FXUS63 KLOT 282055
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CST SAT NOV 28 2009

.DISCUSSION...
255 PM CST

MAIN ISSUES THIS FORECAST PACKAGE REST WITH A COLD FRONT COMING
THROUGH IN THE SHORT TERM AND A POSSIBLE ACCUMULATING SNOWFALL
TOWARD THE MIDDLE OF NEXT WEEK.

RIDICULOUSLY PLEASANT CONDITIONS FOR THE END OF NOVEMBER SHOULD 
CONTINUE INTO THE EVENING WITH AN INCREASE IN DEW POINTS UP INTO THE 
UPPER 30S TO AROUND 40.  A COLD FRONT CURRENTLY STRETCHED ACROSS 
CENTRAL WI/IA WILL INCH CLOSER TO THE FORECAST AREA 
OVERNIGHT...WHICH WITH WINDS GENERALLY REMAINING OUT OF THE SOUTH TO 
SOUTHWEST...SHOULD KEEP LOW TEMPS IN THE UPPER 30S.

CLOUD COVER WILL BE ON THE INCREASE SUNDAY MORNING AS THE VERTICAL 
PROFILE MOISTENS UP AND THE COLD FRONT MOVES INTO NORTHERN
ILLINOIS. SHOWERS/LIGHT RAIN IS EXPECTED TO DEVELOP ALONG/BEHIND
THE SFC COLD FRONT YET AHEAD OF THE 850MB FRONT. THE SOUTHERN
STREAM JET STREAK WILL STRENGTHEN INTO SOUTHERN
ILLINOIS...PUTTING THE FORECAST AREA IN THE FAVORABLE LEFT EXIT
REGION FOR LIFT. HAVE BUMPED UP POPS ON SUNDAY WITH THIS ACTIVITY
EXPECTED TO START UP LATER IN THE MORNING AND CLEAR THE CWA BY
EVENING AS HIGH PRESSURE BUILDS IN FROM THE WEST.

THIS HIGH WILL BUILD IN ACROSS MOST OF THE SOUTHERN US...KEEPING ANY 
WEAK DISTURBANCES NORTH OF THE REGION EARLY NEXT WEEK.  THIS WILL 
KEEP OUR CONDITIONS DRY AND SEASONABLE TEMPERATURE-WISE.  WILL HAVE 
TO KEEP AN EYE ON ONE QUICK MOVING SYSTEM AIMING FOR THE GREAT LAKES 
ON MONDAY...BUT FOR NOW IT LOOKS LIKE IT'LL STAY SAFELY ENOUGH 
NORTH.  TUESDAY IS SHAPING UP TO BE ANOTHER PLEASANT DAY IN A WAA 
REGIME WITH HIGHS IN THE UPPER 40S...POSSIBLY TAGGING 50 AGAIN.

MOST OF THE ATTENTION IN THE EXTENDED PORTION OF THIS FORECAST 
PACKAGE IS IN REGARDS TO THE PESKY SFC LOW/UPPER LEVEL CLOSED LOW 
THAT HAS BEEN ADVERTISED TO TRACK ACROSS THE EASTERN US FOR THE PAST 
FEW SETS OF MODEL RUNS.  MAIN QUESTION HAS BEEN...WHEN AND 
WHERE. THIS QUESTION STILL DOESN'T APPEAR TO BE SETTLED TODAY WITH
THE GFS AND ECMWF HAVING TIMING/TRACK DIFFERENCES. CONFIDENCE
REMAINS LOW WITH THE DETAILS OF WHAT WILL HAPPEN TOWARD THE MIDDLE
OF NEXT WEEK...BUT WITH THE CLOSED UPPER LOW NOW OVER LAND IN
SOUTHERN CALIFORNIA...THE GUIDANCE IS SUGGESTING THAT THIS LOW IS
GOING TO BE PICKED UP BY A NORTHERN STREAM TROF WHICH WILL THEN
TAKE THE SOUTHERN VORT MAX THROUGH TN/KY. WITH COLD AIR WRAPPING
IN BEHIND THIS SYSTEM ACROSS OUR REGION...APPEARS PLAUSIBLE THAT
WE WILL SEE SOME LIGHT SNOW OUT OF THIS SYSTEM WITH THE BEST CHANCES
GOING FROM BENTON COUNTY NORTHWEST. AM CURRENTLY EXPECTING THE
HEAVIEST SNOW BANDS TO STAY WAY SOUTHEAST OF THE FORECAST AREA WITH
THE UPPER/SFC LOW STAYING SOUTHEAST...BUT THIS COULD BE AN
ACCUMULATING SNOWFALL NONE THE LESS. BETTER DETAILS ARE EXPECTED
TO UNFOLD OVER THE NEXT DAY OR SO AS THE NORTHERN KICKER SYSTEM
MAKES IT OVER LAND IN SOUTHWEST CANADA. FOR NOW...HAVE TRENDED
MUCH COLDER THROUGH THE END OF THE EXTENDED PERIOD AND WENT WITH
LIGHT SNOW FOR WEDNESDAY NIGHT INTO EARLY THURSDAY.

HALBACH

&&

.AVIATION...

1800 UTC TAFS...WE WILL ADD MVFR CEILINGS IN THE FORECAST FOR THE 
AIRPORTS OF NORTH CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND
NORTHWEST INDIANA FOR SUNDAY. A WEAK FRONT WILL MOVE THROUGH
SUNDAY MORNING. WE EXPECT CLOUDS TO INCREASE AND LOWER TO 1500 TO
2000 FEET. THIS IS AN OPTIMISTIC FORECAST. THERE MAY BE IFR
CEILINGS SUNDAY. WE WILL SEE WHAT THE LATER RUNS OF OUR FORECAST
MODELS MAY PRODUCE. WE WILL ADD SOME LIGHT RAIN AS A TEMPO GROUP
FOR OHARE SUNDAY AFTERNOON. THE RAIN MAY OCCUR EARLIER AND THE
FORECAST TIME OF RAIN MAY BE ADJUSTED IN LATER TAF ISSUANCE'S.
SOME LIGHT FOG MAY DEVELOP LATE TONIGHT. WE WILL ADD 4 MILES 
VISIBILITY IN LIGHT FOG TO THE FORECASTS AFTER 06 UTC.

&&

.MARINE...
232 PM CST

A FRONT WILL MOVE THROUGH LAKE MICHIGAN TONIGHT. A LOW WILL MOVE 
ACROSS WISCONSIN AND ANOTHER MAY MOVE ACROSS NORTHERN ILLINOIS. 
THIS WILL BRING A WIND SHIFT FROM THE SOUTH AROUND 10 KNOTS TO THE 
NORTH AND INCREASING TO 15 TO 25 KNOTS BY SUNDAY AFTERNOON. THERE
WILL BE AREAS OF RAIN. THE WAVES WILL BE 1 TO 3 FEET. A NORTH WIND
WILL BECOME SOUTHWEST DURING THE DAY MONDAY. WE EXPECT AN INCREASE
IN SPEED TO 15 TO 25 KNOTS FROM THE SOUTHWEST BY MONDAY AFTERNOON. 
THIS IS IN RESPONSE TO A HIGH BUILDING OVER OKLAHOMA BY MONDAY
AFTERNOON. 

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$