Alert archive / Florida / Tornado Watches in 2018

Tornado Watch 369

September 4, 2018Baldwin County, Mobile County, Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida

The Storm Prediction Center issued this tornado watch at Sep 4, 2018, 6:51 PM CDT for Baldwin County, Mobile County, Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued: Sep 4, 2018, 6:51 PM CDT (23:51 UTC)
Expired: Sep 5, 2018, 4:00 AM CDT
In force: 9 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

Counties Baldwin County, AL, Mobile County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL

The radar

The Mobile radar (KMOB), 77 km from the middle of the area, began a volume at 23:51 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: 10%
Ten or more severe wind reports: 10%
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: 20%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 4, 8:24 PM CDT	Flash Flood Warning	MOB	Baldwin	12 hr
Sep 4, 9:00 PM CDT	Flash Flood Warning	MOB	Mobile	6 hr
Sep 4, 9:29 PM CDT	Tornado Warning	MOB	Escambia, Santa Rosa	31 min
Sep 4, 9:55 PM CDT	Tornado Warning Tornado observed	MOB	Santa Rosa	27 min
Sep 4, 10:45 PM CDT	Flash Flood Warning	MOB	Baldwin, Escambia	12 hr
Sep 5, 12:53 AM CDT	Tornado Warning	MOB	Baldwin	25 min
Sep 5, 3:10 AM CDT	Tornado Warning	MOB	Okaloosa, Santa Rosa	29 min
Sep 5, 3:31 AM CDT	Tornado Warning	MOB	Okaloosa	19 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

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.9 hours before the alert went out and 217 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: 592 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 640 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 10 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

597 
WWUS20 KWNS 042347
SEL9  
SPC WW 042347
ALZ000-FLZ000-CWZ000-050900-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 369
NWS Storm Prediction Center Norman OK
645 PM CDT Tue Sep 4 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Extreme southern Alabama
  The extreme western Florida Panhandle
  Coastal Waters

* Effective this Tuesday night and Wednesday morning from 645 PM
  until 400 AM CDT.

* Primary threats include...
  A couple tornadoes possible

SUMMARY...Tropical Storm Gordon will make landfall tonight along the
Mississippi coast (see latest National Hurricane Center advisories
for details).  Conditions will gradually become more favorable for
supercells to reach the coast within the main convective band east
of the center, with an attendant threat for a couple of tornadoes
along the coast of Alabama and the western Florida Panhandle.

The tornado watch area is approximately along and 30 statute miles
north and south of a line from 55 miles west of Pensacola FL to 30
miles south of Crestview FL. For a complete depiction of the watch
see the associated watch outline update (WOUS64 KWNS WOU9).

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 368...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 16040.

...Thompson

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 4, 1:51 PM CDT	Mesoscale Discussion	SPC	Baldwin, Escambia, Mobile	2 hr
Sep 4, 6:04 PM CDT	Mesoscale Discussion	SPC	Baldwin	56 min

Nearby

Tornado Watches in Florida, 2018 Tornado Watches in Alabama, 2018 Every tornado watch in 2018

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.