Tornado Watch 306

Issued

May 18, 2011, 3:48 PM CDT (20:48 UTC)

Expired

May 18, 2011, 7:06 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

The Norman radar (KTLX), 104 km from the middle of the area, began a volume at 20:49 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

40%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 804May 18, 2:44 PM CDT
• Mesoscale Discussion 806May 18, 6:48 PM CDT

509 
WWUS20 KWNS 182052
SEL6
SPC WW 182052
OKZ000-190400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 306
NWS STORM PREDICTION CENTER NORMAN OK
350 PM CDT WED MAY 18 2011

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

       WESTERN AND CENTRAL OKLAHOMA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 350 PM UNTIL
1100 PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTHEAST OF FORT
SILL OKLAHOMA TO 15 MILES NORTH NORTHWEST OF ALVA OKLAHOMA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).

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 305...

DISCUSSION...ISOLATED STORM DEVELOPMENT IS ANTICIPATED WITHIN THE
NEXT ONE TO TWO HOURS ALONG DRYLINE WHICH HAS BECOME STATIONARY OVER
WRN OK.  AIR MASS E OF DRYLINE IS CHARACTERIZED BY DEWPOINTS IN THE
LOW/MID 60S...WHICH WHEN COUPLED WITH MIDLEVEL LAPSE RATES OF AROUND
7 C/KM...IS RESULTING IN A MODERATELY UNSTABLE AND WEAKLY CAPPED
ENVIRONMENT WITH MLCAPE AROUND 2000 J/KG.  PROFILER DATA ACROSS ERN
NM SUGGEST THAT CIRRUS PLUME SPREADING EWD ACROSS WRN TX INTO WRN OK
IS ASSOCIATED WITH A 50 KT MIDLEVEL JET STREAK WHICH WILL SERVE TO
STRENGTHEN DEEP-LAYER SHEAR THROUGH THIS EVENING.  LOW-LEVEL SHEAR
SHOULD ALSO INCREASE AROUND OR SHORTLY AFTER 19/00Z WITH VERTICAL
WIND PROFILES BECOMING QUITE CONDUCIVE FOR SUPERCELL DEVELOPMENT.
VERY LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH TORNADOES WILL
BE POSSIBLE WITH ANY MATURE SUPERCELLS THAT CAN PERSIST INTO THIS
EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24025.


...MEAD

Tornado Watches in Oklahoma, 2011Every tornado watch in 2011

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.