Alert archive / Alabama / Tornado Watches in 1998

Tornado Watch 246

April 18, 19984 states

The Storm Prediction Center issued this tornado watch at Apr 18, 1998, 5:45 PM CDT for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 1998, 5:45 PM CDT (22:45 UTC)
Expired
Apr 18, 1998, 11:00 PM CDT
In force
5 hr
Issued by
the Storm Prediction Center
All 45 counties

Autauga County, AL, Baldwin County, AL, Bibb County, AL, Butler County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Cleburne County, AL, Conecuh County, AL, Coosa County, AL, Dallas County, AL, DeKalb County, AL, Elmore County, AL, Escambia County, AL, Etowah County, AL, Hale County, AL, Jefferson County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Washington County, AL, Wilcox County, AL, Dade County, GA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 109 km from the middle of the area, began a volume at 22:46 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.

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 18, 6:03 PM CDTTornado WarningBMXChilton47 min
Apr 18, 6:16 PM CDTSevere Thunderstorm WarningBMXJefferson49 min
Apr 18, 6:20 PM CDTTornado WarningBMXDallas50 min
Apr 18, 6:26 PM CDTTornado WarningBMXCherokee19 min
Apr 18, 6:48 PM CDTTornado WarningBMXPerry62 min
Apr 18, 6:52 PM CDTTornado WarningBMXShelby63 min
Apr 18, 6:53 PM CDTTornado WarningBMXDeKalb47 min
Apr 18, 6:56 PM CDTTornado WarningBMXEtowah49 min
Apr 18, 7:02 PM CDTTornado WarningBMXJefferson33 min
Apr 18, 7:13 PM CDTSevere Thunderstorm WarningBMXChilton62 min
Apr 18, 7:26 PM CDTFlash Flood WarningBMXDeKalb4 hr
Apr 18, 7:26 PM CDTSevere Thunderstorm WarningBMXSt. Clair, Talladega64 min
Apr 18, 7:30 PM CDTTornado WarningBMXLowndes50 min
Apr 18, 7:36 PM CDTTornado WarningBMXDeKalb44 min
Apr 18, 7:39 PM CDTTornado WarningBMXChilton31 min
Apr 18, 7:42 PM CDTTornado WarningFFCDade33 min
Apr 18, 7:44 PM CDTTornado WarningBMXCherokee46 min
Apr 18, 7:55 PM CDTTornado WarningBMXShelby20 min
Apr 18, 7:58 PM CDTSevere Thunderstorm WarningBMXCalhoun47 min
Apr 18, 8:23 PM CDTTornado WarningBMXTalladega62 min
Apr 18, 9:06 PM CDTSevere Thunderstorm WarningBMXCherokee19 min

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 10.8 hours before the alert went out and 205 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, Birmingham, AL at 12:00Z on 1998-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Birmingham, AL at 12:00Z on 1998-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1180 m above ground
0-6 km bulk shear
76 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
114 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.

495 
WWUS9 KMKC 182234
SEL6  
MKC WW 182234
MSZ000-ALZ000-190400-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 246
STORM PREDICTION CENTER NORMAN OK
534 PM CDT SAT APR 18 1998

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   SOUTHERN MISSISSIPPI                        
   ALABAMA                            
   AND ADJACENT COASTAL WATERS

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 545 PM UNTIL
1100 PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 80 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 30 MILES NORTH NORTHWEST OF BOOTHVILLE
LOUISIANA TO 30 MILES NORTHEAST OF ANNISTON ALABAMA.

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.

DISCUSSION...THUNDERSTORMS HAVE BEGUN TO DEVELOP AND INTENSIFY
ALONG STATIONARY FRONT WHICH EXTENDS ACROSS AREA.  COMBINATION OF
MODERATELY UNSTABLE AIRMASS AND STORM RELATIVE HELICITY VALUES OVER
200 M2/S2 SUGGEST THREAT OF SUPERCELLS AND ISOLATED TORNADOES. 

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 450. 
MEAN STORM MOTION VECTOR 22035.

...HOVIS

305,0893 350,0852 324,0852 283,0893

Nearby

Tornado Watches in Alabama, 1998Tornado Watches in Mississippi, 1998Tornado Watches in Louisiana, 1998Every tornado watch in 1998

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.