Severe Thunderstorm Warning 36, NWS Chicago, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
255 PM CDT TUE MAY 27 2003

PRELIMINARY DISCUSSION FOR 4 PM ZONES/GRIDS

AT NOON FRONT ALONG MS RIVER WITH LOW 60 DPS ALONG IT. AFTER INITIAL
700 DPVA ZONE MOVES THRU THE LEAD SHOWER AREA PULLING OUT OF E
ZONES. DRY AIR REALLY ATE INTO THEM.

CLEARING ALLOWING AIRMASS TO DESTABILIZE ALONG FRONT SO NEW
SCATTERED TS DEVELOPING ALONG FRONT. THIS WILL MOVE OUT OF AREA
EARLY TONIGHT. STRONGEST LIFT WAS WITH INITIAL TROF BUT 110 KT JET
DROPPING SE FROM THE DAKOTAS  PROVIDING RESIDUAL LIFT AS MODEL OMEGA
FIELDS SHOW TO FIRE THE NEW TS. STRONG SHEAR ALOFT SO ISOLATED
SEVERE CELLS POSSIBLE. SOME 1/2 HAIL REPORTS GOOD BET.

NEW SYSTEM DIVES SE OVER THE AREA DURING FRIDAY...PROBABLY A LITTLE
WEAKER THAN THE AVN WHICH IS THE WAY NCEP IS LEANING. MODELS SHOW
GOOD THERMAL RIDGE OVER AREA FRIDAY AND WITH STRONG LOW TO NORTH AND
GOOD FRONT SOME STRONG STORMS WILL BE POSSIBLE DEPENDING ON TIME OF
DAY.

NO REAL CHANGE IS LONG RANGE PATTERN OF TROF OVER E US AND
RIDGE W US. GOOD CHILL BY SATURDAY AS ETA HAS ONLY 3-4C 850 TEMPS BY
SATURDAY EVENING.

WITH TROF STILL SHOWN ALOFT OVER AREA WILL HAVE SOME CLOUDS THRU
NIGHT BEFORE NICE DAY THURSDAY.

SHOULD BE SOME GUSTY WINDS TONIGHT BEHIND FRONT WITH GOOD MIXING.
LOOKS LIKE SOME LAKE COOLING IL SHORE BUT MORE DEFINITE IN SHORE FOR
THURSDAY.

WILL MAKE LAST MINUTE ZONE DECISIONS BASED ON LATEST RADAR.

.CHI...NONE

AF

AVIATION DISCUSSION FOR 18Z TAFS...
PRE-FRONTAL SHOWERS ENDING THEIR PASSAGE ACROSS TAF AREA. COLD FRONT
REMAINS TO THE WEST WITH POSSIBILITY OF SOME PRECIP DEVELOPMENT
LINGERING UNTIL FROPA. FIRST SIGNS OF CU BUILDUP VISIBLE ON
SATELLITE AND A FEW 40 DBZ RETURNS SHOWING ON RADAR BUT ACTIVITY IS
WIDELY SCATTERED. HAVE CHOSEN TO KEEP TAFS DRY FOR NOW WITH THE
EXPECTATION THAT FROPA WILL OCCUR ABOUT/AFTER THE TIME OF BEST
HEATING AND PROB IS RELATIVELY LOW. AM CROSS SECTIONS SUGGEST MAX
UVV GOING THROUGH NORTHEAST IL ATTM FURTHER LIMITING CHANCES. SOME
COLD AIR SC EXPECT BEHIND FRONT TIL SUNSET. TIGHT GRADIENT WILL KEEP
NORTHERLY WIND SPEEDS BRISK UNTIL ABOUT 06Z.

ILZ003>006-008-010>014-019-020>023-032-033-039-
INZ001-002-010-011-019-282200-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
100 PM CDT WED MAY 28 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST
ILLINOIS...NORTHWEST INDIANA...AND THE ADJACENT WATERS OF LAKE
MICHIGAN.

.DAY ONE... THIS AFTERNOON AND TONIGHT

CLEARING SKIES JUST AHEAD OF A COLD FRONT ALONG THE MISSISSIPPI
RIVER AT NOON HAS ALLOWED THE AIRMASS TO RAPIDLY DESTABILIZE.
SCATTERED THUNDERSTORMS WILL DEVELOP ALONG THE FRONT THROUGH 7 PM. A
STRONG JET STREAM COMING INTO THE AREA FROM THE NORTHWEST MAY HELP
PRODUCE SOME STORMS CAPABLE OF PRODUCING STRONG WINDS AND LARGE
HAIL.

.DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY

THERE IS CHANCE OF THUNDERSTORMS FRIDAY AFTERNOON AND EVENING.
ISOLATED SEVERE WEATHER IS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS MAY BE NEED THIS AFTERNOON AND EVENING.

&&

           NWS CHICAGO WEBPAGE

    HTTP://WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
OR  HTTP://WEATHER.NOAA.GOV/CHICAGO (LOWER CASE)