FXUS63 KILX 251800
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1200 PM CST WED NOV 25 2009
.DISCUSSION...
ISSUED 1045 AM CST WED NOV 25 2009
UPDATED THE FORECAST TODAY TO INCREASE CHANCES OF RAIN A BIT TODAY
WITH 40-60% CHANCE OF SHOWERS NORTH OF LINCOLN AND JUST 20% CHANCE
OF LIGHT SHOWERS IN SE IL. A NARROW CLEAR SLOT IN THE LOW CLOUDS
WILL WORK ITS WAY ACROSS CENTRAL/SW IL TODAY WITH MORE SUNSHINE
POSSIBLE IN SW IL WHILE GENERALLY MOSTLY CLOUDY TO OVERCAST SKIES
IN THE NE HALF OF IL TODAY. TEMPS IN THE UPPER 40S TO NEAR 50F
WILL ONLY CLIMB ANOTHER DEGREE OR TWO AND COULD EVEN SLIP IN THE
NW DURING THE AFTERNOON. BREEZY WSW WINDS 10 TO 20 MPH AND GUSTS
AROUND 25 MPH EXPECTED TO CONTINUE.
LATE MORNING SURFACE MAP SHOWS 1003 MB LOW PRESSURE CONTINUE TO
SLOWLY DEEPEN OVER NORTHERN LAKE MI WITH ITS COLD FRONT WELL EAST
OF IL IN CENTRAL OH AND EASTERN PARTS OF KY/TN. ALOFT A STRONG 537
DM 500 MB LOW WAS OVER NW IA AND 541 DM 500 MB LOW OVER NORTHERN
LAKE MI. SCATTERED TO ISOLATED SHOWERS WERE OVER IA/NORTHERN MI
INTO NW IL AND MOVING EAST TOWARD CENTRAL IL.
SHORT RANGE MODELS SHOW LOW PRESSURE LIFTING NE TOWARD JAMES BAY
CANADA TONIGHT WHILE STRONG CUTOFF UPPER LEVEL LOW DIGS INTO THE
IL BY SUNRISE THU. THIS WILL LIKELY BRING MORE SCATTERED LIGHT
RAIN SHOWERS TO CENTRAL IL THIS AFTERNOON AND TONIGHT. WILL BECOME
COLD ENOUGH TO MIX WITH OR CHANGE TO LIGHT SNOW SHOWERS LATER
TONIGHT ESPECIALLY FROM I-74 NORTH.
HUETTL
&&
.AVIATION...
ISSUED 1155 AM CST WED NOV 25 2009
MVFR CEILINGS AND VISIBILITIES WILL PREVAIL ACROSS THE CENTRAL IL
TERMINALS THROUGH THU MORNING. VFR CONDITIONS WILL PROBABLY WORK
INTO SPI AND DEC SITES FOR A TIME THIS AFTERNOON WITH A DRY SLOT
WORKING EASTWARD FROM WESTCENTRAL IL. IFR CEILINGS AND
VISIBILITIES WILL BE POSSIBLE WITH SCATTERED RAIN SHOWERS WHICH
WILL MIX WITH OR CHANGE TO LIGHT SNOW SHOWERS LATE TONIGHT INTO
THU MORNING ESPECIALLY ALONG I-74.
MIDDAY SURFACE MAP SHOWS 1003 MB LOW PRESSURE OVER NORTHERN LAKE
MI WITH A SURFACE TROF EXTENDING SW INTO SE IA AND FAR NW MO.
STRONG 537 DM 500 MB CUTOFF LOW WAS OVER NW IA. BROKEN TO OVERCAST
MVFR TO LOCALLY IFR CEILINGS OVER CENTRAL/NORTHERN IL WITH LARGE
BREAKS/CLEARING AREAS IN SW/SOUTHERN IL. SCATTERED SHOWERS WILL
MOVING EAST FROM IA AND NORTHERN MO INTO THE IL RIVER VALLEY OVER
NW IL. MODELS DIG STRONG UPPER LEVEL LOW/TROF INTO IL BY 12Z/6 AM
THU AND INTO INDIANA BY 18Z/NOON THU. MODELS TRENDING A BIT
QUICKER WITH THIS. SCATTERED LIGHT RAIN SHOWERS WILL LIKELY SPREAD
ACROSS EASTERN IL THIS AFTERNOON AND CONTINUE TONIGHT ESPECIALLY
FROM I-74 NE WHERE LIGHT SNOW SHOWERS POSSIBLE LATE TONIGHT INTO
MID MORNING THU. BREEZY WSW WINDS WILL TURN WNW THU MORNING.
