Severe Thunderstorm Warning 4, NWS Chicago, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
330 PM CDT THU APR 18 2002

ONGOING INTENSE/SEVERE CONVECTION CURRENTLY MOVING ENE OUT OF IA
INTO NW IL WITH MEAN MID LEVEL FLOW. SHOWERS FADED OUT AS MOVED ENE
ACROSS THE MS RIVER OUT OF NE MO INTO W CENTRAL IL EARLIER...BUT NEW
INTENSE CONVECTION HAS RECENTLY DEVELOPED JUST W OF THE MS RIVER AS
SHORT WAVE LIFTS NE INTO MO. EXPECT THESE TWO LINES TO CONTINUE TO
FILL IN AND MOVE INTO NW IL LATE THIS AFTERNOON ALONG AXIS OF
GREATEST INSTABILITY...BUT MAY SLOW A BIT IN THEIR EASTWARD PROGRESS
AS THEY ENCOUNTER LOWER 50 DEW POINTS ACROSS NORTHERN IL. APPROACH
OF DRY LINE AND COLD FRONT LATER THIS EVE WILL KEEP TSRA GOING WELL
INTO THE NIGHT AS IT PUSHES INTO NE IL. COLD FRONT CONTINUES INTO NW
IN DURING THE MORNING BEFORE SLOWING IN CENTRAL IL DURING THE
AFTERNOON AND EVENTUALLY BECOMING STATIONARY ACROSS SOUTHERN IN AND
CENTRAL IA BY EVE AS A SURFACE WAVE DEVELOPS IN MO...MOVING TO THE
LOWER OH VALLEY BY SAT MORNING.  THIS BRINGS OVERRUNNING RAIN INTO
CENTRAL IL AND INTO AT LEAST THE SOUTHERN PART OF THE CWA FRI NIGHT.
THE COLD SURFACE HIGH SETTLES FURTHER ACROSS THE UPPER MIDWEST SAT
IN THE WAKE OF THIS WAVE WITH CONTINUED COLD ADVECTION IN THE LOWER
LAYERS. FLOW DOWN THE LAKE PERSISTS THROUGH WEEKEND AND WILL
CERTAINLY MAKE INFLUENCE OF STILL VERY CHILLY MID LAKE WATERS
KNOWN.

.CHI...NONE

TRS

ILZ003>006-008-010>014-019>023-032>033-039-INZ001>002-010>011-
019-191100-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
400 PM CDT THU APR 18 2002

FOR NORTH CENTRAL AND NORTHEAST ILLINOIS AND NORTHWEST INDIANA...

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN NORTH CENTRAL
ILLINOIS...AND A SLIGHT RISK ELSEWHERE TONIGHT.

FOR LATE THIS AFTERNOON THROUGH THIS EVENING...THE MODERATE RISK IS
NORTH AND WEST OF A MCHENRY TO DIXON LINE...WITH A SLIGHT RISK
ELSEWHERE. THE MAIN THREATS ARE LARGE HAIL AND DAMAGING WINDS...WITH
ISOLATED TORNADOES POSSIBLE IN NORTH CENTRAL ILLINOIS.  DAMAGING
WINDS WILL BECOME THE PREDOMINANT THREAT BY LATE EVENING.

LOW PRESSURE WILL CONTINUE TO MOVE EAST NORTHEAST ACROSS CENTRAL
WISCONSIN THIS EVENING...WITH ITS TRAILING COLD FRONT MOVING EAST
ACROSS IOWA AND INTO NORTHWESTERN ILLINOIS. A MID LEVEL WAVE WILL
MOVE NORTHEAST FROM MISSOURI ACROSS NORTHERN ILLINOIS THIS EVENING.
THIS WAVE...ACTING ON UNSTABLE AIR IN PLACE AHEAD OF THE COLD FRONT
WILL CONTINUE TO SUPPORT THUNDERSTORMS THIS EVENING. THE LINE OF
STORMS WILL MOVE EAST FROM THE MISSISSIPPI VALLEY INTO NORTHERN
ILLINOIS AND ADJACENT NORTHWEST INDIANA TONIGHT.

TRS