Tornado Watch 787

Issued

Aug 18, 2011, 6:38 PM CDT (23:38 UTC)

Expired

Aug 19, 2011, 12:00 AM CDT

In force

5 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

70 kt

The North Platte radar (KLNX), 155 km from the middle of the area, began a volume at 23:40 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

10%

Ten or more severe wind reports

40%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

50%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 2005Aug 18, 2:51 PM CDT
• Mesoscale Discussion 2010Aug 18, 6:00 PM CDT
• Mesoscale Discussion 2011Aug 18, 6:18 PM CDT
• Mesoscale Discussion 2012Aug 18, 8:29 PM CDT
• Mesoscale Discussion 2013Aug 18, 9:52 PM CDT

739 
WWUS20 KWNS 182342
SEL7
SPC WW 182342
IAZ000-MOZ000-NEZ000-190500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 787
NWS STORM PREDICTION CENTER NORMAN OK
640 PM CDT THU AUG 18 2011

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

       EXTREME SOUTHWEST IOWA
       NORTHWEST MISSOURI
       NORTHERN AND EASTERN NEBRASKA

EFFECTIVE THIS THURSDAY NIGHT FROM 640 PM UNTIL MIDNIGHT CDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 100 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH NORTHEAST OF
AINSWORTH NEBRASKA TO 30 MILES WEST OF FALLS CITY NEBRASKA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 785...WW 786...

DISCUSSION...SEVER STORMS OVER NERN NEB ARE TRACKING SEWD ALONG
OUTFLOW BOUNDARY FROM EARLIER SEVERE STORMS...WHERE PRONOUNCED
VEERING WIND PROFILES /REF OAX VAD DISPLAY/ ARE RESULTING IN
SUBSTANTIAL DEEP LAYER SHEAR AND EFFECTIVE SRH.  THIS WILL ENHANCE
THREAT FOR SUPERCELLS WITH POTENTIAL TO PRODUCE A FEW TORNADOES.
OTHER STRONG SUPERCELLS WITH TORNADO POTENTIAL ARE OVER EXTREME
SOUTHWEST IA AND WILL MOVE INTO NWRN MO SOON...WHILE ADDITIONAL
STORMS ARE LIKELY TO SPREAD FROM SD INTO INCREASINGLY MOIST/UNSTABLE
AIR MASS OVER NRN NEB OVER THE NEXT SEVERAL HOURS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
600. MEAN STORM MOTION VECTOR 31025.


...WEISS

Tornado Watches in Nebraska, 2011Tornado Watches in Missouri, 2011Tornado Watches in Iowa, 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.