Tornadoes and Hail in Illinois, September 26, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
200 PM CDT FRI SEP 26 2003

...A COOL WEEK AHEAD WITH PATCHY FROST POSSIBLE...

.DISCUSSION...AREA TO REMAIN UNDER INFLUENCE OF TROFF ALOFT OVER THE
GREAT LAKES REGION FOR MOST OF THE WEEK. THIS WILL BRING
UNSEASONABLY COOL WEATHER TO THE AREA WITH THE CHANCE FOR AT LEAST
PATCHY FROST. NEXT COLD FRONT TO MOVE THROUGH THE AREA TUE MORNING
BUT RAIN CHANCES ARE LOOKING SLIMMER AND SLIMMER AS MOISTURE APPEARS
TO BE LACKING. OTHER THAN TUE...DRY WEATHER THROUGH MOST OF NEXT
WEEK. MODELS SIMILAR SO NO REAL PREFERENCE FOR THIS PACKAGE.

SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...RADAR SHOWING THAT FEW
SHRAS ARE QUICKLY DEVELOPING ACROSS THE CWA. THIS IN RESPONSE TO
SFC HEATING/COLD AIR ALOFT AND NUMEROUS SFC TROFFS AND SHORT WAVES
ALOFT. CRYSTAL CLEAR SKIES THIS MORNING HAVE QUICKLY BECOME PARTLY
TO MOSTLY CLOUDY. THERE WILL BE A LINGERING CHANCE FOR A SHOWER OR
POSSIBLY A BRIEF THUNDERSTORM THIS EVENING...THEN PARTLY CLOUDY
SKIES OVERNIGHT. SKIES MAY BE MOSTLY CLOUDY AT TIMES BUT WILL LEAN
MORE TOWARD PC OVERALL.

DECIDED TO KEEP CHC POPS GOING FOR TOMORROW AS INSTABILITY SHOWERS
DEVELOP AGAIN. SOME QUESTION ABOUT DEGREE OF INSTABILITY AND THUNDER
SO LEFT OUT FOR NOW. DECIDED TO EXTEND POPS ACROSS THE SOUTHERN CWA
TO BE MORE IN LINE WITH NEIGHBORING WFOS. RH APPEARS MORE AMPLE
TOMORROW BUT NOT QUITE AS UNSTABLE OVERALL. A BIT COOLER TOMORROW AS
THE COLDEST TEMPS ALOFT WORK INTO THE AREA/PLUS MORE CLOUDS. WENT
MOSTLY CLOUDY NORTH AND LEFT REST OF THE AREA PC BUT LATER SHIFTS
MAY HAVE TO TWEAK. POPS MAY LINGER INTO TOMORROW EVENING BUT DIDNT
PUT INTO DATABASE FOR NOW. LOWS IN THE UPPER 30S TOMORROW NIGHT.
DIDNT MENTION PATCHY FROST AS FEEL THAT IT WILL BE JUST A TAD TOO
WARM. MAV LOWS LOOK TOO COLD FOR TOMORROW NIGHT SO LEANED MORE
TOWARD ETA/NGM MOS FOR THE SHORT TERM NUMBERS.

A BIT WARMER ON MONDAY WITH LESS CLOUDINESS AND AS COLD AIR ALOFT
RETREATS. PARTLY CLOUDY AND NOT QUITE AS COOL MONDAY NIGHT.

LONG TERM...TUESDAY THROUGH SATURDAY...MEDIUM RANGE MODELS ARE STILL
IN GOOD AGREEMENT. MODELS ARE NOW MOVING THE FRONT (TUE) ALONG A
LITTLE QUICKER. RH STILL LOOKS A BIT LIMITED AND DEBATED ON PULLING
PRECIP CHANCES ALL TOGETHER. DECIDED TO LEAVE CHC POPS IN ACROSS N
1/2 OR SO OF THE CWA AND WILL SPECIFY/USE MORNING WORDING. LATER
SHIFTS WILL HAVE TO RE-EVALUATE. AFTER FROPA TUE THE REST OF THE
WEEK LOOKS DRY. TEMPERATURES WILL CONTINUE BELOW NORMAL WITH A
CHANCE OF FROST...AT LEAST PATCHY...EARLY WED AND THU MORNINGS.
SHELTERED LOW LYING AREAS WILL SEE THE BEST FROST CHANCES.

MODELS HINT AT ANOTHER FRONT/TROFF PASSING THRU THE GREAT LAKES AREA
WED NIGHT/THU MORNING AND AGAIN NEXT SAT. OPTED TO LEAVE THINGS DRY
FOR NOW. WARMING TREND FRI-SAT AS FLOW ALOFT BECOME MORE ZONAL AND
RETURN FLOW SETS UP. MANUAL HPC GUIDANCE/MEX NUMBERS AND ENSEMBLES
LOOK VERY SIMILAR THROUGH THE PERIOD SO DIDNT DEVIATE MUCH AT
ALL.

ISC GRIDS ALL SENT AND LOOK CLOSE WITH SURROUNDING OFFICES. FURTHER
COORDINATION WELCOME.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
IL...NONE
&&

HALL

ILZ027>031-036>038-040>057-061>063-066>068-071>073-271100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
1100 AM CDT FRI SEP 26 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHEAST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FROM I-72 SOUTH WITH A SLIGHT RISK NORTH OF I-72. A VIGOROUS
COLD FRONT WILL PRESS SOUTHEAST INTO NORTHWEST ILLINOIS DURING THIS
AFTERNOON...REACH I-55 TOWARD SUNSET AND EXIT SOUTHEAST ILLINOIS BY
MIDNIGHT. THE COMBINATION OF STRONG WIND FIELDS ACROSS AN
INCREASINGLY UNSTABLE AIR MASS AHEAD OF THE COLD FRONT...WILL LIKELY
SPAWN THE DEVELOPMENT OF THUNDERSTORMS THIS AFTERNOON AND EVENING.
SOME OF THESE STORMS COULD BE SEVERE...ESPECIALLY FROM I-72
SOUTH...WITH VERY LARGE HAIL UP TO 2 INCHES IN DIAMETER...DAMAGING
WIND GUSTS IN EXCESS OF 60 MPH...AND POSSIBLY TORNADOES.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE IS A CHANCE OF THUNDERSTORMS TUESDAY AS YET ANOTHER COLD FRONT
MARCHES SOUTHEAST ACROSS ILLINOIS. HOWEVER...THESE THUNDERSTORMS ARE
NOT EXPECTED TO BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED BETWEEN 2 PM AND MIDNIGHT
TODAY ACROSS CENTRAL AND SOUTHEAST ILLINOIS.

&&
THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC
AND CLIMATE INFORMATION...IS AVAILABLE ON THE WEB AT:

HTTP://WWW.CRH.NOAA.GOV/ILX. THIS ADDRESS IS ALL
IN LOWER CASE.

EH