FXUS63 KILX 111138
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
538 AM CST FRI DEC 11 2009

.DISCUSSION...
ISSUED 209 AM CST FRI DEC 11 2009

WARMING TEMPERATURES WILL BE ON TAP TODAY AND SATURDAY...BEFORE
A WEAK DISTURBANCE POTENTIALLY BRINGS A BRIEF PERIOD OF WINTRY
PRECIPITATION TO THE AREA SATURDAY NIGHT.

07Z SURFACE ANALYSIS SHOWS HIGH PRESSURE ANCHORED OVER THE DEEP
SOUTH...WITH SOUTHERLY RETURN FLOW NOTED ACROSS CENTRAL ILLINOIS.
ALOFT...POLAR JET STREAM EXTENDS FROM WESTERN CANADA SOUTHEASTWARD
ACROSS THE MIDWEST INTO THE MID-ATLANTIC STATES. MEANWHILE...WAVE
EMBEDDED IN SOUTHERN BRANCH OF THE JET IS NOTED OFF THE COAST OF
SOUTHERN CALIFORNIA.

SHORT TERM...TODAY THROUGH SUNDAY

MOSTLY SUNNY SKIES WILL PREVAIL TODAY...WITH PERHAPS A FEW HIGH
CLOUDS DRIFTING ACROSS THE NORTHERN HALF OF THE AREA AS A WEAK
MOISTURE-STARVED WAVE CURRENTLY OVER MONTANA SKIRTS BY TO THE
NORTH. WITH FULL SUN AND SOUTHERLY WINDS...HIGH TEMPERATURES WILL
MODERATE QUITE NICELY. FORECAST SOUNDINGS INDICATE A WELL-MIXED
BOUNDARY LAYER EXTENDING UP TO ABOUT 925MB...RESULTING IN
AFTERNOON HIGHS IN THE LOWER TO MIDDLE 30S. THE EXCEPTION WILL BE
NORTHWEST OF THE ILLINOIS RIVER...WHERE SNOW COVER WILL KEEP TEMPS
IN THE 20S.

EVEN WARMER WEATHER WILL BE IN STORE FOR SATURDAY...AS SOUTHERLY
LOW-LEVEL FLOW CONTINUES. 850MB TEMPS ARE PROGGED TO CLIMB INTO
THE 0 TO +1C RANGE...LEADING TO HIGH TEMPS IN THE UPPER 30S AND
LOWER 40S. ONCE AGAIN...THE SNOW COVER ACROSS KNOX AND STARK
COUNTIES WILL KEEP TEMPS SEVERAL DEGREES COOLER THERE...WITH HIGHS
ONLY IN THE LOWER 30S.

SOUTHERN CALIFORNIA WAVE WILL RAPIDLY APPROACH FROM THE WEST
SATURDAY AFTERNOON...RESULTING IN INCREASING CLOUDINESS. NAM-WRF
AND GFS ARE IN GOOD AGREEMENT WITH ONE ANOTHER CONCERNING THE
TRACK AND TIMING OF THIS SYSTEM...WITH A QUICK SHOT OF LIGHT
PRECIP EXPECTED SATURDAY NIGHT. 00Z DEC 11 RUN OF BOTH MODELS IS
SLIGHTLY FASTER WITH THE WAVE AND SURFACE TEMPS ARE A DEGREE OR
TWO WARMER THAN IN PRIOR RUNS. THERMAL PROFILES SUGGEST MAINLY
LIGHT RAIN ACROSS THE AREA...ALTHOUGH WITH A GOOD DEAL OF LOW-LEVEL
DRY AIR IN PLACE...AM CONCERNED ABOUT EVAPORATIVE COOLING...ESPECIALLY
WITH THE ONSET OF PRECIP DURING THE EVENING. BASED ON EXPECTED
SURFACE TEMPS...HAVE ADJUSTED PREVIOUS PRECIP TYPE FORECAST TO
FEATURE LIGHT FREEZING RAIN ALONG AND NORTH OF I-74 DURING THE
EVENING...CHANGING TO LIGHT RAIN AFTER MIDNIGHT AS THE LOW-LEVELS
MOISTEN AND WARM. ANY ICING WILL BE MINIMAL AND SHORT-LIVED...EXCEPT
PERHAPS ACROSS THE FAR NORTHWEST KILX CWA WHERE EXISTING SNOW COVER
MAY ACT TO KEEP TEMPS AT OR BELOW FREEZING FOR MUCH OF THE NIGHT.
AS A RESULT...WILL MAINTAIN LIGHT FREEZING RAIN ACROSS KNOX AND
STARK COUNTIES FOR THE ENTIRE NIGHT.

WAVE QUICKLY DEPARTS BY SUNDAY MORNING...BRINGING AN END TO ANY
PRECIP. WITH WARM/MOIST FLOW CONTINUING...LOW CLOUDS WILL STICK
AROUND FOR THE REST OF THE DAY. DESPITE CLOUD COVER...SOUTHERLY
WINDS WILL BOOST HIGH TEMPS INTO THE 40S ACROSS MOST LOCATIONS. 

LONG TERM...MONDAY THROUGH THURSDAY

MEDIUM RANGE MODELS CONTINUE TO SHOW NEXT WAVE AND ASSOCIATED
FRONT ARRIVING ON MONDAY. WILL CARRY SLIGHT CHANCE POPS FOR MAINLY
LIGHT RAIN SHOWERS AS THE FRONT SWINGS THROUGH CENTRAL ILLINOIS.
AFTER THAT...ANOTHER BLAST OF COLD CANADIAN AIR WILL INVADE THE
MIDWEST BY TUESDAY AND WEDNESDAY...WITH HIGH TEMPS DROPPING BACK
INTO THE 20S.

BARNES

&&

.AVIATION...
ISSUED 538 AM CST FRI DEC 11 2009

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...DUE TO HIGH PRESSURE
CENTERED SOUTHEAST OF IL. 

SOUTHWEST WINDS WILL CONTINUE TODAY...WITH A FEW GUSTS TO
12-15KTS. AS THE HIGH PULLS FARTHER EAST...WINDS WILL BECOME MORE
SOUTHERLY. 

LITTLE TO NO CLOUDS ARE EXPECTED...WITH NO RESTRICTIONS TO VISIBILITY.

SHIMON
&&

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

$$