Flash Flood Warning 2, NWS Chicago, IL

244 
WGUS73 KLOT 171842
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
142 PM CDT WED APR 17 2013

ILC037-103-141-172300-
/O.CON.KLOT.FF.W.0002.000000T0000Z-130417T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
OGLE IL-DE KALB IL-LEE IL-
142 PM CDT WED APR 17 2013

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR LEE...DE KALB AND OGLE
COUNTIES UNTIL 600 PM CDT...

AT 137 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
ANOTHER BATCH OF THUNDERSTORMS...SOME PRODUCING VERY HEAVY 
RAINFALL...MOVING INTO THE WARNING AREA. DOPPLER RADAR ESTIMATES 
THROUGH 130 PM INDICATE THAT ONE TO THREE INCHES OF RAIN HAS ALREADY 
FALLEN OVER OGLE...NORTHERN AND WESTERN LEE...AND FAR NORTHWEST 
DEKALB COUNTY. 

THIS NEXT BATCH OF THUNDERSTORMS WILL LIKELY PRODUCE AN ADDITIONAL 
ONE TO THREE INCHES OF RAIN THIS AFTERNOON...WITH LOCALIZED RAINFALL 
TOTALS FOR TODAY OVER 4 INCHES POSSIBLE BY EARLY THIS EVENING.  

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLOODING OF SMALL CREEKS
AND STREAMS...COUNTRY ROADS...NORMALLY DRY WASHES... AS WELL AS
FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS.

&&

LAT...LON 4220 8969 4220 8917 4215 8917 4215 8859
      4163 8861 4163 8917 4158 8917 4159 8964
      4192 8963 4193 8969

$$

606 
WGUS73 KLOT 172006
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
306 PM CDT WED APR 17 2013

ILC037-103-141-172300-
/O.CON.KLOT.FF.W.0002.000000T0000Z-130417T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
OGLE IL-DE KALB IL-LEE IL-
306 PM CDT WED APR 17 2013

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR LEE...DE KALB AND OGLE
COUNTIES UNTIL 600 PM CDT...

AT 303 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
ADDITIONAL SHOWERS AND THUNDERSTORMS MOVING ACROSS THE WARNED AREA. 
DOPPLER RADAR INDICATES THAT ONE TO THREE INCHES OF RAIN HAS FALLEN 
ACROSS MUCH OF THE WARNING AREA...ESPECIALLY LEE AND OGLE COUNTIES. 
AN ADDITIONAL HALF INCH TO INCH OF RAIN COULD FALL BY EARLY THIS 
EVENING. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLOODING OF SMALL CREEKS
AND STREAMS...COUNTRY ROADS...NORMALLY DRY WASHES... AS WELL AS
FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS.

&&

LAT...LON 4220 8969 4220 8917 4215 8917 4215 8859
      4163 8861 4163 8917 4158 8917 4159 8964
      4192 8963 4193 8969

$$

905 
WGUS73 KLOT 172203
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
503 PM CDT WED APR 17 2013

ILC037-103-141-172300-
/O.CON.KLOT.FF.W.0002.000000T0000Z-130417T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
OGLE IL-DE KALB IL-LEE IL-
503 PM CDT WED APR 17 2013

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR LEE...DE KALB AND OGLE
COUNTIES UNTIL 600 PM CDT...

AT 456 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
SHOWERS AND THUNDERSTORMS LINGERING ACROSS THE WARNED AREA. DOPPLER 
RADAR INDICATES THAT ONE TO LOCALLY OVER THREE INCHES OF RAIN HAS 
FALLEN ACROSS THE WARNED AREA. SOME ADDITIONAL RAINFALL OF UP TO A 
HALF INCH IS POSSIBLE EARLY THIS EVENING...WITH MORE HEAVY RAINFALL 
POSSIBLE LATER THIS EVENING INTO THE OVERNIGHT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLOODING OF SMALL CREEKS
AND STREAMS...COUNTRY ROADS...NORMALLY DRY WASHES... AS WELL AS
FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS.

&&

LAT...LON 4220 8969 4220 8917 4215 8917 4215 8859
      4163 8861 4163 8917 4158 8917 4159 8964
      4192 8963 4193 8969

$$


IZZI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1123 AM CDT WED APR 17 2013

.MESOSCALE DISCUSSION...
1118 AM CDT

STILL EXPECTING MAINLY ELEVATED HAILERS INTO THE EARLY
AFTERNOON...BUT POTENTIAL EXISTS FOR MORE ORGANIZED ACTIVITY
MOVING OUT OF IOWA...PLUS ONGOING THREAT OF FLASH FLOODING.

