Flash Flood Warning 21, NWS Milwaukee, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
330 AM CDT MON SEP 27 2010

FORECAST FOCUS ON CLOUDS AND TEMPERATURES THROUGH THE WEEK.

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE
MEDIUM TO HIGH.

FROST ADVISORY WILL CONTINUE AS IS UNTIL 7 AM THIS MORNING...WITH
DECOUPLED WINDS AND CLEAR SKIES WITH CORE OF HIGH PRESSURE.
TEMPERATURES DROPPING INTO THE UPPER 30S ACROSS THE ADVISORY
AREA...AND SHOULD DIP INTO THE MID 30S BY SUNRISE. PATCHY FROST
EXPECTED ACROSS MOST OF THE REST OF THE AREA AWAY FROM THE LAKE.

AREA OF LAKE EFFECT CLOUDS WERE AFFECTING FAR SOUTHEAST MILWAUKEE
COUNTY...AS WELL AS FAR EASTERN RACINE AND KENOSHA COUNTIES. THE
CLOUDS WERE ASSOCIATED WITH CONVERGENCE FROM A THERMALLY INDUCED
LOW OVER SOUTHERN LAKE MICHIGAN...AND DELTA T VALUES AROUND 15
DEGREES CELSIUS. THESE CLOUDS WERE HANDLED FAIRLY WELL BY SHORT
TERM MODELS...AND SHOULD LINGER OVER THE FAR SOUTHEAST COUNTIES
THROUGH MID TO LATE MORNING BEFORE SCATTERING OUT. A FEW DIURNAL
CUMULUS MAY LINGER ACROSS THIS AREA DURING THE AFTERNOON.

MOSTLY SUNNY SKIES ARE EXPECTED ACROSS THE REST OF THE AREA...WITH
HIGH PRESSURE PASSING THROUGH. HIGHS MAINLY IN THE MID TO UPPER
60S ARE EXPECTED...WITH 925MB TEMPERATURES OF 12 TO 13 DEGREES
CELSIUS.

MODELS CONTINUE TO SHOW SHORTWAVE TROUGH AND ASSOCIATED VORTICITY
MAXIMUM SLIDING SOUTHEAST ACROSS THE AREA TONIGHT INTO TUESDAY.
LOW LEVEL MOISTURE INCREASES WITH THIS FEATURE...BUT MID TO
UPPER LEVELS REMAIN DRY. WILL BRING PARTLY CLOUDY SKIES THROUGH
WITH THIS FEATURE...BUT KEEP THE DRY FORECAST GOING.

WARM AIR ADVECTION ENSUES BY WEDNESDAY ACROSS THE AREA...WHICH
SHOULD BRING HIGHS INTO THE UPPER 60S TO LOWER 70S. MODELS BRING
ANOTHER SHORTWAVE TROUGH/VORTICITY MAXIMUM SOUTHEAST THROUGH THE
AREA LATE WEDNESDAY AND WEDNESDAY NIGHT. AGAIN...LOW LEVEL
MOISTURE INCREASES...BUT MID TO UPPER LEVELS REMAIN DRY. KEPT THE
DRY FORECAST GOING DURING THIS TIME.

.LONG TERM...THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM.

DRY FORECAST CONTINUES THROUGH THIS PERIOD...WITH MEDIUM RANGE
MODELS SHOWING A GRADUAL LONGWAVE TROUGH DEVELOPING ACROSS
NORTHEAST CANADA AND EXTENDING INTO THE GREAT LAKES REGION. THE
ECMWF IS MORE AGGRESSIVE WITH THE COLDER AIR INTRUSION INTO THE
AREA THAN THE GFS. IF MORE MOISTURE CAN BE FOUND WITH THIS
FEATURE...SOME POPS MAY BE NEEDED OVER THE UPCOMING WEEKEND.

&&

.AVIATION...WEAK WIND FLOW AND LARGE DELTA T/S ARE RESULTING IN
AN AREA OF THERMALLY INDUCED LOW PRESSURE/LOW LEVEL CONVERGENCE
OVER THE SOUTHERN 1/3 OF LAKE MICHIGAN...WHICH IN TURN IS
GENERATING A PERSISTENT LAYER OF LAKE EFFECT CLOUDS BASED AT
BETWEEN 4-4.5KFT. THIS SHOULD ONLY IMPACT THE TWO TAF SITES
CLOSEST TO THE LAKE...KMKE AND KENW THROUGH ABOUT 12-14Z. THEN VFR
THEREAFTER WITH A FEW SCT DIURNAL CU. OTHER CONCERN IS SOME LIGHT
FOG BEFORE SUNRISE AT KMSN AND KUES DUE TO THE CLEAR SKIES/COLD
TEMPS/CALM WIND.

&&

.MARINE...A WEAK LOW PRESSURE SYSTEM PASSING BY TONIGHT INTO
TUESDAY WILL CAUSE NORTH WINDS TO INCREASE OVER LAKE MICHIGAN.
WINDS AND WAVES WILL APPROACH SMALL CRAFT ADVISORY LEVELS TUESDAY
AFTERNOON INTO TUESDAY NIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...FROST ADVISORY UNTIL 7 AM CDT THIS MORNING FOR WIZ046-047-051-
     052-056>059.

LM...NONE.
&&

SHORT/LONG TERM...08/WOOD
AVIATION/MARINE...05/DAVIS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
319 AM CDT MON SEP 27 2010

WIZ046-047-051-052-056>060-062>072-280830-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
319 AM CDT MON SEP 27 2010

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

.DAY ONE...TODAY AND TONIGHT

A FROST ADVISORY REMAINS IN EFFECT THROUGH 7 AM FOR THE AREA ROUGHLY
NORTH OF A LINE STRETCHING FROM SHEBOYGAN TO WEST BEND TO SPRING
GREEN.

A FLASH FLOOD WARNING IS IN EFFECT FOR A SMALL AREA NEAR THE
WISCONSIN RIVER JUST SOUTH OF PORTAGE DUE TO A LEVEE FAILURE.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE IS THE POTENTIAL FOR FROST NEXT WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED IN THE NEXT SEVEN DAYS.

LMZ643>646-280830-
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-
319 AM CDT MON SEP 27 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

LOW PRESSURE PASSING BY TO THE EAST ON TUESDAY WILL CAUSE WINDS TO
INCREASE OUT OF THE NORTH...APPROACHING SMALL CRAFT ADVISORY
LEVELS WITH BUILDING WAVES.

DAVIS
WWW.WEATHER.GOV/MKX