Severe Thunderstorm Warning 283, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
255 AM CDT WED AUG 27 2003

SUPERCOMPUTER PROBLEMS HAVE PROVIDED ONLY A LIMITED AMOUNT OF
RELIABLE MODEL DATA. 00Z CANADIAN MODEL AVAILABLE THRU INTERNET.
MM5 WAS USED FOR ETA/NOGAPS AND UKMET FOR AVN. ALL IN ALL...DIFFICULT
TO MAKE ANY MAJOR CHANGES TO GOING FCST BEYOND FIRST PERIOD.
FORTUNATELY...MODELS HAD BEEN SHOWING FAIRLY GOOD CONTINUITY LONGER
OUT...AND WHAT MODEL DATA IS AVAILABLE CONTINUES TO SUPPORT THE
SAME SCENARIO.

FCST CHALLENGE TODAY IS MAX TEMPS AND PCPN CHANCES. THEN...CHALLENGE
SHIFTS TO APPROACHING COLD FRONT PASSAGE EARLY FRIDAY.

SCATTERED CONVECTION CONTINUES TO PLAGUE NE-E CENTRAL MO AND WEST
CENTRAL IL TONIGHT. THESE STORMS DEVELOPED ALONG 850H THETAE
AXIS...AIDED BY UPPER LVL DIVERGENCE AND HIGH PWAT AIRMASS. AT THE
SFC...APPEARS THREE FRONTS MAY BE A REASONABLE ANALYSIS. FIRST TROF
FROM CENTRAL KS TO SERN TIP OF IOWA. MAIN WIND SHIFT FROM SERN NE TO
NEAR CHICAGO. THIS BOUNDARY SHOWS UP WELL IN KDVN RADAR. FINAL FRONT
FROM WESTERN IOWA TO WEST-CENTRAL MICHIGAN...WHERE TRUE TEMP DROPOFF
OCCURRS. THEREFORE...BELIEVE WIND SHIFT EXPECTED LATER THIS MORNING
ACRS NORTH WILL NOT BRING IN TRUE BEST CAA PATTERN. THEREFORE...HAVE
WARMED TEMPS SEVERAL DEGREES TODAY. ALSO...CONTINUE PCPN CHANCES
TODAY AS MODELS CONT TO SUGGEST POSSIBILITY OF TSRA...ESP SOUTHERN
AREAS LATER THIS AFT/THIS EVE. CAN NOT RULE OUT ACRS NORTH...SO
LOW POPS CONT ALL CWA.

CONSIDERED PULLING POPS THROUGH ENTIRE NIGHT SE SECTIONS. ISC GRIDS
CONVINCED ME TO LEAVE DRY FCST GOING. NOT MUCH ON NOCTURNAL
PARAMETERS AS FAR AS FORCING EITHER. BUT FRONT LIES OUT ACRS
SOUTHERN ILLINOIS OVERNIGHT. CAN NOT RULE OUT WDLY SCT CONVECTION
NORTH OF THE BOUNDARY.

NEXT SYSTEM STILL ON TRACK FOR EARLY FRIDAY. MADE ADJUSTMENTS TO
WIND FCST TIMING OF WIND SHIFT WITH THIS FEATURE. MODELS IN GOOD
AGREEMENT WITH QUICKER FROPA. WESTERN PARTS OF ILX CWA HAVE BEEN
PLACED IN (LATE) DAY 2 SLIGHT RISK. THIS LOOKS REASONABLE.

ONLY MINOR TWEEKS MADE TO REMAINDER OF THE FCST. FRIDAY FRNT
EXPECTED TO STALL OUT SOUTH OF ILX CWA. THEN...S/WV ENERGY DIGGING
INTO NORTHERN PLAINS TO KEEP PCPN IN FCST FOR SATURDAY NORTH OF THE
BOUNDARY. THIS STILL LOOKS REASONABLE. COOLER MORE SEASONABLE LATE
SUMMER WEATHER TO DOMINATE INTO EARLY NEXT WEEK.

.ILX...NONE.

PLAHMER

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
1121 AM CDT TUE AUG 26 2003

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT...MAINLY ALONG AND NORTH OF I-70. THE MAIN SEVERE WEATHER
THREAT WILL BE DAMAGING WINDS AND LARGE HAIL. THIS IS A RESULT OF A
FRONTAL BOUNDARY MOVING SOUTH INTO CENTRAL ILLINOIS AND COLLIDING
WITH A VERY UNSTABLE AIR MASS.

IN ADDITION TO THE SEVERE THUNDERSTORM THREAT LATER TODAY AND
OVERNIGHT...THE COMBINATION OF AFTERNOON TEMPERATURES IN THE MIDDLE
90S AND DEW POINT TEMPERATURES FROM 70 TO 75 DEGREES...WILL DRIVE HEAT
INDEX VALUES TO NEAR 105 DEGREES IN A FEW LOCATIONS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THERE WILL BE ANOTHER THREAT FOR SCATTERED THUNDERSTORMS ACROSS
PARTS OF CENTRAL ILLINOIS ON WEDNESDAY AS THE FRONTAL BOUNDARY
REMAINS CLOSE TO THE STATE.  AT THIS TIME...IT APPEARS THE SEVERE
WEATHER THREAT ACROSS CENTRAL ILLINOIS WILL BE LIMITED DURING THE
DAY. A STRONG COLD FRONT IS FORECAST TO PUSH ACROSS THE REGION LATE
THURSDAY INTO FRIDAY...BRINGING WITH IT ANOTHER THREAT FOR MORE
ORGANIZED THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED LATER THIS AFTERNOON AND EVENING.
IT APPEARS THE PRIMARY THREAT TIME WOULD BE FROM 3 TO 8 PM IN AREAS
ALONG AND NORTH OF INTERSTATE 72...WITH LOCATIONS TO THE SOUTH OF
INTERSTATE SEEING THE ACTIVITY BETWEEN 800 PM AND MIDNIGHT.

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

HTTP://WWW.CRH.NOAA.GOV/ILX

PLEASE NOTE THAT THE WEB ADDRESS SHOULD BE ALL IN LOWER CASE.

BARNES