WATCHING THE EVOLUTION OF STORMS THIS MORNING AND NOT SEEING
ANYTHING BECOMING TOO ORGANIZED JUST YET. THE CLUSTER OVER LEE AND
OGLE COUNTIES AROUND 1030 AM CDT WAS SHOWING 50 DBZ UP TO AROUND
29 KFT BUT 60 DBZ ONLY TO 18-19 KFT. AS OF THIS UPDATE...SO FAR WE
HAVE ONLY RECEIVED PEA SIZED HAIL REPORTS FROM THAT AREA. BASED ON
SOUNDINGS AND HAIL NOMOGRAMS THE 50 DBZ TO 28 KFT SHOULD BE
CAPABLE OF SEVERE HAIL...BUT WE MAY NEED TO SEE 60 DBZ TO AROUND
22 KFT AS WELL. THE STORMS THAT MOVED OUT OF SOUTHEAST HENRY
COUNTY SHOW THERE IS THAT POTENTIAL THIS MORNING...ESPECIALLY
FARTHER SOUTH NEAR THE BETTER MUCAPE VALUES OF 500-1000 J/KG.

BEING WELL NORTH OF THE WARM FRONT...ACARS DATA FROM ORD STILL
SHOW A DEEP INVERSION TO AT LEAST 850 MB WITH EAST WINDS CUTTING
UNDER THE CLUSTERS OF STORMS. ONLY TOWARD SOUTHEASTERN IOWA HAVE
WEST TO NORTHWEST WINDS BEEN ABLE TO WORK DOWN THROUGH THE STABLE
LAYER. IT IS HARD TO TELL WHERE THE WARM FRONT IS LOCATED
EXACTLY...BUT THE BEST SFC MOISTURE AND SOUTHERLY WINDS ARE STILL
FAR SOUTH OF THE AREA...TOWARD SOUTHERN ILLINOIS.

IT APPEARS THAT THE MCS OVER IOWA IS BECOMING BETTER ORGANIZED
WITH STRENGTHENING COLD...IF THIS TREND CONTINUES THEN A LINE OF
STORMS COULD BEGIN TO POSE MORE OF A WIND THREAT ACROSS NORTHERN
ILLINOIS LATER THIS AFTERNOON...IN ADDITION TO HAIL. THE REMNANT
OF THIS ACTIVITY THIS AFTERNOON AND EVENING COULD ALSO POTENTIALLY
ENHANCE THE ADVANCING WARM FRONT BUT ALSO SLOW IT DOWN...WHICH
WOULD LIMIT THE SFC BASED ACTIVITY TO SOUTHERN PORTIONS OF THE
AREA AT BEST.

WILL NEED TO MONITOR FOR THE POTENTIAL FOR ADDITIONAL
THUNDERSTORMS TO DEVELOP IN THE PSEUDO EAST-WEST WAA BAND TO THE
EAST OF THE MCS...SHOULD THIS ACTIVITY FILL IN THEN THE POTENTIAL
FOR FLASH FLOODING COULD INCREASE LATER THIS AFTERNOON FROM I-88
NORTHWARD.

LENNING/IZZI

&&

.DISCUSSION...
338 AM CDT

TODAY THROUGH TONIGHT...
IR IMAGERY EARLY THIS MORNING SHOWS A DEVELOPING RIBBON OF CLOUDS
ALONG A LLVL BOUNDARY STRETCHING FROM CENTRAL NEBRASKA EAST THROUGH
CENTRAL IL INTO SOUTHCENTRAL IN. CLOUD TOPS HAVE BEEN RAPIDLY
COOLING...AS IT APPEARS THE ATMOSPHERIC RIVER IS BEGINNING TO
DEVELOP FROM THE CENTRAL PLAINS STRETCHING NORTHEAST THROUGH THE
WESTERN GREAT LAKES. SOUTH OF THIS BOUNDARY TEMPS ARE MAINLY IN THE
UPR 40S WITH DEW POINTS IN THE MID 40S. TO THE NORTH...WHICH
INCLUDES MUCH OF THE CWFA...TEMPS HAVE ONLY COOLED INTO THE LOW 40S
WITH DEW POINTS SLIGHTLY DRIER IN THE LOW/MID 30S. REGIONAL RADAR
MOSAIC WAS ALSO INDICATING SPOTTY SHOWERS/THUNDERSTORMS BEGINNING TO
BLOSSOM ALONG THIS BOUNDARY. A COUPLE AREAS OF STRONGER JETS WERE
NOTED ACROSS THE FRONT-RANGE OF THE ROCKIES...WITH THE MORE POTENT
SPEED MAX ALONG THE TROUGH AXIS SOUTH OF THE FOUR-CORNERS REGION OF
THE CONUS. WITH ANTI-CYCLONIC FLOW POSITIONED NORTH OF THE
CWFA...THE EASTERLY WIND COMPONENT HAS BEEN ABLE TO KEEP A BULK OF
THE PRECIP SOUTH OF THE CWFA OVERNIGHT. ALTHOUGH THIS FEATURE WAS
SLIDING NORTHEAST INTO QUEBEC EARLY THIS MORNING.

