Alert archive / Florida / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 302, NWS Jacksonville, FL

July 21, 2008Bradford County, Union County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Jul 21, 2008, 5:05 PM EDT for Bradford County, Union County, Florida. It was in force for 40 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
Jul 21, 2008, 5:05 PM EDT (21:05 UTC)
Expired
Jul 21, 2008, 5:45 PM EDT
In force
40 min
Issued by
NWS Jacksonville, FL
Area
Storm-based polygon

Counties Bradford County, FL, Union County, FL

The radar

The Jacksonville radar (KJAX), 77 km from the middle of the area, began a volume at 21:05 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

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 9.1 hours before the alert went out and 200 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, Tallahassee Rgnl, FL at 12:00Z on 2008-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1192 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, Tallahassee Rgnl, FL at 12:00Z on 2008-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 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
1192 J/kg
Mixed-layer CIN
-84 J/kg
Mixed-layer LCL
1128 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Jul 21, 2:45 PM EDT, 2 hours 20 minutes earlier.

Area forecast discussion, Jul 21, 2:45 PM EDT, 2 hours 20 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
245 PM EDT MON JUL 21 2008

.SHORT TERM...TONIGHT THROUGH THURSDAY...
WARM AND HUMID CONDITIONS WILL STICK WITH US OVERNIGHT. TEMPS
WILL REMAIN IN THE 80S THROUGH MUCH OF THE EVENING BEFORE
BOTTOMING OUT ONLY IN THE MID 70S TOWARD DAYBREAK. WE WILL CRUISE
INTO THE 90S ONCE AGAIN ON TUESDAY. MAXIMUM HEAT INDICES WILL RUN
FROM 100 TO 105 DEGREES...WITH THE HIGHEST VALUES OVER SOUTHEAST
GEORGIA. MORE MOISTURE IN THE COLUMN TOMORROW SHOULD RESULT IN AT
LEAST SCATTERED THUNDERSTORM ACTIVITY. FOCUS WILL LIKELY EXIST
ALONG SEABREEZE BOUNDARIES...BUT GFS DEPICTS AN AMPLIFIED 850MB
TROUGH DIPPING THROUGH THE AREA LATE IN THE AFTERNOON. THIS SHOULD
NOT ONLY ENHANCE ACTIVITY BUT ALSO MAINTAIN IT THROUGH MUCH OF THE
EVENING HOURS.

WEDNESDAY AND THURSDAY...ALTHOUGH THE LOCAL FORECAST AREA WILL
REMAIN JUST SOUTH OF THE REGION OF UPPER LEVEL HEIGHT FALLS
ASSOCIATED WITH LONGWAVE TROUGH DIGGING THROUGH THE GREAT LAKES
REGION...DEEP CYCLONIC FLOW WILL EXIST OVER THE REGION. CYCLONIC
FLOW COMBINED WITH SUFFICIENT INSTABILITY AND MOISTURE WILL LEAD
TO SCATTERED TO NUMEROUS AFTERNOON AND EVENING THUNDERSTORMS ON
BOTH WEDNESDAY AND THURSDAY. PRECIP AND CLOUDS ON WEDNESDAY AND
THURSDAY SHOULD HELP TO LIMIT MAX TEMPS A BIT...CLOSER TO 90 BUT
REMAINING HUMID.

.LONG TERM...FRIDAY THROUGH MONDAY...
THE OVERALL WEATHER PATTERN WILL CHANGE VERY LITTLE AS BOTH
SURFACE AND UPPER TROUGHS ARE PROGGED TO REMAIN DRAPED DOWN THE
EAST COAST OF THE UNITED STATES. THIS WILL RESULT IN AT LEAST
SCATTERED COVERAGE OF AFTERNOON AND EVENING THUNDERSTORMS EACH DAY
OF THE EXTENDED. TEMPERATURES WILL CHECK IN AROUND NORMAL
LEVELS...MAXES IN THE LOW 90S AND MINS IN THE LOW 70S.

.AVIATION...HAVE VCTS AT NE FL TAF SITES INTO THE EVENING HOURS
WITH CB MENTIONED AT KSSI. MAY NEED TO INSERT A TEMPO TSRA AT
KGNV SHORTLY. HAZE CONTINUES TO PLAGUE THE AREA WITH TEMPORARY
VSBY REDUCTIONS INTO THE MVFR RANGE STILL POSSIBLE.

