Severe Thunderstorm Warning 137, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
245 AM CDT WED JUN 14 2000

ETA MODEL CONTINUES TO BE FAVORED WITH GOOD INITIALIZATION AND
HANDLING OF TODAY/S NORTHERN STREAM SHORT WAVE FROM E SD INTO MN/WI
AND 2ND ONE APPROACHING IL BY 60HR/12Z FRI. NGM MAINTAINS STRONGER
SHORT WAVES WHICH SEEMS MORE REASONABLE GIVEN STRONG JET STRUCTURE
WITH 90-120 KT H3 JET NOSING FROM THE GULF OF AK INTO THE CENTRAL
ROCKIES. FORECAST CHALLENGE WILL BE THREAT OF SVR WEATHER THIS
AFTN/EVE AND AMOUNT OF COOLING AFTER ANOTHER VERY WARM/HUMID DAY.

07Z SFC ANALYSIS HAS 995 MB LOW IN SE SD WITH COLD FRONT OVER W IA
AND SE KS. BAND OF SHOWERS/THUNDERSTORMS MOVING TOWARD I-55 AND
WEAKENING AS GETTING WAY AHEAD OF FRONT AND OUTFLOW BOUNDARY RACING
E AHEAD OF CONVECTION. SCT CONVECTION EXPECT THROUGH THIS MORNING IN
TROPICAL AIR MASS. THEN EXPECT REDEVELOPMENT OF MORE NMRS SHOWERS
AND THUNDERSTORMS TO FIRE UP ACROSS CENTRAL IL ALONG LINGERING
OUTFLOW BOUNDARYS BY EARLY AFTN AS COLD FRONT APPROACHES. QUITE
UNSTABLE WITH SBCAPES 2500-3500 J/KG AND DEWPOINTS NEAR 70 AND
STRONG UNIDIRECTIONAL SW FLOW. SPC HAS SLIGHT RISK ACROSS CWA FROM
GALESBURG SE...WITH SQUALL LINE MOVING E THROUGH CWA THIS AFTN AND
EXITING EAST CENTRAL AND SE IL DURING THIS EVENING. WILL CONTINUE TO
PLAY LIKELY POPS OF CONVECTION TODAY AND THIS EVENING...EXPECT NW
CWA WILL LOWER POPS TO CHANCE CATEGORY THIS EVE. PRECIPITABLE WATER
VALUES OF 1.25-1.75 INCHES IN TROPICAL AIR MASS INTO THIS EVE WILL
SUPPORT LOCALLY HEAVY RAIN. SHYING AWAY FROM A FLASH FLOOD WATCH
TODAY/EVE AS FFG VALUES 1-2 INCHES/1 HR AND 1.5-3 INCHES/3 HR.

BRUNT OF CONVECTION E OF IL AROUND MIDNIGHT WITH LINGERING SHOWERS
AND A FEW THUNDERSTORMS AFTER MIDNIGHT SE OF I-70 WITH COLD FRONT
REACHING IL RIVER BY 00Z/THU AND PASSING LWV BEFORE 12Z/THU. PLAN TO
KEEP IT DRY IN EASTCENTRAL IL THU WITH PROB30 CHANCE OF SHOWERS
EARLY THU MORNING SE CWA. SOMEWHAT LESS HUMID UNDER PARTLY SUNNY
SKIES WITH WSW WINDS LOWERING DEWPOINTS A GOOD 10 DEGREES INTO THE
UPPER 50S AND LOWER 60S.

TEMPWISE...TRIMMING HIGHS TODAY BACK A CATEGORY FROM IL RIVER NW
WHERE WIDESPREAD RAINS COOLED THEM INTO LOW-MID 60S EARLY THIS
MORNING...AND MORE CLOUDS TODAY. STILL IN THE MID 70S E OF I-55 AND
OUTFLOW BOUNDARY AT 2 AM/07Z. H85 TEMPS OF 18-20C YESTERDAY SLIP TO
15-17C TODAY AND 1-2C COOLER THU...THEN WARM TO 16-18C FRI. LOWS
TONIGHT IN LOW-MID 60S AND HIGHS NEAR 80 THU...LOWER 80S SE LOOK
GOOD. BACK INTO THE 80S ON FRI...AND COOLING A BIT THIS WEEKEND.

MEDIUM RANGE MODELS CONTINUE TO SHOW STRENTHENING SHORT WAVE ENERGY
EJECTING FROM THE GULF OF AK ACROSS THEN NORTHERN PLAINS BY LATE
WEEK WITH STRONG CYCLOGENESIS IN THE CENTRAL HIGH PLAINS LATE THU.
INCREASING S FLOW/WAA THU NIGHT/FRI QUICKLY RETURNS MOISTURE WITH
MUGGY DEWPOINTS BACK NEAR 70. COLD FRONT APPROACHES NW IL BY 00Z/SAT
AND TO SWEEP THRU THE STATE FRI EVENING...CONVECTION APPEARS LIKELY
FRI AFTN/EVE AND WILL NEED TO BE WATCH FOR SEVERE RISK AGAIN.
UNUSUALLY COLD AIR ALOFT GIVING STEEP LAPSE RATES FOR MID JUNE WITH
THIS SYSTEM THIS AND COULD ENHANCE SVR WX THREAT THIS FAR SOUTH.
COULD BE ANOTHER BREAK FROM CONVECTION SAT WITH SHOWERS SUNDAY AND
SUNDAY NIGHT AS OVERRUNNING SETS UP WITH SFC LOW FROM THE SOUTHERN
PLAINS EJECTING NE INTO THE OHIO VALLEY.

THANKS FOR THE COORDINATION DVN.

PRELIMINARY CCF FOLLOWS...

SPI TB 084/062 080/064 084 07751
PIA TB 082/061 078/065 082 07752
DEC TB 084/063 080/064 084 07762
CMI TB 086/064 079/063 083 07762
MTO TB 086/065 080/065 084 07763
LWV TB 087/067 082/066 086 07773

.ILX...NONE.

HUETTL

ILZ027>031-036>038-040>057-061>063-066>068-071>073-151200-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL
1120 AM CDT TUE JUN 14 2000

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FOR MUCH OF CENTRAL ILLINOIS. THE MAIN THREAT WILL BE EAST
OF INTERSTATE 55. PRIMARY SEVERE WEATHER THREAT WILL BE WIND DAMAGE...
ALONG WITH ISOLATED LARGE HAIL.

SPOTTER ACTIVATION MAY BE NEVEDED LATER TODAY.

HEDGES