Hail and Damaging Wind in Illinois, May 30, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
245 PM CDT TUE MAY 30 2006

.DISCUSSION...
SHORT TERM...TONIGHT THROUGH THURSDAY...
MOIST AND MODERATELY UNSTABLE AIRMASS REMAINS OVER THE FORECAST AREA
THIS AFTERNOON. THE INSTABILITY IS NOT AS GREAT AS PREVIOUS DAYS
WITH MLCAPES AROUND 1000 J/KG...AND DEEP LAYER SHEAR VALUES ARE VERY
WEAK. LIFTED INDICES ARE -3 TO -5...RATHER THAN AROUND -9. THIS IS
SHOWING IN THE VISIBILE SATELLITE LOOPS WITH ONLY SCATTERED PATCHES
OF TOWERING CUMULUS. BETTER COMBINATIONS OF SHEAR...MOISTURE...AND
INSTABILITY ARE TO OUR NORTH...EAST...AND SOUTH. MEANWHILE TO THE
WEST...A LARGE AREA OF OVERTURNED AIR PERSISTS COURTESY OF THE
THUNDERSTORM COMPLEX OVER NORTHERN MISSOURI EARLY THIS MORNING. THIS
AIRMASS IS SLOWLY RECOVERING ITS INSTABILITY AS SUGGESTED BY CUMULUS
FIRMING UP AROUND KIRKSVILLE. THE ATTENDING OUTFLOW BOUNDARY EXTENDS
INTO THE FAR WESTERN COUNTIES OF OUR FORECAST AREA...AND THIS MAY
PROVIDE THE FOCUS AND LIFT NECESSARY TO INITIATE CONVECTION LATE
THIS AFTERNOON. ANOTHER FAVORED AREA IS OVER THE EXTREME
SOUTHEAST...WHERE AN OUTFLOW BOUNDARY HAS ARRIVED FROM WIDESPREAD
CONVECTION ALONG THE OHIO RIVER. ANY THUNDERSTORM DEVELOPMENT IN
THESE AREAS THIS EVENING WILL HAVE THE POTENTIAL TO PRODUCE FLOODING
RAINFALL DUE TO THE HIGH PRECIPITABLE WATER VALUES AND SLOW STORM
MOVEMENT. MEAN WIND VECTORS OVER THE SOUTHEAST ARE ONLY 10 TO 15KT
ALL THE WAY UP TO 300MB. WILL TAYLOR EVENING POPS TO ACCOUNT FOR
THESE AREAS... AND JUST HAVE CHANCE POPS AFTER MIDNIGHT.

CONVERGENCE ALONG THE MAIN COLD FRONT IS GETTING REALLY WEAK AS THE
BOUNDARY STRUGGLES TO RETAIN ITS IDENTITY UNDER WEAK PARALLEL FLOW
ALOFT. THERE IS LITTLE MEANINGFUL TEMPERATURE CONTRAST ALONG THE
FRONTAL BOUNDARY...AND MOST WIND SPEEDS ARE LESS THAN 10-15KTS. THE
AIRMASS BEHIND THE FRONT IS QUITE A BIT DRIER THOUGH. THE FRONT IS
EXPECTED TO OOZE TO A MILWAUKEE TO QUINCY LINE BY 12Z WEDNESDAY...
AND TAKE ALMOST 24 HOURS TO TRAVERSE OUR FORECAST AREA. MUCH OF WHAT
HAPPENS ON WEDNESDAY WILL HINGE ON THE EVOLUTION OF CONVECTION
TONIGHT...BUT SUFFICE TO SAY THAT THERE SHOULD BE AT LEAST A COUPLE
OF BOUNDARIES IN ADDITION TO THE SYNOPTIC FRONT FOR STORMS TO
DEVELOP ON. WILL KEEP THE LIKELY POPS GOING WEDNESDAY AND WEDNESDAY
NIGHT...THEN HOLD ON TO CHANCE POPS OVER THE SOUTHEASTERN HALF OF
THE AREA THURSDAY.

LONG TERM...FRIDAY THROUGH TUESDAY...
NOTICABLY DRIER AIR WILL OVERSPREAD THE REGION AS HIGH PRESSURE
MOVES THROUGH ON FRIDAY AND SATURDAY. THE BATTLE BETWEEN THE LONG
RANGE MODELS CONTINUES WITH REGARD TO A POSSIBLE SHORTWAVE AND
FRONTAL SYSTEM SUNDAY AND MONDAY. OUR GUT FEELING IS THAT THE
LONGWAVE PATTERN WILL ALLOW THE ROCKIES UPPER RIDGE TO REMAIN
AMPLIFIED ENOUGH TO PREVENT A STRONG SYSTEM FRO MOVERTOPPING IT AND
DIVE INTO THE MIDWEST. THE GFS MODEL MAY BE TRENDING TOWARD THE
WEAKER ECMWF...BUT THE MODELS ARE FAR FROM CONVERGING ON A SIMILAR
SOLUTION. WILL THEREFORE KEEP SUNDAY THROUGH TUESDAY DRY WITH A
WARMING TREND UNTIL THE LONG TERM TREND BECOMES CLEARER.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

04

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
1118 AM CDT TUE MAY 30 2006

ILZ027>031-036>038-040>057-061>063-066>068-071>073-311100-
KNOX-STARK-PEORIA-MARSHALL-WOODFORD-FULTON-TAZEWELL-MCLEAN-
SCHUYLER-MASON-LOGAN-DE WITT-PIATT-CHAMPAIGN-VERMILION-CASS-
MENARD-SCOTT-MORGAN-SANGAMON-CHRISTIAN-MACON-MOULTRIE-DOUGLAS-
COLES-EDGAR-SHELBY-CUMBERLAND-CLARK-EFFINGHAM-JASPER-CRAWFORD-
CLAY-RICHLAND-LAWRENCE-
1118 AM CDT TUE MAY 30 2006

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN TODAY AS SMALL WEAK
SURFACE BOUNDARIES INTERACT WITH THE WARM AND HUMID AIR MASS
ALREADY IN PLACE ACROSS THE REGION. THERE IS A SLIGHT RISK THAT
SOME OF THESE STORMS COULD BECOME SEVERE...WITH THE PRIMARY SEVERE
WEATHER THREAT BEING HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A COLD FRONT WILL APPROACH THE AREA ON WEDNESDAY AND BRING
ANOTHER ROUND OF THUNDERSTORMS TO CENTRAL AND SOUTHEAST ILLINOIS
THROUGH WEDNESDAY NIGHT. PORTIONS OF SOUTHEAST ILLINOIS COULD SEE
ANOTHER ROUND OF THUNDERSTORMS ON THURSDAY AS WELL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND INTO TONIGHT.

HARDIMAN/AUTEN