AS THE ELEVATED FRONTAL BOUNDARY STEADILY ADVECTS NORTH...PRECIP
CHANCES WILL STEADILY INCREASE FROM SOUTHWEST TO NORTHEAST. HI-RES
LCL ARW INDICATES PRECIP WILL PUSH INTO WESTERN IL ARND 12Z OR
SHORTLY AFT DAYBREAK. THIS MATCHES UP RELATIVELY WELL WITH THE
SHRA/TSRA THAT IS LIFTING NORTHEAST CURRENTLY ACROSS SOUTHWEST IA.

THE CONVECTION THAT IS DEVELOPING OVER THE CENTRAL PLAINS IS IN A
FAVORABLE REGION FOR FURTHER GROWTH...WITH MODERATE MID/LOW LEVEL
MOISTURE CONVERGENCE. AS THE BOUNDARY LIFTS NORTH...PWAT VALUES WILL
STEADILY INCREASE. GUIDANCE HAS CONTINUED TO SUGGEST PRECIPITABLE
VALUES AROUND 1" BY MID-MORNING. THE LARGEST CHALLENGE WILL BE ON
HOW FAR NORTH THE BOUNDARY CAN LIFT THIS AFTN...AS GUIDANCE
CONTINUES TO INDICATE THE I-80 CORRIDOR. IT APPEARS A COMPLEX OF
SHRA/TSRA WILL LIFT NE ACROSS CENTRAL IA INTO WESTERN IL/SOUTHERN
WISC THIS AFTN. BULK SHEAR VALUES RAMP-UP THROUGHOUT THE
AFTN/EVE...WITH GUIDANCE SUGGESTING THE 0-3KM VALUES TO HOVER ARND
40KTS FROM THE SOUTH. THE LARGEST CONCERN FOR TODAY AND ANY STRONG
STORMS THAT DEVELOP WILL BE ON THE POTENTIAL FOR ROTATING
UPDRAFTS...GIVEN THE BACKED WINDS NORTH OF THE BOUNDARY AND HELICITY
VALUES PROGGED IN THE REGION OF THE BOUNDARY.

AS NOTED ABOVE...PWAT VALUES WILL BE ON THE INCREASE. WITH
ADDITIONAL MOISTURE POOLING INTO THE CWFA AND CONTINUES TO ADVECT
NORTH FROM THE WESTERN GULF OVERNIGHT...SOME OF THE THUNDERSTORMS
COULD EASILY PRODUCE HEAVY DOWNPOURS. IN ADDITION PWAT VALUES MAY
TOUCH 1.5-1.75" IN A FEW PORTIONS OF IA/IL OVERNIGHT...WITH
THUNDERSTORMS PERSISTING ALONG THE MOIST BOUNDARY. BASED ON THIS
HAVE MAINTAINED THE FLOOD WATCH AS WELL AS THE MENTION OF HEAVY RAIN
WITHIN THE FORECAST.

GUIDANCE OVERNIGHT INDICATES THE WARM/MOIST BOUNDARY WILL LIFT
OVERHEAD INTO SOUTHERN WISC...PLACING THE ENTIRE CWFA WITHIN THE
WARM SECTOR. THIS WILL PROVIDE A MILD OVERNIGHT...WITH DEW PTS
HOVERING THE LOW 50S. GUIDANCE IS BEGINNING TO INDICATE A LULL IN
THE CONVECTIVE CHANCES OVERNIGHT...MAINLY IN THE 06-12Z THUR WINDOW.
HAVE REFLECTED THIS IN THE FORECAST WITH SLIGHTLY LOWER POPS.

CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN PRECIPITATION/HEAVY RAIN...HIGH.

