Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 311110
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
610 AM CDT FRI JUL 31 2015

.SHORT TERM...(TODAY)
ISSUED AT 243 AM CDT FRI JUL 31 2015

HIGH PRESSURE RIDGE OVER CENTRAL MO WILL SLIDE SOUTH THIS MORNING
AND ALLOW A WEAK COLD FRONT TO DROP INTO THE AREA FOR THIS
AFTERNOON. CONVERGENCE AND MOISTURE ALONG THIS FRONT WILL BE VERY
LIMITED SO BELIEVE ANY CONVECTION COVERAGE WILL BE VERY SPOTTY. IN
KEEPING WITH THE CURRENT THINKING/FORECAST WITH THIS FRONT...WILL
HAVE A SLIGHT CHANCE OF PCPN IN THE FORECAST FOR LATE THIS
AFTERNOON...IN LINE WITH PEAK HEATING. FORECAST CAPE VALUES REACH
NEAR 1500 WITH VERY LOW SHEAR. SO ONLY EXPECTING ISOLATED
CONVECTION. AFTERNOON TEMPS WILL AGAIN GET QUITE WARM...IN THE
UPPER 80S...WHICH IS AROUND GUIDANCE.

.LONG TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 243 AM CDT FRI JUL 31 2015

NOT A LOT OF CHANGE IN THE UPPER PATTERN EXPECTED THE NEXT FEW
DAYS...AS THE RIDGE CONTINUES TO BUILD ACROSS THE WESTERN U.S. AND A
NORTHWEST FLOW PREVAILING FOR US. LONGER RANGE MODELS EXHIBITING
SOME DIFFERENCES TOWARD THE MIDDLE OF NEXT WEEK AS THE RIDGE STARTS
TO BREAK DOWN AND SHIFT EAST...WITH THE GFS HANGING ON TO THE RIDGE
LONGER...BUT THE NET RESULT WILL BE A GRADUAL COOLING TREND OVER
CENTRAL ILLINOIS BEGINNING ON TUESDAY...WITH HIGHS IN THE 70S IN
MANY AREAS BY THE SECOND HALF OF NEXT WEEK.

PRECIPITATION ISSUES WILL BE TIED TO THE TIMING OF VARIOUS WAVES IN
THE NORTHWEST FLOW...WITH CONFIDENCE LOWERING THROUGH NEXT WEEK AS
THE MODELS DIVERGE. GENERAL AGREEMENT EXISTS ON THE SHORTWAVE
PASSING THROUGH LATE SATURDAY NIGHT...WITH MOST MODELS FEATURING
SOME SORT OF MCS ACTIVITY DEVELOPING TO OUR NORTHWEST AND ROLLING
TOWARD OUR AREA OVERNIGHT. WILL CONTINUE TO FOCUS POP`S ON THE
NORTHWEST HALF OF THE FORECAST AREA LATE SATURDAY NIGHT...AND AREA-
WIDE ON SUNDAY AS THE MCS WEAKENS OVER OUR AREA. STRENGTH OF A
SECOND WAVE SUNDAY NIGHT IS MUCH WEAKER...AND ONLY THE GFS REALLY
GENERATES ANYTHING IN OUR AREA...SO WILL MAINLY GO WITH SLIGHT
CHANCES THEN.

TUESDAY AND WEDNESDAY BECOME MORE OF A QUESTION MARK DUE TO THE
SPEED OF THE BREAKDOWN OF THE RIDGE. SOME INDICATIONS IN THE LONGER
RANGE MODELS OF THE BOUNDARY HANGING UP FOR A TIME MONDAY NIGHT
THROUGH TUESDAY IN A CORRIDOR NORTHWEST-SOUTHEAST OVER CENTRAL
ILLINOIS. THE ECMWF IS THEN MUCH MORE PRONOUNCED WITH A LARGER UPPER
TROUGH MID WEEK GENERATING MORE WIDESPREAD SHOWER AND THUNDERSTORM
ACTIVITY...WHILE THE GFS MAINLY KEEPS US ON THE COOLER SIDE OF THE
BOUNDARY WITH LIGHT SHOWERS. HAVE LEANED MORE TOWARD THE ECMWF
COVERAGE BUT NOT AS HIGH WITH THE POP`S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 610 AM CDT FRI JUL 31 2015

VFR CONDITIONS WILL PREVAIL AT ALL SITES NEXT 24HRS. A WEAK FRONT
WILL DROP INTO THE AREA TODAY. WITH FORCING WEAK AND VERY LIMITED
MOISTURE...BELIEVE ONLY ISOLATED STORMS ARE POSSIBLE IN THE AREA
LATE THIS AFTERNOON AND INTO EARLY EVENING. WILL KEEP THE VCTS AT
ALL SITES FOR WHEN BEST CHANCE IS. SHOULD BE ONLY FEW TO SCATTERED
CLOUDS THROUGH THE PERIOD AS WELL. WINDS WILL BE WEST TO SOUTHWEST
AHEAD OF THE FRONT AND THEN BECOME NORTHWEST BEHIND THE FRONT.

&&

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

$$

SHORT TERM...AUTEN
LONG TERM...GEELHART
AVIATION...AUTEN


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