Flash Flood Warning 29, NWS Chicago, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
703 PM CDT SAT SEP 13 2008

.DISCUSSION...
335 AM CDT

VERY ABBREVIATED DISCUSSION THIS AFTERNOON DUE TO MAJOR HYDRO
ISSUES.

LATEST SATLT LOOPS SHOW AREA OF HEAVIEST RAIN STARTINF TO EXIT NERN
IL.  HOWEVER...AFTER A BRIEF LULL THIS EVENING WHEN LIGHTER SHOWERS
ARE EXPECTED...MORE HEAVY RAIN IS EXPECTED TO DVLP A LTL SOUTH OF
CORRIDOR THAT EXPERIENCED EXCESSIVE RAINFALL OVERNIGHT AND EARLIER
TDY.  GFS AND EUROPEAN MDLS ARE IN GOOD AGREEMENT AND GFS HAS BEEN
RATHER CONSISTENT PAST 24 HRS WORTH OF RUNS.  GFS INCREASES STG
OMEGA BAND FROM AROUND QUINCY/ST. LOUIS AREA NEWD ALG I-55 CORRIDOR
BY 06Z AS LLVL MOISTURE CONVERGENCE INCRSS ALONG FRONTAL TROF MOVING
INTO MID/UPR MS VLY ATTM.  IR SATLT PICS DO INDEED SHOW A BAND OF
COOLING CLOUD TOPS ALONG THIS ZONE FROM MKC AREA NEWD TO NR PIA.
THIS LENDS CREDENCE TO GFS FCST.  WILL GO MAINLY WITH RAIN IN PCPN
FCST...BUT WILL HAVE ISOL THUNDER MENTION CNTRL/SRN PORTIONS OF FS
THIS EVENING AS AMS HAS BCM WEAKLY UNSTABLE DURG THIS AFTN.
HOWEVER...WILL GO WITH PLAIN RAIN LATE TNGT AND SUNDAY AS AMS
REMAINS VERY TROPICAL AND FREEZING LVLS ARE QUITE HIGH.

BY SUNDAY...REMNANTS OF HURCN IKE...NOW LOCATED NR TYLER,TX AND MOVG
NWD...ARE FCST TO ACCELERATE NEWD ACROSS CNTTRL IL AND NRN IN.  WENT
WITH GFS FCST TRACK BASED ON REASONABLY GOOD PAST PERFORMANCE. THIS
BRINGS THE CIRCULATION CENTER ABOUT OVER STL AT 15Z SUN...THEN TO
JUST E OF CMI BY 18Z AND OFF TO FWA BY 21Z.  EXCESSIVE RAINFALL
EXPECTED ALONG AND JUST TO LEFT OF THIS TRACK...WITH LESSER AMTS TO
N...TAPERING TO LESS THAN IN INCH ADDL NR WI STATE LINE.  RFD AREA
DID NOT RECEIVE EXCESSIVE RAINFALL TDY...AND WITH MAX QPF AXIS
SHIFTING SWD TNGT AND SUNDAY...HAVE DECIDED TO DROP OGLE...WINNEBAGO
AND BOONE CTYS FROM FFA.  WILL CONTINUE WATCH FOR RMNDR OF FA TIL
04Z MONDAY.

GOOD NEWS IS THAT FCST FROM MONDAY INTO NXT WEEKEND IS DRY AS LARGE
SFC HIGH BUILDS N OF GRTLKS AND KEEPS AREA IN DRY N-NELY FLOW THRU
MIDWEEK.  BY THURS...H5 FLOW IS STILL FCST TO FLATTEN OUT WITH MAIN
BELT OF WLYS SETTING UP ALG CANADIAN BORDER.  THIS SUGGETS DRY WX
WITH TEMPS GRADUALLY WARMING TO ABV SEASONAL NORMALS.

MERZLOCK

&&

.AVIATION...

703 PM CDT

FOR 00Z TAFS...VSBYS/CIGS DUE TO RA/BR CONTINUE TO BE FOCUS FOR
TAFS THIS PERIOD.

