FXUS63 KILX 120522
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1122 PM CST FRI DEC 11 2009

.DISCUSSION...
ISSUED 825 PM CST FRI DEC 11 2009

LATEST SURFACE ANALYSIS INDICATING HIGH PRESSURE WELL OFF TO OUR
SOUTHEAST EARLY THIS EVENING WITH A LIGHT SOUTHERLY FLOW PREVAILING
ACRS THE FORECAST AREA. AREA OF CLOUDINESS THAT WAS PUSHING NE INTO
SOUTHWEST AND SOUTH CENTRAL MO HAS RUN INTO SOME VERY DRY AIR
ACCORDING TO THE EVENING SOUNDINGS...WITH MOST OF THE EXTENSIVE
CLOUD COVER NOW SHIFTING MORE EAST THAN NORTH. HOWEVER...WITH THE
PERSISTENT LOW LEVEL SOUTHERLY FLOW ACRS THE REGION...THE BETTER
MOISTURE CURRENTLY OVER TX WL START TO STREAM NORTHEAST INTO THE
REGION DURING THE DAY SATURDAY...ESPECIALLY IN THE AFTERNOON. 
UNTIL THEN...QUIET WEATHER CONDITIONS TO HOLD ACRS THE AREA. BASED
ON THE TEMP TRENDS THIS EVENING...OUR CURRENT EARLY MRNG LOWS LOOK
REASONABLE. JUST MAKING SOME MINOR TWEAKS TO THE SKY COVER AND
WINDS THIS EVENING...OTHERWISE...THE CURRENT SET OF ZONES IN GOOD
SHAPE. NO EVENING UPDATE WILL BE NEEDED. 

&&

.AVIATION...
ISSUED 1115 PM CST FRI DEC 11 2009

BAND OF LOW VFR CIGS ACRS SRN MO TRACKING MORE EAST THE NORTH LATE
THIS EVENING...WHILE SATELLITE DATA ALSO INDICATING ANOTHER SURGE
OF LOW LEVEL MOISTURE/CLOUDS STREAMING NWD OUT OF ERN OK. STILL 
APPEARS VFR CONDITIONS WILL PREVAIL UNTIL MID AFTN ACRS SPI AND 
PIA AND PROBABLY INTO THE EARLY EVENING ACRS CMI BEFORE A WEAK
WEATHER DISTURBANCE SHIFTS NE ACRS THE AREA SAT NIGHT INTO SUN
MORNING. MODEL DATA CONTINUING TO SHOW A 300 MB SPEED MAX TRACKING
TO OUR SOUTH TMRM NIGHT WITH OUR SRN AREAS IN THE MORE FAVORABLE
LEFT EXIT REGION...WHICH WOULD SUPPORT MORE WIDESPREAD RAINFALL
ACRS THAT AREA. FURTHER NORTH...THE LIFT IS NOT AS STRONG AND THE
MOISTURE NOT AS DEEP ON FORECAST SOUNDINGS...SUGGESTING MORE OF
A LIGHT RAIN OR DRIZZLE SCENARIO. 

INITIALLY...WITH A VERY DRY AIR MASS AT THE LOW LEVELS...THERE IS
THE POSSIBILITY THAT SFC TEMPS MAY SLIP BACK TO OR BELOW FREEZING
AS THE PRECIP STARTS WHICH WOULD BRING A BRIEF PERIOD OF FZRA/FZDZ
TO PIA AND PSBLY BMI. HOWEVER...A PERSISTENT SOUTHERLY WIND SHOULD
BALANCE OUT THE EVAPORATIVE COOLING EFFECTS AND CHANGE ANY FZRA/FZDZ
ACRS OUR FAR NRN TAF SITES TO LIGHT RAIN OR DRIZZLE LATER SATURDAY
EVENING. FOR NOW WL INCLUDE VCSH DURING THE EARLY EVENING HOURS
AND SEE HOW LATER MODEL RUNS CLARIFY ANY PRECIP TYPE ISSUES OVER
THE NORTH.

SURFACE WINDS WILL REMAIN OUT OF THE SOUTH INTO SATURDAY WITH WINDS
BACKING A BIT MORE INTO THE SOUTHEAST BY EVENING. MAY SEE A FEW GUSTS
BY LATE SAT MRNG INTO THE AFTN HOURS. 

SMITH
&&

.PREV DISCUSSION...
ISSUED 255 PM CST FRI DEC 11 2009

12Z SHORT RANGE MODELS REMAIN IN FAIR AGREEMENT THROUGH EARLY NEXT
WEEK AND USED A BLEND. MODELS CONTINUE MILDER TREND SAT NIGHT WITH
PRECIPITATION MORE LIKELY RAIN THOUGH PERIOD OF LIGHT FREEZING
RAIN AND LIGHT SNOW POSSIBLE SAT EVENING FROM NORTH OF I-72.
MODELS TRENDING SLOWER WITH COLD FRONT MOVING EAST ACROSS IL MON
AFTERNOON/EARLY MON EVENING SO LOOKS MILDER MON AND JUST SLIGHT
CHANCE OF LIGHT RAIN SHOWERS. ANOTHER COOL DOWN EXPECTED BEHIND
THIS COLD FRONT DURING MIDDLE OF NEXT WEEK. MET AND MAV GUIDANCE
TEMPS FAIRLY SIMILAR AND USED A BLEND TOO THOUGH WENT COOLER OVER
SNOW PACK OVER KNOX AND STARK COUNTIES AND NW PARTS OF PEORIA AND
MARSHALL COUNTIES LIKE AROUND GALESBURG.

