Alert archive / Florida / Tornado Watches in 2017

Tornado Watch 14

January 21, 20179 counties in Florida; 8 counties in Georgia

The Storm Prediction Center issued this tornado watch at Jan 21, 2017, 1:12 PM CST for 9 counties in Florida; 8 counties in Georgia. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jan 21, 2017, 1:12 PM CST (19:12 UTC)
Expired
Jan 21, 2017, 6:00 PM CST
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt

Counties Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Wakulla County, FL, Berrien County, GA, Brooks County, GA, Colquitt County, GA, Cook County, GA, Grady County, GA, Lanier County, GA, Lowndes County, GA, Thomas County, GA

The radar

The Tallahassee radar (KTLH), 33 km from the middle of the area, began a volume at 19:13 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
30%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jan 21, 2:10 PM CSTSevere Thunderstorm WarningTAECalhoun, Gadsden, Gulf, Liberty50 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

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 7.2 hours before the alert went out and 36 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, Tallahassee Rgnl, FL at 12:00Z on 2017-01-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 352 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, Tallahassee Rgnl, FL at 12:00Z on 2017-01-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 139 square meters per square second.1939587897117Sfc1 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
352 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
613 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
139 m²/s²
0-3 km storm-relative helicity
217 m²/s²
Significant tornado parameter
0.3
Supercell composite
2.0

Open this sounding in Storm Lab

The text

As transmitted.

424 
WWUS20 KWNS 211910
SEL4  
SPC WW 211910
FLZ000-GAZ000-CWZ000-220000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 14
NWS Storm Prediction Center Norman OK
210 PM EST Sat Jan 21 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Florida Panhandle
  South Central Georgia
  Coastal Waters

* Effective this Saturday afternoon and evening from 210 PM until
  700 PM EST.

* Primary threats include...
  A couple tornadoes possible
  Isolated damaging wind gusts to 70 mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A line of strong to severe thunderstorms will sag
southward across the watch area this afternoon.  Strong winds aloft
and sufficient instability suggest a risk of locally gusty or
damaging winds and isolated tornadoes.

The tornado watch area is approximately along and 40 statute miles
north and south of a line from 40 miles west northwest of
Apalachicola FL to 25 miles north northeast of Valdosta GA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU4).

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 12...WW 13...

AVIATION...Tornadoes and 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 450. Mean
storm motion vector 26030.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 21, 3:00 AM CSTMesoscale DiscussionSPCEscambia, Okaloosa, Santa Rosa, Walton90 min
Jan 21, 3:56 AM CSTTornado WatchSPCEscambia, Holmes, Okaloosa, Santa Rosa, Walton8 hr
Jan 21, 7:41 AM CSTMesoscale DiscussionSPCEscambia, Holmes, Jackson, Okaloosa, Santa Rosa, Walton and 1 more94 min
Jan 21, 8:04 AM CSTTornado WatchSPCBay, Calhoun, Gadsden, Gulf, Jackson, Liberty and 1 more6 hr
Jan 21, 9:19 AM CSTMesoscale DiscussionSPCBay, Calhoun, Gadsden, Holmes, Jackson, Liberty and 3 more86 min
Jan 21, 12:06 PM CSTMesoscale DiscussionSPCBay, Calhoun, Gadsden, Gulf, Hamilton, Jackson and 6 more114 min
Jan 21, 3:03 PM CSTMesoscale DiscussionSPCBaker, Columbia, Franklin, Gilchrist, Gulf, Hamilton and 9 more57 min
Jan 21, 5:05 PM CSTMesoscale DiscussionSPCBay, Calhoun, Franklin, Gulf, Jefferson, Leon and 4 more55 min
Jan 21, 12:51 PM CSTTornado WatchSPCAppling, Atkinson, Bacon, Bryan, Bulloch, Burke and 19 more4 hr
Jan 21, 2:06 PM CSTMesoscale DiscussionSPCAppling, Atkinson, Bacon, Brantley, Bryan, Bulloch and 20 more84 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.