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000
FXUS63 KILX 161748
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1248 PM CDT SUN JUN 16 2013

.DISCUSSION...
ISSUED 1037 AM CDT SUN JUN 16 2013

15Z SURFACE MAP PLACED A WEAK COOL FRONT FROM NEAR CHICAGO TO
KANSAS CITY. SOUTH OF THE FRONT...MOSTLY CLOUDY SKIES AND A HUMID
UPPER 60S DEWPOINT AIRMASS RESIDED OVER CENTRAL IL. FARTHER
SOUTH...A ZONE OF ISENTROPIC LIFT AND STRONGER 850 MB MOISTURE
TRANSPORT WAS PRODUCING A CORRIDOR OF SHOWERS AND THUNDERSTORMS
CENTERED ALONG I-70. TRENDS SUGGEST THIS WILL CONTINUE TO EDGE
E/SE THROUGH EARLY AFTERNOON WITH THE MORE CONCENTRATED ACTIVITY
EXITING THE SE CWA BY 20Z. THUS HAVE LIKELY POPS ACROSS THE
SOUTHEAST THIRD THROUGH 18Z...THEN REDUCING TO CHANCE SOUTH OF I-70
THIS AFTERNOON. FARTHER NORTH...GRADUAL CLEARING SHOULD WORK
THROUGH THE NORTHERN CWA THIS AFTERNOON AS SLIGHTLY DRIER AIR
FILTERS IN. HIGHS WILL BE SIMILAR TO THE LAST FEW DAYS...GENERALLY
IN THE LOWER 80S WITH SOME MID 80S POSSIBLE WHERE MORE AFTERNOON
SUN BREAKS THROUGH.



&&

.AVIATION...
ISSUED 1248 PM CDT SUN JUN 16 2013

AN AREA OF MVFR STRATOCU AFFECTING THE TAF SITES THIS AFTERNOON
WILL GRADUALLY RISE INTO VFR RANGE...WHILE SINKING SOUTH THROUGH
00Z. THIS EVENING EXPECT MOSTLY CLEAR SKIES. WINDS GO CALM
OVERNIGHT AS A WEAK GRADIENT SETS UP ACROSS IL. WITH WET GROUND
FROM LAST NIGHTS RAIN AND ENOUGH CLOUD COVER TODAY TO PREVENT A
GOOD MIX-OUT OF THIS LOW LEVEL MOISTURE...FEEL THERES A GOOD SHOT
AT FOG FORMATION AFTER 06Z. THIS IS SUPPORTED BY MOST NUMERICAL
GUIDANCE. VSBYS COULD GET AS LOW AS 1SM WITHIN A FEW HOURS OF
SUNRISE. FOG EXPECTED TO BURN OFF BY 13Z WITH LIGHT WINDS AND
MOSTLY CLEAR SKIES THROUGH 18Z.

25
&&

.PREV DISCUSSION...
ISSUED 313 AM CDT SUN JUN 16 2013

SHORT TERM...TODAY THROUGH TUESDAY

MCS THAT MOVED ACROSS CENTRAL ILLINOIS OVERNIGHT HAS NOW PUSHED
INTO INDIANA AND WEAKENED CONSIDERABLY. 07Z/2 AM RADAR MOSAIC AND
LOCAL OBS SHOW ONLY SCATTERED LIGHT SHOWERS LEFT IN ITS
WAKE...WITH VERY LITTLE RE-DEVELOPMENT NOTED UPSTREAM ACROSS
NORTHERN MISSOURI. HIGH-RES MODELS SUCH AS THE NAM12 AND 4 KM HRRR
INSIST THAT ADDITIONAL CONVECTION WILL DEVELOP ON THE NOSE OF A
30-35 KT LLJ ACROSS MISSOURI OVER THE NEXT COUPLE OF HOURS...THEN
TRACK EASTWARD INTO CENTRAL ILLINOIS EARLY THIS MORNING. HAVE SEEN
LITTLE TO NO EVIDENCE OF THIS HAPPENING...AS IR SATELLITE SHOWS
WARMING CLOUD TOPS WEST OF THE MISSISSIPPI RIVER. DUE TO RATHER
WEAK LLJ AND AN ALREADY WORKED OVER AIRMASS...ORGANIZED CONVECTION
IS UNLIKELY. INSTEAD...THINK SCATTERED SHOWERS WILL CONTINUE TO
DEVELOP WITHIN THE WARM ADVECTION REGIME AND TRACK EASTWARD ACROSS
SOUTH-CENTRAL ILLINOIS THIS MORNING. AS ATMOSPHERE DESTABILIZES...MAY
SEE A FEW THUNDERSTORMS LATER THIS MORNING INTO THE AFTERNOON AS
WELL. WILL THEREFORE CARRY SCATTERED SHOWERS/THUNDER ALONG AND
SOUTH OF I-72 THROUGHOUT THE DAY...WITH ISOLATED SHOWERS FURTHER
NORTH.

