Wildfire in Illinois, April 24, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
302 PM CDT THU APR 24 2003

PUBLIC DISCUSSION FOR 330 PM GRIDS/ZFP

CLOSED AND VERTICALLY STACKED CIRCULATION WELL DEPICTED IN SAT AND
RADAR LOOPS OVER KANSAS THIS AFTERNOON. SOUNDINGS ILX/DTX/ILN/DVN
FROM 12 UTC DRAMATICALLY SHOW DRY AIR BELOW 650-700 MB HOWEVER...AND
PRECIP HAVING A VERY HARD GO OF IT THIS FAR NORTH. FIRST BAND HAS
DECAYED AS IT LIFTED TOWARD FORECAST AREA TODAY...AND EXPECT THIS
TREND TO CONTINUE AS SYSTEM PUSHES EAST INTO THE MID MS AND LOWER OH
VALLEY REGIONS THORUGH FRIDAY. WILL CONTINUE TO CARRY LOW POP FOR
MEASUREABLE PRECIP IN SHOWERS FOR SOUTHERN COUNTIES...BUT WILL JUST
MENTION SPRINKLES NORTH TONIGHT. PRECIP THREAT LINGERS INTO FRIDAY
EVENING FAR SE...BUT DECREASING CLOUDS LIKELY NORTH AS SUBSIDENCE
DEVELOPS IN RESPONSE TO SHORT WAVE RIDGING IN MID LEVELS IN WAKE OF
DEPARTING LOW.

DRY AND WARMER WEATHER THROUGH SATURDAY AS SURFACE RIDGE MOVES
ACROSS WESTERN LAKES...THOUGH COOL NE FLOW WILL KEEP TEMPS LAKE
MICHIGAN SHORES COOLER. INCREASING SOUTHERLY COMPONENT TO LOW LEVEL
WIND FIELD SUNDAY AHEAD OF COLD FRONT TRAILING SHORT WAVE WHICH
MOVES ACROSS CANADA...WITH CHANCE POPS WARRANTED SUNDAY NIGHT.
SURFACE HIGH THEN BUILDS SLOWLY EAST OUT OF THE CENTRAL PLAINS
MONDAY INTO TUESDAY...BEFORE MORE ACTIVE LOOKING PERIOD FOR THE
MIDDLE OF NEXT WEEK. GFS DEVELOPS WARM FRONTAL BOUNDARY IN VICINITY
AND MOVES TO WI BORDER WEDNESDAY...WHILE ENSEMBELE MEAN KEEPING IT
OVER THE FORECAST AREA UNTIL SURFACE LOW MOVES THROUGH EARLY
THURSDAY. AGREE WITH ENSEMBLE IDEA...AS CLIMATOLOGICALLY FAVOR
FRONTAL POSITION SOUTH OF THE COLD LAKE THIS TIME OF YEAR...YIELDING
COOLER TEMPS NORTH DUE TO NE FLOW OFF LAKES. HIGH THEN BUILDS IN
LATE THURSDAY.

.CHI...NONE.

RATZER

AVIATION DISCUSSION FOR 18Z TAFS...

LARGE WX SYS OVR KS WILL TRACK EWD TO S OF OH VLY AND HAVE LITTLE
IMPACT ON FLIGHT OPERATIONS ACROSS NRN IL/NWRN IN.  SATLT LOOPS
SHOWS BANDS OF LAYERED CLOUDS ASSD WITH THIS SYS ROTATING NWD/NEWD
THROUGH MS VLY...BUT BEING SHEARED OFF BY NWLY UPR LVL FLOW OVER CAN
AND NRN U.S.  WITH THRACK OF THIS SYS OFF TO ESE NXT 24-48
HRS...THIS TREND SHOULD CONTINUE.  THEREFORE AM LOOKING FOR CIGS TO
RMN OVC...BUT STAY VFR FOR DURATION OF FCST.  LATEST FCST SOUNDINGS
ALSO SUGGEST THAT AIR WILL REMAIN RATHER DRY BLO ABOUT 8 OR 9 THSD
FT SO ANY PCPN THAT DOES APPEAR TO OVERSPREAD TERMINALS WILL
PROBABLY NOT MAKE IT TO THE SFC.   BASED ON ALL THIS WILL NOT PUT
ANY VIS RESTRICTIONS IN 18Z TAFS.  WITH CIRCULATION CENTER PASSING
TO S OF RGN THIS AFTN AND TNGT...WIND FLOW WILL GRADUALLY BACK FROM
SELY TO NELY BY ERLY FRI.  WIND SPEEDS GENLY IN 10-15 KT
RANGE...WILL LIKEY INCRS TO ARND 15 KTS WITH GUSTS TO 25 KTS BY 18Z
FRI AS PRESSURE GRADIENT INCRSS BETWEEN HIGH PRES OVR NWRN ONT AND
LOW PASSING S OF OH VLY.

MERZLOCK

ILZ003>006-008-010>014-019-020>023-032-033-039-
INZ001-002-010-011-019-251100-

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE CHICAGO IL
430 PM CDT THU APR 24 2003

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

.DAY ONE... TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

HAZARDOUS CONDITIONS FOR SMALL CRAFT ON LAKE MICHIGAN ARE LIKELY
FRIDAY.

THERE IS A CHANCE OF THUNDERSTORMS SUNDAY AND SUNDAY NIGHT.
OTHER CHANCES OF THUNDERSTORMS WILL OCCUR ON TUESDAY...TUESDAY
NIGHT AND WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS WILL NOT BE NEEDED.

           NWS CHICAGO WEBPAGE

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