Alert archive / Florida / Tornado Watches in 2008
Tornado Watch 939
The Storm Prediction Center issued this tornado watch at Nov 30, 2008, 9:51 AM EST for 24 counties in Florida. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 30, 2008, 9:51 AM EST (14:51 UTC)
- Expired
- Nov 30, 2008, 4:39 PM EST
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 24 counties
Alachua County, FL, Baker County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Duval County, FL, Flagler County, FL, Hernando County, FL, Hillsborough County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Nassau County, FL, Orange County, FL, Osceola County, FL, Pasco County, FL, Pinellas County, FL, Polk County, FL, Putnam County, FL, Saint Johns County, FL, Seminole County, FL, Sumter County, FL, Union County, FL, Volusia County, FL
The radar
The Jacksonville radar (KJAX), 108 km from the middle of the area, began a volume at 14:50 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 10%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 50%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 30, 11:30 AM EST | Severe Thunderstorm Warning | TBW | Levy | 30 min |
| Nov 30, 12:54 PM EST | Tornado Warning | MLB | Orange, Seminole | 39 min |
| Nov 30, 1:35 PM EST | Tornado Warning | MLB | Volusia | 25 min |
| Nov 30, 1:49 PM EST | Tornado Warning | MLB | Brevard, Volusia | 31 min |
| Nov 30, 2:50 PM EST | Severe Thunderstorm Warning | MLB | Brevard, Osceola | 55 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Jacksonville, FL (KJAX), launched 12:00Z, 2.9 hours before the alert went out and 110 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 996 m above ground
- 0-6 km bulk shear
- 66 kt
- 0-1 km storm-relative helicity
- 288 m²/s²
- 0-3 km storm-relative helicity
- 318 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 301450
SEL9
SPC WW 301450
FLZ000-GAZ000-CWZ000-302200-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 939
NWS STORM PREDICTION CENTER NORMAN OK
950 AM EST SUN NOV 30 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHERN AND CENTRAL FLORIDA
EXTREME SOUTHEAST GEORGIA
COASTAL WATERS
EFFECTIVE THIS SUNDAY MORNING AND AFTERNOON FROM 950 AM UNTIL 500
PM EST.
TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE
MILES EAST AND WEST OF A LINE FROM 35 MILES EAST NORTHEAST OF
JACKSONVILLE FLORIDA TO 30 MILES EAST SOUTHEAST OF SAINT
PETERSBURG FLORIDA. FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).
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.
OTHER WATCH INFORMATION...CONTINUE...WW 938...
DISCUSSION...LINE OF STORMS WITH EMBEDDED BOW ECHOES AND SUPERCELL
STRUCTURES WILL CONTINUE EAST THROUGH THE NRN AND CNTRL FL PENINSULA
THIS AFTERNOON. THE ATMOSPHERE DOWNSTREAM ACROSS THE FL PENINSULA
WILL CONTINUE TO DESTABILIZE WITH DIABATIC HEATING AND INCREASING
LOW LEVEL DEWPOINTS SUPPORTING MLCAPE FROM 500 TO 1000 J/KG.
HODOGRAPHS AND VERTICAL SHEAR PROFILES WILL REMAIN FAVORABLE FOR
SUPERCELLS AND BOWING STRUCTURES AHEAD OF EWD ADVANCING UPPER TROUGH
SUPPORTED BY STRONG SWLY LOW AND MID LEVEL JETS. ISOLATED DAMAGING
WIND AND TORNADOES WILL BE THE PRIMARY THREATS.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450.
MEAN STORM MOTION VECTOR 24035.
...DIAL/HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 30, 3:46 AM EST | Mesoscale Discussion | SPC | Columbia, Franklin, Hamilton, Jefferson, Lafayette, Leon and 4 more | 89 min |
| Nov 30, 4:59 AM EST | Tornado Watch | SPC | Columbia, Dixie, Franklin, Gilchrist, Hamilton, Jefferson and 6 more | 7 hr |
| Nov 30, 7:54 AM EST | Mesoscale Discussion | SPC | Alachua, Baker, Bradford, Columbia, Dixie, Gilchrist and 4 more | 96 min |
| Nov 30, 12:24 PM EST | Mesoscale Discussion | SPC | Flagler, Hillsborough, Lake, Marion, Orange, Osceola and 6 more | 96 min |
| Nov 30, 1:05 PM EST | Tornado Watch | SPC | Brevard, Broward, Charlotte, Collier, DeSoto, Glades and 13 more | 8 hr |
| Nov 30, 3:53 PM EST | Mesoscale Discussion | SPC | Broward, Collier, Hendry, Martin, Miami-Dade, Monroe and 2 more | 2 hr |
Nearby
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.