151
FXUS63 KILX 041935
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
235 PM CDT SAT JUL 4 2009
DISCUSSION
ISSUED 235 PM CDT SAT JUL 4 2009
MAIN ISSUE WILL BE TIMING THE END OF THE RAIN THIS EVENING.
18Z SURFACE CHART SHOWS LOW PRESSURE OVER NORTHERN MISSOURI...WITH
WARM FRONTAL BOUNDARY EXTENDING EASTWARD ACROSS CENTRAL ILLINOIS
ALONG AND SOUTH OF THE I-72 CORRIDOR. LARGE AREA OF OVERRUNNING
RAIN STILL IN PLACE ACROSS MUCH OF ILLINOIS AND INDIANA...WITH
EXTENSIVE CLOUD COVER AND SCATTERED LIGHT SHOWERS WESTWARD INTO
IOWA/NORTHERN MISSOURI. MEANWHILE...PRIMARY OUTFLOW BOUNDARY FROM
ONGOING MCS IS EVIDENT WELL TO THE SOUTH ACROSS SOUTHERN MISSOURI
INTO WESTERN KENTUCKY.
SHORT TERM...TONIGHT THROUGH TUESDAY
RAIN AREA WILL CONTINUE TO SHIFT EASTWARD LATE THIS AFTERNOON AND
EVENING...ALLOWING THE STEADY RAIN TO DIMINISH TO SCATTERED LIGHT
SHOWERS. MAIN CONCERN FOR ANY ADDITIONAL CONVECTIVE DEVELOPMENT
WILL STAY SOUTH OF THE AREA ACROSS THE OZARKS AND LOWER OHIO
VALLEY...WHERE BEST INSTABILITY AND LIFT EXISTS AHEAD OF OUTFLOW
BOUNDARY. WILL CHECK LATEST RADAR TRENDS BEFORE DECIDING ON POPS
FOR THIS EVENING...BUT RIGHT NOW LOW POPS IN THE 20 TO 30 RANGE
SHOULD SUFFICE FOR MOST OF THE KILX CWA...EXCEPT LIKELY POPS
FURTHER SOUTH ALONG AND SOUTH OF THE I-70 CORRIDOR. THINK MOST
LOCATIONS WILL BE DRY AFTER ABOUT 8 OR 9 PM...WITH PERHAPS A FEW
LINGERING SPRINKLES HERE AND THERE. CONDITIONS WILL REMAIN
OVERCAST THROUGHOUT THE NIGHT...AS WEAK HIGH PRESSURE OVER THE
NORTHERN PLAINS HAS LITTLE INFLUENCE ON THE WEATHER. SKIES WILL BE
SLOW TO CLEAR ON SUNDAY...AS BOTH NAM-WRF/GFS INDICATE PLENTY OF
LOW-LEVEL MOISTURE LINGERING UNTIL THE AFTERNOON HOURS. GIVEN
CONTINUED NORTHEASTERLY FLOW AND ONLY WEAK PUSH OF SLIGHTLY DRIER
AIR...WILL BE PESSIMISTIC ABOUT CLEARING. WILL START THE DAY
CLOUDY ACROSS THE BOARD...FOLLOWED BY A SLOW CLEARING TREND FROM
NORTH TO SOUTH DURING THE AFTERNOON. THANKS TO AMPLE CLOUD COVER
FOR A GOOD PART OF THE DAY...TEMPS WILL ONCE AGAIN BE SEVERAL
DEGREES BELOW NORMAL. HIGHS WILL MAINLY BE IN THE MIDDLE TO UPPER
70S...WITH LOWER 80S ACROSS THE FAR NORTH WHERE MORE SUNSHINE WILL
OCCUR.
WARMER WEATHER WILL BE ON TAP FOR MONDAY...AS TEMPS RETURN TO
NEAR NORMAL FOR THIS TIME OF YEAR IN THE MIDDLE 80S. UPPER RIDGE
WILL BEGIN TO BUILD EASTWARD INTO THE REGION...HOWEVER WEAK
DISTURBANCE RIDING UP AND OVER THE TOP OF THE RIDGE MAY BRING
SCATTERED THUNDERSTORMS INTO THE AREA MONDAY AFTERNOON/EVENING.
NAM-WRF IS SHOWING WEAK SURFACE TROUGH SETTING OFF WIDELY
SCATTERED CONVECTION DURING PEAK HEATING...MAINLY ALONG AND NORTH
OF I-72. MEANWHILE...BOTH THE GFS AND ECMWF ARE DRY. WILL FOLLOW
THE NAM-WRF HERE...DUE TO ITS SUPERIOR LOW-LEVEL RESOLUTION AND
RECENT GOOD TRACK RECORD. HAVE THEREFORE OPTED TO INCLUDE 20 POPS
ACROSS THE NORTHERN TWO-THIRDS OF THE CWA MONDAY AFTERNOON.
