida...
  Northwestern St. Johns County in northeastern Florida...

* Until 915 PM EDT.

* At 607 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 3 inches are 
  possible in 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...
  Jacksonville, Orange Park, Arlington, Mandarin, Fruit Cove, 
  Riverside, Ortega, San Marco, Nas Jax, Normandy, 
  Bellair-Meadowbrook Terrace, Cisco Gardens, Lakeside, Doctors 
  Inlet, Fleming Island, Tallyrand and Jacksonville Heights.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3041 8180 3042 8178 3046 8175 3046 8170
      3047 8166 3046 8164 3046 8159 3041 8155
      3033 8156 3029 8158 3018 8159 3017 8160
      3008 8162 3011 8179

FLASH FLOOD...RADAR INDICATED

$$

NGUYEN

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 16, 3:02 PM EDTSpecial Weather StatementJAXDuval, Nassau28 min
Sep 16, 4:55 PM EDTSpecial Weather StatementJAXNassau35 min
Sep 16, 5:28 PM EDTSpecial Weather StatementJAXDuval32 min
Sep 16, 5:55 PM EDTSpecial Weather StatementJAXDuval35 min

Nearby

Flash Flood Warnings in Florida, 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.