Alert archive / Florida / Tornado Watches in 1998

Tornado Watch 855

September 30, 199812 counties in Florida; 4 counties in Georgia

The Storm Prediction Center issued this tornado watch at Sep 30, 1998, 1:30 PM EDT for 12 counties in Florida; 4 counties in Georgia. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Sep 30, 1998, 1:30 PM EDT (17:30 UTC)
Expired: Sep 30, 1998, 8:00 PM EDT
In force: 7 hr
Issued by: the Storm Prediction Center

Counties Alachua County, FL, Baker County, FL, Bradford County, FL, Clay County, FL, Duval County, FL, Flagler County, FL, Levy County, FL, Marion County, FL, Nassau County, FL, Putnam County, FL, Saint Johns County, FL, Union County, FL, Camden County, GA, Glynn County, GA, Liberty County, GA, McIntosh County, GA

Warnings issued inside it

3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Sep 30, 1:37 PM EDT	Severe Thunderstorm Warning	JAX	Alachua	63 min
Sep 30, 1:39 PM EDT	Tornado Warning	JAX	Alachua	66 min
Sep 30, 2:14 PM EDT	Tornado Warning	JAX	Bradford	46 min

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 5.5 hours before the alert went out and 30 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: 2 J/kg
Mixed-layer CIN: -150 J/kg
Mixed-layer LCL: 1382 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 174 m²/s²
0-3 km storm-relative helicity: 237 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

480 
WWUS9 KMKC 301659
SEL5  
MKC WW 301659
FLZ000-GAZ000-010000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 855
STORM PREDICTION CENTER NORMAN OK
1259 PM EDT WED SEP 30 1998

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   NORTHEAST FLORIDA                            
   SOUTHEAST GEORGIA                            
   AND ADJACENT COASTAL WATERS

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 130 PM UNTIL
800 PM EDT.

TORNADOES...THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS
LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 55 STATUTE MILES EAST AND WEST
OF A LINE FROM 40 MILES SOUTH SOUTHEAST OF GAINESVILLE FLORIDA TO
70 MILES NORTHEAST OF BRUNSWICK GEORGIA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.


DISCUSSION...88-D VAD WIND PROFILES AT JAX ARE STILL FAVORABLE  FOR
SUPERCELLS AND ISOLATED TORNADOS WITH HELICITIES AROUND 300 MS/S2. 
AIRMASS IS DESTABILIZING WITH AFTERNOON HEARTING AT CAPES CLIMB TO
NEAR 200 J/KG.  BANDS OF THUNDERSTORMS WILL CONTINUE TO MOVE SLOWLY
EWD AHEAD OF REMNANTS OF GEORGE.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH EXTREME
TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI
WITH MAXIMUM TOPS TO 500.  MEAN STORM MOTION VECTOR 20040.


...HALES

290,0825 315,0813 315,0794 290,0810

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 30, 5:00 AM EDT	Tornado Watch	SPC	Alachua, Baker, Bradford, Clay, Columbia, Dixie and 8 more	5 hr

Nearby

Tornado Watches in Florida, 1998 Tornado Watches in Georgia, 1998 Every tornado watch in 1998

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.