FXUS63 KILX 290206
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
806 PM CST SAT NOV 28 2009

.DISCUSSION...
ISSUED 806 PM CST SAT NOV 28 2009

EVENING SURFACE ANALYSIS SHOWS HIGH PRESSURE ANCHORED OVER THE
SOUTHEAST STATES...WHILE A SLOW MOVING FRONTAL BOUNDARY REMAINS
DRAPED ACROSS SOUTHERN WISCONSIN/EASTERN IOWA. PLENTY OF HIGH
CLOUDS ARE STREAMING NORTHWARD ALONG THE FRONT...WITH LOWER CLOUDS
NOW BEGINNING TO MAKE NORTHWARD PROGRESS ACROSS EAST TEXAS/ARKANSAS.
MODELS INDICATE THIS LOW-LEVEL MOISTURE WILL SPREAD INTO WEST-CENTRAL
ILLINOIS LATER TONIGHT...THEN ACROSS THE ENTIRE KILX CWA EARLY
SUNDAY MORNING. END RESULT WILL BE INCREASING CLOUDINESS TONIGHT.
TEMPS ACROSS THE AREA RANGE FROM AROUND 40 NORTHWEST...TO THE
LOWER 50S FURTHER SOUTH AROUND KSPI AND KDEC WHERE HIGH CLOUDS
HAVE PREVENTED TEMPS FROM FALLING MUCH. HAVE ADJUSTED HOURLY TEMPS
TO ACCOUNT FOR CURRENT TRENDS...BUT DID NOT ALTER OVERNIGHT LOWS
IN THE LOWER 40S. CHANGES ARE MINOR ENOUGH THAT A ZONE UPDATE IS
NOT NEEDED AT THIS TIME.

BARNES
&&

.AVIATION...
ISSUED 530 PM CST SAT NOV 28 2009

FRONTAL BOUNDARY CURRENTLY EXTENDING FROM CENTRAL WISCONSIN
INTO IOWA AND NORTHERN MISSOURI...WILL SLOWLY PUSH SOUTHEASTWARD
OVERNIGHT. MOISTURE ALONG AND AHEAD OF THE FRONT IS CURRENTLY
RATHER SPARSE...WITH ONLY A SHIELD OF HIGH CLOUDS NOTED. LOW-LEVEL
MOISTURE IS BEGINNING TO POOL ACROSS EASTERN TEXAS/LOUISIANA...AS
EVIDENCED BY CEILINGS OF 4000-5000FT. THIS LOW-LEVEL MOISTURE
IS PROGGED TO SPREAD NORTHWARD AHEAD OF THE FRONT...EVENTUALLY
IMPACTING THE TAF SITES BY SUNDAY MORNING. BASED ON 18Z NAM-WRF
FORECAST SOUNDINGS...IT APPEARS LOWEST CEILINGS OF AROUND 2500FT
WILL ARRIVE AT KPIA BY 12Z...THEN FURTHER EAST TO KCMI BY 14Z. AS
THE FRONT PUSHES FURTHER EAST...DEEPER MOSITURE WILL BE TAPPED
INTO...RESULTING IN SCATTERED SHOWERS DURING THE AFTERNOON ACROSS
EAST-CENTRAL AND SOUTHEAST ILLINOIS. BEST BET FOR PRECIP WILL BE
AT THE EASTERNMOST TERMINALS BETWEEN 18Z AND 00Z...SO HAVE
INCLUDED LOWER CEILINGS OF 1500FT AND VCSH AT BOTH KDEC AND KCMI
DURING THAT TIME. WINDS WILL INITIALLY BE SOUTHERLY AT AROUND 5KT
TONIGHT...THEN WILL INCREASE TO BETWEEN 10 AND 15KT AND VEER TO
WESTERLY SUNDAY MORNING...THEN NORTHWESTERLY BY AFTERNOON.

BARNES
&&

.PREV DISCUSSION...
ISSUED 110 PM CST SAT NOV 28 2009

LOW LEVEL SOUTHWEST FLOW COUPLED WITH ABUNDANT SUNSHINE HAS BROUGHT
UNSEASONABLY WARM TEMPERATURES TO CENTRAL ILLINOIS THIS AFTN. EARLY
AFTN TEMPS ALREADY WELL INTO THE 50S...WITH MID 60S REPORTED ACRS
THE WESTERN AND SRN COUNTIES. COLD FRONT OVER CENTRAL IOWA IS EXPECTED
TO PUSH INTO OUR AREA SUNDAY MORNING BRINGING AN INCREASE IN CLOUDS
AND CHANCES FOR LIGHT RAIN...ESPECIALLY ALONG AND EAST OF INTERSTATE
55.

SHORT TERM MODELS SHOWING DECENT AGREEMENT WITH THE FROPA ON 
SUNDAY...WITH MEDIUM RANGE MODELS SHOWING A BIT MORE AGREEMENT WITH
THE MID-WEEK SYSTEM/PRECIP CHANCES...ESP ACRS THE SOUTHEAST.

