Alert archive / Florida / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 77

April 2, 201618 counties in Florida

The Storm Prediction Center issued this severe thunderstorm watch at Apr 2, 2016, 6:00 AM EDT for 18 counties in Florida. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Apr 2, 2016, 6:00 AM EDT (10:00 UTC)
Expired: Apr 2, 2016, 1:00 PM EDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 55 kt

Counties Alachua County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Flagler County, FL, Gilchrist County, FL, Hernando County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Orange County, FL, Pasco County, FL, Putnam County, FL, Saint Johns County, FL, Seminole County, FL, Sumter County, FL, Union County, FL, Volusia County, FL

The radar

The Tampa radar (KTBW), 149 km from the middle of the area, began a volume at 10:01 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: 10%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 5%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 40%

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
Apr 2, 9:21 AM EDT	Severe Thunderstorm Warning	JAX	Bradford, Clay, Union	22 min
Apr 2, 11:56 AM EDT	Tornado Warning	TBW	Hillsborough, Pasco	16 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 00:00Z, 10.0 hours before the alert went out and 149 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: 52 J/kg
Mixed-layer CIN: -175 J/kg
Mixed-layer LCL: 1340 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 92 m²/s²
0-3 km storm-relative helicity: 136 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

As transmitted.

710 
WWUS20 KWNS 020958
SEL7  
SPC WW 020958
FLZ000-CWZ000-021700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 77
NWS STORM PREDICTION CENTER NORMAN OK
600 AM EDT SAT APR 2 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
  NORTHERN FLORIDA
  COASTAL WATERS

* EFFECTIVE THIS SATURDAY MORNING AND AFTERNOON FROM 600 AM UNTIL
  100 PM EDT.

* PRIMARY THREATS INCLUDE...
  ISOLATED DAMAGING WIND GUSTS TO 65 MPH POSSIBLE
  A TORNADO OR TWO POSSIBLE

SUMMARY...A LINE OF THUNDERSTORMS IS EXPECTED TO MOVE FROM THE
NORTHEASTERN GULF OF MEXICO ACROSS MUCH OF NORTHERN FLORIDA THROUGH
THE REMAINDER OF THE MORNING.  EMBEDDED DAMAGING DOWNDRAFTS ARE THE
MAIN HAZARD...THOUGH A BRIEF TORNADO CANNOT BE RULED OUT.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES SOUTH
SOUTHWEST OF OCALA FLORIDA TO 20 MILES NORTHWEST OF ST AUGUSTINE
FLORIDA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 55 KNOTS.
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM MOTION
VECTOR 26035.


...EDWARDS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 1, 9:02 PM EDT	Tornado Watch	SPC	Alachua, Baker, Bay, Bradford, Calhoun, Clay and 21 more	9 hr
Apr 1, 11:39 PM EDT	Mesoscale Discussion	SPC	Baker, Bradford, Columbia, Franklin, Hamilton, Jefferson and 7 more	66 min
Apr 2, 2:19 AM EDT	Mesoscale Discussion	SPC	Dixie, Gilchrist, Lafayette, Taylor	56 min
Apr 2, 4:18 AM EDT	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Citrus, Clay, Columbia and 15 more	117 min
Apr 2, 8:42 AM EDT	Mesoscale Discussion	SPC	Hernando, Pasco, Pinellas	93 min
Apr 2, 12:01 PM EDT	Mesoscale Discussion	SPC	Hernando, Lake, Orange, Pasco, Seminole, Sumter and 1 more	59 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.