MID AFTERNOON SURFACE MAP SHOWS 1033 MB POLAR HIGH PRESSURE OVER
EAST TN AND RIDGING ACROSS THE SE STATES INTO EASTERN IL AND WI.
THIS PROVIDING AMPLE SUNSHINE AGAIN ACROSS CENTRAL/SE IL WITH
LIGHTER SW WINDS 7 TO 13 MPH. SCATTERED MID/HIGH CLOUDS NW OF THE
IL RIVER INTO IOWA. TEMPS MOSTLY IN THE 30S BUT RANGE FROM 27F
OVER SNOW FIELD AT GALESBURG TO THE UPPER 30S FROM SPRINGFIELD TO
ROBINSON SOUTH.

SHORT TERM...TONIGHT THROUGH MONDAY.

HIGH PRESSURE DRIFTS EAST INTO THE MID ATLANTIC STATES BY DAWN SAT
AND PROVIDING FAIR SKIES OVER IL WITH JUST SOME SCATTERED MID/HIGH
CLOUDS MOVING IN. LOWS IN THE UPPER TEEN AND LOWER 20S EXCEPT A
FEW DEGREES COLDER OVER SNACK PACK AROUND GALESBURG. 

HIGH PRESSURE DRIFTS EAST OFF THE MID ATLANTIC COAST SAT WHILE
WEAK LOW PRESSURE AROUND 1010 MB OVER MT/ND BRINGS A WEAK COLD
FRONT INTO THE CENTRAL PLAINS. CLOUDS TO INCREASE DURING THE DAY
SAT AS THEY LOWER AHEAD OF THIS FRONT. HIGHS SAT RANGE FROM THE
MID 30S FROM PEORIA NORTH TO THE MID 40S SE OF I-70. INCREASING
WARM AIR ADVECTION AND ISENTROPIC LIFT ALONG WITH WEAK SHORT WAVES
OVER IL SAT NIGHT TO BRING GOOD CHANCE OF LIGHT RAIN SHOWERS.
COULD BE ENOUGH EVAPORATIVE COOLING FOR A BRIEF PERIOD OF LIGHT
SNOW/SLEET AT ONSET ESPECIALLY FROM LINCOLN NORTH WHERE ALSO LIGHT
FREEZING RAIN POSSIBLE SAT EVENING WITH SURFACE TEMPS NEAR
FREEZING. HEAVY QPF STAYS SE OF THE OHIO RIVER. INCREASE POPS TO
LIKELY ACROSS EASTERN IL SAT NIGHT. MAINLY JUST LIGHT RAIN
OVERNIGHT SAT NIGHT THOUGH COULD STILL BE LIGHT FREEZING
RAIN/DRIZZLE OVER SNOW PACK NW OF THE IL RIVER. PATCHY DRIZZLE
COULD LINGER SUNDAY MORNING AS WEAK FRONT DISSIPATE OVER IL. SOME
SUNSHINE WILL APPEARS SUNDAY AFTERNOON ESPECIALLY IN SE IL. 

ANOTHER COLD FRONT WILL MOVE EAST ACROSS IL MON AFTERNOON AND EXIT
SE IL BY THE WABASH RIVER EARLY MON EVENING. BEST MOISTURE STAYS
SE OF IL WHILE UPPER LEVEL DYNAMICS LAG NW OF CENTRAL IL BEHIND
THE COLD FRONT. SO JUST SLIGHT CHANCE OF LIGHT RAIN SHOWERS MON.
HIGHS MON IN THE UPPER 30S NW OF THE IL RIVER AND UPPER 40S AND
LOWER 50S IN EASTERN IL WITH MILDEST READINGS BY LAWRENCEVILLE. COULD
BE A SLIGHT CHANCE OF LIGHT FREEZING RAIN NW OF THE IL RIVER LATER
SUN NIGHT AND INTO MID MORNING MON OVER THE SNOW PACK WHERE
SURFACE TEMPS COLDER. SLIGHT CHANCE OF SHOWERS LINGERS NEAR THE
IL/IN BORDER EARLY MON EVENING THEN TURNING COLDER AGAIN BEHIND
THIS FRONT.

LONG TERM...MONDAY NIGHT THROUGH FRIDAY.

EXTENDED MODELS/ENSEMBLES CONTINUE TO BUILD A FAIRLY STRONG 1039
MB CANADIAN HIGH PRESSURE FROM THE CANADIAN ROCKIES INTO THE
MIDWEST DURING THE MIDDLE OF NEXT WEEK RETURNING DRY AND COLDER
WEATHER STARTING TUE. BRISK NW WINDS TUE WITH HIGHS IN THE 20S
OVER CENTRAL IL AND LOW TO MID 30S IN SE IL. POLAR VORTEX OVER
EASTERN CANADA INTO NE USA WILL HAVE SHORT WAVES PIVOTING ACROSS
THE GREAT LAKES KEEPING MORE CLOUDS AND CHANCES OF LIGHT SNOW
SHOWERS NE OF CENTRAL IL TUE. CANADIAN HIGH PRESSURE SHOULD BE
NEAR IL WED WITH COLD CONDITIONS BUT LIGHTER WINDS. HIGH PRESSURE
DRIFTS INTO THE EASTERN STATES THU/FRI WITH RETURN SOUTHERLY FLOW
WARMING TEMPS BACK UP TOWARD NORMAL BY NEXT FRI.

HUETTL

&&

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

$$