Tornado Warning 69, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
145 PM CDT FRI JUL 9 1999

FOR A SECOND DAY MODELS IN EXCELLENT AGREEMENT THIS WEEKEND AS COLD
FRONT SLOWLY SLIDES SE THROUGH CENTRAL IL THRU THIS AFTERNOON/TONIGHT.
FORECAST CHALLENGE IS TIMING OF FRONT AND ASSOCIATED SLIGHT RISK OF SVR
WX AND HEAVY RAINS TONIGHT SE I-70. THEN ADDRESSING AMOUNT OF COOLING
AND DRYER CANADIAN AIR ADVECTING IN THIS WEEKEND AS BROAD UPPER LEVEL
LOW EXPANDS ACROSS THE NE QUARTER OF THE U.S.

18Z COLD FRONT STRETCHES FROM 1000 MB LOW OVER LAKE HURON SW THRU
BMI/UIN AND INTO CENTRAL KS. FRONT TO SLIDE SE TO I-70 AROUND 03Z AND
TO LWV AROUND 09Z...ABOUT 3 HRS THAN MODEL RUN 24 HRS AGO. STRONG SHORT
WAVE OVER N MN TO SHEAR ESE ACROSS THE GREAT LAKES TONIGHT WITH STRONG
UVV DEVELOPING SE OF I-70 THIS EVENING AS THIS AREA GETS IN RIGHT REAR
QUADRANT OF W-E 100-110 KT JET STREAMING E INTO THE GREAT LAKES...THEN
UVV WEAKENING SE BETWEEN 6-12Z. LIKELY CHANCE OF SHOWERS/THUNDERSTORMS
SE CWA TONIGHT WITH HIGH INSTABILITY...CAPES 2200-3500 J/KG AND LIFTED
INDICES OF MINUS 4-7C THIS EVENING. PRECIPITABLE WATER VALUES OF
1.75-2.15 INCHES SE OF I-70 SUPPORTS HEAVY RAINS WITH ETA AGAIN WETTER
AND SHOWING 1.50-2.00 INCHES NEAR LWV. PROB30/40 CHANCE OF AN EVENING
SHOWER/THUNDERSTORM HEART OF CWA ALONG I-72 MAINLY BEFORE SUNSET THEN
CLEARING...CLEARING SKIES N CWA WHERE FRONT HAS ALREADY PASSED.
SECONDARY TROUGH OVER N WI/CENTRAL MN AND CENTRAL DAKOTAS TO ACCELERATE
SE AND KEEP ASSOCIATED BKN STRATOCUMULUS FIELD MOSTLY NE OF CENTRAL IL.

PROB30 CHANCE OF A MORNING SHOWER SE NEAR LWV SAT...OTHERWISE PARTLY
SUNNY SKIES AND DRY WITH SCT...TEMPO BKN CUMULUS DECK. AN ISOLATED
AFTERNOON SHOWER COULD APPEAR ESPECIALLY NEAR INDIANA BORDER WITH WEAK
SHORT WAVE SLIDING SE THROUGH AREA...BUT MOISTURE LACKING SO YANKING 30
POPS OUT. LAYERED RH FIEDS REMAIN FAIRLY DRY SAT NIGHT/SUNDAY SO MOSTLY
CLEAR-PARTLY CLOUDY SKIES AS 1028 MB HIGH PRESSURE OVER SOUTHERN
ALBERTA MOVES INTO THE CENTRAL PLAINS AND RIDGES ACROSS THE SOUTHERN
GREAT LAKES.

DRYER AIR ALREADY ADVECTING INTO N CWA WHERE DEWPOINTS FALLING THROUGH
THE 60S. LOW-MID 70S DEWPOINTS TODAY TO LOWER INTO THE 50S SAT RANGING
FROM A FEW UPPER 40S N CWA AND 60-65 CWA BY SAT AFTERNOON. SIMILAR
DEWPOINTS EXPECTED SUNDAY. BELOW NORMAL FWC/FAN TEMP GUIDANCE ONLY 0-3
DEGREES APART NEXT 48 HOURS AND FOLLOWED CLOSELY.

LONG TERM FORECAST CONTINUES TO SHOW STRONG UPPER LEVEL HIGH PRESSURE
BUILDING OVER THE GREAT BASIN AND EXPANDING E NEXT WORK WEEK WITH A
GRADUALL WARMUP TO ABOVE NORMAL TEMPS BY WED WITH INCREASING HUMIDITY.

PRELIMINARY TEMPS/POPS

SPI BB 064/079 055/081 055  07320
PIA BB 061/077 053/080 055  07220
DEC BB 065/078 056/080 054  07420
CMI BB 064/077 055/079 054  07420
MTO BB 066/080 057/081 057  07620
LWV BB 069/082 060/082 059  07730

.ILX...
IL...NONE.

