Tornado Watch 596

Issued

Jul 17, 2009, 12:59 PM MDT (18:59 UTC)

Expired

Jul 17, 2009, 7:00 PM MDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

70 kt

The Cheyenne radar (KCYS), 107 km from the middle of the area, began a volume at 18:59 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

20%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1597Jul 17, 12:06 PM MDT
• Mesoscale Discussion 1607Jul 17, 6:32 PM MDT

710 
WWUS20 KWNS 171904
SEL6  
SPC WW 171904
COZ000-NEZ000-WYZ000-180100-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 596
NWS STORM PREDICTION CENTER NORMAN OK
100 PM MDT FRI JUL 17 2009

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

       NORTHEASTERN COLORADO
       WESTERN NEBRASKA
       EXTREME SOUTHEASTERN WYOMING

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 100 PM UNTIL 700
PM MDT.

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 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 15 MILES NORTHWEST OF
SCOTTSBLUFF NEBRASKA TO 55 MILES SOUTHEAST OF LIMON COLORADO. 
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 592...WW 593...WW
594...WW 595...

DISCUSSION...STORMS ARE DEVELOPING OVER THE HIGHER TERRAIN OF SERN
WY/NRN CO...AND SHOULD ALSO DEVELOP ALONG AN OUTFLOW BOUNDARY IN ERN
CO LATER THIS AFTERNOON. THE MOIST BOUNDARY LAYER...DEWPOINTS IN THE
MID AND UPPER 50S...COMBINED WITH STEEP MID LEVEL LAPSE RATES WAS
RESULTING IN STRONG INSTABILITY...MUCAPES UP TO 3000 J/KG. THIS
AMOUNT OF INSTABILITY AND STRONGLY VEERING WIND PROFILES WILL BE
FAVORABLE FOR INTENSE SUPERCELLS. THE PRIMARY THREAT WILL BE VERY
LARGE HAIL...THOUGH STORMS NEAR THE BOUNDARY IN ERN CO/WRN NEB MAY
INGEST ENOUGH LOW LEVEL SHEAR/HELICITY FOR TORNADOES.

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
500. MEAN STORM MOTION VECTOR 34025.


...IMY

Tornado Watches in Colorado, 2009Tornado Watches in Nebraska, 2009Tornado Watches in Wyoming, 2009Every tornado watch in 2009

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.