Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 021143
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
643 AM CDT TUE JUN 2 2015

.SHORT TERM...(TODAY)
ISSUED AT 321 AM CDT TUE JUN 2 2015

CLOUD COVER WILL BE A CONCERN EARLY THIS MORNING. A WEAK SURFACE
TROUGH EXTENDING SOUTHWEST INTO OUR AREA FROM SW MICHIGAN SEEMS TO
BE CAUSING A BAND OF MID CLOUDS ALONG A LINE INCLUDING CHAMPAIGN TO
DECATUR TO TAYLORVILLE. ADDITIONAL CLOUDS ASSOCIATED WITH AN UPPER
LOW OVER EASTERN KENTUCKY ARE AFFECTING OUR SOUTHEAST COUNTIES SOUTH
OF I-70. THE SURFACE TROUGH IS EXPECTED TO WEAKEN WITH TIME THIS
MORNING...AND THE UPPER LOW OVER KENTUCKY IS PROJECTED TO SLIDE
EASTWARD TODAY. THOSE TWO THINGS SHOULD WORK TO REDUCE OUR CLOUD
COVER AS THE MORNING PROGRESSES. CU RULE OUTPUT INDICATES ONLY MINOR
CU FORMATION DURING PEAK HEATING...SO WE WILL TREND TOWARD A
MOSTLY SUNNY SKY IN THE GRIDS. SINCE 850 MB TEMPS DO NOT
APPRECIABLY WARM TODAY OVER YESTERDAY...THE ADDITIONAL SUNSHINE
TODAY OVER YESTERDAY ALONE SHOULD HELP BOOST HIGHS ABOUT 6-8
DEGREES ABOVE YESTERDAY...OR INTO THE LOW TO MID 70S. WINDS WILL
REMAIN GENERALLY BELOW 10 MPH FROM THE EAST AS A SURFACE RIDGE
AXIS CONTINUES TO EXTEND ACROSS THE AREA...KEEPING THE PRESSURE
GRADIENT RELATIVELY WEAK.

.LONG TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 321 AM CDT TUE JUN 2 2015

DRY CONDITIONS ON TAP THROUGH WEDNESDAY NIGHT AS WE REMAIN ON THE
PERIPHERY OF A SLOWLY DEPARTING HIGH PRESSURE AREA OVER THE GREAT
LAKES. THE MAIN QUESTION AS THE WEEK PROGRESSES IS THE AMOUNT OF
MOISTURE RETURN THAT WILL BE AVAILABLE...DUE TO THE MEANDERING UPPER
LOW CURRENTLY OVER THE WESTERN TENNESSEE VALLEY. THIS FEATURE WILL
MAKE ONLY SLOW EASTWARD PROGRESSION AND SHOULD BE IN NORTH CAROLINA
BY THURSDAY EVENING. LATEST NAM MODEL IS MOST AGGRESSIVE IN BRINGING
RAIN CHANCES BACK IN THURSDAY...MAINLY I-57 WESTWARD AS A FRONTAL
BOUNDARY TRAVERSING THE NORTHERN GREAT LAKES LINKS UP WITH A
DEVELOPING WARM FRONT OVER THE CENTRAL PLAINS. GFS AND ECMWF
STRUGGLE TO GET ANYTHING PAST THE ILLINOIS RIVER DURING THE DAY...
AND THE GFS ACTUALLY KEEPS US PRETTY MUCH DRY UNTIL FRIDAY EVENING.
HOWEVER...THE LATEST ECMWF...AND THE CANADIAN MODEL TO AN EXTENT...
BRING AN MCS THROUGH THE WESTERN CWA THURSDAY NIGHT AND FRIDAY.
LEANED CLOSER TO THE ECMWF SOLUTION AND WILL HAVE CHANCE POP`S I-55
WEST THURSDAY NIGHT AND HEALTHY 40-50% POP`S EVERYWHERE ON FRIDAY.

TRENDS FOR THE WEEKEND ARE A BIT MORE MUDDLED...AS THERE IS NOT MUCH
AGREEMENT AMONGST THE MODELS FOR SATURDAY. THE ECMWF IS INITIALLY
STRONGER WITH AN UPPER WAVE THAT WILL BE DIGGING SOUTHEAST OUT OF
THE CANADIAN PRAIRIES SATURDAY NIGHT...BUT STARTS TO COME BACK INTO
AGREEMENT WITH THE GFS BY SUNDAY. HAVE LARGELY KEPT JUST 20% POP`S
FOR SATURDAY AND SATURDAY NIGHT...BUT INCLUDED HEALTHY CHANCES ON
SUNDAY AS BOTH MODELS FEATURE SOME SORT OF MCS POTENTIAL NEARBY.

TEMPERATURES SHOULD BE FAIRLY UNIFORM THROUGH THE PERIOD...WITH
DAYTIME HIGHS A FEW DEGREES EITHER SIDE OF 80. THURSDAY LIKELY TO BE
THE WARMEST AS SUNSHINE WILL BE MOST PREVALENT ON THAT DAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 643 AM CDT TUE JUN 2 2015

A WEAKENING SURFACE TROUGH WILL KEEP A LINGERING BAND OF LOW VFR
CLOUDS NEAR OUR WESTERN TAF SITES OF PIA, BMI, AND SPI FOR A
COUPLE HOURS THIS MORNING. TURBULENT MIXING OF DRY AIR FROM ALOFT
WILL HELP TO SCOUR THEM OUT AS THE MORNING PROGRESSES. MVFR
CLOUDS ASSOCIATED WITH LOW PRESSURE IN WESTERN KENTUCKY WILL
LINGER SOUTHEAST OF I-70 THIS MORNING, AND SHOULD NOT REACH AS FAR
NORTH AS DEC. THAT LOW WILL DRIFT EAST AWAY FROM OUR AREA TODAY,
PULLING THOSE CLOUDS OUT OF SOUTHEAST IL BY AFTERNOON.

FORECAST SOUNDINGS IN THE RAP AND NAM SHOW DECREASING MOISTURE IN
THE CLOUD LAYER, SO GENERAL CLEARING IS EXPECTED THIS MORNING. CU
RULES SHOW ONLY MINOR REDEVELOPMENT OF CUMULUS CLOUDS DURING PEAK
HEATING, SO SKIES SHOULD REMAIN SCT.

WINDS WILL START OUT NORTHEAST, THEN BECOME EAST BY 15-16Z WITH
SPEEDS OF 7-10KT. EAST WINDS WILL CONTINUE TONIGHT AS SKIES BECOME
MOSTLY CLEAR UNDER PATCHY CIRRUS CLOUDS.

&&

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

$$

SHORT TERM...SHIMON
LONG TERM...GEELHART
AVIATION...SHIMON



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