Alert archive / Florida / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 314, NWS Jacksonville, FL

September 12, 2015Saint Johns County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Sep 12, 2015, 2:59 PM EDT for Saint Johns County, Florida. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Sep 12, 2015, 2:59 PM EDT (18:59 UTC)
Expired: Sep 12, 2015, 3:30 PM EDT
In force: 31 min
Issued by: NWS Jacksonville, FL
Area: Storm-based polygon

County Saint Johns County, FL

The radar

The Jacksonville radar (KJAX), 70 km from the middle of the area, began a volume at 19:00 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, 7.0 hours before the alert went out and 71 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: 232 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 1045 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: -7 m²/s²
0-3 km storm-relative helicity: 84 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.7

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Jacksonville, FL wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 12, 2:38 PM EDT, 21 minutes earlier.

Area forecast discussion, Sep 12, 2:38 PM EDT, 21 minutes before

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Hazardous weather outlook, Sep 12, 4:13 AM EDT, 10 hours 46 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSONVILLE FL
413 AM EDT SAT SEP 12 2015

AMZ450-452-454-470-472-474-FLZ020>025-030>033-035>038-040-124-125-
GAZ132>136-149>154-162>166-130830-
COASTAL WATERS FROM ALTAMAHA SOUND TO FERNANDINA BEACH FL OUT
20 NM-
COASTAL WATERS FROM FERNANDINA BEACH TO ST. AUGUSTINE FL OUT
20 NM-
COASTAL WATERS FROM ST. AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM-
WATERS FROM ALTAMAHA SOUND GA TO FERNANDINA BEACH FL FROM 20 TO
60 NM-
WATERS FROM FERNANDINA BEACH TO ST. AUGUSTINE FL FROM 20 TO 60 NM-
WATERS FROM ST. AUGUSTINE TO FLAGLER BEACH FL FROM 20 TO 60 NM-
HAMILTON-SUWANNEE-COLUMBIA-BAKER-INLAND NASSAU-INLAND DUVAL-UNION-
BRADFORD-CLAY-ST. JOHNS-GILCHRIST-ALACHUA-PUTNAM-FLAGLER-MARION-
COASTAL NASSAU-COASTAL DUVAL-COFFEE-JEFF DAVIS-BACON-APPLING-
WAYNE-ATKINSON-WARE-PIERCE-BRANTLEY-INLAND GLYNN-COASTAL GLYNN-
ECHOLS-CLINCH-CHARLTON-INLAND CAMDEN-COASTAL CAMDEN-
413 AM EDT SAT SEP 12 2015

...ISOLATED STRONG TO SEVERE THUNDERSTORMS POSSIBLE TODAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST FLORIDA...
SOUTHEAST GEORGIA AND THE ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT...

SHOWERS AND SCATTERED THUNDERSTORMS ARE EXPECTED TODAY. ISOLATED
STRONG TO SEVERE STORMS ARE POSSIBLE OVER NORTHEAST FLORIDA.
THE MAIN CONCERN WILL BE GUSTY WINDS OF 50 TO 60 MPH IN THE
STRONGER STORMS. LOCALLY HEAVY RAIN IS EXPECTED AT TIMES.
SHOWERS AND STORMS WILL END FROM NORTH TO SOUTH LATER THIS
EVENING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THERE IS A CHANCE OF THUNDERSTORMS TUESDAY THROUGH FRIDAY...WITH
LOCALLY HEAVY RAIN POSSIBLE.

THERE WILL BE AN INCREASED RISK OF RIP CURRENTS BY MONDAY AND
CONTINUE MUCH OF THE WEEK DUE TO PERSISTENT EASTERLY FLOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE REQUESTED TO SELF ACTIVATE IF WARNINGS ARE ISSUED
TODAY.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE
IN JACKSONVILLE WEBSITE ON THE INTERNET AT WEATHER.GOV/JAX.

In the hours before

Special weather statement, Sep 12, 1:31 PM EDT, 1 hour 28 minutes before

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Local storm report, Sep 12, 1:38 PM EDT, 1 hour 21 minutes before

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Special weather statement, Sep 12, 2:11 PM EDT, 48 minutes before

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Special weather statement, Sep 12, 2:25 PM EDT, 34 minutes before

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Local storm report, Sep 12, 2:49 PM EDT, 10 minutes before

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Local storm report, Sep 12, 2:56 PM EDT, 3 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 12, 6:01 AM EDT	Special Weather Statement	JAX	Alachua, Gilchrist	44 min
Sep 12, 12:12 PM EDT	Special Weather Statement	JAX	Gilchrist	33 min
Sep 12, 12:55 PM EDT	Special Weather Statement	JAX	Alachua	35 min
Sep 12, 1:04 PM EDT	Severe Thunderstorm Warning	JAX	Alachua	26 min
Sep 12, 1:31 PM EDT	Special Weather Statement	JAX	Bradford	29 min
Sep 12, 1:42 PM EDT	Severe Thunderstorm Warning	JAX	Bradford, Clay	33 min
Sep 12, 2:11 PM EDT	Special Weather Statement	JAX	Clay	34 min
Sep 12, 2:16 PM EDT	Special Marine Warning	JAX		119 min
Sep 12, 2:25 PM EDT	Special Weather Statement	JAX	Saint Johns	35 min
Sep 12, 3:06 PM EDT	Special Weather Statement	JAX	Flagler	24 min
Sep 12, 4:14 PM EDT	Special Marine Warning	JAX		91 min

Nearby

Severe Thunderstorm Warnings in Florida, 2015 Every severe thunderstorm warning in 2015

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.