&&

.MARINE...GENERALLY QUIET CONDITIONS WILL CONTINUE WITH NOCTURNAL
WIND SURGES MOSTLY STAYING BELOW SMALL CRAFT CAUTION CRITERIA.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  74  98  72  92 /  10  30  30  50
SSI  78  91  76  88 /  10  30  20  40
JAX  74  95  73  90 /  20  60  20  50
SGJ  75  92  74  90 /  10  50  30  50
GNV  72  94  72  91 /  10  40  30  60
OCF  71  93  72  89 /  10  40  30  50

&&

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

&&

SHULER/CARROLL/KEEGAN
Hazardous weather outlook, Jul 21, 4:35 AM EDT, 12 hours 30 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSONVILLE FL
435 AM EDT MON JUL 21 2008

FLZ020>025-030>033-035>038-040-GAZ132>136-149>154-162>166-221000-
HAMILTON-SUWANNEE-COLUMBIA-BAKER-NASSAU-DUVAL-UNION-BRADFORD-CLAY-
ST JOHNS-GILCHRIST-ALACHUA-PUTNAM-FLAGLER-MARION-COFFEE-
JEFF DAVIS-BACON-APPLING-WAYNE-ATKINSON-WARE-PIERCE-BRANTLEY-
INLAND GLYNN-COASTAL GLYNN-ECHOLS-CLINCH-CHARLTON-INLAND CAMDEN-
COASTAL CAMDEN-
435 AM EDT MON JUL 21 2008

THIS OUTLOOK IS FOR NORTHEAST FLORIDA AND SOUTHEAST GEORGIA.

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

...VERY HOT CONDITIONS TODAY WITH HEAT INDICES AROUND 105 DEGREES...
...ISOLATED STRONG THUNDERSTORMS POSSIBLE THIS AFTERNOON AND EVENING...

AFTERNOON MAXIMUM TEMPERATURES IN THE 95 TO 100 DEGREE RANGE WILL
LEAD TO HEAT INDICES AROUND 105 DEGREES...MAINLY ACROSS INLAND
PORTIONS OF SOUTHEAST GEORGIA. PLEASE USE EXTRA CAUTION IF ENGAGING
IN OUTDOOR ACTIVITIES TODAY.

ISOLATED STRONG THUNDERSTORMS WILL BE POSSIBLE LATER THIS AFTERNOON
AND EVENING...MAINLY ACROSS NORTHEAST FLORIDA. GUSTY WINDS UP TO
50 MPH...LOCALLY HEAVY RAINFALL AND EXCESSIVE CLOUD TO GROUND
LIGHTNING WILL BE POSSIBLE. STORM MOTION WILL GENERALLY BE TOWARD
THE EAST AT 5 TO 10 MPH OR BECOME ERRATIC DUE TO OUTFLOW AND SEA
BREEZE INTERACTIONS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED THROUGH THE
PERIOD WITH STRONG THUNDERSTORMS POSSIBLE AT TIMES WITH GUSTY
WINDS TO 50 MPH...LOCALLY HEAVY RAINFALL AND EXCESSIVE CLOUD TO
GROUND LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT REQUESTED AT THIS TIME.

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, Jul 21, 4:11 PM EDT, 54 minutes before
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Special weather statement, Jul 21, 4:33 PM EDT, 32 minutes before
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Special weather statement, Jul 21, 4:39 PM EDT, 26 minutes before
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Special weather statement, Jul 21, 4:43 PM EDT, 22 minutes before
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Local storm report, Jul 21, 4:51 PM EDT, 14 minutes before
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Special weather statement, Jul 21, 5:03 PM EDT, 2 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 4:37 PM EDTAreal Flood AdvisoryJAXClay53 min
Jul 21, 4:56 PM EDTSpecial Marine WarningJAX61 min
Jul 21, 5:26 PM EDTAreal Flood AdvisoryJAXBradford, Clay, Columbia, Union64 min
Jul 21, 5:36 PM EDTSevere Thunderstorm WarningJAXBaker, Columbia, Union18 min

Nearby

Severe Thunderstorm Warnings in Florida, 2008Every severe thunderstorm warning in 2008

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.