Tornado Warning 50, NWS Chicago, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
315 PM CDT MON JUL 5 2004

.DISCUSSION FOR AFTERNOON ZONES/GRIDS:
MAIN WX PROBLEM THIS AFTN CONCERNS ANTICIPATED DVLPMT OF TSTMS.
CURRENT VIS SATLT TRENDS SHOW ELEVATED CONVECTION DVLPG IN ARC FROM
NRN IA-NWRN IL...ALG AND JUST N OF SFC BOUNDARY.  STGST DVLPMT IS
OVR NRN IA WHERE DEEP LYR MOIST CONVERGENCE IS STRONGEST.  THIS AREA
FCST WELL ON 700 MB OMEGA FIELD FROM 12Z GFS RUN.  AREA IS FCST TO
MOVE E-ENEWD INTO WI OVERNIGHT.  HOWEVER...ADDITIONAL TSTM DVLPMT
EXPECTED ACRS SWRN IA/NRN MO NXT FEW HRS AS STG MID LVL CIRCULATIION
EVIDENT OVR SWRN IA LIFTS NEWD.  THIS IS THE ACTIVITY THAT SHOULD
MOVE INTO FA THIS LATER THIS EVENING.  AREA WILL LIKELY GET DRY
SLOTTED AS MID LVL TROF AXIS MOVES THRU AND MAIN AREA OF PCPN LIFTS
N AND E OF AREA.  HOWEVER...WILL KEEP POPS IN FOR TUES INTO TUES
EVENING AS PER MOS GUID.  AS UPR SYS MOVES N OF FA ON TUES...ASSD
COLD POOL MAY BE SUFFICIENT TO ALLOW SCT INSTABILITY SHWRS/TSTMS TO
DVLP AGAIN. EFFECTIVE COLD FROPA EXPECTED TUES AFTN-EVE WITH SIG AMS
CHG TUES NGT.  GFS SHOWS 1000-500 MB THKNS DROP OF ARND 100 M WITH
DECENT LO LVL COLD ADVECTION.  COLD ADVECTION TO CONT MOST OF WED AS
WELL AND INSTABILITY SHWRS COULD DVLP AGAIN WED AFTN...BUT THIS
LOOKS MOST LIKELY TO N OF FA SO WILL NOT MENTION FOR NOW.  SFC RIDGE
AXIS THEN FCST TO MOVE THRU ON THUR.  AS THIS FEATURE MOVES E OF
AREA BY FRI...MORE SUMMERLIKE CONDS TO RETURN.  BY WEEKEND...BROAD
H5 RIDGE FCST TO BUILD OVR SRN U.S. SUGGESTING ONSET OF MORE
TROPICAL REGIME DURG EXTENDED PERIOD...WITH SEASONABLY WARM TEMPS
AND NOTABLE INCRS IN HUMIDITY.  GFS/MRF HAS AREA ALG PERIPHERY OF
THIS RIDGE SO WILL GO A LTL ABV CLIMO AND EXPECT WARM HUMID DAYS
WITH MUGGY NIGHTS OVR WEEKEND AND INTO NXT WEEK...WITH A DAY-TO-DAY
CHC OF AN AFTN TSTM.

MERZLOCK

&&

.AVIATION...
18Z TAFS...SFC HEATING ALLOWING ENUF MIXING DOWN OF DRIER AIR TO
ERODE AWAY ST ACROSS FAR NE IL INTO SE WI EXC NEAR LK FM CIH NWRD
WHERE NERLY BL FLO OFF LK MI KEEPING SFC TEMPS IN 60S. NRN EXTENT OF
TSRA ACROSS E CNTRL IL INTO SWRN IND IS ABOUT DNV...AND NOT EXPECTED
TO REACH MUCH FURTHER N AS IS UNDER MID/UPR RDG AXIS ATTM SO SHUD
START TO TURN SLGTLY SEWRD. WK ECHOES EXTEND NWWRD S OF QUAD CITIES
INTO IA ALONG/N OF WMNFT THO VIS SAT INDICATES LTL CONVECTIVE
DVLPMNT AS BOTH BEST LO LVL CONVERGENCE AND UPR SUPPORT FURTHER W IN
IA. INCREASING CONVERGENCE AND LIFT TO SPREAD E ALONG WMFNT INTO NRN
IL THIS EVE AS SHRTWV LIFTS ACROSS IA BUT STILL MAIN AREA OF TSRA TO
MOVE NEWRD MAINLY TO NW AND N OF TERMINALS. BEST TIME FRAME FOR TSRA
04Z-07Z WITH GREATEST UVV/ISENTROPIC UPGLIDE AS WMFNT APPROACHES.

TRS

&&

.LOT...WATCHES/WARNINGS/ADVISORIES...
.IL...NONE.
.IN...NONE.
.LK MI...NONE.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
630 PM CDT MON JUL 5 2004

ILZ003>006-008-010>014-019>022-023-032-033-039-INZ001-002-010-011-019
-061100-
WINNEBAGO-BOONE-MCHENRY-LAKE IL-OGLE-LEE-DE KALB-KANE-DU PAGE-COOK-
LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-IROQUOIS-FORD-
LAKE IN-PORTER-NEWTON-JASPER-BENTON-
630 PM CDT MON JUL 5 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL
AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT
SCATTERED THUNDERSTORMS ACROSS NORTH CENTRAL AND NORTHEAST ILLINOIS
WILL DIMINISH BY AROUND 8 PM CDT. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO SPREAD BACK ACROSS THE AREA AFTER 10
PM CDT THIS EVENING. THE THUNDERSTORMS ARE EXPECTED TO DIMINISH
AFTER 2 AM CDT. THERE IS A SLIGHT CHANCE FOR SEVERE THUNDERSTORMS
BETWEEN 10 PM AND 2 AM CDT. THE MAIN THREATS WITH THESE STORMS WILL
BE LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY...MAINLY
EAST OF A LINE FROM CHICAGO TO PONTIAC.

THUNDERSTORMS ARE ALSO POSSIBLE AGAIN ON SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY AFTER 9 PM CDT THIS EVENING.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE
NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

LMZ740>746-766-051100-
WINTHROP HARBOR IL TO NEW BUFFALO MI-
LAKE MICHIGAN-
630 PM CDT MON JUL 5 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS
AND INDIANA WATERS OF LAKE MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THUNDERSTORMS ARE EXPECTED TO MOVE ACROSS SOUTHERN LAKE MICHIGAN
TONIGHT.

THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AFTER 10 PM CDT
THIS EVENING. SOME OF THE STORMS MAY PRODUCE WIND GUSTS IN EXCESS OF
35 KNOTS ALONG WITH SOME HAIL. THE THREAT FOR THUNDERSTORMS IS
EXPECTED TO DIMINISH AFTER 3 AM CDT.

DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE IS A CHANCE OF THUNDERSTORMS AGAIN ON TUESDAY.

THUNDERSTORMS ARE POSSIBLE AGAIN ABOUT SATURDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE
NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

MARSILI