Damaging Wind in Wisconsin, July 23, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
316 PM CDT FRI JUL 22 2011

.VERY SHORT TERM...TONIGHT AND SATURDAY. FORECAST CONFIDENCE
MEDIUM.

RAIN SHOWERS AND ISOLATED CONVECTION OVER NORTH CENTRAL IOWA
ASSOCIATED WITH MESOSCALE CONVECTIVE VORTEX CONTINUES TO SLOWLY MOVE
EAST NORTHEAST. LOW LEVEL JET NOSE TO ITS SOUTHWEST IS WEAK...SO NOT
EXPECTING TOO MUCH MORE DEVELOPMENT WITH THIS FEATURE. STILL...WITH
ELEVATED CAPE LINGERING ACROSS THE AREA...THERE IS A SMALL CHANCE
THEY SHIFT TOWARD OR INTO THE FAR WESTERN AND SOUTHWESTERN COUNTIES
LATE THIS AFTERNOON OR THIS EVENING. THE EVENING MAY BE TOUGH WITH
LOSS OF DAYTIME HEATING...PER HIGH RESOLUTION RAPID REFRESH MODEL
TRENDS. THUS...WENT WITH LOW CHANCE/SLIGHT CHANCE POPS IN THESE
AREAS.

LOW LEVEL JET NOSE AND FOCUSED WARM AIR ADVECTION POINTS TO NORTH
CENTRAL IOWA BY 06Z SATURDAY...THEN VEERS TOWARD SOUTHWEST WISCONSIN
BY 12Z SATURDAY. NAM/GFS/ECMWF ARE SIMILAR WITH THESE FEATURES.
RESULTANT CONVECTION AND QPF TRIES TO SHIFT SOUTHEAST INTO THE AREA
LATER TONIGHT...WITH SURFACE FRONT REMAINING SOUTH AND WEST OF THE
AREA ON NAM/ECMWF...AND NORTHWEST TO SOUTHEAST ACROSS THE AREA PER
GFS. CORE OF MESOSCALE CONVECTIVE VORTEX STAYS WELL NORTHWEST OF THE
AREA...WITH RIGHT REAR QUADRANT OF JET STREAK NORTH OF THE AREA.
GIVEN LACK OF UPPER AIR SUPPORT...WILL GO WITH HIGH CHANCE POPS
INSTEAD OF LIKELY POPS FOR LATER TONIGHT. DECENT ELEVATED CAPES WITH
WEAK TO MODEST DEEP LAYER WIND SHEAR WITH HIGH PRECIPITABLE WATER
VALUES EXPECTED LATER TONIGHT. SO...IF STORMS DO MOVE THROUGH...A
ROUND OF HEAVY RAINFALL WOULD BE POSSIBLE. WARM AND HUMID CONDITIONS
LINGER ACROSS THE AREA.

LEFT HIGH CHANCE POPS GOING FOR SATURDAY...WITH SURFACE WARM FRONT
MEANDERING ACROSS OR JUST SOUTHWEST OF THE AREA...DEPENDING ON THE
MODEL. AGAIN...LACK OF UPPER LEVEL FEATURE PRECLUDES HIGHER POPS AT
THIS TIME. FOCUSED WARM AIR ADVECTION TRIES TO MOVE INTO THE
AREA...THOUGH BEST AREA IS TO THE NORTHWEST. DECENT ELEVATED CAPES
AND MODEST DEEP LAYER SHEAR SUGGEST THAT SEVERE STORMS MAY BE
POSSIBLE...PER SPC DAY 2 SLIGHT RISK. HIGH PRECIPITABLE WATER VALUES
COULD BRING HEAVY RAINFALL WITH ANY STORMS. TEMPERATURES WILL BE
TRICKY WITH POSSIBLE CLOUDS AND WARM FRONTAL POSITION UNCERTAINTY.
KEPT HIGHS IN THE LOWER TO MID 80S FOR MOST LOCATIONS.

.SHORT TERM...SATURDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE
LOW TO MEDIUM.

SOME FORCING FOR ASCENT AT 00Z SUNDAY OVER UPPER GREAT LAKES
SUPPORTED BY BROAD UPPER DIVERGENCE BETWEEN JET MAXES ASSOCIATED
WITH SHORT WAVES CROSSING SOUTHERN CANADA.

