National Weather Service Raw Text Product

680 
FXUS63 KILX 190302
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
902 PM CST TUE DEC 18 2012

.DISCUSSION...
ISSUED 900 PM CST TUE DEC 18 2012

LOW PRESSURE AT THE SOUTHERN TIP OF LAKE MICHIGAN IS QUICKLY
DEPARTING TO THE EAST-NORTHEAST. LOW CLOUDS BEHIND THE LOW ARE
COVERING THE NORTHERN HALF OF OUR COUNTIES...WITH SOME VERY GUSTY
WINDS IN THE PRESSURE RISES BEHIND THE LOW. PRESSURE GRADIENT IS
RATHER COMPACT FOR SEVERAL HUNDRED MILES BEHIND THE LOW. WINDS
SHOULD DECREASE BY MIDNIGHT FROM WEST TO EAST...AS THE PRES
GRADIENT WEAKENS. 

CLOUDS WILL REMAIN ALL NIGHT ALONG AND NORTH OF I-74...WITH
VARIABLE SOUTHERN EDGE AS FAR SOUTH AS RUSHVILLE-LINCOLN-
CHAMPAIGN/DANVILLE FOR A TIME. 

LOWS TONIGHT WILL BE A LITTLE TOUGHER TO PINPOINT FROM NORTH TO
SOUTH DUE TO THE CLOUD COVER AND DIFFERENT WIND REGIMES ACROSS
THE AREA. WILL PROBABLY BE SLIGHTLY COLDER IN THE SOUTH THAN WE
HAVE GOING...DUE TO LESS CLOUDS AND LIGHTER WINDS FOR A LONGER
PERIOD OF THE NIGHT. NO MAJOR CHANGES FOR THE SHORT TERM
GRIDS...OTHER THAN UPDATING SKY/WIND. MINOR TEMP ADJUSTMENTS
NEEDED AS WELL.

A QUICK PEEK AT THE 00Z NAM FOR THE STORM FOR WED NIGHT-THUR NIGHT
SHOWS NO BIG CHANGES. RAIN WED NIGHT INTO THURS MORNING...WITH
RAIN CHANGING TO SNOW LATE MORNING NW OF IL RIVER AND CHANGING TO
SNOW EAST OF THERE IN THE AFTERNOON. 1-3" STILL ON TRACK FOR OUR
NW COUNTIES...WITH THE BULK OF THE SNOW FALLING THUR AFTERNOON
WHEN THE WINDS REALLY PICK UP...35-50 MPH AT TIMES. IT WILL BE A
MESS AS WE HEAD INTO THURS NIGHT AND THE TEMPS FALL DRAMATICALLY.

SHIMON
&&

.AVIATION...
ISSUED 600 PM CST TUE DEC 18 2012...FOR THE 00Z TAFS

LOW PRESSURE CENTERED JUST NORTH OF LACON AT 5 PM WILL MOVE EAST-
NORTHEAST THIS EVENING. MVFR CLOUDS AT 2000 FT BEHIND THE LOW
WILL MOVE ACROSS PIA BETWEEN 00-01Z AND BMI BY 02Z. THE MVFR
CLOUDS WILL BE FOLLOWED BY MVFR VIS AFTER MIDNIGHT...WITH MOST
AREAS IN THE 3-4SM BR RANGE AT SOME POINT TONIGHT. CONDITIONS
SHOULD RETURN TO VFR BY 13-15Z IN MOST AREAS. PIA MAY REMAIN MVFR
DUE TO LIGHT FOG FOR A GOOD PORTION OF THE DAY AS THAT AREA
REMAINS IN HIGHER MOISTURE CONTENT NEAR THE SURFACE.

RAIN ASSOCIATED WITH THE NEXT MAJOR STORM SYSTEM MAY BEGIN BY
20-22Z WED AFTERNOON FOR PIA AND SPI...AS STRONG MID LEVEL WINDS
BRING MOISTURE INTO THE AREA. WE WENT WITH VCSH IN PIA/SPI/BMI FOR
NOW. SURFACE WINDS WILL SWING AROUND TO THE EAST-SOUTHEAST BY
AFTERNOON...JUST AHEAD OF THE RAIN.

HEAVIER RAINS SHOULD HOLD OFF UNTIL WED NIGHT...AFTER THIS TAF
PERIOD. 

SHIMON
&&

.PREV DISCUSSION...
ISSUED 325 PM CST TUE DEC 18 2012

MODELS IN FAIRLY GOOD AGREEMENT THIS AFTERNOON BUT DIFFER STILL ON
PLACEMENT OF HEAVIEST SNOWFALL WITH UPCOMING WINTER STORM. MODELS
HOWEVER DO AGREE ON PATH OF LOW TRACK AND 500MB LOW CUTTING OFF
AND TRACKING ACROSS NORTHERN HALF OF IL. MAIN CONCERN IS THE
WINTER STORM WED NIGHT THROUGH THUR NIGHT ACROSS THE REGION. SEEMS
NAM MAY BE ODD MODEL OUT WITH TIMING OF HEAVIEST SNOWFALL...QUICKER
THAN OTHERS. SO WILL LEAN TOWARD A BLEND OF THE GFS/ECMWF/SREF FOR
THIS PACKAGE. OTHER CONCERNS ARE IN THE EXTENDED WITH ANOTHER
SYSTEM ON OR JUST AFTER CHRISTMAS. WILL JUST FOLLOW ALLBLEND FOR
NOW UNTIL MODELS GET BETTER AGREEMENT. 

