Alert archive / Florida / Tornado Watches in 2005

Tornado Watch 805

September 20, 20054 counties in Florida

The Storm Prediction Center issued this tornado watch at Sep 20, 2005, 4:30 PM EDT for 4 counties in Florida. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued: Sep 20, 2005, 4:30 PM EDT (20:30 UTC)
Expired: Sep 21, 2005, 1:00 AM EDT
In force: 9 hr
Issued by: the Storm Prediction Center

Counties Broward County, FL, Collier County, FL, Miami-Dade County, FL, Monroe County, FL

The radar

The Key West radar (KBYX), 74 km from the middle of the area, began a volume at 20:31 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 20, 4:30 PM EDT	Tornado Warning	MFL	Miami-Dade	30 min
Sep 20, 5:01 PM EDT	Tornado Warning	MFL	Collier	44 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

Key West, FL (KEYW), launched 12:00Z, 8.5 hours before the alert went out and 78 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: 1392 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 652 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 75 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.1

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 202029
SEL5  
SPC WW 202029
FLZ000-CWZ000-210500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 805
NWS STORM PREDICTION CENTER NORMAN OK
430 PM EDT TUE SEP 20 2005

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

       SOUTH FLORIDA INCLUDING THE KEYS
       COASTAL WATERS

EFFECTIVE THIS TUESDAY AFTERNOON AND WEDNESDAY MORNING FROM 430 PM
UNTIL 100 AM EDT.

TORNADOES...HAIL TO 0.5 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 55 STATUTE MILES
EAST AND WEST OF A LINE FROM 20 MILES EAST SOUTHEAST OF KEY WEST
FLORIDA TO 50 MILES NORTHWEST OF MIAMI FLORIDA.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU5).

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...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 803. WATCH NUMBER 803 WILL NOT BE IN EFFECT AFTER 430
PM EDT. CONTINUE...WW 804...

DISCUSSION...CONVECTIVE BANDS ASSOCIATED WITH HURRICANE RITA WILL
CONTINUE TO AFFECT SOUTH FL AND THE KEYS FOR ANOTHER SEVERAL HOURS. 
SHEAR PROFILES ARE SLOWLY WEAKENING ACROSS THE REGION AS THE SYSTEM
MOVES AWAY...BUT POTENTIAL WILL REMAIN THROUGH THE EVENING FOR BRIEF
TORNADOES AND WATERSPOUTS.  THE FORECAST MAXIMUM WIND GUSTS AND MEAN
CELL MOTION APPLY TO SEVERE THUNDERSTORMS OUTSIDE THE HURRICANE
EYEWALL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550.
MEAN STORM MOTION VECTOR 14035.


...HART

242,0821 261,0814 261,0795 242,0803

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 20, 4:40 AM EDT	Tornado Watch	SPC	Broward, Collier, Hendry, Miami-Dade, Monroe, Palm Beach	12 hr
Sep 20, 2:42 PM EDT	Mesoscale Discussion	SPC	Broward, Collier, Hendry, Miami-Dade, Monroe, Palm Beach	2 hr

Nearby

Tornado Watches in Florida, 2005 Every tornado watch in 2005

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.