THURSDAY...POSITIVE TILTED DEEP TROUGH CONTINUES TO SLOWLY PUSH EAST
OF THE ROCKIES. WARM/MOIST ENVIRONMENT IS POISED TO CONTINUE THRU
THUR...WITH THE GREATEST FOCUS BEING ON POTENTIAL FOR SEVERE
WEATHER. 850MB THERMAL RIDGE OF 13-15 DEG C WITH SFC TEMPS WARMING
WELL INTO THE UPR 60S TO LOW 70S AHEAD OF THE COLD FRONTAL PASSAGE.
SFC LOW HAS SLOWED IN THE ARRIVAL WITH LATEST GUIDANCE...AND
INDICATING SOME STRENGTHENING PRIOR TO ARRIVAL. THE DYNAMICS REMAIN
VERY IMPRESSIVE...WITH EFFECTIVE SHEAR PROGGED TO BE ARND 50KTS. LCL
WRF-ARW IS INDICATING LLVL FLOW MAY BEGIN TO BACK JUST AHEAD OF THE
SHORTWAVE THUR. WHICH MAY PROVIDE SOME ENHANCEMENT TO THE HELICITY
AND POTENTIAL OF ROTATING UPDRAFTS AND AN ISOLATED TORNADO. AT THIS
TIME THE THINKING IS THAT AS HEATING OCCURS AND THE BOUNDARY
APPROACHES FROM THE WEST...CONVECTION WILL QUICKLY DEVELOP AND PUSH
EAST. AT THE ONSET A FEW ISOLATED STRONG STORMS WILL MOST LIKELY
EVOLVE INTO A LINEAR SEGMENT. GIVEN THE SHEAR PROGGED FOR
THUR...THESE STORMS COULD EASILY TAKE ON A BOW-LIKE FEATURE AS THEY
PUSH EAST.

HEAVY RAINFALL REMAINS POSSIBLE AGAIN THUR WITH THE CONVECTION THAT
IS EXPECTED...AND HAVE MAINTAINED MENTION OF THIS WITHIN THE
FORECAST. GUIDANCE CONTINUES TO SUGGEST PRECIP TOTALS WED/THUR IN
EXCESS OF 3" FOR PORTIONS OF NORTHERN IL.

CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN PRECIPITATION/HEAVY RAIN...MEDIUM.

FRIDAY THROUGH TUESDAY...
EXTENDED PERIODS THROUGH SUN CONTINUE TO DEPICT MINIMAL SPREAD
AMONGST ENSEMBLE MEMBERS...WITH GROWING DIVERGENCE FOR EARLY NEXT
WEEK. THE 500MB TROUGH AXIS WILL ARRIVE FRI ACROSS THE GREAT
LAKES/OHIO VALLEY...HOWEVER IT DOES APPEAR THAT THE TROUGH WILL
BEGIN TO SLOW IN ANY FORWARD PROGRESSION. A DOWNSTREAM
RIDGE...PLACED ACROSS THE WESTERN ATLANTIC...WILL SLOW THE
PROGRESSION OF THE TROUGH. THIS DOWNSTREAM RIDGE HAS SHOWN SOME
STRENGTHENING OVER THE PAST COUPLE OF DAYS...INDICATING THAT THE
COOLER AIR EXPECTED TO PUSH OVER THE CWFA LATER THIS WEEK/EARLY
WEEKEND MAY LINGER. WELL UPSTREAM ACROSS THE PAC-NW IS ANOTHER HIGH
AMPLITUDE RIDGE THAT DOESN'T APPEAR TO MAKE ANY PUSH EAST OVER THE
BULK OF THE EXTENDED. WITH THE PLACEMENT OF THE TWO MID-LVL
RIDGES...THIS SETUP SUGGESTS THAT THE EXTENDED PERIODS MAY CONTINUE
TO SEE UNSEASONABLY COOL WEATHER FOR THE CWFA. THE CAVEAT COULD BE
THE ANTI-CYCLONIC FLOW THAT WILL ARRIVE FRI NGT/SAT BEGINS TO DRIFT
EAST SUN. THIS MAY ALLOW A BRIEF SOUTHERLY FLOW AND ADVECT WARMER
AIR BACK INTO THE REGION SUN/MON. HOWEVER...IT DOES APPEAR PRECIP
CHANCES RETURN IN THIS SAME TIMEFRAME.

CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN PRECIPITATION...MEDIUM.

BEACHLER

&&

.HYDROLOGY...
350 PM CDT

WITH SEVERAL AREA RIVERS ALREADY NEAR OR ABOVE FLOOD STAGE...CONCERN
IS INCREASING FOR SIGNIFICANT ADDITIONAL RIVER RISES MID TO LATE
WEEK. PERIOD SHOWERS AND THUNDERSTORMS BEGINNING OVER THE
SOUTHERN PORTIONS OF THE CWA LATE TONIGHT WILL BRING SOME
RAINFALL... AGGRAVATING THE SITUATION AS IN ADDITION TO THE AREA
RIVERS THAT ARE ALREADY AT OR NEAR FLOOD FLOOD STAGE...THERE HAVE
BEEN REPORTS OF MANY DRAINAGE PONDS AND SMALLER STREAMS AT
CAPACITY. WHILE THE INITIAL THUNDERSTORM ACTIVITY EXPECTED THROUGH
THE DAY TOMORROW WILL BRING SOME LOCALLY HEAVY RAINFALL...THE
PRIMARY FLOODING CONCERN WILL INCREASE THROUGH WEDNESDAY NIGHT
WITH HEAVY RAIN LIKELY TO PERSIST INTO FRIDAY MORNING.

