Damaging Wind in Illinois, May 1, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
400 AM CDT WED MAY 1 2002

CONCERNS FOR THIS FCST PD...

MDT RISK SVR TSTMS OVR MOST OF CWA TDA/THIS EVE
HVY PCPN
TEMP FCSTS
FOG

SFC LOW NOW OVR NRN OK FCST TO DPN AND LIFT NEWD ACRS E CNTRL MO
THIS AFTN AND INTO IN TNGT.  MODELS STILL DIVERGE AS TO LOCATION OF
SFC LOW CNTR AS IT LIFTS ENEWD TWD INDIANA TNGT. ETA STILL FURTHEST
SOUTH AND NGM/AVN STILL HOLDING IT FURTHER N. PROB IS THAT DENSE FOG
HAS FORMED N OF WRM FNT ACRS SRN THIRD MO.

SGFNT SVR WX FCST TO DVLP NR SFC LO AND ALG/NR WRM FRONTAL
BOUNDARY.  SPC HAS OUTLOOKED MOST OF CWA IN MDT RISK FOR TDA AND
TNGT.  THIS FOG DVLPMT HAS COMPLICATED MATTERS AS ELY FLOW N OF LOW
WL TEND TO HOLD IT IN AND MID/HI CLDS BEGINNING TO DEVELOP OVR WRN
MO OVERHEAD TO EXASTERBATE THE PROBLEM. CURRENT PRES FALLS STILL IN
OK NEAR LOW AS IT BEGINS TO DEEPEN SLOWLY.

MODELS ALL DVLP PCPN IN COLD AIR OVR NRN MO/CNTRL IL TDA AND THIS EVE
BUT DO LITTLE IN THE WARM AIR...HWVER COND WILL CONTINUE TO HEAT UP
AND DEVELOP W/TIME TDA. HAVE OPTED TO FOLLOW AVN MODEL AGAIN TODAY
AND ALLOW WRM FNT TO LIFT NWD AS LOW DEEPENS NEWD.  PROB IS WHAT TO
DO WITH FOG/LOW CLDS N OF LOW.  LOOKS LIKE THIS MAY LIFT NWD INTO E
CNTRL MO/SRN IL FOR AWHILE THIS MRNG. HV MODIFIED TEMPS DOWN A BIT
DUE TO COLD AIR PLACEMENT AND THE EWD ORIENTATION OF LLJ.

OFFICE HAS SET UP A STAFFING PATTERN FOR SGFNT SVR WX EPISODE THIS
AFTN/EVE.

NEXT THING IS HVY PCPN. FLOOD GUIDANCE LESS THAN 2 INCHES IN MOST
AREAS AND 1.00 TO 1.50 IN MANY PLACES...PCPBL WATER TOTALS ARE
UNSEASONABLY HIGH HWVR CELL MVMTS WILL BE RAPID AND LOCATION STILL
IN DOUBT...SO WILL MENT LOCALLY HEAVY AMOUTS IN IL ZONES BUT NO
HIGHLIGHTS FOR FLOODING.

STILL IN A QUANDRY ABOUT TEMPS...60S NORTH...FOG MAY HOLD AREAS
ALG/NR I-70 AROUND 70 DEG WITH WELL INTO 80S SOUTH.  IF LOW TREKS
ALG AVN  FCST GUIDELINES LOOK FOR SKIES TO CLEAR AND TEMPS TO JUMP
QUICKLY.

FOG....WL MENT DENSE FOG OVR SRN ZONES THIS MRNG BUT NOT ISSUE AN
ADVISORY AS DAYLIGHT WILL ALLOW FOR BETTER DRIVING VISIBILITIES
QUICKLY.

.STL...NONE

PEDIGO