000
FXUS63 KILX 301151
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
651 AM CDT FRI JUL 30 2010

.DISCUSSION...
ISSUED 230 AM CDT FRI JUL 30 2010

CWA REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE OVER THE GREAT
LAKES EARLY THIS MORNING. THE FRONTAL BOUNDARY WHICH PASSED THE
AREA A COUPLE DAYS AGO WAS NEAR THE OHIO VALLEY...THEN ARCING
NORTHWEST INTO THE CENTRAL PLAINS. MID LEVEL CLOUDS WERE MOVING
ACROSS ABOUT THE NORTHERN HALF OF THE CWA...AHEAD OF A PAIR OF MCS
SYSTEMS FROM MINNESOTA SOUTHWEST INTO NEBRASKA.

PRIMARY FORECAST CHALLENGE INVOLVES RAIN CHANCES THROUGH
SATURDAY.

SHORT TERM...TODAY THROUGH SUNDAY...

BULK OF PRECIPITATION TO REMAIN WEST OF THE CWA TODAY...AS THE
HIGH SLOWLY GIVES UP ITS GRIP ON OUR WEATHER. HAVE CONTINUED WITH
30-40 POPS ACROSS THE WEST THIS AFTERNOON AS THE FRONT APPROACHES.

00Z MODELS HAVING SOME DISCREPANCIES IN THE EVOLUTION OF THIS
STORM SYSTEM MOVING ACROSS OUR CWA TONIGHT AND FRIDAY. LATEST NAM
MODEL TOOK A MAJOR SHIFT NORTHWARD WITH ITS TRACK OF THE
LOW...HAVING IT CENTERED OVER WESTERN LAKE SUPERIOR BY 12Z
SATURDAY VS OVER NORTHERN ILLINOIS ON THE 18Z RUN. HAVE DISCOUNTED
ITS SOLUTION. THE GFS...ECMWF AND SREF CONTINUE TO BRING THE LOW
OVER NORTHERN OR CENTRAL ILLINOIS...ALTHOUGH THE GFS IS WEAKER
WITH THIS FEATURE. THE ECMWF WOULD SUGGEST THE REFORMATION OF THE
MINNESOTA MCS TODAY AND ROLLS IT SOUTHEAST OVER THE CWA AFTER
MIDNIGHT...WHILE THE GFS BRINGS SCATTERED SHOWERS FOR THE MOST
PART. LEANED MORE TOWARD THE ECMWF COVERAGE BUT NOT AS INTENSE
WITH THE PRECIPITATION...BRINGING MENTIONABLE CHANCES EAST TO I-57
THIS EVENING AND OVER THE REMAINDER OF EASTERN ILLINOIS AFTER
MIDNIGHT. RAIN TO END FROM WEST TO EAST ON SATURDAY...AS HIGH
PRESSURE BEGINS TO PUSH IN FROM THE WEST. THIS HIGH WILL RESULT IN
DRY CONDITIONS FOR THE SECOND HALF OF THE WEEKEND.

LONG TERM...MONDAY THROUGH THURSDAY...

UPPER LEVEL RIDGING...WHICH WILL BE A PROMINENT FEATURE OVER THE
WESTERN PLAINS THROUGH THE WEEKEND...IS PROGGED TO FLATTEN A BIT
EARLY NEXT WEEK...AS A SHORTWAVE RIDES ALONG THE TOP OF THE RIDGE.
ECMWF AND GFS ARE IN REASONABLE AGREEMENT WIT THESE UPPER LEVEL
FEATURES THROUGH MIDWEEK...ALTHOUGH HAVE SOME DISCREPANCIES WITH
THE SURFACE BOUNDARY AS IT BECOMES PARALLEL TO THE UPPER FLOW.
BOTH MODELS SUGGEST PERIODIC MCS ACTIVITY GENERALLY TRACKING FROM
IOWA ACROSS NORTHERN ILLINOIS.

GEELHART

.AVIATION...
ISSUED 651 AM CDT FRI JUL 30 2010

12Z TAF PERIOD WILL BE TOUGH TO FORECAST WITH RESPECT TO BEST TIME
FOR SHOWER/STORMS. HOWEVER...ON THE WHOLE...VFR CONDITIONS ARE
ANTICIPATED. A FEW WEAK UPPER LEVEL DISTURBANCES WILL DRIFT ACROSS
THE REGION TODAY INTO TONIGHT UNDER NORTHWEST FLOW. AT THIS POINT...
THE STRONGEST DISTURBANCE...AND BEST CHANCE FOR THUNDER...APPEARS
TO BE HEADED THROUGH TONIGHT. HOWEVER...CONFIDENCE IN TIMING IS
TOO LOW TO GO ABOVE A VCSH/VCTS MENTION AT THIS TIME. EXPECT WINDS
TO STAY GENERALLY LIGHT FROM THE SOUTHEAST.

BAK

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.