FXUS63 KILX 090759
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
159 AM CST WED DEC 9 2009
.DISCUSSION...
ISSUED 159 AM CST WED DEC 9 2009
EXTREMELY WINDY AND SHARPLY COLDER CONDITIONS EXPECTED TODAY...AS
POWERFUL STORM SYSTEM LIFTS INTO THE GREAT LAKES.
07Z SURFACE ANALYSIS SHOWS 984MB LOW PRESSURE JUST EAST OF
MOLINE...WITH OCCLUDED FRONTAL BOUNDARY EXTENDING SOUTHEASTWARD
ACROSS CENTRAL ILLINOIS. BAND OF MODERATE RAIN ASSOCIATED WITH
FRONT IS RAPIDLY LIFTING NORTHWARD THROUGH THE KILX CWA...WHILE
HEAVY SNOW CONTINUES TO FALL NORTHWEST OF THE LOW TRACK ACROSS
IOWA. AREA OF LIGHTER SNOW ASSOCIATED WITH UPPER LOW IS CURRENTLY
TRACKING ACROSS NORTH-CENTRAL MISSOURI.
SHORT TERM...TODAY THROUGH FRIDAY
LOW PRESSURE WILL TRACK NORTHEASTWARD TO AROUND MILWAUKEE BY
12Z...THEN TO LAKE HURON BY EVENING. AS PARENT UPPER LOW LIFTS
NORTHEASTWARD AS WELL...LIGHT SNOW CURRENTLY ACROSS MISSOURI WILL
SPREAD ACROSS THE NORTHERN HALF OF THE KILX CWA THIS MORNING.
BASED ON RADAR IMAGERY AND UPSTREAM OBS SHOWING VISBYS GENERALLY
IN THE 2 TO 4SM RANGE...AM NOT EXPECTING MUCH SNOW ACCUMULATION.
MOST AREAS ALONG AND NORTH OF I-72 WILL ONLY SEE A FEW TENTHS OF
AN INCH...WHILE LOCATIONS ALONG AND NORTHWEST OF THE ILLINOIS
RIVER MAY SEE AN INCH OR TWO.
MAIN WEATHER STORY TODAY WILL BE THE WINDS...AS PRESSURE GRADIENT
TIGHTENS CONSIDERABLY. BUFKIT FORECAST SOUNDINGS ARE INDICATING 55
TO 60MPH WINDS AT THE TOP OF THE MIXED LAYER...SUGGESTING GUSTS AT
THE SURFACE OF UP TO 50MPH. WOULD NOT BE SURPRISED TO SEE ISOLATED
GUSTS CLOSE TO 60MPH AT TIMES. THIS FALLS A LITTLE SHY OF A HIGH WIND
WARNING...SO WILL CONTINUE WITH THE WIND ADVISORY ACROSS MOST OF
THE AREA. FURTHER WEST...WILL MAINTAIN THE WINTER WEATHER ADVISORY
ALONG AND WEST OF THE ILLINOIS RIVER AND THE WINTER STORM WARNING
ACROSS KNOX AND STARK COUNTIES. WILL STRONGLY WORD THE WSW TO
HIGHLIGHT THE IMPACTS OF THE EXPECTED STRONG WINDS...INCLUDING
DOWNED TREES...POWER OUTAGES...AND BLOWING AND DRIFTING SNOW ACROSS
THE WARNING AREA.
AS THE WESTERLY WINDS BEGIN TO INCREASE THIS MORNING...MUCH COLDER
AIR WILL POUR INTO THE AREA FROM THE WEST. HIGH TEMPERATURES WILL
BE ACHIEVED EARLY...RANGING FROM THE UPPER 20S FAR WEST...TO THE
LOWER 40S ALONG THE INDIANA BORDER. AFTER THAT...READINGS WILL
DROP OFF QUICKLY...WITH TEMPS DIPPING INTO THE TEENS AND 20S BY
LATE MORNING/AFTERNOON. ANOTHER ISSUE THAT WILL ARISE DUE TO THE
HIGH WINDS AND MUCH COLDER CONDITIONS IS A RAPIDLY DECREASING
WIND-CHILL FACTOR. WITH ACTUAL AIR TEMPS PLUNGING INTO THE SINGLE
DIGITS AND TEENS TONIGHT...WIND-CHILL READINGS WILL DROP WELL
BELOW ZERO...ESPECIALLY ACROSS THE ILLINOIS RIVER VALLEY WHERE A
LIGHT SNOW COVER WILL BE IN PLACE. DAY SHIFT WILL NEED TO CONSIDER
AN ADVISORY FOR LOCATIONS ALONG AND WEST OF THE ILLINOIS
RIVER...WHERE WIND-CHILL READINGS WILL RANGE FROM -15 TO -20 AFTER
MIDNIGHT.