ECMWF...GFS...WRF-ARW AND GEMNH FOCUS HEAVIEST PCPN ACROSS NRN AND
NERN WISCONSIN CLOSER TO CVA WITH WESTERN WAVE AND BEST
FRONTOGENETIC RESPONSE ON NOSE OF STRONGER 850 MB WINDS REFLECTED IN
STRONGEST LAYER Q-VECTOR CONVERGENCE. THEY ALL HAVE LIGHTER QPF
AMOUNTS WITH WEAKER FORCING ALONG COLD FRONT/SFC TROUGH CROSSING THE
STATE LATE SATURDAY NIGHT INTO THE DAY SUNDAY. NAM TAKING AN MCS
THAT FORMS ON NOSE OF SECONDARY 850 MB WIND MAX IN S CENTRAL MN
ACROSS NE IOWA/SW WISCONSIN OVERNIGHT SATURDAY AND THEN DRY. ECMWF
IS CLOSER TO NAM WITH POSITION OF 850 MB BAROCLINIC ZONE AND HAS
ENOUGH CROSS-ISOTHERM FLOW TO SUPPORT AN POTENTIAL MCS INTO THE
FORECAST AREA SO LEFT HIGH CHANCE TO LIKELY POPS FOR SATURDAY NIGHT.

SURFACE FRONT THEN DROPS ACROSS REGION AT A DIURNALLY UNFAVORABLE
TIME. CONVERGENCE ALONG FRONT IS WEAK...AS IS SURFACE TO 850MB
FRONTOGENESIS. GFS SOUNDINGS MORE UNSTABLE AND FAVORABLE FOR
THUNDERSTORMS AHEAD OF FRONT BUT PREDICATED ON SURFACE DEW POINTS IN
THE UPPER 70S. WHILE THESE DEW POINTS APPEAR TO BE A BIT TOO
RICH...BELIEVE ENOUGH MOISTURE POOLING AND FORCING ALONG FRONT FOR
AT LEAST SCATTERED PRECIPITATION...SO WILL HAVE CHANCE POPS TO TRACK
ALONG WITH SFC FRONT/TROUGH. COLD AIR ADVECTION LAGS THE FRONT A
BIT...SO HIGH TEMPERATURES IN THE MID-UPPER 80S LOOK TO BE REACHED
BY EARLY AFTERNOON...THEN LEVEL OFF OR SLOWLY FALL WITH COOLER AIR
MOVING IN.

EXPECT ALL PRECIPITATION TO END BY LATE SUNDAY AFTERNOON WITH
SUBSIDENCE BEHIND TROUGH AND DRY NW UPPER FLOW AS RIDGING BUILDS
OVER THE PLAINS FOR MONDAY...WITH A SURFACE HIGH PASSING OVER THE
STATE. DEW POINTS DROP TO THE MID TO UPPER 50S BY SUNRISE
MONDAY...WITH A LITTLE INCREASE TO THE LOW 60S LATE MONDAY
AFTERNOON. LITTLE WIND AND 2C SUPER-ADIABATIC BUMP TO FORECASTED 925
MB TEMPERATURES BRINGS MID 80S TO THE WEST AND LOW 80S EAST...THOUGH
EXPECTED LAKE BREEZE TO COOL READINGS ALONG THE LAKE AFTER EARLY
AFTERNOON HIGHS.

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY. FORECAST CONFIDENCE LOW
TO MEDIUM.

MAIN QUESTION IS HOW FAST TO BRING THUNDERSTORM CHANCES BACK INTO
THE REGION. RETURN FLOW SETS UP MONDAY NIGHT AHEAD OF PLAINS
CYCLOGENESIS...BUT MAIN FOCUS OF LOW-LEVEL JET REMAINS TO THE WEST
MONDAY NIGHT AND TUESDAY. WILL HOLD OFF POPS UNTIL WEDNESDAY WHEN A
SERIES OF SHORT WAVES THEN DRAGS A SURFACE TROUGH AND 850 BAROCLINIC
ZONE WITH ASSOCIATED CONVERGENCE/LIFT OVER THE REGION THROUGH THE
REST OF THE EXTENDED. WILL HAVE HIGHER POPS ACROSS NRN CWA AS BETTER
FORCING SIGNALS FAVOR CENTRAL AND NORTHERN WISCONSIN UNTIL TROUGH
SAGS INTO SRN WISCONSIN LATER THURSDAY INTO FRIDAY. EXPECT BOUNDARY
TO SAG FAR ENOUGH SOUTH FOR A DRY SATURDAY NEXT WEEK. BEING ON WARM
SIDE OF BOUNDARY UNTIL THEN BRINGS MID TO UPPER 80S HIGHS WEDNESDAY
AND THURSDAY.