MOIST TROPICAL AIRMASS REMAINS ACROSS FORECAST AREA EARLY THIS
EVENING. GOES VAPOR IMAGERY INDICATES MINOR MID LEVEL SHORT WAVE
TROUGH MOVING FROM NORTHEASTERN MO INTO NORTHERN IL AT THIS
TIME...WITH REGIONAL WIND PROFILERS DEPICTING 50 KNOT SPEED MAX
WITH THIS FEATURE AROUND 700 MB. CURRENT RADAR MOSAIC INDICATING
AREA OF MODERATE/HEAVY RAIN ASSOCIATED WITH ENHANCED LIFT FROM
THIS FEATURE EXTENDING FROM NORTHEAST MO TO NORTHERN
IL...INCLUDING AREA OF THUNDERSTORMS ALONG KPIA...KPNT...KIKK/KJOT
AXIS. EXPECT THUNDERSTORMS/HEAVIEST RAIN TO REMAIN JUST SOUTH OF
TERMINAL LOCATIONS THIS EVENING WHERE RUC MESOANALYSIS DATA
INDICATES 500-1000 J/KG MLCAPE AXIS AS SHORT WAVE RIPPLES THROUGH.
CURRENT THINKING IS THAT THUNDER WILL REMAIN SOUTH OF KORD/KMDW
TERMINALS...THOUGH EXTRAPOLATION OF RADAR REFLECTIVITY IMAGERY
SUGGESTS KGYY WILL LIKELY BE CLIPPED BY THUNDER/HEAVIER RAIN.
OF COURSE...LIGHTER SCATTERED SHOWERS CONTINUE ACROSS REMAINDER
OF FORECAST AREA...WITH ASSOCIATED REDUCTIONS TO VISIBILITY AND
IFR CIGS IN OTHERWISE PREVAILING LOW MVFR CONDITIONS. WEAK SURFACE
LOW/FRONTAL BOUNDARY MOVING ACROSS THE MISSISSIPPI RIVER AND INTO
AREA AFTER MIDNIGHT TONIGHT TO SHIFT WINDS FROM CURRENT SOUTHWEST
TO WEST/NORTHWEST...WITH FRONT PUSHING SOUTHEAST OF TERMINALS BY
MORNING.

ATTENTION TURNS THEN TO FORMER HURRICANE IKE...NOW A MINIMAL
TROPICAL STORM CENTERED OVER NORTHEAST TX. THIS SYSTEM TO
ACCELERATE NORTHEASTWARD THROUGH OHIO VALLEY/EASTERN GREAT LAKES
NEXT 24 HOURS AS IT GETS INGESTED IN FASTER FLOW REGIME AHEAD OF
BROAD LARGER SCALE UPPER TROUGH OVER UPPER MIDWEST. INTERACTION OF
IKE REMNANTS AND FRONTAL/BAROCLINIC ZONE ACROSS THE REGION TO
RESULT IN ANOTHER SLUG OF HEAVIER RAIN LIFTING ACROSS FORECAST
AREA LATE TONIGHT/SUNDAY MORNING...AND IS EXPECTED TO RESULT IN
PREVAILING IFR CONDITIONS THROUGH SUNDAY MORNING. MAIN UPPER
TROUGH THEN MOVES ACROSS MIDWEST SUNDAY AFTERNOON/EVENING AS IKES
SURFACE LOW MOVES QUICKLY OFF TO THE EAST...WITH FORECAST
SOUNDINGS INDICATING TREND TOWARD MID/UPPER LEVEL DRYING ACROSS
TERMINALS DURING MID/LATE AFTERNOON HOURS. THIS SHOULD ALLOW
DECREASE IN RAIN/SHOWER COVERAGE AS THE AFTERNOON WEARS ON...WITH
ASSOCIATED IMPROVEMENT IN CIGS/VSBYS.

AS FOR WINDS...SPEEDS INCREASING A BIT WITH SOME GUSTS INTO UPPER
TEENS THIS EVENING AS PRESSURE FALLS INCREASE AHEAD OF APPROACHING
TROF/COLD FRONT. FRONT EXPECTED TO MOVE THROUGH TERMINALS AFTER
MIDNIGHT WITH SHIFT TO WEST/NORTHWEST. GRADIENT THEN INCREASES
MIDDAY SUNDAY AS IKES SURFACE PASSES SOUTH OF THE FORECAST AREA.
MOMENTUM TRANSFER FROM FORECAST SOUNDINGS INDICATE GUSTS
APPROACHING 20 KNOTS AGAIN BY MID/LATE AFTERNOON SUNDAY.

RATZER

&&

.MARINE...
230 PM CDT

SURFACE LOW PRESSURE ACROSS EASTERN IOWA WILL TRACK INTO NORTHERN
LOWER MICHIGAN THIS EVENING AND INTO SOUTHEAST ONTARIO BY MORNING.
A COLD FRONT TRAILING THIS LOW WILL TRACK ACROSS LAKE MICHIGAN
TONIGHT RESULTING IN WINDS SHIFTING TO THE NORTH TONIGHT. NORTH
WINDS WILL STRENGTHEN DURING THE DAY ON SUNDAY AS SFC LOW
ASSOCIATED WITH THE REMNANTS OF IKE MOVES INTO NORTH CENTRAL
INDIANA. HAVE SOME CONCERN ABOUT SOME WIND GUSTS APPROACHING GALE
FORCE DURING THE DAY SUNDAY INTO EARLY EVENING. HAVE MAINTAINED
IDEA OF 30 KNOT NORTH WINDS FOR TOMORROW INTO TOMORROW
EVENING...AND SMALL CRAFT ADVISORIES WILL BE NEEDED. WINDS WILL
SUBSIDE ON TUESDAY AS A RIDGE OF HIGH PRESSURE ACROSS NORTHERN
MISSOURI APPROACHES THE MID MS RIVER VALLEY. ANOTHER LOW PRESSURE
AREA WILL TRACK ACROSS JAMES BAY LATE MONDAY INTO TUESDAY WHICH
WILL RESULT IN STRENGTHENING SOUTHWEST WINDS ACROSS NORTH PART OF
LAKE MICHIGAN TUESDAY MORNING.

