749 
FXUS63 KILX 271816
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1215 PM CST TUE JAN 27 2004

.DISCUSSION...
UPDATED THE FORECAST THIS AFTERNOON TO CONTINUE THE WINTER WEATHER 
ADVISORY UNTIL 6 PM. PERIODS OF LIGHT SNOW NORTH OF I-70 DIMINISHING 
TO FLURRIES WITH LESS THAN 1 INCH ADDITIONAL ACCUMULATIONS. BUT WEST 
TO NORTHWEST WINDS 20 TO 30 MPH AND GUSTY TO CAUSE BLOWING AND 
DRIFTING OF THE 1 TO 5 INCH SNOW COVER. TEMPS IN THE LOWER 20S 
SLIPPING INTO THE TEENS DURING THE AFTERNOON.

999 MB LOW IN FAR SE LOWER MICHIGAN NEAR PORT HURON HAS A TROF 
ARCHING SW ACROSS EASTERN IL NEAR I-57. CUTOFF UPPER LEVEL LOW WAS 
OVER NW INDIANA. EXPANSIVE AREA OF LIGHT SNOW OVER CENTRAL AND NE IL 
FROM I-70 NORTH AND PIVOTING SLOWLY EASTWARD. LIGHT SNOW HAS ALREADY 
DIMINISHED OR ENDED FROM SPRINGFIELD SW. 1041 MB ARCTIC HIGH 
PRESSURE OVER ALBERTA CANADA AND RIDGING SOUTH ACROSS THE PLAINS 
STATES INTO EAST TEXAS. STRONG PRESSURE GRADIENT ACROSS IL BETWEEN 
THESE SYSTEM WITH WNW WINDS 15 TO 25 MPH AND GUSTY FROM 25 TO 35 MPH. 
TEMPS HAVE SLIPPED INTO THE UPPER TEENS WEST AND LOWER 20S EAST. AS 
COLD AS 14 AT GALESBURG...12 AT QUINCY AND 13 AT MOLINE. SAINT LOUIS 
WHICH IS NORMALLY WARMER THAN CENTRAL IL IS AT 17 DEGREES.

DEEP LOW PRESSURE AND CUTOFF UPPER LEVEL LOW TO DRIFT NE INTO 
SOUTHERN ONTARIO BY MIDNIGHT WITH LIGHT SNOW DIMINISHING TO FLURRIES 
FROM WEST TO EAST DURING THE AFTERNOON WITH AN ADDITIONAL SNOW 
ACCUMULATIONS UP TO 1 INCH NE AREAS FROM BMI AND CMI NE. WNW WINDS 
20 TO 30 MPH AND GUSTS UP TO 35 MPH TO CAUSE BLOWING AND DRIFTING SNOW 
THIS AFTERNOON...THEN WINDS TO SUBSIDE TOWARD LATE EVENING AND 
OVERNIGHT. WITH AMPLE LOW CLOUD COVER AND STRONG COLD AIR ADVECTION 
IN WAKE OF STORM SYSTEM...TEMPS TO CONTINUE TO SLIP INTO THE TEENS 
ACROSS CENTRAL AND SE IL THIS AFTERNOON. WIND CHILLS TO RANGE FROM 5 
BELOW ZERO TO 5 ABOVE.   

.PREV DISCUSSION...
SHORT TERM...TODAY AND WEDNESDAY...
UPPER VORT MAX IS CURRENTLY OVER SPRINGFIELD...WITH THE ASSOCIATED 
SURFACE LOW CENTER OVER EASTERN INDIANA. SURFACE REFLECTION OF THE 
UPPER SYSTEM IS SEEN AS A TROUGH EXTENDING FROM THE LOW WESTWARD 
INTO NORTHERN MISSOURI. FIRST BATCH OF SNOW HAS MOVED NORTH THROUGH 
THE AREA AND CURRENTLY LIES ACROSS THE NORTHERN HALF OF THE CWA. 
WRAP-AROUND BEHIND THE VORT MAX IS APPROACHING WESTERN ILLINOIS AND 
EXTENDS AS FAR SOUTH AS SOUTHWEST OF ST LOUIS. AS THIS ACTIVITY 
CONTINUES TO MOVE EAST...EXPECT SNOW TO CONTINUE THROUGH THE MORNING 
HOURS. THE SOUTHEASTERN PORTIONS OF THE CWA ARE CURRENTLY GETTING 
DRY-SLOTTED...BUT THE PRECIPITATION SOUTHWEST OF ST LOUIS STILL HAS 
A SHOT AT MAKING IT OVER THERE LATER THIS MORNING. 

AS THE ENTIRE SYSTEM PUSHES EAST LATER TODAY...EXPECT SNOW TO TAPER 
OFF DURING THE AFTERNOON AND PRETTY MUCH END BY 00Z. INCREASING 
PRESSURE GRADIENT WILL MAKE WINDS PRETTY STRONG...AND WILL KEEP 
BLOWING SNOW IN THE FORECASTS AS WELL AS AN ADDITIONAL 1 TO 3 INCHES 
OF SNOW. CURRENT ADVISORIES WILL BE MAINTAINED. AFTER THIS SYSTEM 
MOVES EAST...EXPECT QUIET WEATHER FOR WEDNESDAY AND MOST OF 
WEDNESDAY NIGHT.

LONG TERM...THURSDAY AND BEYOND...
ATTENTION IN THE LONGER TERM TURNS TO THE EXPECTED PENETRATION OF 
ARCTIC AIR INTO THE PLAINS STATES AROUND THURSDAY. WILL SIDE WITH 
THE ETA SOLUTION AS IT NORMALLY HANDLES THESE SITUATIONS BETTER. THE 
EXTENDED PERIODS OF THE GFS HAVE ALSO TRENDED TOWARD THE ETA. THIS 
MEANS THAT THE COLD AIR SHOULD PUSH THROUGH IN ERNEST THURSDAY AND 
THURSDAY NIGHT. WILL MAINTAIN MEAGER CHANCES FOR PRECIPITATION LATE 
WEDNESDAY NIGHT INTO EARLY THURSDAY. DEPTH OF COLD AIR SUGGESTS THAT 
MOST OF THE PRECIPITATION TYPE SHOULD BE SNOW...POSSIBLY RAIN OR 
SNOW IN THE SOUTHEAST THURSDAY.

THE EXTENDED GFS STILL TRIES TO BRING A STRONG LOW PRESSURE SYSTEM 
INTO THE PLAINS DURING THE WEEKEND. THE PREVIOUS RUN OF THE MODEL 
HAD THE SURFACE LOW WAY TOO FAR NORTH INTO THE COLD AIR. THE LATEST 
RUN THIS MORNING IS TRENDING FURTHER SOUTH...BUT IS PROBABLY STILL 
TOO FAR NORTH AS IT BRINGS THE SURFACE LOW INTO MISSOURI BY THE END 
OF THE DAY SATURDAY. WONT MAKE TOO MANY CHANGES TO THE WEEKEND 
FORECAST...BUT WILL TREND THE TEMPERATURE GRIDS COLDER FOR THE 
SECOND HALF OF THE WEEK.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY ENTIRE AREA TODAY.

&&

$$
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