Severe Thunderstorm Warning 166, NWS Lincoln, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
200 PM CDT SUN JUN 28 1998

18Z SFC ANALYSIS SHOWED COLD FRONT EXTENDING FROM WI INTO NWRN IL TO NRN
MO WITH WAVE DVLPING ON FRONT IN NERN KS.  DWPTS IN MID TO UPPER 70S
WITH TEMPS AROUND 90.  INSTABILITY IS VERY HIGH OVER AREA.  CU HAS DVLPD
ACRS MOST AREA WITH GREATEST EXTENT IN MO AND IA.  BASED ON SAT VIS
LOOP...LACK OF CU FIELD IN WRN IL AND ERN MO IS DUE TO EARLIER MCS
OUTFLOW BNDRY.  AIRMASS COULD BE SLIGHTLY CAPPED...THOUGH BUFKIT AND MDL
DATA SAYS NO AND MODIFIED 12Z SOUNDING ALSO SAYS NO.  TEMPS ON BOTH ILX
AND DVN SOUNDINGS AT 700MB WAS +10C WITH +12 ACRS NRN AND CNTRL MO.  CU
DOES HAVE MORE VERTICAL EXTENT TO IT THAT YSTRDY...BUT STILL SHALLOW.
FEW RWS HOWEVER POPPING UP ON RADAR AND NOT LASTING LONG.  MDLS DO
INDICATE MOISTURE CONVERGENCE AND UP LVL DIVERG OVER ERN MO/WRN IL THIS
EVE.  INSTABILITY IS FCSTD TO REMAIN HIGH WITH CAPE VALUES ABOVE 3000
J/KG.  LOW LVL DEWPOINTS WILL REMAIN IN MID TO UPPER 70S ON SFC AND +16C
AT 850.  COLD FRONT MOVING SLOWLY SOUTH INTO STATE THIS AFTN...WITH
STRONGEST FORCING IN WI AND NRN AND NWRN MO.  STORMS WILL DVLP ON FRONT
IN CWA OR OUTSIDE AND THEN MOVE IN.  EITHER WAY POPS SHOULD CONT IN CWA
FOR TONIGHT.  MDL ALSO INDICATES POTENTIAL FOR ANOTHER MCS DVLPING IN
NRN MO/IA OVERNIGHT. THIS WILL PROPAGATE INTO CNTRL IL OVERNIGHT.

FOR TOMORROW...STNRY FRONT OVER CNTRL IL WILL ACT AS FOCUS FOR MORE
CONVECTION.  HIGH MOISTURE WILL REMAIN INPLACE WITH CAPES AROUND 2500
J/KG.  INSTABILITY ALSO REMAINS HIGH AND 700MB TEMPS WILL BE
COOLER...FOR NO CAP.  PLUS FACTOR WILL BE WIND DYNAMICS...BETTER SHR AND
HELICITY FOR ROTATION.  AGREE WITH SPC DAY2 OUTLOOK AND DISCUSSION.

TEMPS OVERNIGHT WILL COOL LIKE THEY DID THIS MORNING WHEN OUTFLOW BNDRY
WENT THRU.  TOMORROW HIGHS DEPENDANT ON POSITION OF FRONT...90S SOUTH
AND 80S NORTH.

INPUT WILL FOLLOW SHORTLY.

PIA  73/88  57
SPI  77/92  57
DEC  77/92  57
CMI  75/90  57
LWV  78/93  57

AUTEN