Alert archive / Florida / Severe Thunderstorm Warnings in 2014

Severe Thunderstorm Warning 18, NWS Jacksonville, FL

February 21, 2014Saint Johns County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Feb 21, 2014, 1:28 PM EST for Saint Johns County, Florida. It was in force for 17 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
Feb 21, 2014, 1:28 PM EST (18:28 UTC)
Expired
Feb 21, 2014, 1:45 PM EST
In force
17 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 18:29 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Feb 21, 6:39 AM ESTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 6.5 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-pSkew-T log-p diagram, Jacksonville, FL at 12:00Z on 2014-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 968 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Jacksonville, FL at 12:00Z on 2014-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 137 square meters per square second.193958Sfc1 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
968 J/kg
Mixed-layer CIN
-28 J/kg
Mixed-layer LCL
609 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.5
Supercell composite
4.3

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 Feb 21, 10:08 AM EST, 3 hours 20 minutes earlier.

Area forecast discussion, Feb 21, 10:08 AM EST, 3 hours 20 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
1008 AM EST FRI FEB 21 2014

...SEVERE STORMS ONGOING OVER SE GA...

.UPDATE...A PRE-FRONTAL SQUALL LINE OF SEVERE STORMS WAS TREKKING
RAPIDLY EASTWARD OVER SE GA WITH SPEEDS 40-50 MPH. BOWING LINE SEGMENTS
HAVE PRODUCED WIND DAMAGE OVER COFFEE COUNTY. MODERATE ROTATION IN
COUPLETS ALONG BOWING SEGMENTS WILL CONTINUE TO SUPPORT AN
ISOLATED TORNADO THREAT. EXTENDED THE SEVERE TSTORM WATCH EASTWARD
FOR ALL OF SE GA AND TO INCLUDE NASSAU COUNTY. WILL LIKELY NEED TO
ADD MORE NE FL COUNTIES TO THE WATCH AS THE LINE MOVES FARTHER
EAST.

&&

.AVIATION...

DETERIORATING CONDITIONS TO MVFR EXPECTED AT ALL SITES AS SQUALL
LINE BLOWS THROUGH GENERALLY BETWEEN 17Z-21Z TODAY. STRONG LOW
LEVEL JET OF 40-45 KTS FROM SW WILL CONTINUE BUMPY CONDITIONS IN
THE LOWER LEVELS. CONTINUED TO SHOW GUSTS TO 40 KT POSSIBLE AS
SQUALL LINE MOVES THROUGH.

&&

.MARINE...A MARINE WEATHER STATEMENT WAS ISSUED TO ALERT MARINERS
OF THE SQUALL LINE PUSHING OFFSHORE OF THE SE GA COAST BY MIDDAY
AND THE FL COAST DURING THE EARLY AFTN HOURS. A SMALL CRAFT
EXERCISE CAUTION CONTINUES FOR THE OFFSHORE WATERS DUE TO
SOUTHERLY WINDS 15-20 KTS AND SEAS UP TO 6 FT IN THE GULF STREAM.

RIP CURRENTS: LOW RISK TODAY AND SAT.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  70  43  70  47 / 100  10  10  10
SSI  72  52  65  51 / 100  20  10  10
JAX  77  50  70  51 / 100  30  10  10
SGJ  77  56  66  56 / 100  40  20  10
GNV  76  54  73  53 / 100  40  20  10
OCF  79  57  75  56 / 100  40  20  10

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&

ENYEDI/TRABERT/SHASHY/NELSON/SANDRIK/WALKER
Hazardous weather outlook, Feb 21, 1:28 PM EST, 0 minutes before
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In the hours before

