Small Craft Advisory 53, NWS Milwaukee, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
315 PM CDT FRI JUL 24 2009

.SHORT TERM /TONIGHT THROUGH MONDAY/...
IMMEDIATE FOCUS LIES ON THUNDERSTORM THREAT FOR THE REMAINDER OF THE
AFTERNOON INTO THIS EVENING.  SCATTERED CONVECTION HAS DEVELOPED
JUST TO THE NORTH OF SEVERE THUNDERSTORM CURRENTLY JUST WEST OF
KDBQ.  THINKING CONVECTION IS A RESULT OF INCREASING MID LEVEL WARM
AIR ADVECTION AND THETA-E ADVECTION...WHICH SPREADS ACROSS SOUTH
CENTRAL WISCONSIN THROUGH EARLY EVENING.  MID LEVEL LAPSE RATES IN
THE TRI-STATE AREA HAVE INCREASED TO 7-7.5 DEGREES SO ATMOSPHERE
RECUPERATING RAPIDLY DESPITE RECENT CONVECTION.  MUCAPE IN THIS AREA
AROUND 1000 J/KG WITH SURGE OF MID 60 DEGREE DEWPOINTS.  BULK WIND
SHEAR HAS INCREASED TO 50 KTS IN THIS AREA AS WELL.  DESPITE JUST
BEING REMOVED FROM SPC SLIGHT RISK...COULD STILL SEE SOME LARGE HAIL
AND DAMAGING WIND INTO THIS EVENING WITH BEST POTENTIAL IN THE
WESTERN CWA AS DEPICTED BY LATEST WRF4G MESOMODEL.  PWAT VALUES
INCREASE TO AROUND 1.5 INCHES AHEAD OF APPROACHING SURFACE FRONT
WHICH MOVES THROUGH DURING THE EVENING.  SYNOPTICALLY...AREA OF
UPPER LEVEL DIVERGENCE ASSOCIATED WITH NOSE OF 300MB JET.  WIND
PROFILER NETWORK AND WATER VAPOR IMAGERY SHOW POTENT SHORT WAVE
TROUGH UPSTREAM OVER SRN MN...SO STILL THINKING SHOWERS AND
THUNDERSTORMS WILL BE LIKELY ACROSS CWA THIS EVENING...DIMINISHING
RAPIDLY FROM LATE EVENING THRU 09Z.

POTENT SHORT WAVE TROUGH ROTATES AROUND UPPER LOW SETTLING OVER
GREAT LAKES ON SATURDAY.  STEEP LAPSE RATES AND LINGERING LOW LEVEL
MOISTURE SHOULD PRODUCE AT LEAST SCATTERED SHOWERS.  WEAK ELEVATED
INSTABILITY SO WL CONTINUE TO MENTION ISO THUNDER.  SECONDARY WEAKER
SHORT WAVE ON SUNDAY ROTATES AROUND DEPARTING LOW SO WL CONTINUE
SMALL THREAT.  MORE POTENT SHORT WAVE TROUGH ROTATES THROUGH LATER
MONDAY AND MONDAY NIGHT.  SLIGHT DELAY IN TROUGH ARRIVAL...HOWEVER
LOW LEVEL WARM AIR ADVECTION SPREADS IN MONDAY MORNING SO WL
CONTINUE LOW POPS THROUGH MONDAY...WITH BETTER THREAT MONDAY
EVENING.

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
EXTENDED GUIDANCE IN REASONABLE AGREEMENT ON BRINGING COLD FRONT AND
STRONGER UPPER LEVEL SHORT WAVE ACROSS WISCONSIN IN THE MONDAY
AFTERNOON INTO TUESDAY TIME FRAME.  GFS LIKELY OVERDOING AMOUNT OF
LOW LEVEL MOISTURE AVAILABLE BUT BEST THREAT FOR MORE WIDESPREAD
CONVECTION AT THIS TIME...AFTER TONIGHT.  LATEST GFS AND HI RES
ECMWF SHOWING SOME FLATTENING OF PERSISTENT LONG WAVE TROFFING
ACROSS UPPER MIDWEST INTO SRN CANADA POST CDFNT NEXT TUE THROUGH
THU.  12Z GFS SHOWING STRONG SHORT WAVE AFFECTING SRN WI ON
WED...BUT MEDIUM RANGE ENSEMBLE POPS HAS POPS LESS THAN 20 PERCENT.
MORE STOCK PLACED IN MREF DUE TO FAIR TO GOOD AGREEMENT IN ENSEMBLE
MEMBERS.  HI RES AND CANADIAN IN AGREEMENT ON DRIER WEATHER FROM TUE
NIGHT INTO THU SO PER COORDINATION WITH NEIGHBORING OFFICES...HAVE
REMOVED POPS FOR MOST OF THIS PERIOD.