SHORT TERM...TONIGHT THROUGH FRIDAY

CONFIDENCE IN NEAR TERM FORECAST HIGH WITH MODELS AGREEING ON
LOCATION OF STORM TRACK AND RESULTING PLACEMENT OF HEAVIEST
SNOWFALL. NAM SEEMS TOO QUICK WITH SNOWFALL/PCPN THROUGH THE
PERIOD SO LIKE A BLEND OF GFS/ECMWF FOR TIMING. LOW PRESS AREA
WILL COME OUT OF PLAINS TOMORROW EVENING AND MOVE NORTHEAST
THROUGH THURSDAY...REACHING TO NEAR PONTIAC BY 18Z THURSDAY. AS
THIS SYSTEM DEVELOPS/DEEPENS IN THE SOUTHERN PLAINS IT WILL BRING
IN QUITE A BIT OF WARM MOIST AIR INTO THE MISS VALLEY THROUGH
TOMORROW NIGHT. THIS COMBINED WITH A STRONG DYNAMIC
SYSTEM...EXPECTING PLENTY OF RAIN/RAIN SHOWERS ACROSS THE AREA
BEGINNING TOMORROW AND CONTINUING INTO TOMORROW NIGHT. SHOULD BE
ENOUGH INSTABILITY ON THE SFC IN THE WARM SECTOR AND ELEVATED
CLOSE TO THE WARM FRONT...TO HAVE SOME ISOLATED/CHANCE OF
THUNDERSTORMS EMBEDDED IN THE RAIN. BY THURSDAY MORNING AS THE
SYSTEM CONTINUES TO MOVE NORTHEAST AND DEEPEN SOME...THE THUNDER
CHANCES WILL GET PUSHED QUICKLY TO THE EAST AND MUCH COLDER AIR
WILL ADVECT IN FROM THE WEST. PCPN WILL CONTINUE ACROSS THE AREA
WITH RAIN BECOMING MIXED WITH SNOW DURING THE MORNING HOURS AND
THEN CHANGING TO ALL SNOW BY LATE MORNING INTO THE AFTERNOON HOURS
IN THE EAST. ALONG WITH THIS...THE PRESSURE GRADIENT WILL TIGHTEN
WITH THIS SYSTEM AND BRING VERY STRONG GUSTY WINDS TO THE NORTHERN
THIRD OF THE CWA. IN AREAS THAT HAVE SNOWFALL...THERE WILL BE
BLOWING SNOW AS WELL...MAINLY THURSDAY INTO THURSDAY NIGHT. WIND
GUSTS WILL BE ADVISORY CRITERIA...AND COMBINE WITH SNOWFALL OF 1-3
INCHES NORTHWEST OF A JACKSONVILLE TO BLOOMINGTON LINE...WITH
HIGHEST AMOUNTS AROUND GALESBURG...A WINTER WEATHER ADVISORY MAY
BE NEEDED FOR THE 4TH THROUGH 5TH PERIODS. BEING THIS EVENT IS FAR
ENOUGH AWAY...WILL LET TONIGHTS SHIFT DECIDE ON ADVISORY AND
CONTINUE TO HIGHLIGHT CONCERNS FOR THUR AND THUR NIGHT IN THE HWO
AND SPS.

ONCE THE SNOW AND BLOWING STOPS LATE THURSDAY NIGHT...DRY AND
COLDER WEATHER IS EXPECTED FOR FRIDAY.

TEMPS WILL BE VERY WARM AHEAD OF THE NEXT SYSTEM AND THEN TEMPS
WILL BE FALLING ON THURSDAY WITH WARMEST TEMPS EARLY THURSDAY
MORNING AND THEN FALLING 20+ DEGREES IN THE AFTERNOON. 

LONG TERM...FRIDAY NIGHT THROUGH TUESDAY

DRY WEATHER EXPECTED THROUGH THE WEEKEND AND THEN ANOTHER SYSTEM
IS POSSIBLE NEXT WEEK. ECMWF BRING SYSTEM IN FOR CHRISTMAS DAY
WHILE GFS IS MUCH LATER. FOR NOW WILL JUST STICK WITH THE ALL-
BLEND WHICH HAS POPS FOR WED NIGHT AND TUESDAY. THIS EVENT FAR
ENOUGH AWAY THAT MODELS SHOULD HOPEFULLY COME INTO BETTER
AGREEMENT. 

AUTEN

&&

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

$$