Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 031156
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
656 AM CDT THU SEP 3 2015

.SHORT TERM...(TODAY)
ISSUED AT 318 AM CDT THU SEP 3 2015

ANOTHER HOT LATE SUMMER DAY IS ANTICIPATED ACROSS CENTRAL ILLINOIS
TODAY...AS UPPER RIDGING CONTINUES TO DOMINATE THE REGION.  A
VIGOROUS SHORT-WAVE TROUGH NOTED ON 07Z/2AM WATER VAPOR IMAGERY OVER
NORTHERN LAKE MICHIGAN WILL TRACK SLOWLY SOUTHEASTWARD TO NEAR LAKE
HURON BY LATER THIS AFTERNOON.  CONVECTION ASSOCIATED WITH THIS
FEATURE WILL REMAIN TO THE N/NE OF THE KILX CWA...PRIMARILY FROM
THE CHICAGO AREA INTO NORTHERN INDIANA. WILL NEED TO KEEP AN EYE
ON A TRAILING VORT MAX EXTENDING SOUTHWARD FROM THIS FEATURE THAT
COULD POTENTIALLY TRIGGER AN ISOLATED SHOWER ACROSS CENTRAL
ILLINOIS THIS MORNING...HOWEVER HIGH-RES MODELS KEEP CONDITIONS
DRY AND LATEST RADAR IMAGERY DOES NOT SUPPORT THIS. AS A
RESULT...WILL GO WITH A DRY FORECAST TODAY WITH HIGH TEMPERATURES
ONCE AGAIN REACHING THE LOWER TO MIDDLE 90S.

.LONG TERM...(TONIGHT THROUGH Wednesday)
ISSUED AT 318 AM CDT THU SEP 3 2015

UPPER WAVE WILL STALL OVER THE GREAT LAKES FOR THE NEXT COUPLE OF
DAYS.  MOST MODEL SOLUTIONS SUGGEST THIS FEATURE MAY COME CLOSE
ENOUGH TO TRIGGER A FEW SHOWERS/THUNDERSTORMS ACROSS THE NE KILX CWA
BOTH FRIDAY AND SATURDAY AFTERNOON.  GIVEN GOOD MODEL AGREEMENT AND
RUN-TO-RUN CONSISTENCY...HAVE ADDED SLIGHT CHANCE POPS
ALONG/NORTHEAST OF A LACON TO PARIS LINE FRIDAY AFTERNOON BOTH DAYS.
OTHERWISE HOT AND DRY WEATHER WILL CONTINUE WITH HIGH TEMPERATURES
IN THE LOWER TO MIDDLE 90S.

MAIN CHALLENGE IN THE EXTENDED CONTINUES TO BE THE PATTERN CHANGE
NEXT WEEK.  MODELS ARE STILL HAVING TROUBLE DECIDING HOW FAST TO
BREAK DOWN THE PREVAILING UPPER RIDGE AND BRING A STRONG COLD FRONT
THROUGH THE REGION.  AS IS TYPICALLY THE CASE IN THESE
SITUATIONS...MODELS HAVE BEEN SLOWING THIS PROCESS FROM RUN-TO-
RUN...WITH BOTH THE 00Z SEP 3 GFS AND ECMWF NOW DELAYING A
SIGNIFICANT AIRMASS CHANGE UNTIL NEXT THURSDAY.  A LARGE UPPER LOW
CURRENTLY SPINNING OVER BRITISH COLUMBIA WILL DROP SOUTHWARD INTO
THE PACIFIC NORTHWEST/NORTHERN ROCKIES OVER THE WEEKEND...THEN WILL
LIFT INTO SOUTHERN MANITOBA BY EARLY NEXT WEEK.  THIS WILL GRADUALLY
FLATTEN THE RIDGE AND NUDGE A DISSIPATING COLD FRONT INTO CENTRAL
ILLINOIS ON MONDAY.  WITH MINIMAL UPPER SUPPORT AND RELATIVELY WEAK
CONVERGENCE ALONG THE BOUNDARY...THINK ONLY SCATTERED CONVECTION
WILL OCCUR MAINLY NORTH OF THE I-70 CORRIDOR.  FRONT WILL BECOME
PARALLEL TO THE UPPER FLOW AND WILL STALL ACROSS CENTRAL
ILLINOIS...KEEPING LOW CHANCE POPS IN THE FORECAST MONDAY NIGHT INTO
TUESDAY.  AFTER THAT...A SECOND WAVE DROPPING SOUTHEASTWARD OUT OF
WESTERN CANADA WILL DRIVE A STRONGER COLD FRONT INTO THE REGION ON
WEDNESDAY.  AS A RESULT...HIGHER RAIN CHANCES WILL BE LIKELY AT THAT
TIME...FOLLOWED BY MUCH COOLER CONDITIONS FOR THE END OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z Friday MORNING)
ISSUED AT 653 AM CDT THU SEP 3 2015

ASIDE FROM SOME PATCHY MORNING MVFR FOG, QUIET/VFR AVIATION
WEATHER CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS TERMINALS
THROUGH THE 12Z TAF VALID TIME. A COUPLE UPPER LEVEL DISTURBANCES
PASSING NEARBY WILL PROVIDE PERIODS OF MID/HIGH LEVEL CIGS, BUT
THESE CLOUDS SHOULD ALSO HELP PRECLUDE MUCH IN THE WAY OF FOG
REDEVELOPMENT LATER TONIGHT. GENERALLY LIGHT SOUTHERLY WINDS WILL
PERSIST THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Bak



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