WITH THE DEEP UPPER TROUGH AND DEVELOPING LOW PRESSURE SYSTEM OVER
THE PLAINS...COPIOUS AMOUNTS OF GULF MOISTURE WILL STREAM
NORTHWARD INTO THE MIDWEST. FORECAST PRECIPITABLE WATER VALUES
ARE EXPECTED TO BE VERY HIGH...IN EXCESS OF 1.5 INCHES...WHICH IS
2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL BY WEDNESDAY AND MAY GET
CLOSE TO 2 INCHES BY THURSDAY...WHICH WOULD BE 3 TO 4 STANDARD
DEVIATIONS ABOVE NORMAL. IN OTHER WORDS...THE POTENTIAL FOR
HEAVY/EXCESSIVE RAINFALL IS HIGH. THE LATEST FORECAST UPDATE IS FOR
NEARLY 4 INCHES OF STORM TOTAL PCPN...WHICH INCLUDES THE INITIAL
CONVECTIVE ACTIVITY EARLY WEDNESDAY...THROUGH THE PERIOD OF
GREATEST HEAVY RAIN POTENTIAL ON THURSDAY AND THE WRAPAROUND
LIGHTER PCPN FOLLOWING THE FROPA ON FRIDAY.

CONFIDENCE IS INCREASING FOR A HEAVY PRECIPITATION EVENT FOR
NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE POTENTIAL EXISTS FOR
UP TO 4 INCHES OF RAINFALL WEDNESDAY INTO FRIDAY...WHICH WOULD SEND
RIVERS NEAR OR ABOVE FLOOD STAGE MODERATE OR MAJOR FLOOD
LEVEL...WHILE RIVERS CURRENTLY WELL BELOW FLOOD OR BANK FULL STAGE
LIKELY REACH OR EXCEED FLOOD STAGE. ALSO...WIDESPREAD HEAVY
RAINFALL MAY LEAD TO URBAN FLOODING ISSUES FOR VIADUCTS AND LOW.
ALSO...STORM DRAINS AND DRAINAGE DITCHES AND PONDS MAY NOT HAVE
THE CAPACITY TO HANDLE SOME PERIODS OF THE HEAVIEST RAINFALL...
LEADING TO FURTHER FLOODING ISSUES FOR ROADWAYS AND SUBURBAN AREAS
AS WELL.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* SHOWERS AND THUNDERSTORMS MOVING THROUGH THE AREA THIS MORNING.
* THUNDERSTORMS REDEVELOPING MID AFTERNOON AND CONTINUING INTO
  TONIGHT.
* GUSTY EASTERLY WINDS TODAY SHIFTING TO SOUTHERLY TONIGHT.
* CEILINGS LOWERING THROUGH THE DAY. IFR LIKELY LATE THIS EVENING.

PAW

//DISCUSSION...UPDATED 12Z...

SCATTERED SHOWERS AND SOME THUNDERSTORMS CONTINUE TO DEVELOP WITHIN
A STRENGTHENING WARM AIR ADVECTION REGIME ACROSS PORTIONS OF
NORTHERN ILLINOIS THIS MORNING. THE MORE WIDESPREAD ACTIVITY HAS
REMAINED FARTHER WEST ACROSS IOWA AND FAR NORTHWESTERN ILLINOIS
CLOSER TO THE BEST MOISTURE CONVERGENCE ALONG THE NOSE OF A 40 KT
LOW LEVEL JET. THIS ACTIVITY WILL BEGIN TO AFFECT THE RFD AREA
BETWEEN 12 AND 13 UTC THIS MORNING. IT APPEARS MORE WIDELY SCATTERED
SHOWERS AND A FEW THUNDERSTORMS LOOK TO AFFECT THE EASTERN TERMINALS
THROUGH THIS MORNING AFTER 13 UTC.

