Alert archive / Alabama / Tornado Watches in 2018

Tornado Watch 49

April 14, 201813 counties in Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida; George County, Greene County, Mississippi

The Storm Prediction Center issued this tornado watch at Apr 14, 2018, 6:55 PM CDT for 13 counties in Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida; George County, Greene County, Mississippi. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 14, 2018, 6:55 PM CDT (23:55 UTC)
Expired
Apr 15, 2018, 12:43 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt

Counties Baldwin County, AL, Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Escambia County, AL, Lowndes County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, George County, MS, Greene County, MS

The radar

The Mobile radar (KMOB), 87 km from the middle of the area, began a volume at 23:58 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
30%
Ten or more severe wind reports
50%
One or more gusts of 65 knots or more
20%
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
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 14, 6:57 PM CDTSevere Thunderstorm WarningMOBMobile20 min
Apr 14, 9:03 PM CDTSevere Thunderstorm WarningMOBBaldwin42 min
Apr 14, 9:22 PM CDTFlash Flood WarningBMXDallas, Perry6 hr
Apr 14, 9:50 PM CDTSevere Thunderstorm WarningMOBButler, Conecuh, Covington40 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 235 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, Slidell Radar S, LA at 12:00Z on 2018-04-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1802 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2018-04-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 222 square meters per square second.193958Sfc1 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
1802 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
534 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
222 m²/s²
0-3 km storm-relative helicity
293 m²/s²
Significant tornado parameter
1.6
Supercell composite
12.6

Open this sounding in Storm Lab

The text

As transmitted.

673 
WWUS20 KWNS 142353
SEL9  
SPC WW 142353
ALZ000-FLZ000-MSZ000-CWZ000-150700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 49
NWS Storm Prediction Center Norman OK
650 PM CDT Sat Apr 14 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southern Alabama
  Florida Panhandle
  Far southeast Mississippi
  Coastal Waters

* Effective this Saturday night and Sunday morning from 650 PM
  until 200 AM CDT.

* Primary threats include...
  A few tornadoes and a couple intense tornadoes possible
  Scattered damaging wind gusts to 70 mph possible

SUMMARY...Storms are expected to persist and gradually intensify
along composite outflow across the region with a gradual
east/northeastward acceleration this evening. Increasing low-level
shear and the presence of a weak area of low pressure will maintain
long/somewhat curved low-level wind profiles supportive of a
quasi-linear convective mode with embedded supercells/mesovortices
capable of a few tornadoes along with damaging winds.

The tornado watch area is approximately along and 60 statute miles
east and west of a line from 40 miles west northwest of Troy AL to
70 miles south of Gulfport MS. 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 48...

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 500. Mean
storm motion vector 24025.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 14, 4:35 AM CDTMesoscale DiscussionSPCColbert, Fayette, Franklin, Lamar, Lauderdale, Marion and 1 more115 min
Apr 14, 6:37 AM CDTMesoscale DiscussionSPCSumter83 min
Apr 14, 9:40 AM CDTMesoscale DiscussionSPCAutauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more95 min
Apr 14, 10:36 AM CDTTornado WatchSPCAutauga, Baldwin, Bibb, Blount, Butler, Chilton and 22 more8 hr
Apr 14, 12:41 PM CDTMesoscale DiscussionSPCAutauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more94 min
Apr 14, 2:56 PM CDTMesoscale DiscussionSPCAutauga, Chilton, Coosa, Dallas, Lowndes, Mobile and 5 more94 min
Apr 14, 6:17 PM CDTMesoscale DiscussionSPCBaldwin, Butler, Clarke, Conecuh, Covington, Escambia and 2 more118 min
Apr 13, 7:22 PM CDTTornado WatchSPCCatahoula, Concordia, East Carroll, Franklin, Madison, Morehouse and 3 more3 hr
Apr 13, 8:54 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 10 more66 min
Apr 13, 9:53 PM CDTTornado WatchSPCBeauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 14 more8 hr
Apr 13, 10:12 PM CDTTornado WatchSPCCatahoula, Concordia, East Carroll, Franklin, Madison, Morehouse and 3 more10 hr
Apr 14, 2:10 AM CDTMesoscale DiscussionSPCAllen, Avoyelles, Beauregard, Bienville, Caldwell, Catahoula and 20 more2 hr
Apr 14, 6:57 AM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 22 more7 hr

Nearby

Tornado Watches in Alabama, 2018Tornado Watches in Florida, 2018Tornado Watches in Mississippi, 2018Every 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.