Severe Thunderstorm Warning 105, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
155 PM CDT FRI MAY 31 2002

WATER VAPOR LOOP SHOWING WEAK SHORTWAVE ACRS NRN WISCONSIN SHIFTING EWD
EARLY THIS AFTN. VORT LOBE SHIFTING SEWD ACRS IA RESPONSIBLE FOR MID
LVL CLD DECK AND SHOWERS SHOWING UP ON REGIONAL MOSAIC. CU FIELD STARTING
TO DVLP ALONG WHAT LOOKS LIKE A PRE-FRONTAL TROF EXTDG FROM JUST SOUTH
OF LAF AND HUF TO NEAR CMI. SHORT TERM MODELS DVLPG CONVECTION ALONG
THIS PREFRONTAL TROF THIS AFTERNOON AND EVENING. ACTUAL COLD FRONT
OR DEW POINT DICONTINUITY SOUTH OF PIA AND BMI. MODELS FAIRLY CLOSE
IN THEIR OVERALL DEPICTION OF WHERE THE BNDRY WL LIE OUT LATER THIS
EVENING AND OVERNIGHT AND RESULTANT POPS. ETA AND AVN/S PAST
PERFORMANCE NOT REAL SPARKLING WITH THEIR SOLUTION OF PUSHING THE
BNDRY INTO SE IL BY LATER THIS AFTN. OVERALL...MODELS NOT SHOWING
ANY SIG DIFFERENCES IN THEIR DEPICTING OF THE BNDRY WHICH IS FCST
TO SHIFT SEWD ACRS THE CWFA INTO THIS EVENING AND THEN BECOME STNRY
OVRNGT. MODELS SHOWING DIFFERENCES THOUGH AFTR 36 HRS WITH BNDRY
LOCATION WHICH WL MAKE SIG DIF IN WHERE TO PLACE BEST POPS.

WHAT CONVECTION WE GET ALONG BNDRY THIS EVENING IS FCST TO WEAKEN BY
MIDNIGHT WITH ATTENTION TURNING OUT TO OUR WEST WHERE MCS FCST TO
DVLP DURING THE EARLY MORNING HOURS. INCRG THETA-E ADV AND MOISTURE
TRANSPORT AS WELL AS UPPER LVL DIVERGENCE POINTING TWDS CNTRL IL BY
MRNG SO WL TRY TO BREAK POPS UP UNTIL MIDNIGHT AND AGAIN AFTR 09Z.
IF MCS DOES DVLP...BNDRY LOCATION TO BECOME A REAL PROBLEM. WL TEND
TO LEAN MORE TWDS THE ETA SOLUTION ON SATURDAY BASED ON EXPCTD
CONVECTION LATE TNT INTO SATURDAY MORNING. CONVECTIVE TRENDS SHOULD
BEGIN TO DIMINISH LATE MORNING ON SATURDAY WITH A RENEWED THREAT
AGAIN LATE SAT AFTN INTO THE EVENING. THEN ETA TRIES TO LIFT SYNOPTIC
BNDRY NWD SAT NIGHT INTO SUNDAY AS UPPER LVL RIDGE BUILDS ACRS THE SRN
PLAINS. IF THIS DOES HAPPEN...POP CHANCES WL SHIFT NORTH AS WELL.
NOT REAL CONFIDENT ABT THAT SOLUTION WITH THE FURTHER SOUTH SOLUTION
DEPICTED ON THE AVN FOR LATE SAT NIGHT INTO SUN LOOKING MORE
REASONABLE. AS A RESULT...CONTINUED CHANCES FOR TSRA THRU THE SECOND
HALF OF WEEKEND.

MODELS THEN TRY TO GRDLY SHIFT THE SYNOPTIC BNDRY SOUTHWARD EARLY
NEXT WEEK WITH SVL WAVES RIDING ALONG FEATURE ENHANCING THE LOW LVL
CONVERGENCE AND PRECIP CHANCES ACRS MIDWEST. NO REAL SIG CHANGES TO
PATTERN UNTIL MIDWEEK WHEN MODELS GRDLY PROGRESS TROF EWD INTO THE
MIDWEST WITH FLOW BECOMING MORE ZONAL BY END OF WEEK. PRECIP CHANCES
STILL LOOKING GOOD THRU THUR WITH SOMEWHAT DRIER AIR FCST TO MIGRATE
EWD INTO THE MIDWEST FRIDAY AND EARLY SATURDAY.

ALTHOUGH NO REAL SIG DIF IN GUID NUMBERS THRU 24 HRS...WL LEAN MORE
TWDS THE ETA 2 METER TEMPS AS THEY HAVE DONE VERY WELL WITH OVRNGT
LOWS AND AFTN HIGHS THE PAST COUPLE OF DAYS.

...PRELIMINARY CCF FOR COORDINATION PURPOSES...

SPI BB 068/091 068/090 068 44343
PIA BB 066/090 066/089 066 44344
DEC BB 068/091 068/090 068 44343
CMI BB 065/090 068/090 067 44343
MTO BB 066/090 067/089 068 44433
LWV BB 068/090 068/090 068 44433

.ILX...NONE.

SMITH