Local storm report, Feb 21, 12:35 PM EST, 53 minutes before
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Special weather statement, Feb 21, 12:48 PM EST, 40 minutes before
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Local storm report, Feb 21, 12:53 PM EST, 35 minutes before
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Special weather statement, Feb 21, 1:02 PM EST, 26 minutes before
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Local storm report, Feb 21, 1:09 PM EST, 19 minutes before
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Local storm report, Feb 21, 1:28 PM EST, 0 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Feb 21, 9:26 AM ESTSevere Thunderstorm WarningJAXHamilton, Suwannee49 min
Feb 21, 9:58 AM ESTSpecial Weather StatementJAXColumbia, Gilchrist, Suwannee47 min
Feb 21, 10:06 AM ESTSpecial Weather StatementJAXBradford, Clay, Union39 min
Feb 21, 10:10 AM ESTSevere Thunderstorm WarningJAXBaker, Columbia, Hamilton, Suwannee50 min
Feb 21, 10:39 AM ESTSpecial Marine WarningJAX2 hr
Feb 21, 10:49 AM ESTSpecial Weather StatementJAXColumbia, Gilchrist, Suwannee, Union41 min
Feb 21, 10:51 AM ESTSpecial Weather StatementJAXBradford, Duval, Nassau39 min
Feb 21, 10:58 AM ESTSpecial Marine WarningJAX2 hr
Feb 21, 10:59 AM ESTSpecial Weather StatementJAXBaker31 min
Feb 21, 11:21 AM ESTSpecial Weather StatementJAXClay39 min
Feb 21, 11:31 AM ESTSpecial Weather StatementJAXAlachua, Bradford, Duval, Gilchrist, Nassau, Union44 min
Feb 21, 11:35 AM ESTSevere Thunderstorm WarningJAXAlachua, Clay, Putnam40 min
Feb 21, 11:58 AM ESTSpecial Weather StatementJAXDuval47 min
Feb 21, 12:10 PM ESTTornado WarningJAXPutnam35 min
Feb 21, 12:16 PM ESTSpecial Weather StatementJAXClay44 min
Feb 21, 12:19 PM ESTSpecial Weather StatementJAXAlachua41 min
Feb 21, 12:29 PM ESTSpecial Marine WarningJAX2 hr
Feb 21, 12:43 PM ESTSevere Thunderstorm WarningJAXSaint Johns47 min
Feb 21, 12:48 PM ESTSpecial Weather StatementJAXClay42 min
Feb 21, 1:02 PM ESTSpecial Weather StatementJAXAlachua, Clay, Putnam43 min
Feb 21, 1:34 PM ESTSpecial Weather StatementJAXFlagler41 min
Feb 21, 1:44 PM ESTSpecial Weather StatementJAXPutnam, Saint Johns46 min
Feb 21, 2:01 PM ESTSpecial Weather StatementJAXCitrus44 min
Feb 21, 2:13 PM ESTSevere Thunderstorm WarningJAXFlagler, Saint Johns47 min
Feb 21, 2:21 PM ESTSpecial Marine WarningJAX54 min
Feb 21, 2:33 PM ESTSpecial Weather StatementJAXMarion42 min
Feb 21, 3:15 PM ESTSpecial Weather StatementJAXMarion45 min
Feb 21, 4:02 PM ESTSpecial Weather StatementJAXMarion43 min
Feb 21, 8:46 AM ESTSevere Thunderstorm WarningJAXBacon, Coffee, Jeff Davis44 min
Feb 21, 9:05 AM ESTSevere Thunderstorm WarningJAXAtkinson, Coffee, Ware40 min
Feb 21, 9:28 AM ESTSevere Thunderstorm WarningJAXAppling, Bacon, Coffee, Jeff Davis, Pierce, Ware and 1 more47 min
Feb 21, 9:40 AM ESTSpecial Weather StatementJAXJeff Davis35 min
Feb 21, 9:45 AM ESTSpecial Weather StatementJAXPierce30 min
Feb 21, 10:07 AM ESTSevere Thunderstorm WarningJAXAppling, Bacon, Brantley, Glynn, Pierce, Ware and 1 more38 min
Feb 21, 10:19 AM ESTTornado WarningJAXCharlton, Clinch, Ware26 min
Feb 21, 10:46 AM ESTSpecial Weather StatementJAXBrantley, Glynn44 min
Feb 21, 10:56 AM ESTSevere Thunderstorm WarningJAXBrantley, Camden, Charlton49 min
Feb 21, 11:28 AM ESTSpecial Weather StatementJAXGlynn32 min
Feb 21, 11:47 AM ESTSpecial Weather StatementJAXGlynn28 min

Nearby

Severe Thunderstorm Warnings in Florida, 2014Every severe thunderstorm warning in 2014

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.