Flash Flood Warning 12, NWS Milwaukee, WI

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
846 PM CDT SAT AUG 18 2007

.UPDATE...HAVE EXPANDED FLASH FLOOD WATCH TO INCLUDE COLUMBIA AND
DODGE COUNTIES. WILL CONTINUE FLASH FLOOD WATCH FOR COUNTIES THAT
WAS ISSUED EARLIER.

&&

.SHORT TERM...EXPANDED WATCH AS 1 INCH RAINFALL TOTALS HAVE
ALREADY OCCURRED OVER COLUMBIA AND DODGE COUNTIES. IN ADDITION A
SLOW EASTWARD PROGRESSION OF COLD CLOUD TOPS SHOWN IN IR
SATELLITE ASSOCIATED WITH BAND OF CONVECTION EXPECTED TO BRING
ADDITIONAL RAINFALL LATER TONIGHT TO THAT AREA AS WELL AS REMAINDER
OF FLASH FLOOD WATCH AREA. TREND OF BACK BUILDING OF CONVECTION
NOTED IN RADAR AND SATELLITE LOOPS LAST FEW HOURS WILL INSURE
WIDESPREAD PRECIPITATION FOR THE OVERNIGHT HOURS. CURRENT UPPER AIR
ANALYSIS SHOWS 30+ LOW LEVEL JET FEEDING FROM IOWA INTO SOUTHERN
WISCONSIN WHERE TIGHT BAROCLINIC ZONE REMAINS NEARLY STATIONARY.

&&

.PREV DISCUSSION... /ISSUED 335 PM CDT SAT AUG 18 2007/

DISCUSSION...FCST FOCUS IS ON HEAVY RAIN POTENTIAL TONIGHT INTO
SUNDAY AND WET AND UNSETTLED WEATHER INTO MID WEEK.

WARM AIR ADVECTION SHOWERS AND A FEW THUNDERSTORMS OVERSPREADING
STATE AS EXPECTED ON NOSE OF 30-35KT 850 MB WINDS RUNNING OVER TIGHT
BAROCLINIC ZONE...850 TEMPS +8C AT GRB WHILE +16C AT DVN ON 12Z
SOUNDINGS...AHEAD OF SHRT WAVE TROUGH LOCATED OVER S CNTRL MN/N
CNTRL IA AT 19Z. HEAVIEST PCPN HAS TRACKED WELL WITH STRONGEST
850-700MB FRONTOGENETIC FORCING. NAM CONTINUES TO BE AN OUTLIER WITH
PUSH OF SFC AND 850 MB WARM FRONTS FARTHER NORTH THAN CONSENSUS...SO
WILL FOLLOW THE GFS FOR DETAILS.

RGNL 88-D REFLECTIVITY RETURNS SHOW DISCRETE CONVECTIVE CELLS
FORMING CLOSER TO SFC WRM FRONT IN CNTRL IL AND ELEVATED CELLS
..PER RUC SNDG FOR DBQ...FROM SW WI BACK TWDS S CNTRL MN IN RGN OF
BETTER ISENTROPIC LIFT NOTED ON 305K SURFACE...AND STRONG 750-800 MB
FRONTOGENETIC FORCING. THIS POCKET OF BETTER ISENTROPIC LIFT AND
FORCING CROSSES SRN WI BETWEEN 06Z AND 12Z...WITH RGN UNDER THE
RIGHT ENTRANCE REGION OF 100-115KT 300 MB JET AIDING LARGE SCALE
LIFT. PRECIPITABLE WATER VALUES BETWEEN 2 INCHES AND 2.20
INCHES...AND PRECIP EFFICIENCIES OF 1.70 TO 2.0 ASSURING MAXIMUM
POTENTIAL ACCUMULATIONS.

STORM TOTAL QPF STILL TARGETS THE MORE SUSCEPTIBLE SRN COUNTIES OF
THE CWA SO WILL LEAVE THE GOING FLASH FLOOD WATCH AS IS. IF AXIS OF
MAX QPF DOES SHIFT A BIT FARTHER NORTH...NRN COUNTIES HAVE BEEN MUCH
DRIER AND 1-3-6 HRLY FLASH FLOOD GUIDANCE MOSAICS INDICATE THE NRN 2
TIERS OF COUNTIES WOULD NEED FAR MORE RAINFALL THAN IS FCST...2.75
TO 3.5 INCHES IN ONE HOUR...TO WARRANT ADDING TO THE WATCH. STILL
ALL OF CWA WILL HAVE TO BE MONITORED FOR THE POSSIBILITY OF
URBAN/LOWLAND LOCALIZED FLOODING IN ADDITION TO FLASH FLOOD
POTENTIAL IN THE SOUTH.