&&

.AVIATION...SCATTERED MID LEVEL CLOUDS ARE EXPECTED THROUGH THE
EVENING ACROSS TAF SITES. LIGHT ONSHORE WINDS AT THE EASTERN SITES
SHOULD LINGER THROUGH THE EVENING AS WELL...WITH LIGHT SOUTH WINDS
INLAND. THE LIGHT WINDS AND MOIST AIRMASS SHOULD LEAD TO SOME MVFR
VISIBILITIES LATER TONIGHT...LASTING INTO MID MORNING ON SATURDAY.

VFR CEILINGS ARE EXPECTED LATER TONIGHT AND SATURDAY...AS CHANCES
FOR SHOWERS AND THUNDERSTORMS INCREASE ACROSS THE AREA. STILL SOME
UNCERTAINTY WITH WHERE STORMS WILL FORM AND MOVE...SO JUST WENT WITH
VICINITY THUNDER WORDING IN TAFS LATE TONIGHT AND SATURDAY. MVFR/IFR
VISIBILITIES ARE POSSIBLE IN ANY STORMS.

&&

.MARINE...CONSIDERED ADDING PATCHY FOG TO NEARSHORE WATERS FOR
TONIGHT AND SATURDAY WITH LIGHT WINDS AND MOIST AIRMASS IN PLACE.
HOWEVER...WATER TEMPERATURES ON LAKE MICHIGAN IN THE LOWER
70S...SIMILAR TO THE EXPECTED DEW POINTS...SO NOT EXPECTING MUCH
DEVELOPMENT.

&&

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

SHORT/LONG TERM...09/REM
VERY SHORT TERM/AVIATION/MARINE...08/WOOD

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
400 PM CDT FRI JUL 22 2011

WIZ046-047-051-052-056>060-062>072-232100-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
400 PM CDT FRI JUL 22 2011

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

.DAY ONE...TONIGHT

THUNDERSTORMS ARE EXPECTED TO DEVELOP TO THE WEST OVER IOWA AND
MINNESOTA...AND MOVE SOUTHEAST ALONG A NEARLY STATIONARY BOUNDARY
INTO SOUTHERN WISCONSIN LATE TONIGHT INTO EARLY SATURDAY MORNING.

THERE IS A SLIGHT RISK FOR SEVERE STORMS...MAINLY WEST OF
MADISON...WITH DAMAGING WIND. HEAVY RAIN IS ALSO POSSIBLE WITH THE
THUNDERSTORMS...WITH 1 TO 2 INCH RAINFALL TOTALS OVER A SHORT PERIOD
OF TIME OVER ALL OF SOUTHERN WISCONSIN.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE CHANCE FOR THUNDERSTORMS WILL CONTINUE FROM TIME TO TIME
SATURDAY THROUGH SUNDAY AFTERNOON. THERE IS A SLIGHT RISK FOR SEVERE
THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS SATURDAY NIGHT INTO
SUNDAY...AS A LOW PRESSURE SYSTEM AND COLD FRONT MOVE THROUGH THE
AREA.

COOLER AND DRIER WEATHER RETURNS FOR MONDAY...BUT MORE STORMS ARE
EXPECTED FOR WEDNESDAY THROUGH THURSDAY...AS ANOTHER LOW PRESSURE
SYSTEM SLOWLY APPROACHES THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER TONIGHT...AND AGAIN SATURDAY
NIGHT INTO SUNDAY.

LMZ643>646-232100-
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-
400 PM CDT FRI JUL 22 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

THUNDERSTORMS ARE EXPECTED TO REACH LAKE MICHIGAN LATE TONIGHT INTO
EARLY SATURDAY MORNING. ANY STORMS SHOULD REMAIN BELOW SEVERE
LEVELS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE CHANCE FOR THUNDERSTORMS WILL CONTINUE FROM TIME TO TIME
SATURDAY THROUGH SUNDAY AFTERNOON. THERE IS A SLIGHT RISK FOR SEVERE
THUNDERSTORMS LATE SATURDAY NIGHT INTO SUNDAY...AS A LOW PRESSURE
SYSTEM AND COLD FRONT MOVE THROUGH THE AREA.

COOLER AND DRIER WEATHER RETURNS FOR MONDAY...BUT MORE STORMS ARE
EXPECTED FOR TUESDAY THROUGH THURSDAY...AS ANOTHER LOW PRESSURE
SYSTEM SLOWLY APPROACHES THE AREA.

CORRECTED TO REMOVE SEVERE WORDING OVER LAKE TONIGHT

REM/WOOD
WWW.WEATHER.GOV/MKX