000
FXUS63 KILX 180754
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
254 AM CDT TUE JUN 18 2013

.DISCUSSION...
ISSUED 254 AM CDT TUE JUN 18 2013

SHORT TERM...TODAY THROUGH THURSDAY

07Z/2AM SURFACE ANALYSIS SHOWS A WEAK COLD FRONT EXTENDING FROM
NORTHEAST IOWA E/SE ACROSS NORTH-CENTRAL ILLINOIS. THIS BOUNDARY
WILL BE THE PRIMARY FOCUSING MECHANISM FOR WIDELY SCATTERED
CONVECTION AS IT SAGS SLOWLY SOUTHWARD LATER TODAY. VIGOROUS
SHORT-WAVE TROUGH CURRENTLY NOTED ON WATER VAPOR IMAGERY OVER
SOUTHERN MINNESOTA WILL TRACK SOUTHEASTWARD AS WELL...PROVIDING
ENHANCED LIFT ACROSS THE AREA DURING PEAK HEATING. WITH SURFACE
DEWPOINTS ALONG/SOUTH OF THE BOUNDARY IN THE MIDDLE TO UPPER
60S...CAPE VALUES WILL REACH THE 1500 TO 2500J/KG RANGE. IN
ADDITION...0-6KM SHEAR WILL INCREASE TO AROUND 40KT ON THE SOUTHERN
PERIPHERY OF THE APPROACHING WAVE. ALL THESE INGREDIENTS WILL COME
TOGETHER TO PRODUCE SCATTERED THUNDERSTORMS THIS AFTERNOON...A FEW
OF WHICH COULD PRODUCE GUSTY WINDS AND HAIL. WILL CARRY 30-40 POPS
ACROSS THE ENTIRE AREA ACCORDINGLY. AS DAYTIME INSTABILITY IS
LOST...CONVECTION WILL DISSIPATE AFTER SUNSET. WILL LINGER A
SLIGHT CHANCE POP ACROSS THE S/SW KILX CWA THIS EVENING...THEN
WILL GO DRY ACROSS THE BOARD OVERNIGHT.

SURFACE HIGH PRESSURE BUILDING INTO THE REGION BEHIND THE
DEPARTING FRONT WILL PROVIDE WARM/DRY WEATHER ON WEDNESDAY...WITH
AFTERNOON HIGHS IN THE LOWER 80S AND OVERNIGHT LOWS IN THE LOWER
60S. NEXT APPROACHING UPPER WAVE WILL COME INTO THE PICTURE ON
THURSDAY...AS A PIECE OF ENERGY EJECTS EASTWARD FROM DEEP UPPER
LOW SPINNING OFF THE COAST OF THE PACIFIC NORTHWEST. THIS WAVE IS
PROGGED TO TRACK ACROSS CENTRAL ILLINOIS ON THURSDAY. DESPITE
SYNOPTIC LIFT ASSOCIATED WITH THIS FEATURE...AIRMASS WILL BE
RATHER DRY...SO AM NOT EXPECTING MUCH IN THE WAY OF PRECIP. HAVE
GONE WITH A PARTLY SUNNY FORECAST...WITH JUST A SLIM CHANCE FOR
SHOWERS/THUNDER WEST OF I-55 THURSDAY AFTERNOON.

LONG TERM...FRIDAY THROUGH MONDAY

UPPER RIDGE IS EXPECTED TO BUILD ACROSS THE MIDWEST BY THE END OF
THE WEEK...LEADING TO A HOT AND LARGELY DRY EXTENDED FORECAST.
STILL SOME QUESTION AS TO HOW QUICKLY THE RIDGE WILL BUILD AND
WHETHER ANY NOCTURNAL MCS ACTIVITY WILL IMPACT PARTS OF THE AREA
FRIDAY/SATURDAY...HOWEVER MODEL CONSENSUS CONTINUES TO SUGGEST
MOST OF THIS PRECIP WILL BE FOCUSED FURTHER NORTH ACROSS THE UPPER
MIDWEST INTO THE GREAT LAKES. WILL THEREFORE CONTINUE WITH A
MAINLY DRY FORECAST ACROSS CENTRAL ILLINOIS...WITH JUST SLIGHT
CHANCE POPS ACROSS THE FAR NORTH. MAIN STORY WILL BE THE HEAT...AS
HIGH TEMPS REACH THE 90S OVER THE WEEKEND. NEXT BIG QUESTION WILL
BE HOW QUICKLY THE RIDGE WILL FLATTEN EARLY NEXT WEEK. 00Z JUN 18
GFS/ECMWF ARE IN GOOD AGREEMENT THROUGH 168HR/00Z TUE...THEN
SOLUTIONS DIVERGE BY THE MIDDLE OF NEXT WEEK AS GFS HOLDS ONTO
RIDGING ACROSS THE MIDWEST...WHILE THE ECMWF SHIFTS THE RIDGE
FURTHER WEST INTO THE ROCKIES. BASED ON THE PATTERN WE HAVE BEEN
IN FOR MUCH OF THE SPRING...THINK ECMWF HAS A MORE REALISTIC
ANSWER. WILL THEREFORE GRADUALLY INTRODUCE SHOWERS/THUNDERSTORMS
INTO THE FORECAST ACROSS THE NORTHERN HALF OF THE CWA BY
MONDAY/MONDAY NIGHT...THEN EVERYWHERE TUESDAY AS THE RIDGE WEAKENS
AND A FRONTAL BOUNDARY SAGS SOUTHWARD INTO THE REGION.

BARNES
&&

.AVIATION...
ISSUED 1153 PM CDT MON JUN 17 2013

SCATTERED HIGH CIRRUS WILL SLOWLY MOVE ACROSS AND OUT OF THE AREA
OVERNIGHT AT ALL SITES. THEN EXPECTING LIGHT FOG TO
REDEVELOP...BUT NOT AS BAD AS LAST NIGHT AND NOT AS SOON. SO LIGHT
FOG WILL BE IN MVFR CATEGORY TOWARD MORNING AND LIKELY DISSIPATE
QUICKLY AFTER SUNRISE. THEN EXPECTING SOME SCATTERED CU DURING THE
MORNING HOURS AHEAD OF THE NEXT SYSTEM COMING DOWN FROM THE
NORTHWEST. MODELS SUGGEST A POSSIBILITY OF SCATTERED THUNDERSTORMS
ACROSS PARTS OF CENTRAL ILLINOIS DURING THE AFTERNOON
HOURS...MAINLY ALONG THE I-74 CORRIDOR. SO WILL HAVE VCTS AT
PIA...BMI...CMI FOR THE AFTERNOON. HAVE DECIDED TO INCLUDE SPI AND
DEC AS WELL GIVEN THEY WILL BE CLOSE TO THE BOUNDARY AS WELL AND
OUTFLOW BOUNDARIES FROM EXISTING STORMS COULD PRODUCE ADDITIONAL
STORMS TO THE WEST OF THE BOUNDARY. THEN AROUND SUNSET EXPECTING
PCPN TO END AND ALSO PUSH TO THE EAST AND SOUTHEAST. SKIES SHOULD
BECOME SCATTERED AGAIN FOR THE EVENING. DO NOT SE FOG POTENTIAL
TOMORROW NIGHT AS DRIER AIR SHOULD ADVECT INTO THE REGION. WINDS
WILL BE LIGHT AND VARIABLE OVERNIGHT AND THEN BECOME NORTHERLY
ALONG THE FRONT AND TOMORROW EVENING.

AUTEN
&&

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

$$