Alert archive / Florida / Tornado Watches in 2017

Tornado Watch 131

April 6, 201728 counties in Florida; 7 counties in Georgia

The Storm Prediction Center issued this tornado watch at Apr 6, 2017, 12:15 AM EDT for 28 counties in Florida; 7 counties in Georgia. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 6, 2017, 12:15 AM EDT (04:15 UTC)
Expired
Apr 6, 2017, 6:31 AM EDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 35 counties

Alachua County, FL, Baker County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Columbia County, FL, Dixie County, FL, Duval County, FL, Flagler County, FL, Gilchrist County, FL, Hamilton County, FL, Hernando County, FL, Lafayette County, FL, Lake County, FL, Levy County, FL, Madison County, FL, Marion County, FL, Nassau County, FL, Orange County, FL, Pasco County, FL, Putnam County, FL, Saint Johns County, FL, Seminole County, FL, Sumter County, FL, Suwannee County, FL, Taylor County, FL, Union County, FL, Volusia County, FL, Brantley County, GA, Camden County, GA, Charlton County, GA, Clinch County, GA, Echols County, GA, Glynn County, GA, Ware County, GA

The radar

The Jacksonville radar (KJAX), 101 km from the middle of the area, began a volume at 04:15 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
50%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 6, 12:49 AM EDTSevere Thunderstorm WarningJAXBaker, Columbia, Hamilton41 min
Apr 6, 1:29 AM EDTSevere Thunderstorm WarningJAXNassau46 min
Apr 6, 2:10 AM EDTTornado WarningJAXNassau15 min
Apr 6, 3:54 AM EDTSevere Thunderstorm WarningTBWCitrus, Hernando36 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 00:00Z, 4.3 hours before the alert went out and 102 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-pSkew-T log-p diagram, Jacksonville, FL at 00:00Z on 2017-04-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1177 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Jacksonville, FL at 00:00Z on 2017-04-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 122 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
1177 J/kg
Mixed-layer CIN
-25 J/kg
Mixed-layer LCL
1408 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
122 m²/s²
0-3 km storm-relative helicity
132 m²/s²
Significant tornado parameter
0.6
Supercell composite
3.8

Open this sounding in Storm Lab

The text

As transmitted.

238 
WWUS20 KWNS 060412
SEL1  
SPC WW 060412
FLZ000-GAZ000-CWZ000-061200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 131
NWS Storm Prediction Center Norman OK
1210 AM EDT Thu Apr 6 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  northern Florida
  southern Georgia
  Coastal Waters

* Effective this Thursday morning from 1210 AM until 800 AM EDT.

* Primary threats include...
  A few tornadoes possible
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Isolated damaging wind gusts to 70 mph possible

SUMMARY...Storms are expected to intensify as they develop northeast
through northern Florida into southern Georgia with supercells and
bowing segments posing a risk for a few tornadoes, damaging wind and
large hail.

The tornado watch area is approximately along and 80 statute miles
east and west of a line from 45 miles north northwest of
Jacksonville FL to 75 miles south southwest of Ocala FL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 129...WW 130...

AVIATION...Tornadoes and 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 24035.

...Dial

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 5, 11:15 PM EDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Clay, Columbia, Duval and 8 more2 hr
Apr 6, 3:12 AM EDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Citrus, Clay, Columbia and 25 more2 hr
Apr 6, 6:10 AM EDTMesoscale DiscussionSPCHardee, Hillsborough, Lake, Manatee, Orange, Osceola and 4 more2 hr
Apr 5, 9:58 PM EDTTornado WatchSPCBibb, Butts, Chattahoochee, Clayton, Coweta, Crawford and 27 more3 hr
Apr 5, 11:34 PM EDTMesoscale DiscussionSPCElbert, Lincoln, Wilkes56 min
Apr 5, 11:50 PM EDTSevere Thunderstorm WatchSPCBaldwin, Bleckley, Burke, Clarke, Columbia, Elbert and 24 more6 hr
Apr 6, 2:54 AM EDTMesoscale DiscussionSPCBurke, Columbia, Dodge, Emanuel, Jefferson, Jenkins and 4 more96 min

Nearby

Tornado Watches in Florida, 2017Tornado Watches in Georgia, 2017Every tornado watch in 2017

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.