Alert archive / Florida / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 109, NWS Jacksonville, FL

July 21, 2002Columbia County, Florida

NWS Jacksonville, FL issued this severe thunderstorm warning at Jul 21, 2002, 10:51 AM EDT for Columbia County, Florida. It was in force for 39 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, 2002, 10:51 AM EDT (14:51 UTC)
Expired: Jul 21, 2002, 11:30 AM EDT
In force: 39 min
Issued by: NWS Jacksonville, FL
Area: Whole counties

County Columbia County, FL

The nearest sounding before it

Jacksonville, FL (KNIP), launched 12:00Z, 2.9 hours before the alert went out and 94 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: 231 J/kg
Mixed-layer CIN: -174 J/kg
Mixed-layer LCL: 1181 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 24 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, 9:50 AM EDT, 1 hour 1 minute earlier.

Area forecast discussion, Jul 21, 9:50 AM EDT, 1 hour 1 minute before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
950 AM EDT SUN JUL 21 2002

CURRENTLY...PERSISTENT UPPER TROF CONTINUES FROM MID-ATLC TO CENTRAL
GULF COAST. AT THE SFC...WEAK CONVOLUTED PRES PATTERN. NOTABLE
FEATURES INCLUDE TROF FROM COASTAL CAROLINAS TO CENTRAL GA...THEN S
TO NR KPNS. THIS IS A SFC EXPRESSION OF UPPER FEATURE...AND INCLUDES
WK LOW ALONG IT W OF KCHS. 12Z SOUNDING SHOWS LEVELS BELOW 500MB
UNIFORMLY 1 TO 2 DEG C COOLER THAN YESTERDAY AT THIS TIME (A RESULT
OF YESTERDAYS STRONG TO SVR CONVECTION). CAPES ARE BETWEEN 2000 AND
3000 J/KG OVER MOST OF THE CWA...ALTHO SURROUNDING SOUNDINGS MORE
UNSTABLE. KTBW SOUNDING SIMILAR TO YESTERDAYS. VIS SAT PIX SHOWING
MUCH MORE CLOUD COVER THAN YESTERDAY...BOTH FROM DEBRIS AND ONGOING
EARLY CONVECTION OVER BIG BEND/SUWANNEE VALLEY...AND IN EXTREME SE
GA.

FORECAST...MESO-ETA SHOWS VORT AXIS RUNNING WNW-ESE NEAR AXIS OF
THIS MORNINGS CONVECTION. EXPECT THIS AREA TO CONTINUE TO BE MOST
FAVORED FOR WIDESPREAD CONVECTION...AND MODEL INDICATES IT WILL
SHIFT SLIGHTLY N THRU THE DAY. THUS... WILL KEEP 70% POPS FOR FL
ZONES. GA IS A BIT MORE TRICKY. MESO-ETA Q-N VECTOR PROGS SHOW
CONVERGENT QUAD OF VERY WK JETLET OVER N GA ZONES. THIS WOULD POINT
TO SLIGHTLY LESS CONVECTION. HOWEVER...THIS IS ALSO NR SFC TROF
AXIS. THINK SITUATION WILL BE SIMILAR TO YESTERDAY...WITH CONVECTION
DEVELOPING A BIT N OF AREA ALONG TROF AND CONVECTION OVER FL SENDING
OUTFLOWS WHICH WILL EVENTUALLY POP LATE CONVECTION OVER N ZONES.
HOWEVER... WILL PROBABLY LOWER POPS 10% OVER THAT AREA. TEMPS WILL
BE TOUGH AS WELL. CLOUDS AND PRECIP WILL KEEP TEMPS DOWN...AND TEMPS
STARTED OUT MUCH LOWER THAN PREVIOUS DAYS. WARMEST TEMPS WILL BE IN
SE AND EXTREME N ZONES...WHERE LITTLE CHANGE TO PACKAGE IS EXPECTED.
WILL BUMP REMAINING ZONES DOWN ABOUT A CAT...AND POSSIBLE MORE OVER
SUWANNEE VALLEY. OF COURSE...THIS TIME OF YEAR...A COUPLE OF HOURS
OF SUN CAN BLOW A TEMP FORECAST

MARINE...NEW 41012 BUOY COMING IN WITH SW WINDS AROUND 10 KTS. GRAYS
REEF A BIT HIGHER AND MORE WLY WITH PROXIMITY OF SFC LOW. WILL
REWORD PRECIP FCST A BIT FOR TSTMS MOVING OFFSHORE DURING AFTN AND
USE SW-W WINDS. OTHERWISE...LITTLE CHANGE.

.JAX...
.GA...NONE.
.FL...NONE.

CARROLL/BOONE

In the hours before

Special weather statement, Jul 21, 5:30 AM EDT, 5 hours 21 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
Jul 21, 1:18 PM EDT	Severe Thunderstorm Warning	JAX	Marion	42 min
Jul 21, 2:19 PM EDT	Severe Thunderstorm Warning	JAX	Flagler	41 min
Jul 21, 3:53 PM EDT	Severe Thunderstorm Warning	JAX	Coffee	37 min

Nearby

Severe Thunderstorm Warnings in Florida, 2002 Every severe thunderstorm warning in 2002

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.