Severe Thunderstorm Watch 520

Issued

Jul 25, 2012, 7:38 PM EDT (23:38 UTC)

Expired

Jul 26, 2012, 3:00 AM EDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Green Bay radar (KGRB), 36 km from the middle of the area, began a volume at 23:39 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

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

80%

One or more gusts of 65 knots or more

60%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

40%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1587Jul 25, 3:57 PM EDT
• Mesoscale Discussion 1590Jul 25, 7:25 PM EDT
• Mesoscale Discussion 1593Jul 25, 9:28 PM EDT
• Mesoscale Discussion 1594Jul 25, 9:40 PM EDT
• Mesoscale Discussion 1595Jul 26, 12:09 AM EDT
• Mesoscale Discussion 1596Jul 26, 12:34 AM EDT
• Mesoscale Discussion 1598Jul 26, 2:40 AM EDT

511 
WWUS20 KWNS 252343
SEL0
SPC WW 252343
MIZ000-WIZ000-LMZ000-260700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 520
NWS STORM PREDICTION CENTER NORMAN OK
640 PM CDT WED JUL 25 2012

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

       WESTERN LOWER MICHIGAN
       CENTRAL AND EAST-CENTRAL WISCONSIN
       LAKE MICHIGAN

EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 640 PM
UNTIL 200 AM CDT.

HAIL TO 2 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 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES NORTH OF
CAMP DOUGLAS WISCONSIN TO 45 MILES EAST OF ROBEN HOOD MICHIGAN.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 518...WW 519...

DISCUSSION...RECENT TSTM INITIATION HAS OCCURRED JUST W OF GRB INVOF
SURFACE LOW AND COLD FRONT WHERE LOW-LEVEL CONVERGENCE IS BEING
ENHANCED.  STRENGTHENING SWLY LLJ THIS EVENING SHOULD BOOST
CONVERGENCE ALONG THE COLD FRONT...FOSTERING AN INCREASE IN STORMS
OVER E-CNTRL WI WITHIN AN ENVIRONMENT CHARACTERIZED BY MLCAPE OF
2000-3000 J/KG AND 40-50 KT OF DEEP-LAYER SHEAR.  INITIAL STORM MODE
MAY BE SUPERCELLULAR WITH A RISK FOR LARGE HAIL AND POSSIBLY A
TORNADO.  UPSCALE GROWTH INTO A BOW ECHO IS ANTICIPATED LATER ACROSS
LOWER MI WHERE CORRIDORS OF WIND DAMAGE WILL BE POSSIBLE.

AVIATION...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 500. MEAN STORM
MOTION VECTOR 28040.


...MEAD

Severe Thunderstorm Watches in Michigan, 2012Severe Thunderstorm Watches in Wisconsin, 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.