FXUS63 KILX 201156
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
656 AM CDT SAT MAR 20 2010

.DISCUSSION...
ISSUED 330 AM CDT SAT MAR 20 2010

FORECAST CONCERN IS HOW MUCH SNOW WILL FALL ACROSS THE IL RIVER
VALLEY THROUGH TONIGHT...AND STILL LOOKS LIKE 1-3 INCHES NW OF THE
IL RIVER TODAY INTO TONIGHT. 00Z SHORT RANGE MODELS TRENDING SLOWER
WITH FRONTOGENETIC PRECIPITATION MOVING SLOWLY SE INTO CENTRAL IL
THIS MORNING. LIGHT SNOW IS STILL NW OF GALESBURG AND QUINCY AT 3
AM. NCEP FEELS NAM AND GFS MAYBE A BIT TOO FAR SOUTH WITH WEATHER
SYSTEMS THIS WEEKEND AND TRENDED QPF FIELDS A BIT FURTHER NORTH
THAN THESE TWO MODELS PROTRAYED. STRONG UPPER LEVEL LOW THAT MOVES
EAST ACROSS THE SOUTHERN STATES HAS INCREASED RAIN CHANCES SUNDAY
AFTERNOON/NIGHT EAST OF I-55.

EARLY MORNING SURFACE MAP SHOWS A COLD FRONT MOVING SLOWLY SE
ACROSS CENTRAL IN/IL TOWARD I-70 AND INTO SE MO TO 1011 MB LOW
PRESSURE IN NW AR AND STRONGER 1007 MB LOW PRESSURE IN SW TX. POST
FRONTAL PRECIPITATION IN FROM OF LIGHT TO MODERATE SNOW HAS BEEN
FROM ROCKFORD TO QUAD CITIES TO KIRKSVILLE AND STILL NW OF
GALESBURG AND QUINCY. TEMPS HAVE FALLEN TO THE MID TO UPPER 30S NW
OF THE IL RIVER WITH NORTH WINDS 10-20 MPH AND GUSTING TO 20-30 MPH.
WHILE 40S SE OF THE IL RIVER.

SHORT TERM...TODAY THROUGH MONDAY NIGHT.

MODELS SLOW DOWN COLD FRONT AS IT MOVES INTO SE IL TODAY WHILE
FRONTEGENETIC FORCING AND ISENTROPIC LIFT BEHIND THE COLD FRONT
BRINGS RAIN/SNOW SE ACROSS THE IL RIVER VALLEY THIS MORNING AND
INTO CENTRAL IL THIS AFTERNOON IN FORM OF RAIN FROM I-55 EAST.
MIXED PRECIPITATION TURNS TO SNOW BY AFTERNOON ACROSS THE IL RIVER
VALLEY. JUST A SLIGHT CHANCE OF RAIN SHOWERS SE OF I-70 THIS
AFTERNOON NEAR THE FRONTAL BOUNDARY. ABOUT A 30 DEGREE TEMPERATURE
SPREAD TODAY FOR HIGHS ACROSS CWA RANGING FROM 36F FAR NW BY
GALESBURG TO 65F FAR SE IL BY LAWRENCEVILLE WHERE AHEAD OF COLD
FRONT AND SOME PEAKS OF SUNSHINE ESPECIALLY THIS MORNING.

LOWERED PRECIPITATION CHANCES TONIGHT AS FRONTOGENETIC FORCING
WEAKS OVER CENTRAL IL WHILE FORCING FOCUSED SW OF IL CLOSER TO
STRONG UPPER LEVEL LOW DEVELOPING OVER THE SOUTHERN PLAINS. STILL
HAVE LIKELY CHANCES OF LIGHT SNOW OVER THE IL RIVER VALLEY THIS
EVENING THEN TURNS BACK TO A MIX OF RAIN OVERNIGHT AS WARMER AIR
AT 850 MB MOVES NW. AREAS NW OF THE IL RIVER COULD SEE 1-3 INCHES
WITH HIHGEST AMOUNTS FROM GALESBURG TO MACOMB TO RUSHVILLE WEST.
BELOW SNOW ADVISORY CRITERIA OF 3 INCHES.

RAIN CHANCES INCREASE BY SUNDAY AFTERNOON ACROSS AREAS EAST OF
I-55 AND ESPECIALLY SUNDAY NIGHT AS STRONG UPPER LEVEL LOW MOVES
INTO THE SOUTHERN TN VALLEY. SPC HAS CHANCES OF THUNDER JUST SE OF
LAWRENCEVILLE SUNDAY NIGHT SO THIS WILL NEED TO BE WATCHED FOR IF
SE IL NEEDS THUNDER MENTIONED. INCREASE QPF AMOUNTS ACROSS SE IL
SUNDAY AFTERNOON AND SUNDAY NIGHT AND THIS MAY CAUSE SOME RIVERS
TO GO BACK INTO FLOOD. FOLLOWED COOLER GUIDANCE HIGHS SUNDAY WITH
LOW CLOUDS AND RAIN CHANCES INCREASING ESPECIALLY EASTERN/SE IL.

CHANCES OF LIGHT RAIN MON OVER EASTERN IL EAST OF I-55 MAINLY MON
MORNING AS UPPER LEVEL LOW EXITS EAST OF THE TN VALLEY.

LONG TERM...TUESDAY THROUGH FRIDAY.

DRY WEATHER EXPECTED FROM MONDAY NIGHT THROUGH WED WITH TEMPERATURES
MODIFYING AS UPPER LEVEL RIDGE BRIEFLY BUILDS BACK INTO IL.
REMOVED SLIGHT CHANCE OF RAIN WED AS EXTENDED MODELS IN AGREEMENT
OF NEXT WX SYSTEM BEING SLOWER TO EJECT NE FROM THE SOUTHERN
PLAINS TOWARD THE MIDWEST. NEXT BEST CHANCE OF RAIN WILL BE
THU/FRI.

HUETTL
&&

.AVIATION...
ISSUED 656 AM CDT SAT MAR 20 2010

PCPN HAS BEGUN TO SPREAD BACK INTO NORTHWEST IL AFFECTING ONLY PIA
TAF WTIH -RA AND LOWER CIGS. BELIEVE LOWER CIGS WILL AFFECT PIA
THROUGH REMAINDER OF THE PERIOD. CURRENT PCPN IS RAIN...BUT LATER
THIS MORNING SHOULD BECOME MIXED WITH RAIN...AND THEN LATER CHANGE
TO ALL SNOW. BY THIS AFTERNOON...ALL PCPN AT PIA WILL BE SNOW.
CIGS WILL ALSO BE LOWER WITH THIS SYTEM. BASED ON SATELLITE
LOOPS...PCPN WILL BE SLOW TO AFFECT BMI AND SPI SO WILL JUST HAVE
VCSH FOR EARLY AFTERNOON...BUT CONTINUING ONLY AT BMI. SPI...DEC
AND CMI WILL ONLY HAVE VCSH WITH A LITTLE TEMPO LIGHT RAIN DURING
THE EVENING HOURS. CIGS WILL ALL BE MVFR THROUGH THE PERIOD. NNE
WINDS SHOULD BECOME QUITE GUSTY FOR NOW.

AUTEN
&&

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

$$