HUETTL
&&
.PREV DISCUSSION...
ISSUED 215 AM CST WED NOV 25 2009
SATELLITE AND RADAR IMAGERY SHOWS THE CENTER OF THE STACKED
LOW JUST NORTHEAST OF GALESBURG. SHOWERS CONTINUE TO PINWHEEL
AROUND THIS LOW...MAINLY AFFECTING AREAS NORTH OF I-72 OVER THE
LAST FEW HOURS. A SECONDARY TROUGH WAS ASSOCIATED WITH THIS
LOW...AND WAS POISED TO BEGIN MOVING INTO THE NORTHWEST CWA.
MEANWHILE...WATER VAPOR IMAGERY SHOWED A SECOND UPPER LOW EGINNING
TO CROSS THE MANITOBA/NORTH DAKOTA BORDER.
THE LINGERING EFFECTS OF THESE TWO SYSTEMS THROUGH THANKSGIVING
DAY...ALONG WITH ASSOCIATED PRECIPITATION TYPES...MAKE UP THE
FORECAST CHALLENGES FOR THIS PACKAGE.
SHORT TERM...TODAY THROUGH FRIDAY...
CURRENT SURFACE LOW EXPECTED TO QUICKLY LIFT NORTHEAST INTO THE
GREAT LAKES TODAY AND WEAKEN...AS THE NEW CLOSED UPPER LOW DIVES
SOUTHEAST INTO CENTRAL ILLINOIS BY MIDNIGHT. SHOWERS ACROSS THE
NORTHERN CWA EXPECTED TO TAPER OFF BY LATE MORNING...WITH A NEW
ROUND MOVING IN TOWARD MID TO LATE AFTERNOON AS THE NEW UPPER LOW
MOVES INTO THE AREA. TRICKY PART OF THE FORECAST IS WHEN THE
TRANSITION FROM RAIN TO SNOW OCCURS. MODEL AND BUFKIT SOUNDINGS
SHOW THIS TO BEGIN OCCURRING TOWARD MIDNIGHT...WITH A POTENTIAL
SWITCH BACK TO RAIN AS THE PRECIPITATION ENDS THURSDAY MORNING
ACROSS THE WESTERN CWA...AND IN THE EARLY AFTERNOON ACROSS THE
EAST. GROUND TEMPERATURES IN THE 40-45F RANGE...AND THE BULK OF
THE DEFORMATION ZONE PRECIP REMAINING JUST TO OUR NORTH...WOULD
LIMIT ANY ACCUMULATIONS THAT MAY OCCUR.
GUSTY WINDS TO NEAR 25-30 MPH EXPECTED ON THURSDAY AS A TROUGH
ZIPS THROUGH THE AREA. WINDS WILL SUBSIDE THURSDAY NIGHT...WITH A
HIGH PRESSURE RIDGE PUSHING EAST ACROSS THE MISSISSIPPI VALLEY.
THIS RIDGE WILL RESULT IN QUIET WEATHER FOR FRIDAY...AND SOUTHWEST
WINDS WILL HELP BOOST TEMPERATURES SEVERAL DEGREES FROM
THANKSGIVING DAY HIGHS.
LONG TERM...SATURDAY THROUGH TUESDAY...
WEAK UPPER RIDGING TO MOVE EAST ACROSS THE CONUS THE FIRST PART OF
THE WEEKEND. MAIN CONCERNS IN THE LONG TERM CONTINUE TO FOCUS ON
TWO SYSTEMS IN THE NORTHERN AND SOUTHERN JET STREAMS. GFS IS
STRONGER WITH THE NORTHERN SYSTEM...DROPPING IT INTO THE SOUTHERN
PLAINS TO GREATLY ENHANCE THE SOUTHERN STREAM SYSTEM BY
MIDWEEK...WHILE THE ECMWF GENERALLY KEEPS THE STREAMS SEPARATE.
HOWEVER...THE MORE SIGNIFICANT DIFFERENCES COME BEYOND THE END OF
THE CURRENT FORECAST PERIOD.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
