Alert archive / Florida / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 89

April 15, 201615 counties in Florida

The Storm Prediction Center issued this severe thunderstorm watch at Apr 15, 2016, 3:14 PM EDT for 15 counties in Florida. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Apr 15, 2016, 3:14 PM EDT (19:14 UTC)
Expired: Apr 15, 2016, 9:24 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

Counties Brevard County, FL, Broward County, FL, Collier County, FL, Glades County, FL, Hendry County, FL, Highlands County, FL, Indian River County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Okeechobee County, FL, Osceola County, FL, Palm Beach County, FL, Polk County, FL, Saint Lucie County, FL

The radar

The Melbourne radar (KMLB), 119 km from the middle of the area, began a volume at 19:16 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: 10%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 50%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 15, 3:41 PM EDT	Severe Thunderstorm Warning	MLB	Saint Lucie	49 min
Apr 15, 4:39 PM EDT	Severe Thunderstorm Warning	MLB	Martin	36 min
Apr 15, 4:42 PM EDT	Severe Thunderstorm Warning	MLB	Saint Lucie	63 min
Apr 15, 4:55 PM EDT	Severe Thunderstorm Warning	MLB	Martin	35 min
Apr 15, 5:01 PM EDT	Severe Thunderstorm Warning	MFL	Palm Beach	29 min
Apr 15, 5:02 PM EDT	Severe Thunderstorm Warning	MLB	Indian River, Saint Lucie	40 min
Apr 15, 5:08 PM EDT	Severe Thunderstorm Warning	MLB	Martin, Saint Lucie	35 min
Apr 15, 5:23 PM EDT	Severe Thunderstorm Warning	MFL	Palm Beach	37 min
Apr 15, 5:54 PM EDT	Severe Thunderstorm Warning	MFL	Broward, Palm Beach	66 min
Apr 15, 6:56 PM EDT	Severe Thunderstorm Warning	MFL	Broward, Miami-Dade, Palm Beach	49 min
Apr 15, 7:59 PM EDT	Severe Thunderstorm Warning	MFL	Broward, Miami-Dade	46 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

Miami, FL (KMFL), launched 12:00Z, 7.2 hours before the alert went out and 153 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: 785 J/kg
Mixed-layer CIN: -154 J/kg
Mixed-layer LCL: 856 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: -29 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.3

Open this sounding in Storm Lab

The text

As transmitted.

943 
WWUS20 KWNS 151912
SEL9  
SPC WW 151912
FLZ000-CWZ000-160200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 89
NWS STORM PREDICTION CENTER NORMAN OK
315 PM EDT FRI APR 15 2016

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 315 PM UNTIL
  1000 PM EDT.

* PRIMARY THREATS INCLUDE...
  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2
    INCHES IN DIAMETER POSSIBLE
  ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

SUMMARY...THUNDERSTORMS ARE EXPECTED TO INTENSIFY THIS AFTERNOON
OVER PARTS OF CENTRAL AND SOUTH FL...WHERE A MOIST AND UNSTABLE AIR
MASS IS PRESENT.  THE STRONGEST STORMS MAY POSE A RISK OF LARGE HAIL
AND GUSTY/DAMAGING WIND GUSTS THROUGH THE EARLY EVENING.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF
MELBOURNE FLORIDA TO 50 MILES SOUTH SOUTHWEST OF MIAMI FLORIDA. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 27030.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 15, 2:09 PM EDT	Mesoscale Discussion	SPC	Broward, DeSoto, Glades, Hardee, Hendry, Highlands and 7 more	3 hr
Apr 15, 4:33 PM EDT	Mesoscale Discussion	SPC	Brevard, Broward, Glades, Hendry, Highlands, Indian River and 7 more	87 min
Apr 15, 6:55 PM EDT	Mesoscale Discussion	SPC	Broward, Miami-Dade, Palm Beach	95 min

Nearby

Severe Thunderstorm Watches in Florida, 2016 Every severe thunderstorm watch in 2016

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.