000
FXUS63 KILX 171708
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1208 PM CDT MON JUN 17 2013

.DISCUSSION...
ISSUED 1010 AM CDT MON JUN 17 2013

EARLY MORNING FOG HAS LARGELY LIFTED...WITH JUST A BIT OF HAZE
LINGERING NEAR THE INDIANA BORDER. LARGE CIRRUS SHIELD SPREADING
OVER MOST OF THE FORECAST AREA...ALTHOUGH A BAND OF ALTOCUMULUS IS
ALONG THE I-70 CORRIDOR. THIS IS IN THE SAME GENERAL AREA AS A
WEAK SURFACE BOUNDARY...AND IS THE MOST LIKELY LOCATION FOR ANY
CONVECTION TO DEVELOP...MAINLY DURING THE AFTERNOON HOURS. WITH A
BROAD POOL OF DEW POINTS NEAR 70 ALONG THE I-72 CORRIDOR...
SCATTERED STORMS ARE ALSO POSSIBLE THERE WITH THE BOUNDARY NOT TOO
FAR AWAY...BUT THEY SHOULD NOT BE THAT ORGANIZED. ANOTHER BOUNDARY
DROPPING INTO THE NORTHWEST PART OF THE FORECAST AREA MAY ALSO
TRIGGER A COUPLE SHOWERS/STORMS THIS AFTERNOON AS WELL IN THAT
AREA.

HAVE SENT SOME UPDATED ZONES/GRIDS...MAINLY TO UPDATE THE
PRECIPITATION TRENDS.

GEELHART


&&

.AVIATION...
ISSUED 1204 PM CDT MON JUN 17 2013

MAIN CONCERN WITH 18Z TAF SET INVOLVES POTENTIAL FOR POP-UP
CONVECTION. MIDDAY SURFACE MAP SHOWS A COUPLE WEAK BOUNDARIES OVER
CENTRAL ILLINOIS AND LATEST VISIBLE SATELLITE SHOWING CUMULUS
STARTING TO DEVELOP ALONG THEM. THE BOUNDARIES SHOULD NOT MOVE
MUCH DURING THE AFTERNOON...BUT DRIER AIR IS SPREADING SOUTHWARD
TOWARD THEM. THUS...AM THINKING THAT ONLY KSPI/KDEC/KCMI MAY SEE A
THREAT OF THUNDER THIS AFTERNOON...AS THEY ARE CLOSEST TO THE
BOUNDARY. COVERAGE CURRENTLY NOT EXPECTED TO BE ENOUGH TO WARRANT
MORE THAN A VCTS MENTION AT THESE SITES. ANY THUNDER NEAR THE TAF
SITES SHOULD FADE WITH SUNSET. LATE IN THE PERIOD...MAY SEE SOME
MVFR CONDITIONS AT TIMES JUST BEFORE SUNRISE...BUT DO NOT THINK IT
WILL GET AS WIDESPREAD OR DENSE AS THIS MORNING...DUE TO HIGHER
RANGES BETWEEN TEMPERATURE AND DEW POINT.

GEELHART

&&

.PREV DISCUSSION...
ISSUED 252 AM CDT MON JUN 17 2013

SHORT TERM...TODAY THROUGH WEDNESDAY

VERY WEAK SURFACE BOUNDARY EXTENDING ACROSS SOUTH-CENTRAL ILLINOIS
WILL BE THE PRIMARY FOCUSING MECHANISM FOR SCATTERED THUNDERSTORMS
TODAY. WITH ONE UPPER-WAVE PASSING WELL TO THE NORTH ACROSS THE
GREAT LAKES AND ANOTHER TRACKING TO THE S/SW INTO THE LOWER OHIO
RIVER VALLEY...VERY LITTLE UPPER SUPPORT WILL BE IN PLACE FOR
WIDESPREAD CONVECTION ACROSS CENTRAL ILLINOIS. DESPITE LACK OF
UPPER DYNAMICS...VERY MOIST AIR MASS IN PRESENCE OF WEAK SURFACE
FORCING WILL BE ENOUGH TO TRIGGER A FEW SHOWERS/THUNDERSTORMS
LATER TODAY. HRRR SUGGESTS DEVELOPMENT AROUND MIDDAY...ESPECIALLY
IN CLOSER PROXIMITY TO BOUNDARY. WILL THEREFORE INCLUDE LOW CHANCE
POPS TODAY...WITH BEST RAIN CHANCES SOUTH OF I-72.

SHORT-WAVE TROUGH CURRENTLY EVIDENT ON WATER VAPOR IMAGERY OVER
SOUTHERN SASKATCHEWAN MAY PROVIDE A NEW WRINKLE IN THE FORECAST
FOR TUESDAY. WHILE WE PREVIOUSLY THOUGHT TUESDAY WOULD BE
DRY...LATEST MODEL GUIDANCE IS INDICATING THE POTENTIAL FOR
ISOLATED CONVECTION DURING THE AFTERNOON. THANKS TO A CONTINUED
MOIST AIR MASS AND THE ARRIVAL OF MODEST UPPER FORCING DURING PEAK
HEATING...HAVE INCLUDED A SLIGHT CHANCE FOR THUNDER TUESDAY
AFTERNOON. ONCE THE WAVE PUSHES FURTHER EAST...SURFACE HIGH
PRESSURE WILL BUILD INTO THE REGION FOR TUESDAY NIGHT AND
WEDNESDAY...PROVIDING SEASONABLY WARM AND DRY CONDITIONS.

LONG TERM...THURSDAY THROUGH SUNDAY

00Z 17 JUN MODELS CONTINUE TO SUGGEST A VERY WARM AND LARGELY DRY
EXTENDED FORECAST. ALL MODELS BUILD AN UPPER-LEVEL RIDGE ACROSS
THE PLAINS ON THURSDAY...THEN SHIFT IT INTO THE MIDWEST OVER THE
WEEKEND. PREVIOUS RUNS DISAGREED ON THE EXACT STRENGTH/POSITIONING
OF THE RIDGE...WHICH BROUGHT INTO QUESTION WHETHER ANY MCS
ACTIVITY COULD RIDE UP/OVER THE RIDGE INTO THE AREA DURING THE
PERIOD. LATEST GFS/ECMWF/GEM ARE ALL LOOKING STRONGER WITH THE
RIDGING...KEEPING BEST FORCING FOR NOCTURNAL MCS DEVELOPMENT
FURTHER NORTH ACROSS THE UPPER MIDWEST INTO THE GREAT LAKES. MODELS
INDICATE ONE CONVECTIVE COMPLEX MAY BRUSH THE KILX CWA TO THE
NORTH FRIDAY NIGHT...BEFORE RIDGE BUILDS EVEN FURTHER ON SATURDAY.
HAVE THEREFORE INCLUDED CHANCE POPS ALONG AND NORTH OF A CANTON TO
BLOOMINGTON LINE FRIDAY NIGHT...BUT HAVE GONE WITH A DRY FORECAST
ACROSS THE BOARD FOR THE REMAINDER OF THE EXTENDED. WILL LIKELY
HAVE TO WAIT UNTIL RIDGE BEGINS TO FLATTEN EARLY NEXT WEEK BEFORE
ANY WIDESPREAD RAIN CHANCES RETURN TO THE AREA. GIVEN BUILDING
UPPER HEIGHTS AND LACK OF CONVECTION...HIGH TEMPERATURES WILL
REACH THE UPPER 80S/LOWER 90S WHILE OVERNIGHT LOWS ONLY DROP INTO
THE LOWER 70S FRIDAY THROUGH SUNDAY.

BARNES


&&

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

$$