Damaging Winds in Illinois, July 4, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
200 AM CDT FRI JUL 4 2003

PUBLIC DISCUSSION FOR GRIDS AND ZONES...

FIREWORKS ON THE PLAINS HEADING FOR OUR AREA. SEVERE WEATHER AND
HEAVY RAIN THREAT IN THE NEXT 24-48 HOURS.

ONGOING WWA FOR FAR WESTERN COUNTIES. MAY OR MAY NOT HAVE TO BE
EXTENDED FARTHER EAST LATER ON SHIFT.

EARLY MORNING ANALYSIS SHOWING A SURFACE BOUNDARY E-W ACROSS
NORTHERN IOWA INTO EXTREME SOUTHERN WI.  MCS VICINITY OF NORTH
CENTRAL
IOWA AT 6Z...SRN PORTION STILL INTENSIFYING...LIKELY TO CONTINUE
FEEDING ON VEERING LOW LEVEL JET, AS PER PROFILERS, AND PLOW ENEWD
ACROSS IOWA INTO WI AND POSSIBLY A FAR SOUTH AS OUR CWFA SHORTLY
AFTER SUNRISE. MUCH STRONGER THAN ETA/MESOETA BELIEVE. ALSO MCS WEST
CENTRAL MN APPRS ON TRACK TO MERGE WITH THE SOUTHERN ONE. ALTHOUGH
SYSTEM MAY WEAKEN ESPECIALLY IN ILLLINOIS ON SOUTH END, CURRENT
COORDINATED THINKING IS FOR A POSSIBLE CONTINUOUS DERECHO EVENT
ACROSS NORTHERN TIER CWFA. AS PER SPS CONFERENCE CALL AND
DISCUSSION, AFTER THIS INITIAL SYSTEM GOES THRU AND WITH
UNCERTAINTIES OF ITS TRACK, THINGS BECOME EVEN MORE MUDDLED WITH
BOUNDARIES LEFT OVER FOR LATER ACTIVITY. SAID ACTIVITY IS ALREADY
TREKKING ACROSS THE DAKOTAS. ALL THIS WILL COMPLICATE TEMPERATURE
FORECAST AS WELL AS BEST AXIS OF NEXT ROUND OF THUNDERSTORMS
FORECAST BY ETA/GFS DURING THE MID AFTERNOON THROUGH EVENING
HOURS.   SOUTH OF ANY BOUNDARY THAT EXISTS MID 70S DEWPOINTS AND
90-95 TEMPS SHOULD PRODUCE CAPES AS HIGH AS 4000 AND LITTLE CAP.
RATHER UNIDIRECTIONAL SHEAR PROFILE DOES FAVOR ADDITIONAL BOW
ECHO/DERECHO ACTIVITY POSSIBLE WITH AFTERNOON AND NIGHT ACTIVITY.
GRIDS WILL WILL SPREAD AROUND OF POSSIBLY SEVERE STORMS FROM WNW TO
ESE AGAIN AFTER 20Z OR SO THROUGH AROUND 04Z.  CONCERN THEN SHIFTS
TO HEAVY RAIN POSSIBILITIES AS MESO ETA MAINTAINS BOUNDARY FOCUS
ACROSS SOUTHERN CWFA AS A COUPLE MORE WAVES COME ACROSS LATER
TONIGHT THROUGH MORNING SATURDAY.  HARD TO GET TOO CUTE HERE WITH
ALL
THE UNCERTAINTY THAT PRECEDES IT BUT AS PER NCEP QPF WILL PROBABLY
HAVE POTENTIAL HEAVY RAIN SOUTHERN COUNTIES WITH SOME QPF TOTALS OF
NEAR 2 INCHES IN 24 HOURS POSSIBLE.

LITTLE CHANGE ANTICIPATED TO GOING FORECAST AFTER THE NEXT COUPLE
DAYS.

.CHI...NONE

KAPLAN

ILZ003>006-008-010>014-019-020>023-032-033-039-INZ001-002-010-011-019
-051100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
600 AM CDT FRI JUL 4 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST
ILLINOIS...NORTHWEST INDIANA...AND THE ADJACENT WATERS OF LAKE
MICHIGAN.

.DAY ONE... TODAY AND TONIGHT

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS NORTH OF I 80
DURING THE EARLY FORENOON UNTIL AROUND 9 AM. A SQUALL LINE WILL BE
PLOWING ACROSS THE AREA BETWEEN 6 AND 9 AM WITH DAMAGING WINDS TO 70
MPH OR MORE POSSIBLE.  THEN FROM MID AFTERNOON ON THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS AGAIN...ACROSS THE ENTIRE AREA. THE
SECOND ROUND OF THUNDERSTORMS WOULD BEGIN IN THE NORTH CENTRAL
ILLINOIS BETWEEN 2 AND 5 PM...PROGRESS TO NORTHEAST ILLINOIS BETWEEN
4 AND 8 PM...AND NORTHWEST INDIANA BETWEEN 6 AND 10 PM.

ON THIS FOURTH OF JULY ANYONE PLANNING OUTDOOR ACTIVITIES SHOULD
KEEP A CLOSE EYE ON THE SKY AND AN EAR OF WEATHER RADIO OR OTHER
BROADCAST MEDIA. BE PREPARED TO MOVE TO A STRONG BUILDING IF SEVERE
WEATHER APPROACHES.  BOATERS SHOULD STAY CLOSE TO SHORE AND BE
PREPARED TO SEEK SAFE HARBOR WHEN THUNDERSTORMS APPROACH.

AFTER THE SEVERE WEATHER...THERE IS A THREAT OF HEAVY RAIN FROM
REPEAT THUNDERSTORMS GENERALLY SOUTH OF I 80 BEGINNING AFTER
MIDNIGHT. URBAN AND SMALL STREAM FLOODING COULD EASILY RESULT FROM
ANY REPEAT THUNDERSTORMS IN THE SAME AREA.

HEAT INDICES ACROSS MOST OF THE AREA WILL RANGE FROM THE UPPER 90S
TO AS HIGH AS 105.  BE SURE NOT TO OVERDO OUTDOOR ACTIVITIES IN THE
HOT HUMID WEATHER AND DRINK PLENTY OF WATER.

.DAYS TWO THROUGH SEVEN... SATURDAY THROUGH THURSDAY

THERE IS A CHANCE OF THUNDERSTORMS AGAIN SATURDAY NIGHT INTO SUNDAY
MORNING...AND AGAIN SUNDAY NIGHT THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS WILL BE NEEDED THIS MORNING AND AGAIN IN THE AFTERNOON AND
EVENING.

&&

           NWS CHICAGO WEBPAGE

    HTTP://WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
OR  HTTP://WEATHER.NOAA.GOV/CHICAGO (LOWER CASE)