ANOTHER WAVE IS PROGGED TO RIDE UP AND OVER THE RIDGE ON
TUESDAY...WITH THE NAM-WRF AGAIN BRINGING A WEAK SURFACE TROUGH
AND SCATTERED CONVECTION INTO THE AREA. VORTICITY FIELD LOOKS A
BIT SUSPECT THIS TIME AROUND ON THE NAM-WRF...WITH POSSIBLE
CONVECTIVE FEEDBACK ISSUES. WILL THEREFORE FOLLOW THE GFS/ECMWF
WHICH BOTH KEEP UPPER WAVE FURTHER NORTH/NORTHEAST ACROSS THE
UPPER MIDWEST/GREAT LAKES. THIS WILL MEAN A WARM AND DRY FORECAST
ACROSS CENTRAL ILLINOIS FOR TUESDAY...WITH HIGHS IN THE MIDDLE
80S.
LONG TERM...WEDNESDAY THROUGH SATURDAY
UPPER RIDGING WILL PREVAIL THROUGH MUCH OF THE EXTENDED...BEFORE A
MORE SIGNIFICANT WAVE TRIES TO FLATTEN THE RIDGE BY THE END OF THE
WEEK. MODELS ARE FAIRLY CONSISTENT IN SUGGESTING FRONTAL BOUNDARY
SINKING SOUTHWARD INTO CENTRAL ILLINOIS LATE FRIDAY INTO SATURDAY.
HAVE INCLUDED 20 POPS ACROSS THE NORTH FOR FRIDAY...THEN 30S ALONG
AND NORTH OF I-72 FOR FRIDAY NIGHT. THINK FRONT WILL GRADUALLY
WASH OUT AS IT PUSHES INTO THE RIDGE AXIS OVER THE WEEKEND...SO
WILL GO WITH ONLY SLIGHT CHANCE POPS FOR SATURDAY. TEMPS WILL
GRADUALLY CLIMB WEDNESDAY THROUGH FRIDAY...WITH HIGHS REACHING THE
LOWER 90S. SLIGHTLY COOLER AIRMASS WILL SETTLE INTO CENTRAL
ILLINOIS NEXT WEEKEND...RESULTING IN HIGHS DROPPING BACK INTO THE
MIDDLE TO UPPER 80S.
BARNES
AVIATION
ISSUED 1255 PM CDT SAT JUL 4 2009
LARGE MCS OVER IL WITH WIDESPREAD SHOWERS WITH MVFR VSBYS OVER
CENTRAL IL EARLY THIS AFTERNOON WITH MOVE SLOWLY EAST DURING THE
AFTERNOON WITH SHOWERS BECOMING MORE SCATTERED IN NATURE DURING
THE AFTERNOON LIKE WHAT IS HAPPENING NEAR SPI. THUNDERSTORMS
CHANCES WILL MAINLY BE CONFINED SOUTH OF I-72 WHERE BETTER
INSTABILITY WITH JUST ISOLATED THUNDER POSSIBLE FROM I-72 NORTH
THIS AFTERNOON SO LEFT THUNDER OUT OF TAF BUT WILL UPDATE AS
NEEDED. MVFR CEILINGS IN EASTERN IL WHILE IFR CEILINGS OF 600 TO
900 FT IN WESTERN IL BY PIA AND SPI TO SPREAD EAST ACROSS
BMI...DEC AND CMI NEXT FEW HOURS. THESE IFR CLOUDS SHOULD STICK
AROUND TONIGHT AND EVEN GET LOWER TO POSSIBLY LIFR OF 400 TO 500
FT LATER THIS EVENING WITH VSBYS OF 2 TO 4 MILES IN FOG. MODELS
SHOULD LOW CLOUDS STICKING AROUND SUNDAY MORNING WITH SOME DRIER
AIR MOVING SOUTHERN ACROSS NORTHERN IL...BUT PROBABLY WILL NOT GET
INTO CENTRAL IL UNTIL SUNDAY AFTERNOON. LIFTED CEILINGS UP TO MVFR
NEAR 1500 FT AFTER 15Z/10 AM SUNDAY WITH LIGHT HAZE. ESE WINDS
NEAR 10 KTS THIS AFTERNOON TO BECOME NE 5 TO 10 KTS TONIGHT AND
SUNDAY.
HUETTL
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page