Severe Thunderstorm Warning 203, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
230 PM CDT SAT JUN 24 2000

FORECAST CHALLENGE IS WHETHER TO CONTINUE FLASH FLOOD WATCH THIS
EVENING AND RISK OF MORE SEVERE WEATHER. SPC ISSUED NEW SEVERE
THUNDERSTORM WATCH TIL 8 PM CDT FROM DANVILLE-EFFINGHAM AND EAST.

12Z/JUN 24 SHORT RANGE MODELS IN BETTER AGREEMENT THAN LAST RUN.
GOOD INITIALIZATION AND MODELS...ESPECIALLY ETA...MORE INTENSE WITH
MID LEVEL SHORT WAVE/MCV OVER SOUTHCENTRAL IA JUST SW OF KOTM AT 18Z
MOVING E INTO CENTRAL IL BY 00Z/SUN AND INTO CENTRAL AND NORTHERN
INDIANA BY 06Z/SUN. AVG MODEL QPF HALF TO 1 INCH ACROSS CWA THIS
AFTERNOON AND EVENING WITH LOCAL 1-2 INCH POCKETS EAST OF A
BMI-TAYLORIVILLE LINE WHERE FLASH FLOOD WATCH TO CONTINUE THIS
EVENING AND COORDINATED WITH NEIGHBORING OFFICES. FFG ACROSS FCWA
AS LOW AS A HALF TO 1 INCH/1 HR AND 1-1.5 INCHES/3 HR WITH A FEW
POINTS ALONG SE CWA RIVERS ABOVE FLOOD STAGE.

19Z SURFACE ANALYSIS HAS 1006 MB LOW JUST S OF KOTM WITH S FLOW AND
TROPICAL AIR MASS OVER CENTRAL IL AHEAD OF THE FEATURE WITH
DEWPOINTS 70-75. LEADING EDGE OF BAND OF CONVECTION/STRENGTHENING
THUNDERSTORMS JUST PASSING E OF I-57 AT 19Z AND MOVING ENE 30-40
MPH. DEVELOPING BANDS OF CONVECTION ACROSS IL WITH MORE WIDSPREAD
CONVECTION OVER N IL N OF PIA/BMI. MODELS TAKE THIS LOW E INTO N CWA
BY 00Z AND INTO N INDIANA BY 06Z. MORE VIGOROUS MID LEVEL SHORT WAVE
DEPICTED WELL ON VISIBLE SATELLITE TO FOLLOW SIMILAR PATH AND
INITIATE WIDESPREAD CONVECTION E OF IL RIVER LATE THIS AFTERNOON...
AND EXITING E INTO INDIANA AROUND MIDNIGHT. PWAT 1.5-2 INCHES
COMBINED WITH ABOVE FFG AND TIMING OF SHORT WAVE...SUPPORT FLASH
FLOOD WATCH THIS EVENING FROM I-55 EAST. HEAVY RAINS POSSIBLE W OF
I-55 BUT EARLY THIS EVENING B4 SUNSET...THEREFORE WILL NOT CONTINUE
FFA THERE.

SUNDAY LOOKS ALMOST DRY AS NO SHORT WAVE ENERGY TO SPEAK OF AND H5
RIDGE SLOWLY BUILDING BACK N. MODEL GUIDANCE POPS HAVE LOWER 30-50%
FOR SUNDAY AND BELOW 10%. WILL KEEP A PROB30 CHANCE OF A LATE DAY
AIR MASS THUNDERSTORM ALONG ANY REMAINING OUTFLOW BOUNDARY ADMIST
LINGERING HUMID AIR MASS AS DEWPOINTS IN THE UPPER 60S/LOWER 70S.

FAIRLY STRONG NORTHERN STREAM SHORT WAVE DEPARTS BRITISH COLUMBIA
AND MOVES ESE ACROSS THE NORTHERN PLAINS SUNDAY AND GREAT LAKES MON.
ASSOCIATED COLD FRONT SLIDES SE TO GALESBURG BY 12Z/MON...THEN TO
PASS SE OF KLWV BY SUNSET/MON. WILL HAVE PROB50 CONVECTION NW CWA
AND PROB30 SE SUNDAY NIGHT...THEN GOOD CHANCE MONDAY ACROSS FCWA.

TEMPWISE...FWC/FAN CLOSE WITH LOWS 65-70 TONIGHT AND SUN NIGHT AND
FOLLOWED. LIKE WARMER FWC HIGHS IN MID-UPPER 80S SUNDAY WITH PARTLY
SUNNY SKIES AND H85 TEMPS ELEVATING TO 19-20C. COOLER FWC HIGHS MON
AROUND 80 NW CWA AND LOW 80S CENTRAL WITH MORE CLOUDS AND CONVECTION
WITH FRONT SLIDING THROUGH...MID-UPPER 80S SE OF I-70 AS FRONT NOT
TO PASS THROUGH UNTIL END OF DAY.

QUICK MEDIUM RANGE PEAK TUE-THU LOOKS FAIRLY DRY TUE/THU WITH
CONVECTION CHANCES WED WITH SFC WAVE RIDING ENE ALONG STALLED OUT
FRONTAL BOUNDARY IN THE MID MS AND LOWER OHIO VALLEY. PROGRESSIVE
ZONAL FLOW ACROSS THE NORTHERN U.S. AROUND H5 LOW OVER HUDSON BAY
RACES SHORT WAVE ENERGY E AND MAY KICK OFF SCT CONVECTION N CWA
THU AFTN. COOLER TEMPS WITH HIGHS IN THE UPPER 70S/LOWER 80S AND
LOWS IN THE UPPER 50S/LOWER 60S. RETURN TO SUMMER HEAT AND HUMIDITY
NEXT WEEKEND AS UPPER LEVEL RIDGE BUILDS IN ALONG WITH UPPER 80S
AND LOWER 90S.

THANKS FOR THE COORDINATION...IND...DVN...LSX...CHI...PAH.

PRELIMINARY CCF FOR COORDINATION PURPOSES...

SPI BE 066/087 068/081 061 07634
PIA BE 065/085 065/079 059 07635
DEC BE 066/086 068/081 061 07734
CMI BE 066/086 068/080 061 07733
MTO BE 068/086 069/083 063 07733
LWV BE 070/089 071/088 067 07633

.ILX...FLASH FLOOD WATCH THIS EVENING FROM I-55 EAST TO INDIANA.

HUETTL

ILZ027>031-036>038-040>057-061>063-066>068-071>073-251100-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL
1208 PM CDT SAT JUN 24 2000

...FLASH FLOOD WATCH IN EFFECT FOR CENTRAL ILLINOIS TODAY...

AN AREA OF LOW PRESSURE WILL MOVE ACROSS ILLINOIS THIS AFTERNOON
BRINGING WITH IT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. THOUGH
THE PRIMARY THREAT OVER CENTRAL ILLINOIS IS FROM HEAVY RAINFALL...
THERE IS A CHANCE THAT SOME OF THESE STORMS COULD BECOME SEVERE
LATER THIS AFTERNOON...SOUTHEAST OF A SPRINGFIELD TO BLOOMINGTON
LINE.

THEREFORE SPOTTER ACTIVATION MAY BE REQUIRED LATER THIS AFTERNOON
AND INTO TONIGHT.

AUTEN