Alert archive / Florida / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 396

June 15, 201214 counties in Florida

The Storm Prediction Center issued this severe thunderstorm watch at Jun 15, 2012, 3:56 PM EDT for 14 counties in Florida. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jun 15, 2012, 3:56 PM EDT (19:56 UTC)
Expired: Jun 15, 2012, 9:00 PM EDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

Counties Broward County, FL, Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Highlands County, FL, Lee County, FL, Manatee County, FL, Miami-Dade County, FL, Monroe County, FL, Palm Beach County, FL, Sarasota County, FL

The radar

The Tampa radar (KTBW), 140 km from the middle of the area, began a volume at 19:59 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jun 15, 3:57 PM EDT	Severe Thunderstorm Warning	MFL	Palm Beach	33 min
Jun 15, 4:16 PM EDT	Severe Thunderstorm Warning	MFL	Miami-Dade	29 min
Jun 15, 5:18 PM EDT	Severe Thunderstorm Warning	MFL	Miami-Dade, Monroe	27 min
Jun 15, 5:19 PM EDT	Severe Thunderstorm Warning	MFL	Glades, Hendry	26 min
Jun 15, 5:32 PM EDT	Severe Thunderstorm Warning	MFL	Hendry	28 min
Jun 15, 5:34 PM EDT	Severe Thunderstorm Warning	TBW	Charlotte, DeSoto, Manatee, Sarasota	26 min
Jun 15, 5:42 PM EDT	Severe Thunderstorm Warning	MFL	Glades, Hendry	26 min
Jun 15, 5:57 PM EDT	Severe Thunderstorm Warning	MFL	Collier, Hendry	63 min
Jun 15, 6:00 PM EDT	Severe Thunderstorm Warning	TBW	Charlotte, DeSoto, Lee, Sarasota	45 min
Jun 15, 6:21 PM EDT	Severe Thunderstorm Warning	MFL	Collier, Hendry	54 min
Jun 15, 7:14 PM EDT	Severe Thunderstorm Warning	MFL	Collier, Miami-Dade	31 min
Jun 15, 7:24 PM EDT	Severe Thunderstorm Warning	MFL	Collier	36 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

Tampa Bay, FL (KTBW), launched 12:00Z, 7.9 hours before the alert went out and 140 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: 413 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 857 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 49 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

765 
WWUS20 KWNS 151953
SEL6
SPC WW 151953
FLZ000-CWZ000-160100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 396
NWS STORM PREDICTION CENTER NORMAN OK
355 PM EDT FRI JUN 15 2012

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

       CENTRAL AND SOUTH FLORIDA
       COASTAL WATERS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 355 PM UNTIL 900
PM EDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHEAST OF
SARASOTA FLORIDA TO 45 MILES SOUTH OF MIAMI FLORIDA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU6).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 395...

DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO CONTINUE TO
INTENSIFY THIS AFTERNOON OVER THE CENTRAL AND SOUTHERN FL
PENINSULA...MAINLY IN VICINITY OF SEA BREEZE CONVERGENCE ZONES.
AMPLE LOW LEVEL MOISTURE/INSTABILITY AND SUFFICIENT WESTERLY FLOW
ALOFT WILL PROMOTE ORGANIZED MULTICELL OR BRIEF SUPERCELL STORM
STRUCTURES CAPABLE OF DAMAGING WINDS AND HAIL.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 27020.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 15, 3:11 PM EDT	Mesoscale Discussion	SPC	Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 7 more	64 min
Jun 15, 7:13 PM EDT	Mesoscale Discussion	SPC	Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 7 more	62 min

Nearby

Severe Thunderstorm Watches in Florida, 2012 Every severe thunderstorm watch in 2012

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.