Severe Thunderstorm Warning 131, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CDT MON JUL 23 2001

SFC ANALYSIS SHOWS A WK TROF PROGRESSING ACROSS THE MIS RVR INTO
IL.  SHRA/TSRA STARTING TO DVLP ALONG THIS BOUNDARARY ATTM AS SFC
CONVG PROVIDING ENOUGH LIFT.  LOTS OF UNSTABLE AIR LAYING AROND CEN
IL TO INTERACT WITH THIS FRONT  WITH SFC DWPTS NR 80.  MAIN SFC COLD
FRONT IS LAGGING ACROSS SRN MN WITH RELATIVELY DRIER AIR.

MAIN CONCERNS TDY WILL BE TSRA CHC TNGT AND TUES...AND THE DRIER
AIRMASS MOVING INTO THE AREA FOR WED.   PREFER THE ETA MODEL THIS
CYCLE AS ITS DOING A FAIRLY GOOD JOB WITH VORT MAXES AND SFC
BOUNDARIES.  ETA BRINGS SFC TROF ACROSS NRN SECTIONS OF CEN IL THIS
EVE...WITH SHRA/TSRA.  THIS VERIFIES PRETTY WELL WITH CURRENT 88D
TRENDS.  LOTS OF OTHER SFC BOUNDARIES AVAILABLE FOR TSRA
INITIATION.  SO WILL GO CATEGORICAL POPS FOR THIS EVE MOST PLACES.
WILL ONLY KEEP TSRA WORDING DURING THE EVE HOURS FOR NRN SECTIONS OF
CEN IL...AS OUTFLOW FROM CURRENT CONVECTION PUSHES SOUTH TOWARDS SRN
IL...WITH BUBBLE HIGH IN PLACE NORTH.  EVENING RAINS WILL KEEP TEMPS
DOWN A BIT SOMEWHAT OVERNIGHT...JUST BELOW HEAT ADVIS LEVELS.  WILL
KEEP ADVIS GOING FOR THE EVE HOURS...AS HEAT INDEX STAYS ABOVE
100...BUT WILL DISCONTINUE ADVIS FOR THE OVRNGT EXCEPT FOR SERN
IL.   PREFER THE SLIGTHLY WARMER MAV NUMBERS FOR LOW TEMPS...AS WARM
AIRMASS WILL STILL BE IN PLACE TNGT.

MAIN SFC FRONT MAKES ITS WAY SOUTH INTO IL ON EARLY TUES.  THIS IS A
LITTLE FASTER THAN PREVIOUS RUNS.  BOUNDARY PUSHES THROUGH NRN
SECTIONS OF CEN IL MAINLY DRY...WITH DVLPMT EXPECTED ALONG THIS
BOUNDARY DURING THE DAY ON TUES ACROSS CEN IL.  BELEIVE ETA MODEL
MAY BE A BIT FAST WITH THIS FRONT...SO WILL LEAVE GOING POPS FOR
MOST AREAS ALONE...BUT NIGHT SHIFT MAY HAVE TO ADJUST POPS FOR TUES
GIVEN SPEED OF FRONT.  CLOUD DEBRIS OVHD ON TUES AND EARLY FROPA
WILL BRING A SOMEWHAT DRIER AIRMASS TO NRN SECTIONS OF CEN IL ON
TUES.  EVEN THOUGH TEMPS WILL STILL BE AROUND 90...DWPTS WILL BE
SLIGTHLY LOWER...SO SEE NO NEED TO CONTINUE HEAT ADVIS FOR NRN
SECTIONS.  WILL CONTINUE HEAT ADVIS FOR SOUTH OF I-70 AS FRONT WILL
STALL OUT IN CEN IL TUES NIGHT.

ANOTHER S/WV MOVES ALONG THE STATIONARY FRONT ON WED...WITH THE BEST
CHC OF WIDESPREAD RAIN EXPECTED BY WED AFTN FOR CEN IL AS SHRA
OVERRUN THE BOUNDARY. THIS REINFORCING SHOT OF DRIER AIR WILL BRING
A NOTICEABLE TEMP/DWPT CHANGE FOR WED NGT INTO THU.  FAN/MAV NUMBERS
LOOK TOO COOL FOR HIGHS...SO WILL GO WITH A COMPROMISE BETWEEN THEM
AND TOO WARM FWC NUMBERS.

SHRA/TSRA CHC LINGERS IN SERN IL EARLY THU AS FRONT HANGS UP ACROSS
THIS AREA.  WILL DRY THINGS OUT ELSEWHERE...WITH MORE PLEASANT TEMPS
ACROSS THE AREA. LATER STAGES OF THE AVN KEEP THINGS DRY ACROSS THE
AREA FRI AND SAT AS HIGH PRESS RIDGE MOVES ACROSS THE GRT LKS.  WARM
AIRMASS RETURNS FOR THE WEEKEND...WITH NOCTURNAL TSRA CHC BACK FOR A
VISIT.  WILL ADD TSRA CHC FOR SUN INTO MON AS INSTABILITY RETURNS.

...PRELIMINARY CCF FOR COORDINATION PURPOSES ONLY...

SPI TB 074/089 069/084 061 22666
PIA TB 073/088 067/082 060 22664
DEC TB 075/089 069/084 061 22666
CMI TB 075/088 070/083 059 22666
MTO TB 076/091 072/082 065 22466
LWV GT 077/093 074/084 065 22446

.ILX...HEAT ADVISORY THIS EVENING FOR CENTRAL/EASTERN
ILLINOIS.        HEAT ADVISORY TONIGHT INTO TUESDAY ALONG AND SOUTH
OF I-70.

KETCHAM

ILZ027>031-036>038-040>057-061>063-066>068-071>073-231830-

HAZARDOUS WEATHER OUTLOOK FOR CENTRAL ILLINOIS
NATIONAL WEATHER SERVICE LINCOLN IL
1225 PM CDT MON JUL 23 2001

...HOT WEATHER WILL BE ACCOMPANIED BY AFTERNOON THUNDERSTORMS...

HOT AND HUMID CONDITIONS CAN BE EXPECTED IN CENTRAL AND SOUTHEAST
ILLINOIS THIS AFTERNOON. TEMPERATURES CLIMBING INTO THE 90 TO 95 DEGREE
RANGE WILL COMBINE WITH HIGH LEVELS OF HUMIDITY TO PRODUCE HEAT INDICES
RANGING FROM 105 TO 110 THIS AFTERNOON INTO EARLY THIS EVENING. A
HEAT ADVISORY IS IN EFFECT FOR ALL OF CENTRAL AND SOUTHEAST ILLINOIS
THIS AFTERNOON AS A RESULT.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP IN CENTRAL ILLINOIS
THIS AFTERNOON. SOME OF THE THUNDERSTORMS WILL HAVE THE CAPABILITY
OF PRODUCING GUSTY WINDS AND VERY HEAVY RAINFALL...HOWEVER...THE THREAT
FOR ANY ORGANIZED SEVERE WEATHER APPEARS TO BE LIMITED.

SMITH