Severe Thunderstorm Watch 678

Issued

Dec 9, 2012, 5:47 PM CST (23:47 UTC)

Expired

Dec 10, 2012, 12:00 AM CST

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

60 kt

The Shreveport radar (KSHV), 37 km from the middle of the area, began a volume at 23:49 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.

Two or more tornadoes

10%

One or more EF2 to EF5 tornadoes

10%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

20%

One or more hailstones of 2 inches or more

20%

Six or more combined severe hail and wind reports

60%

• Mesoscale Discussion 2141Dec 9, 5:04 PM CST
• Mesoscale Discussion 2144Dec 9, 8:38 PM CST
• Mesoscale Discussion 2145Dec 9, 9:59 PM CST
• Mesoscale Discussion 2146Dec 9, 11:24 PM CST

697 
WWUS20 KWNS 092350
SEL8  
SPC WW 092350
ARZ000-LAZ000-MSZ000-TXZ000-100600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 678
NWS STORM PREDICTION CENTER NORMAN OK
550 PM CST SUN DEC 9 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 

       SOUTHERN ARKANSAS
       WESTERN AND NORTHERN LOUISIANA
       EXTREME WESTERN MISSISSIPPI
       SOUTHEAST TEXAS

EFFECTIVE THIS SUNDAY AFTERNOON FROM 550 PM UNTIL MIDNIGHT CST.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90
STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH
NORTHWEST OF MONTICELLO ARKANSAS TO 45 MILES SOUTHEAST OF
HUNTSVILLE TEXAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 677...

DISCUSSION...SCATTERED TSTMS NEAR FRONT...AS WELL AS CLUSTERED
CONVECTION TO ITS E...SHOULD POSE RISK FOR SVR HAIL AND DAMAGING
GUSTS THROUGH EVENING.  MRGL SUPERCELL SCENARIO EXISTS FOR
DISCRETE/PREFRONTAL CONVECTION...WITH 45-55 KT EFFECTIVE SHEAR
MAGNITUDES BUT WEAK NEAR-SFC WINDS.  EFFECTIVELY SFC-BASED PARCELS
SHOULD PERSIST THROUGH ABOUT 06Z OVER MUCH OF AREA AS LONG AS
WARM/MOIST ADVECTION OFFSETS DIABATIC SFC COOLING.  TSTMS NEAR FRONT
SHOULD BE UNDERCUT QUICKLY...PER SPC MESOSCALE DISCUSSION 2141.

AVIATION...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 23035.


...EDWARDS

Severe Thunderstorm Watches in Louisiana, 2012Severe Thunderstorm Watches in Texas, 2012Severe Thunderstorm Watches in Arkansas, 2012Every severe thunderstorm watch in 2012

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.