ADDITIONAL CONVECTIVE ACTIVITY STILL LOOKS TO BE A DECENT BET THIS
AFTERNOON AS WELL...AS THE ACTIVITY CURRENTLY ACROSS EASTERN NEBRASKA
...KANSAS AND NORTHWESTERN MISSOURI LIFTS EAST-NORTHEASTWARD ALONG
THE 850 MB WARM FRONT THROUGH THE DAY. THE OVERALL TIMING APPEARS TO
BE BY MID TO LATE AFTERNOON. HOWEVER...CONFIDENCE ON THE EXACT
TIMING IS FAIRLY LOW AT THIS TIME.

ONCE THIS INITIAL COMPLEX OF ACTIVITY MOVES ACROSS THE AREA THIS
AFTERNOON AND EARLY THIS EVENING...THERE COULD BE A TEMPORALLY LULL
IN THE CONVECTIVE ACTIVITY. HOWEVER...SOME LOWER VISIBILITIES MAY
REMAIN IN PLACE INTO THE EVENING WITH VERY LOW CLOUDS AND FOG AHEAD
OF THE APPROACHING SURFACE WARM FRONT. WINDS WILL REMAIN EASTERLY
THROUGH EARLY THIS EVENING...AND COULD BECOME A BIT GUSTY.
HOWEVER...LATER THIS EVENING AND OVERNIGHT THE SURFACE WARM FRONT
SHOULD SURGE NORTHWARD ACROSS THE AREA. SOME STRONGER SOUTHERLY
WINDS WILL SET UP LATE TONIGHT AND INTO THURSDAY.

THE NEXT SHOT AT MORE WIDESPREAD CONVECTIVE ACTIVITY LOOKS TO BE
THURSDAY MORNING. THIS SECOND BATCH OF THUNDERSTORMS WILL LIKELY
CONTAIN VERY HEAVY RAINFALL WITH LOW VIS AND CIGS...AND THIS
ACTIVITY WILL EXTEND BEYOND THE CURRENT 30 HOUR ORD TAF PERIOD INTO
THURSDAY AFTERNOON. SOME STRONG STORMS ARE ALSO POSSIBLE ACROSS THE
AREA.

I HAVE ALSO ADDED SOME LOW LEVEL WIND SHEAR TO THE TAFS FOR THIS
EVENING AND INTO THE OVERNIGHT. A STRONG 50 KT LOW LEVEL JET IS
EXPECTED TO DEVELOP AROUND 2000 FEET AGL AND UNTIL SURFACE WINDS
BEGIN TO GUST IN THE WAKE OF THE WARM FRONT...IT APPEARS THAT LOW
LEVEL WIND SHEER WILL BE FAIRLY HIGH.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE IN SHOWER AND THUNDERSTORM DETAILS
  THIS MORNING.
* MEDIUM CONFIDENCE IN TIMING OF THUNDERSTORMS THIS AFTERNOON.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN CEILING TREND AND DETAILS.

PAW

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...TSRA LIKELY MAINLY IN THE EVENING. PERIODS OF IFR.

FRIDAY...CHANCE SHRA. PERIODS OF MVFR.

SATURDAY...VFR.

SUNDAY...VFR.

MONDAY AND TUESDAY...VFR. CHANCE SHRA.

KJB

&&

.MARINE...
318 AM CDT

A STRONG STORM SYSTEM WILL TAKE SHAPE ACROSS THE CENTRAL AND
SOUTHERN PLAINS TODAY. EASTERLY WINDS ARE EXPECTED TO SLOWLY
INCREASE IN INTENSITY TODAY AND TONIGHT AS THE LOW CONTINUES TO
STRENGTHEN. EASTERLY WINDS UP AROUND 20 TO 25 KT ARE EXPECTED...AND
THIS WILL RESULT IN SOME HIGHER WAVES OF 3 TO 5 FT INTO THE
NORTHEASTERN ILLINOIS NEAR SHORE WATERS TODAY AND TONIGHT. I WILL
HOLD OFF ON A SMALL CRAFT ADVISORY...BUT CONDITIONS WILL BE CLOSE.

A SURFACE WAVE AND WARM FRONT WILL SURGE NORTHWARD ACROSS THE
SOUTHERN HALF OF THE LAKE LATER TONIGHT AND INTO THURSDAY. THIS
FRONT WILL MARK THE DIVIDING LINE BETWEEN EAST NORTHEASTERLY WINDS
ACROSS THE NORTH END OF THE LAKE...TO SOUTHERLY WINDS SOUTH DURING
THE DAY ON THURSDAY. STRONG SOUTHERLY WINDS LOOK TO DEVELOP SOUTH OF
THE WARM FRONT. SOUTHERLY WINDS OF 30 KT...WITH SOME GALE FORCE
GUSTS ARE EXPECTED OVER THE OPEN WATERS OF SOUTHERN LAKE MICHIGAN.
MUCH WARMER AIR MOVING OVER THE LAKE WILL LIKELY KEEP EVEN STRONGER
WINDS ALOFT FROM REACHING THE WATER SURFACE. HOWEVER...THIS WILL NOT
NECESSARILY BE THE CASE FOR THE NEAR SHORE WATERS FROM CHICAGO
EASTWARD INTO NORTHERN INDIANA. THE OFFSHORE COMPONENT WILL LIKELY
ALLOW SOUTHERLY GALES OF 35 TO 40 KT TO AFFECT THE NEAR SHORES.
BECAUSE OF THIS...I WILL ISSUE A GALE WATCH FOR THE NEAR SHORES FROM
CHICAGO TO MICHIGAN CITY FOR THE DAY ON THURSDAY.