MARSILI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH...ILZ005-ILZ006-ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-
     ILZ019-ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039
     UNTIL 11 PM SUNDAY.

IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 11 PM
     SUNDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...1 PM SUNDAY TO 7 AM TUESDAY.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 PM CDT SAT SEP 13 2008

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
142100-
WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE-
DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-
IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON-
359 PM CDT SAT SEP 13 2008 /459 PM EDT SAT SEP 13 2008/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST INDIANA.

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

  PERIODS OF HEAVY RAIN WITH ISOLATED THUNDERSTORMS.

  HEAVY RAINFALL WILL RESULT IN AN EXPANSION OF AREAL FLOODING AS
  WELL AS RIVER FLOODING.

  AREAS AFFECTED AND TIMING:

  THE THREAT OF HEAVY RAINFALL AND FLOODING WILL EXIST ACROSS
  ALL BUT OGLE...WINNEBAGO AND BOONE COUNTIES THROUGH TONIGHT.

  DISCUSSION:

  WAVES OF MODERATE TO HEAVY RAINFALL AS WELL AS SCATTERED
  THUNDERSTORMS WILL CONTINUE THROUGH TONIGHT. ADDITIONAL HEAVY
  RAINFALL WILL ONLY AGGRAVATE AND EXPAND AREAL FLOODING AND
  RIVER FLOODING ALREADY OCCURRING ACROSS MUCH OF NORTHERN
  ILLINOIS AND NORTHWEST INDIANA.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

  MANY CREEKS AND RIVERS WILL REMAIN IN FLOOD INTO EARLY NEXT
  WEEK.

  THERE IS AN INCREASED RISK OF RIP CURRENTS ALONG THE ILLINOIS AND
  INDIANA SHORELINE AREAS SUNDAY NIGHT THROUGH MONDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT...
HOWEVER SPOTTERS ARE ENCOURAGED TO REPORT HEAVY RAINFALL TOTALS
TO THE NATIONAL WEATHER SERVICE CHICAGO.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ740>745-142100-
WINTHROP HARBOR TO WILMETTE HARBOR-
WILMETTE HARBOR TO NORTHERLY ISLAND-
NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY-
GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-
359 PM CDT SAT SEP 13 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE ILLINOIS
NEARSHORE WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE
WATERS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

STRONG WINDS AND HIGH WAVES WILL LEAD TO HAZARDOUS CONDITIONS FOR
SMALL CRAFT SUNDAY AND SUNDAY NIGHT IN BOTH ILLINOIS AND INDIANA
NEARSHORE WATERS.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-142100-
LAKE MICHIGAN FROM MICHIGAN CITY IN TO ST. JOSEPH MI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM SEUL CHOIX POINT TO ROCK ISLAND PASSAGE 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN SOUTH OF A LINE FROM SEUL CHOIX POINT TO THE
MACKINAC BRIDGE AND NORTH OF A LINE FROM CHARLEVOIX MI TO SOUTH
FOX ISLAND 5 NM OFFSHORE-
LAKE MICHIGAN FROM CHARLEVOIX TO POINT BETSIE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM POINT BETSIE TO MANISTEE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM ROCK ISLAND PASSAGE TO STURGEON BAY WI-
LAKE MICHIGAN FROM STURGEON BAY TO TWO RIVERS WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM TOW RIVERS TO SHEBOYGAN WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM SHEBOYGAN TO PORT WASHINGTON WI 5 NM OFFSHORE
TO MID LAKE-
LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM NORTH POINT LIGHT TO WIND POINT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WIND POINT WI TO WINTHROP HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WINTHROP HARBOR TO WILMETTE HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WILMETTE HARBOR IL TO MICHIGAN CITY IN 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM PENTWATER TO MANISTEE MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM WHITEHALL TO PENTWATER MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM GRAND HAVEN TO WHITEHALL MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM HOLLAND TO GRAND HAVEN MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM SOUTH HAVEN TO HOLLAND MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM ST. JOSEPH TO SOUTH HAVEN MI 5 NM OFFSHORE TO
MID LAKE-
359 PM CDT SAT SEP 13 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE OPEN WATERS
OF LAKE MICHIGAN.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

MERZLOCK

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