UPR JET MAX LINGERS OVER REGION THRU MONDAY...WITH 850 BAROCLINIC
ZONE DRAPED OVER CWA WITH PERSISTENT CROSS-ISOTHERM FLOW AND
FRONTOGENETIC FORCING...SO WILL LEAVE LIKELY WORDING IN FOR SUNDAY.
SFC BNDRY REMAINS ACROSS NRN IL/SRN WI WITH MODELS INDICATING A
SERIES OF COMPLEXES MOVING ALONG BNDRY.

GENERALLY FOLLOWED MAV GUIDANCE FOR TEMPS...THOUGH TEMPERED TUESDAY
MAXES A BIT.

EXTENDED...SOME VARIABILITY WITH TIMING AND STRENGTH OF SHRT WAVES
IN ZONAL FLOW OVER THE NRN U.S. AND SFC BOUNDARY THAT WILL OSSCILATE
OVER THE WRN GREAT LAKES THRU THE PERIOD. APPEARS ENOUGH AGREEMENT
AMONG MODELS WITH COLD FRONT SAGGING THRU WI WED AND STALLING NEAR
THE NRN IL/WI BORDER WITH WEAK WAVES RUNNING THE BOUNDARY THRU FRI.
GFS MAY BE HAVING SOME CONVECTIVE FEEDBACK ISSUES WITH COMPACT
VIGOROUS VORTICITY MAXIMAS AND ASSOCIATED QPF AMOUNTS...BUT PATTERN
SUGGESTS CWA IS IN REGION DOWNSTREAM FROM NOCTURNAL MCS/S DEVELOPING
JUST TO OUR WEST ON PERIPHERY OF 500 MB HIGH OVER THE SE U.S. AND
MOVING EWD ALONG BOUNDARY. WITH POTENTIAL FOR THESE COMPLEXES AND
EVEN WEAK MCV/S CROSSING CWA WILL HAVE TO KEEP POPS IN FCST EACH
DAY...THO NO ALL DAY RAIN OUTS. GENERALLY ACCEPTED HPC/MEXMOS FOR
TEMPERATURES THOUGH BACKED OFF ON WED HI/S DUE TO EXPECTED PCPN AND
CLOUDS ALONG FRONT WHICH CONSENSUS FCSTS HAVE MOVING THRU CWA BY
LATE MORNING/EARLY AFTERNOON.

AVIATION...XPCT WDSPRD MVFR CONDS IN -RA/-TSRA/BR THRU 00Z MON.
AREAS OF IFR CIGS/VSBYS EXPCTD IN PDS OF HVY RA/TSRA INTO 18Z MON.
STNRY FNT ACRS IA AND NRN IL THRU PD WITH MSTR LIFTING OVR FNT INTO
SRN WI.

MKX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WIZ056-062-063-067>069.

FLASH FLOOD WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR
WIZ064>066-070>072.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 6 AM CDT SUNDAY FOR WIZ056-057-062-063-
067>069.

FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR WIZ058-064>066-
070>072.

&&

TZ

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
855 PM CDT SAT AUG 18 2007

WIZ046-047-051-052-056>060-062>072-191000-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
855 PM CDT SAT AUG 18 2007

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

.DAY ONE...TONIGHT

PERIODS OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TONIGHT. HEAVY
RAIN IS POSSIBLE...WITH POTENTIAL RAINFALL RATES BETWEEN 1 AND 2
INCHES PER HOUR. THERE IS A POTENTIAL FOR FLASH FLOODING TONIGHT
SOUTH OF A LINE FROM LAKE DELTON TO BEAVER DAM TO BAYSIDE IN
MILWAUKEE COUNTY DUE TO HEAVY RAINS ON TOP OF SATURATED GROUND. THE
MOST FLOOD PRONE AREAS WILL BE WHERE THE TERRAIN IS HILLY OR
BUILT-UP URBAN LOCATIONS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS ARE LIKELY SUNDAY THROUGH MONDAY. HEAVY RAIN IS
POSSIBLE SUNDAY MORNING. FLASH FLOODING IS POSSIBLE SUNDAY MORNING
OVER THE SOUTHEASTERN COUNTIES. THERE IS A CHANCE OF THUNDERSTORMS
TUESDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED...BUT RAINFALL REPORTS WOULD
BE APPRECIATED.

LMZ643>646-665-191000-
SHEBOYGAN TO PORT WASHINGTON-
PORT WASHINGTON TO NORTH POINT LIGHTHOUSE-
NORTH POINT LIGHTHOUSE TO WIND POINT-
WIND POINT TO WINTHROP HARBOR ILLINOIS-
WISCONSIN ADJACENT OPEN WATERS OF LAKE MICHIGAN TO MID LAKE-
855 PM CDT SAT AUG 18 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

PERIODS OF THUNDERSTORMS ARE EXPECTED TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS ARE LIKELY SUNDAY THROUGH MONDAY. THERE IS A CHANCE OF
THUNDERSTORMS TUESDAY THROUGH SUNDAY.

TZ
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