A SECOND LOW IS EXPECTED TO TRACK NORTHEASTWARD ALONG THE SURFACE
BOUNDARY...WHICH LOOKS TO SET UP SOMEWHERE ACROSS THE MID SECTION OF
LAKE MICHIGAN. ONCE THIS SECOND LOW PASSES OVER THE LAKE LATER
THURSDAY NIGHT...THE WINDS WILL BECOME MORE WESTERLY. STRONG WEST TO
NORTHWEST WINDS WILL LIKELY SETUP LAKE-WIDE DURING THE DAY ON FRIDAY...AND
THEN CONTINUE INTO FRIDAY NIGHT. THIS WILL BE THE TIME WHEN GALES
ARE FAVORED OVER THE OPEN WATERS.

IN ADDITION TO THE WINDS...THERE WILL LIKELY BE SEVERAL WAVES OF
SHOWERS AND THUNDERSTORMS LATER TODAY THROUGH THURSDAY EVENING.
SOME OF THESE STORMS COULD PRODUCE SEVERE WEATHER OVER SOUTHERN LAKE
MICHIGAN...ESPECIALLY TONIGHT AND ON THURSDAY.

THINGS FINALLY SETTLE DOWN FOR A PERIOD THIS WEEKEND AND A SURFACE
RIDGE OF HIGH PRESSURE BUILDS OVER THE GREAT LAKES REGION.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-
     ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023-
     ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY.

IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM
     FRIDAY.

LM...GALE WATCH...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...5 AM THURSDAY
     TO 10 PM THURSDAY.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1046 AM CDT WED APR 17 2013

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
181600-
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-
1046 AM CDT WED APR 17 2013 /1146 AM EDT WED APR 17 2013/

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...A FEW MAY PRODUCE:
  HAIL TO ONE INCH.
  STRONG DAMAGING WIND GUSTS IN EXCESS OF 60 MPH.
  HEAVY RAINFALL.
  ISOLATED TORNADOES.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS ARE DEVELOPING ACROSS NORTHERN ILLINOIS THIS
  MORNING AND WILL INCREASE IN COVERAGE THROUGH THE DAY AND
  TONIGHT. THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL PERSIST
  OVER MUCH OF THE OUTLOOK AREA THROUGH LATE THIS AFTERNOON...AND
  MAY BE POSSIBLE INTO TONIGHT.

  DISCUSSION:

  A WARM FRONT IS EXPECTED TO LIFT NORTH ACROSS THE AREA THIS
  AFTERNOON...WITH AN ANOMALOUSLY WARM AND MOIST AIRMASS TO THE
  SOUTH OF THIS BOUNDARY. THUNDERSTORMS ARE EXPECTED TO DEVELOP
  ALONG THIS WARM FRONT AND CONTINUE TO RIDE ALONG THIS BOUNDARY
  THROUGH TONIGHT. THUNDERSTORMS MAY BECOME SEVERE THIS AFTERNOON
  THROUGH TONIGHT AS THE INSTABILITY CONTINUES TO INCREASE
  THROUGHOUT THE DAY. AT THIS TIME THE GREATEST HAZARDS FROM
  THUNDERSTORMS WILL BE DAMAGING WIND GUSTS AND HAIL TO ONE INCH
  IN DIAMETER... ALONG WITH HEAVY RAINFALL. IN ADDITION...SOME OF
  THE STRONGER THUNDERSTORMS MAY BEGIN TO ROTATE ALONG OR JUST
  NORTH OF THE WARM FRONTAL BOUNDARY. THUS THE POTENTIAL FOR AN
  ISOLATED TORNADO MAY OCCUR THIS AFTERNOON INTO TONIGHT.

