Damaging Wind in Indiana, May 6, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
240 PM CDT SUN MAY 6 2001

THE UPPER TROUGH OVER THE CANADIAN ROCKIES WILL DEEPEN SLIGHTLY AND
CONTINUE ITS SLOW EASTWARD MOVEMENT THROUGH THIS FORECAST CYCLE. THE
CWA WILL REMAIN UNDER THE INFLUENCE OF THE LOW WITH SOME SHOWERS AND
THUNDERSTORMS TONIGHT AND INTO MONDAY.

THE 18Z SURFACE ANALYSIS PLACES A NEARLY STATIONARY WARM FRONT
ACROSS NORTHERN AND CENTRAL ILLINOIS FROM AROUND MOLINE SOUTHEAST TO
AROUND CHAMPAIGN. ALTHOUGH THE SURFACE WIND FIELD SUGGESTS THIS
PLACEMENT ITS BEST SEEN IN THE DEWPOINT GRADIENT ACROSS THE SAME
AREA. SURFACE DEWPOINTS VARYING BY 10 TO 12 DEGREES ACROSS THE
BOUNDARY WITH VALUES IN THE LOWER 60S SOUTH AND SOUTHWEST OF THE
FRONT AND VALUES AS LOW AS THE UPPER 40S TO THE NORTH AND NORTHEAST.

THE MODELS SUGGEST SOME LONG AWAITED MOVEMENT OF THE SURFACE
BOUNDARY THIS EVENING/TONIGHT AS THE FIRST OF AT LEAST TWO SHORT
WAVES ROTATE THROUGH THE BOTTOM OF THE UPPER TROUGH AND PROVIDE A
MECHANISM FOR MOVING THE SURFACE FEATURE. THE EFFECTS OF THESE SHORT
WAVES CAN BE SEEN IN THE TIME CROSS-SECTIONS WHERE TWO UVV MAXES ARE
EVIDENT OVER NORTHEAST ILLINOIS -- ONE TONIGHT AND THE SECOND DURING
THE FIRST HALF OF MONDAY.

GIVEN THE MOISTURE FIELD IN PLACE AND TO BE ADVECTED TONIGHT ALONG
WITH SOME MODERATE OMEGA, THE CURRENT FORECAST FOR LIKELY PRECIP
LOOKS GOOD. AS WAS THE CASE YESTERDAY AFTERNOON, DEVELOPMENT SHOULD
BE ALONG THE WARM FRONTAL BOUNDARY AND NOT PERSISTS TOO FAR AWAY
FROM IT.

THE SECOND VORT MAX MOVES THROUGH AROUND 18Z MONDAY AND IS
ASSOCIATED WITH THE TRAILING COLD FRONTAL PASSAGE. THIS SHOULD HELP
WITH A SECOND CHANCE FOR PRECIP -- ESPECIALLY IN THE EARLY PART OF
THE DAY TOMORROW. THOUGH THE FRONT PASSES SOMETIME MONDAY AFTERNOON,
RH FIELDS SUGGEST A RATHER RAPID DRYING ALONG THE FRONT THAT SHOULD
BE ENOUGH TO CUT OFF THE CHANCE FOR ANY FURTHER PRECIP.

THE UPPER LOW IS SLOW TO LEAVE THE UPPER LAKES SO IT SHOULD REMAIN
RELATIVELY CLOUDY AFTER FROPA WITH ONLY A WEAK RIDGE BUILDING ACROSS
THE AREA LATE WEDNESDAY AHEAD OF THE NEXT SYSTEM.

ALTHOUGH TEMPERATURE GUIDANCE NUMBERS ARE FAIRLY CLOSE AMONG THE
THREE SETS OF MOS, THE FAN NUMBERS APPEARS ON THE LOW SIDE FOR
MONDAY GIVEN THAT THE AREA WILL BE IN THE WARM AIR. OTHERWISE MOS
LOOKS OK.

.CHI...NONE

SOMREK

ILZ003>006-008-010>014-019>023-032>033-039-INZ001>002-010>011-019-
071100-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
1200 PM CDT/EST SUN MAY 6 2001

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

ALTHOUGH THUNDERSTORMS ARE EXPECTED TO DEVELOP LATE THIS AFTERNOON
AND TONIGHT OVER THE AREA...NONE OF THE THUNDERSTORMS ARE EXPECTED
TO BECOME SEVERE.

A NEAR STATIONARY FRONT LIES ACROSS NORTHERN AND CENTRAL ILLINOIS
FROM NEAR MOLINE TO NEAR CHAMPAIGN. THE FRONT WILL MOVE NORTH AS A
WARM FRONT LATE THIS AFTERNOON AND EVENING WITH SOME THUNDERSTORMS
EXPECTED TO DEVELOP NEAR THE FRONT.

SOMREK