FRONTAL BOUNDARY CURRENTLY DRAPED ACROSS THE UPPER MIDWEST WILL
GET A PUSH SOUTHWARD THIS EVENING...AS VIGOROUS UPPER WAVE DIGS
INTO THE NORTHERN GREAT LAKES. WITH BOUNDARY SAGGING TOWARD THE
OHIO RIVER...ANY LINGERING RAIN CHANCES WILL COME TO AN END. LULL
IN THE PRECIP CHANCES WILL BE SHORT-LIVED HOWEVER...AS LINGERING
BOUNDARY AND APPROACHING SHORT-WAVES WILL TRIGGER SCATTERED
SHOWERS/THUNDER ONCE AGAIN ON MONDAY. THIS TIME AROUND...CENTRAL
ILLINOIS WILL BE SANDWICHED BETWEEN TWO UPPER WAVES...WITH ONE
TRACKING INTO THE UPPER GREAT LAKES AND THE OTHER SLIDING BY TO
THE S/SW. STRONGEST LIFT ASSOCIATED WITH THESE FEATURES WILL
MAINLY BE TO THE NORTH AND SOUTH OF THE KILX CWA...SO PRECIP
CHANCES WILL REMAIN LOW ACROSS MUCH OF THE AREA. THE EXCEPTION
WILL BE LOCATIONS ALONG/SOUTH OF I-70 WHICH COULD BE IMPACTED BY
AN MCS TRACKING OUT OF CENTRAL/SOUTHERN MISSOURI. WILL CARRY
LIKELY POPS ACROSS THE FAR SE CWA ACCORDINGLY.

UPPER WAVES WILL GRADUALLY PUSH EAST OF THE AREA MONDAY
NIGHT...BRINGING AN END TO THE PRECIP CHANCES FROM WEST TO EAST
OVERNIGHT. AFTER THAT...HIGH PRESSURE WILL BUILD INTO THE REGION
FROM THE NORTHWEST...BRINGING COOLER/DRIER WEATHER BY TUESDAY.

LONG TERM...WEDNESDAY THROUGH SATURDAY

STILL SOME DISAGREEMENT AMONG THE OPERATIONAL MODELS CONCERNING
PRECIP CHANCES IN THE EXTENDED...HOWEVER SOLUTIONS ARE BEGINNING
TO CONVERGE ON MUCH WARMER WEATHER BY THE END OF THE WEEK. BOTH
THE GFS AND ECMWF BUILD AN UPPER-LEVEL RIDGE OVER THE MIDWEST...WITH
THE 591DM 500MB HEIGHT LINE COMING INTO CENTRAL ILLINOIS BY FRIDAY.
THIS WOULD RESULT IN HIGH TEMPS IN THE UPPER 80S AND LOWER 90S BY
FRIDAY AND SATURDAY.

AFTER A DRY AND SEASONABLY WARM DAY WITH HIGH TEMPERATURES IN THE
LOWER 80S ON WEDNESDAY...HIGH PRESSURE WILL SHIFT EAST OF THE
REGION ON THURSDAY. WITH WARM ADVECTION DEVELOPING ON THE BACK SIDE
OF THE DEPARTING HIGH...GFS TRIGGERS A CLUSTER OF CONVECTION
ACROSS THE PLAINS WEDNESDAY NIGHT...THEN TRACKS IT EASTWARD ACROSS
PORTIONS OF CENTRAL AND SOUTHEAST ILLINOIS ON THURSDAY. THINK GFS
IS SUFFERING FROM CONVECTIVE FEEDBACK...AS THIS FEATURE IS
COMPLETELY ABSENT ON THE ECMWF. WILL THEREFORE MAINTAIN A DRY
FORECAST FOR THURSDAY. AFTER THAT...EXACT DEGREE OF UPPER RIDGE
AMPLIFICATION WILL DETERMINE POP FORECAST OVER THE WEEKEND. GFS IS
MAINLY DRY FRIDAY/SATURDAY...WHILE THE ECMWF IS SLIGHTLY FLATTER
WITH THE RIDGE AND FEATURES CONVECTION ACROSS NORTHERN ILLINOIS.
WILL ONLY MENTION SLIGHT CHANCE FOR SHOWERS/THUNDER ACROSS THE
NORTHERN CWA AT THIS TIME...WITH BETTER CHANCES FOR PRECIP HOLDING
OFF UNTIL SUNDAY WHEN GFS/ECMWF/GEM ALL FLATTEN RIDGE AND BRING
FRONTAL BOUNDARY SOUTHWARD INTO CENTRAL ILLINOIS.

BARNES


&&

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

$$