  THUNDERSTORMS ARE EXPECTED TO TRAIN ACROSS THE SAME LOCATIONS
  THIS EVENING AND TONIGHT...WHICH MAY LEAD TO FLOODING. WITH
  SATURATED SOILS ALREADY...ANY HEAVY RAINFALL WILL FURTHER
  EXACERBATE THE CURRENT FLOODING CONDITIONS.

PORTIONS OF MANY AREA RIVERS AND STREAMS WILL REMAIN NEAR OR
ABOVE FLOOD STAGE DUE TO RECENT RAINFALL.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

SEVERAL ROUNDS OF HEAVY RAIN PRODUCING THUNDERSTORMS WILL
CONTINUE THROUGH THURSDAY. THIS MAY LEAD TO SIGNIFICANT FLOODING
ON AREA RIVERS...SOME OF WHICH ARE ALREADY NEAR OR ABOVE FLOOD
STAGE FROM PREVIOUS RAINFALL. LOCALLY HEAVY RAINFALL MAY ALSO
LIKELY RESULT IN FLOODING OF LOW LYING AND URBAN AREAS.

PORTIONS OF MANY AREA RIVERS AND STREAMS WILL REMAIN NEAR OR
ABOVE FLOOD STAGE DUE TO RECENT RAINFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THROUGH TONIGHT.

&&

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

LMZ740>745-181600-
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-
1046 AM CDT WED APR 17 2013

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PERIODIC THUNDERSTORMS ARE LIKELY THIS AFTERNOON THROUGH TONIGHT.
A FEW THUNDERSTORMS COULD PRODUCE STRONG...GUSTY WINDS.

GALE FORCE WINDS ARE POSSIBLE LATE TONIGHT THROUGH THE
OVERNIGHT FROM CHICAGO TO MICHIGAN CITY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

PERIODIC THUNDERSTORMS ARE LIKELY THURSDAY.

GALE FORCE WINDS ARE POSSIBLE FRIDAY THROUGH FRIDAY NIGHT FOR THE
ENTIRE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA.

&&

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-
870-872-874-876-878-181600-
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 TWO 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-
1046 AM CDT WED APR 17 2013

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PERIODIC THUNDERSTORMS ARE LIKELY THIS AFTERNOON THROUGH TONIGHT
FOR THE SOUTHERN HALF OF LAKE MICHIGAN. A FEW THUNDERSTORMS
MAY PRODUCE STRONG...GUSTY WINDS.

OCCASIONAL GALE FORCE GUSTS MAY OCCUR THIS EVENING THROUGH
TONIGHT MAINLY FOR THE SOUTHERN TIP OF LAKE MICHIGAN.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

PERIODIC THUNDERSTORMS ARE LIKELY THURSDAY.

GALE FORCE WINDS ARE POSSIBLE FRIDAY THROUGH FRIDAY NIGHT.

&&

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

KREIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1155 AM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1120 AM     HAIL             4 WSW GILBERTS          42.08N 88.43W
04/17/2013  E0.25 INCH       KANE               IL   COCORAHS

&&

C

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1157 AM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1137 AM     HAIL             ELGIN                   42.04N 88.29W
04/17/2013  E0.75 INCH       KANE               IL   TRAINED SPOTTER

&&

C

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1158 AM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1155 AM     HAIL             SCHAUMBURG              42.03N 88.08W
04/17/2013  E0.25 INCH       COOK               IL   TRAINED SPOTTER

&&

C

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 PM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1148 AM     HAIL             NNW WALTON              41.72N 89.44W
04/17/2013  E0.88 INCH       LEE                IL   PUBLIC

            NICKEL SIZED HAIL COVERING THE GROUND.

&&

LENNING

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1204 PM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     HAIL             INVERNESS               42.12N 88.10W
04/17/2013  E0.50 INCH       COOK               IL   TRAINED SPOTTER

&&

LENNING

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1214 PM CDT WED APR 17 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1153 AM     HEAVY RAIN       4 SW PINGREE GROVE      42.02N 88.46W
04/17/2013  U0.00 INCH       KANE               IL   911 CALL CENTER

            INTERSECTION OF ROUTE 47 AND PLATO ROAD IS COMPLETELY
            FLOODED.

1153 AM     HEAVY RAIN       2 SE ALGONQUIN          42.14N 88.28W
04/17/2013  U0.00 INCH       KANE               IL   911 CALL CENTER

            WATER RUSHING OVER THE ROAD AT SANDBLOOM RD AND BOLZ RD.

1210 PM     HEAVY RAIN       5 SSW ALGONQUIN         42.10N 88.34W
04/17/2013  U0.00 INCH       KANE               IL   911 CALL CENTER

            STANDING WATER IN THE ROADWAY AT ROUTE 72 AND RANDALL
            ROAD.

&&

LENNING