HUETTL

ILZ027>031-036>038-040>057-061>063-066>068-071>073-100900-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL
1105 AM CDT FRI JUL 9 1999

A FEW STRONG THUNDERSTORMS ARE EXPECTED ACROSS CENTRAL AND
SOUTHEAST ILLINOIS THIS AFTERNOON AND EARLY TONIGHT.

A COLD FRONT ACROSS EASTERN IOWA THIS MORNING IS FORECAST TO TRACK
SLOWLY THROUGH CENTRAL ILLINOIS TODAY. THE AIR MASS AHEAD OF THE
FRONT SHOULD BECOME VERY UNSTABLE THIS AFTERNOON AND EVENING.
SCATTERED SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS PARTS OF
CENTRAL ILLINOIS THIS MORNING WITH BETTER STORM ORGANIZATION
EXPECTED ALONG THE FRONTAL BOUNDARY THIS AFTERNOON AND EVENING.
PRESENT INDICATIONS SUGGEST THE PRIMARY THREAT WITH SOME OF THE
STRONGER STORMS THIS AFTERNOON WILL BE STRONG GUSTY WINDS...HEAVY
RAINFALL AND HAIL. THE MAIN THREAT AFTER DARK WILL BE HEAVY RAINFALL
MAINLY SOUTHEAST OF A SPRINGFIELD TO DANVILLE LINE.

EMERGENCY MANAGERS AND SPOTTERS SHOULD MONITOR LATER FORECASTS
FOR POSSIBLE ACTIVATION THIS AFTERNOON AND EVENING.

PLAHMER

ILZ027>031-036>038-040>057-061>063-066>068-071>073-100900-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL          ...UPDATED RISK...
1225 PM CDT FRI JUL 9 1999

A COLD FRONT IS FORECAST TO MOVE SLOWLY SOUTH THROUGH ILLINOIS
THIS AFTERNOON AND THIS EVENING. A VERY UNSTABLE AIR MASS AHEAD OF
THE FRONT WILL INTERACT WITH THE BOUNDARY TO PRODUCE SCATTERED
THUNDERSTORMS THIS AFTERNOON AND THIS EVENING. SOME OF THESE STORMS
MAY BE SEVERE AT LOCATIONS ALONG AND EAST OF A BLOOMINGTON TO
JACKSONVILLE LINE. THE PRIMARY SEVERE WEATHER THREAT WILL BE
DAMAGING WINDS...HEAVY RAINFALL AND HAIL.

THE FRONT IS EXPECTED TO BECOME NEARLY STATIONARY ACROSS SOUTHERN
ILLINOIS TONIGHT. THEREFORE...THE MAIN THREAT AFTER DARK WILL BE
HEAVY RAINFALL AT LOCATIONS ALONG AND SOUTH OF INTERSTATE 70.

ACTIVATION OF EMERGENCY MANAGERS AND STORM SPOTTERS MAY BE NECESSARY
LATER THIS AFTERNOON AND THIS EVENING AT LOCATIONS ALONG AND EAST OF
A BLOOMINGTON TO JACKSONVILLE LINE.

PLAHMER

ILZ027>031-036>038-040>057-061>063-066>068-071>073-100900-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL          ...UPDATED RISK...
1225 PM CDT FRI JUL 9 1999

A COLD FRONT IS FORECAST TO MOVE SLOWLY SOUTH THROUGH ILLINOIS
THIS AFTERNOON AND THIS EVENING. A VERY UNSTABLE AIR MASS AHEAD OF
THE FRONT WILL INTERACT WITH THE BOUNDARY TO PRODUCE SCATTERED
THUNDERSTORMS THIS AFTERNOON AND THIS EVENING. SOME OF THESE STORMS
MAY BE SEVERE AT LOCATIONS ALONG AND EAST OF A BLOOMINGTON TO
JACKSONVILLE LINE. THE PRIMARY SEVERE WEATHER THREAT WILL BE
DAMAGING WINDS...HEAVY RAINFALL AND HAIL.

THE FRONT IS EXPECTED TO BECOME NEARLY STATIONARY ACROSS SOUTHERN
ILLINOIS TONIGHT. THEREFORE...THE MAIN THREAT AFTER DARK WILL BE
HEAVY RAINFALL AT LOCATIONS ALONG AND SOUTH OF INTERSTATE 70.

ACTIVATION OF EMERGENCY MANAGERS AND STORM SPOTTERS MAY BE NECESSARY
LATER THIS AFTERNOON AND THIS EVENING AT LOCATIONS ALONG AND EAST OF
A BLOOMINGTON TO JACKSONVILLE LINE.

PLAHMER