ONCE UPPER/SURFACE LOW MOVES FURTHER AWAY FROM THE REGION...WINDS
WILL DIMINISH AND SKIES WILL CLEAR LATE TONIGHT. SUNNY BUT COLD
WEATHER WILL BE ON TAP FOR THURSDAY...WITH HIGHS RANGING FROM THE
TEENS NORTHWEST...TO THE UPPER 20S FAR SOUTHEAST. SLIGHTLY WARMER
WEATHER WILL ARRIVE ON FRIDAY...AS ZONAL FLOW BEGINS TO TAKE
HOLD ACROSS THE CONUS. HIGHS WILL MODERATE INTO THE LOWER TO
MIDDLE 30S ACROSS MUCH OF THE AREA...BUT WILL HOVER IN THE 20S
NORTHWEST OF THE ILLINOIS RIVER WHERE SNOW WILL REMAIN ON THE GROUND.
LONG TERM...SATURDAY THROUGH TUESDAY
A WEAK IMPULSE WILL TRAVEL ALONG IN THE ZONAL FLOW LATE FRIDAY
INTO SATURDAY...BUT SHOULD STAY WELL TO THE SOUTH OF CENTRAL
ILLINOIS ACROSS THE GULF COAST STATES. FURTHER OUT...A WAVE COMING
OFF THE CENTRAL PACIFIC WILL RACE ACROSS THE COUNTRY AND PUSH AN
AREA OF LOW PRESSURE AND AN ACCOMPANYING FRONT THROUGH THE MIDWEST
SUNDAY OR MONDAY. SHOULD BE ENOUGH RETURN FLOW OF MOISTURE FROM
THE GULF BY THEN TO GENERATE SOME LIGHT PRECIP. ONLY ISSUE IS
EXACT TIMING OF SYSTEM...AS GFS AND ECMWF DIFFER SOMEWHAT. AT THIS
POINT...WILL TREND TOWARD THE ECMWF...WHICH BRINGS PRECIP INTO THE
AREA SUNDAY NIGHT INTO MONDAY MORNING. WILL ONLY INCLUDE A 20 POP
FOR NOW...PENDING BETTER SUPPORT FROM FUTURE MODEL RUNS.
BARNES
&&
.AVIATION...
ISSUED 1115 PM CST TUE DEC 8 2009
LITTLE CHANGE FROM PREVIOUS THINKING. SFC LOW NOW NEAR QUINCY
EXPECTED TO TRACK TO NEAR CHICAGO BY 12Z. WINDS SHOULD REMAIN
LIGHT WITH THE LOW MOVING OVERHEAD OVER THE NEXT SEVERAL HOURS
BUT THAT WILL DRAMATICALLY CHANGE BY WED MRNG AS THE INTENSE
STORM SHIFTS AWAY FROM CNTRL IL. IFR/LIFR CIGS AND VSBYS WL
GRDLY LIFT TO BECOME MVFR CIGS BY TMRW AFTN INTO THE EVENING
HOURS. A BAND OF RAIN PUSHING IN WITH THE COLD FRONT WILL SWING
NE ACRS THE TAF SITES EARLY IN THIS FCST PERIOD WITH AREAS OF
SNOW DEVELOPING IN THE STRONG COLD ADVECTION LATE TNT INTO
WEDNESDAY.
SFC WINDS WILL SHIFT INTO THE SOUTHWEST AND THEN WEST LATE TNT
INTO WED MRNG WITH SPEEDS INCREASING TO 25 TO 35 KTS WITH A FEW
GUSTS ARND 40 KTS PSBL FROM WED MRNG INTO THE EARLY EVENING
HOURS...WITH A GRDL DECREASE IN WIND SPEEDS TMRW NIGHT AS THE LOW
SHIFTS QUICKLY AWAY FROM CENTRAL IL. VSBYS MAY BE CUT DOWN TO
AROUND A MILE FOR A BRIEF TIME WITH SCATTERED SNOW SHOWERS. IF WE
DO SEE ANY BLOWING SNOW...IT WOULD BE ARND THE PIA AND BMI AREAS
BUT FOR NOW...WITH MOSTLY RAIN OCCURRING AND ONLY GRDLY CHANGING
OVER TO SNOW OVERNIGHT...AND AMTS AN INCH OR LESS LOOKING MORE
LIKELY...WL KEEP ANY BLSN OUT FOR THE TIME BEING.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR ILZ038-042>057-
061>063-066>068-071>073.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR
ILZ029>031-036-037-040-041.
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR ILZ027-028.
&&
$$