SHORT TERM...TONIGHT THROUGH TUESDAY

COLD FRONT TO PUSH TWDS THE ILLINOIS RIVER VALLEY BY 12Z SUNDAY
WITH A SOUTHERLY WIND FLOW EXPECTED TO KEEP TEMPS WARMER THAN
THE PAST FEW NIGHTS. FORECAST SOUNDINGS CONTINUING TO SHOW AN
INCREASE IN LOW LEVEL MOISTURE AFTER MIDNIGHT ACRS THE SOUTHWEST
AND THEN SPREADING NE OVER THE REMAINDER OF THE AREA DURING THE
MORNING. NOT A GREAT DEAL OF GULF MOISTURE FORECAST AHEAD OF THE
COLD FRONT...AT LEAST UNTIL THE BOUNDARY GETS INTO SE IL. MOISTURE
RETURN ACRS TEXAS EARLY THIS AFTN NOT REAL IMPRESSIVE WITH ONLY LOW
TO MID 50 DEW POINTS SHOWING UP OVER EAST CENTRAL TX...BUT THAT
SHOULD CHANGE SOME AS THE PERSISTENT SOUTHERLY FLOW DRAWS MOISTURE
NWD LATE TONIGHT INTO SUNDAY. WILL CONTINUE TO CARRY ANY MENTIONABLE
POPS ALONG AND EAST OF I-55 TOMORROW ALONG THE COLD FRONT...WITH
SLIGHT CHANCES TO THE NORTHWEST. 

ANY LINGERING PRECIP CHANCES WILL BE CONFINED TO THE SOUTHEAST
SUNDAY EVENING CLOSER TO THE FRONTAL BOUNDARY. COOLER WEATHER TO
FOLLOW THRU TUESDAY AS HIGH PRESSURE BUILDS IN BEHIND THE UPPER
TROF AND SFC COLD FRONT. GUID VALUES SEEM REASONABLE INTO MONDAY
NIGHT BUT IT APPEARS MOS GUID IS TOO AGRESSIVE IN BRINGING TEMPS
BACK UP ON MONDAY BASED ON THE 850 MB TEMP FORECASTS ACRS THE AREA.
WL TEND TO FOLLOW MORE OF A MAV/MET BLEND ON MONDAY WITH ANY WARM
ADVECTION HOLDING OFF UNTIL TUESDAY...AND THAT WOULD BE MAINLY ACRS
OUR WEST. 

LONG TERM...WEDNESDAY THROUGH SATURDAY

MUCH COLDER WEATHER FORECAST TO SHIFT INTO THE MIDWEST AFTER THE
MIDWEEK STORM SYSTEM. 

STARTING TO SEE A BIT MORE CONSISTENCY WITH THE HANDLING OF THE
SPLIT FLOW PATTERN OVER THE LOWER 48 AND THE EVENTUAL MOVEMENT
OF THE NRN AND SRN STREAM SYSTEMS THAT WILL BE AFFECTING PARTS 
OF OUR AREA STARTING ON WEDNESDAY. STILL QUITE A BIT OF
UNCERTAINTY WITH RESPECT TO THE AFFECTS OF THE NRN STREAM WAVE
ON THE UPPER LOW OVER THE SRN MISSISSIPPI VALLEY. QUITE A LARGE
PRECIP SHIELD WL BE SHIFTING NORTH AND EAST INTO PARTS OF THE 
OHIO RIVER VALLEY WITH AREAS ALONG AND SOUTH OF INTERSTATE 70
SEEING THE BEST CHANCES FOR RAIN WEDNESDAY WITH FORECAST SOUNDINGS
SUGGESTING A MIX OR CHANGEOVER TO SNOW WED NIGHT ALONG THE NW
EDGE OF THE PRECIP SHIELD. LATEST ECMWF MORE BULLISH ON THE
DEVELOPMENT OF AN EAST COAST LOW WHICH WILL CUT DOWN ON ANY
SIGNIFICANT RAIN/SNOW ACRS OUR AREA...BUT THE SYSTEM IS STILL TOO
FAR OFF TO PUT MUCH DETAIL IN THE ZONES AT THIS POINT. WL INCREASE
POPS ACRS THE SOUTHEAST STARTING ON WEDNESDAY AND CONTINUE INTO 
THURSDAY WITH PROGRESSIVELY LOWER POPS AS YOU HEAD NW.

ANY LINGERING RAIN/SNOW ACRS THE FAR SOUTHEAST SHOULD MOVE OUT BY
THU AFTERNOON...WITH COLD HIGH PRESSURE SETTLING SOUTHEAST INTO
THE MIDWEST FOR THE REMAINDER OF THE FORECAST PERIOD. 850 MB TEMPS
RANGE FROM -10 TO -13 DEGREES C INTO SATURDAY SUGGESTING AFTN
HIGHS WILL HAVE A TOUGH TIME GETTING OUT OF THE 30S. THE LATEST
ECMWF CONTINUES TO INDICATE LITTLE SUPPORT FOR ANY ADDITIONAL
PRECIP ACRS THE AREA AFTER THURSDAY.

&&

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

$$