Alert archive / Florida / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 415, NWS Tallahassee, FL

December 20, 20124 counties in Florida

NWS Tallahassee, FL issued this severe thunderstorm warning at Dec 20, 2012, 11:45 AM CST for 4 counties in Florida. It was in force for 45 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Dec 20, 2012, 11:45 AM CST (17:45 UTC)
Expired: Dec 20, 2012, 12:30 PM CST
In force: 45 min
Issued by: NWS Tallahassee, FL
Area: Storm-based polygon

Counties Bay County, FL, Holmes County, FL, Walton County, FL, Washington County, FL

The radar

The Eglin Afb radar (KEVX), 21 km from the middle of the area, began a volume at 17:46 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 was reported inside it

Time	Report	Where	Remark
Dec 20, 11:47 AM CST	TSTM WND DMG	2 S Freeport, FL	MULTIPLE POWERLINES DOWN IN SOUTHERN WALTON COUNTY

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Dec 20, 9:19 AM CST	Tornado Watch	SPC	9 hr

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 5.8 hours before the alert went out and 166 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2063 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 200 m²/s²
0-3 km storm-relative helicity: 202 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.

090 
WUUS52 KTAE 201745
SVRTAE
FLC005-059-131-133-201830-
/O.NEW.KTAE.SV.W.0415.121220T1745Z-121220T1830Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1145 AM CST THU DEC 20 2012

THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WEST CENTRAL BAY COUNTY IN THE PANHANDLE OF FLORIDA...
  EXTREME SOUTHWESTERN HOLMES COUNTY IN THE PANHANDLE OF FLORIDA...
  SOUTHEASTERN WALTON COUNTY IN THE PANHANDLE OF FLORIDA...
  WESTERN WASHINGTON COUNTY IN THE PANHANDLE OF FLORIDA...

* UNTIL 1230 PM CST

* AT 1142 AM CST...THE NATIONAL WEATHER SERVICE HAS DETECTED A LINE
  OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
  EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
  FROM 19 MILES WEST OF VERNON TO 41 MILES SOUTH OF SANTA ROSA
  BEACH...AND MOVING EAST AT 20 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  VERNON BY 1230 PM CST...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY. PEOPLE OUTSIDE SHOULD MOVE INSIDE A STRONG BUILDING BUT
AWAY FROM WINDOWS.

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. IF A TORNADO
IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY.

&&

LAT...LON 3044 8625 3039 8615 3039 8613 3045 8617
      3047 8623 3074 8607 3074 8558 3028 8582
      3026 8584 3023 8584 3020 8585 3027 8600
      3036 8629
TIME...MOT...LOC 1745Z 271DEG 18KT 3071 8600 2984 8644

$$

22-BARRY

The office that day

Everything else NWS Tallahassee, FL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 20, 2:50 AM CST	Freeze Watch	TAE	Bay, Calhoun, Dixie, Franklin, Gadsden, Gulf and 10 more	24 hr
Dec 20, 3:31 AM CST	Gale Warning	TAE		26 hr
Dec 20, 3:39 AM CST	Rip Current Statement	TAE	Bay, Gulf, Walton	38 hr
Dec 20, 8:20 AM CST	Dense Fog Advisory	TAE	Gadsden, Leon, Wakulla	100 min
Dec 20, 8:30 AM CST	Marine Dense Fog Advisory	TAE		4 hr
Dec 20, 10:50 AM CST	Severe Thunderstorm Warning	TAE	Holmes, Walton	40 min
Dec 20, 10:51 AM CST	Special Marine Warning	TAE		114 min
Dec 20, 11:26 AM CST	Severe Thunderstorm Warning	TAE	Holmes, Walton	64 min
Dec 20, 12:25 PM CST	Severe Thunderstorm Warning	TAE	Bay, Calhoun, Holmes, Jackson, Washington	50 min
Dec 20, 12:41 PM CST	Special Marine Warning	TAE		3 hr
Dec 20, 1:16 PM CST	Tornado Warning	TAE	Bay, Gulf	29 min
Dec 20, 2:55 PM CST	Special Marine Warning	TAE		3 hr
Dec 20, 3:28 PM CST	Severe Thunderstorm Warning	TAE	Jefferson, Leon, Madison	47 min
Dec 20, 4:22 PM CST	Tornado Warning	TAE	Taylor	23 min
Dec 20, 4:47 PM CST	Severe Thunderstorm Warning	TAE	Madison	28 min
Dec 20, 5:48 PM CST	Special Marine Warning	TAE		42 min

Nearby

Severe Thunderstorm Warnings in Florida, 2012 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.