STRONGER SHORT WAVE TROUGH AMPLIFIES UPSTREAM TROFFING ACROSS NORTH
CENTRAL CONUS LATER NEXT WEEK WITH THREAT FOR CONVECTION RETURNING
BY THU NIGHT/FRIDAY.  TEMPERATURES THROUGH THE END OF THE WEEK LOOK
TO CONTINUE BELOW NORMAL FOR LATE JULY.

GFS 5 DAY 500MB ANOMALIES SHOW LITTLE CHANGE TO THE OVERALL PATTERN
INTO THE FIRST WEEK OF AUGUST...WITH LARGE POSITIVE ANOMOLY
PERSISTING ACROSS WRN CANADA INTO PAC NW...WITH DOWNSTREAM LONG WAVE
TROFFING ACROSS CENTRAL CANADA INTO GTLAKES.

&&

.AVIATION...STILL EXPECT A ROUND OF THUNDERSTORMS TO CROSS SOUTHERN
WISCONSIN THIS EVENING WITH APPROACHING LOW PRESSURE CENTER AND
ASSOCIATED FRONTAL BOUNDARIES. POTENTIAL FOR SEVERE WEATHER WITH
THESE STORMS.  OVERALL EXPECT VFR CONDITIONS BUT IFR CONDITIONS
POSSIBLE IN AND AROUND STRONGER THUNDERSTORMS. COLD FRONT EXPECTED
TO MOVE THROUGH BTWN 06Z AND 12Z WITH WINDS SHIFTING TO THE
NORTHWEST BEHIND THE FRONT. POSSIBLE THUNDERSTORM DEVELOPMENT ONCE
AGAIN TOMORROW AFTERNOON BUT LEFT OUT OF TAFS FOR NOW WITH ONLY
CHANCE POPS.

&&

.MARINE...GUSTY SOUTHWEST WINDS EXPECTED TONIGHT AHEAD OF COLD FRONT
MOVING THROUGH. THUNDERSTORM CHANCES ALSO INCREASE THIS EVENING WITH
SOME SEVERE THUNDERSTORMS POSSIBLE.  WINDS INCREASE OUT OF THE
NORTHWEST SATURDAY AFTERNOON BUT AT THIS TIME EXPECT TO REMAIN BELOW
SMALL CRAFT LEVELS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

SHORT/LONG TERM...MBK
AVIATION/MARINE...PZ

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
330 PM CDT FRI JUL 24 2009

WIZ046-047-051-052-056>060-062>072-251030-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
330 PM CDT FRI JUL 24 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
WISCONSIN...SOUTH CENTRAL WISCONSIN AND SOUTHEAST WISCONSIN.

.DAY ONE...TONIGHT

THUNDERSTORMS ARE EXPECTED THIS EVENING ACROSS SOUTHERN WISCONSIN.
ISOLATED SEVERE ACTIVITY IS POSSIBLE...ESPECIALLY SOUTHWEST OF A
WISCONSIN DELLS...TO MADISON...TO BELOIT LINE...HOWEVER MOST STORMS
SHOULD STAY BELOW SEVERE LIMITS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE EACH DAY FROM THE
WEEKEND INTO EARLY NEXT WEEK AS RELATIVELY COLD AIR WILL BE
PRESENT IN THE UPPER ATMOSPHERE MAKING FOR UNSTABLE CONDITIONS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION SHOULD NOT BE NEEDED TONIGHT.

LMZ643>646-251030-
SHEBOYGAN TO PORT WASHINGTON WI-
PORT WASHINGTON TO NORTH POINT LIGHT WI-
NORTH POINT LIGHT TO WIND POINT WI-
WIND POINT WI TO WINTHROP HARBOR IL-
330 PM CDT FRI JUL 24 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE EXPECTED THIS EVENING.  THESE STORMS
SHOULD STAY BELOW SEVERE LIMITS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE EACH DAY FROM THE
WEEKEND INTO THE EARLY NEXT WEEK AS RELATIVELY COLD AIR WILL BE
PRESENT IN THE UPPER ATMOSPHERE MAKING FOR UNSTABLE CONDITIONS.

WWW.WEATHER.GOV/MKX

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