Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 041152
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 AM CST THU FEB 4 2016

.SHORT TERM...
232 AM CST

THROUGH SATURDAY NIGHT...

THE SHORT TERM PERIOD FEATURES RELATIVELY PROGRESSIVE NW FLOW...BUT
GENERALLY COOL AND QUIET CONDITIONS WITH VARIABLE CLOUDINESS.
CURRENT WATER VAPOR IMAGERY DEPICTS AN UPPER LEVEL SHORTWAVE
EMBEDDED IN A FAIRLY BROAD UPPER LEVEL TROUGH JUST EAST OF THE
AREA...WITH SEVERAL ADDITIONAL DISTURBANCES EMBEDDED IN THE NW
FLOW ON THE BACK EDGE OF THE UPPER TROUGH. A SURFACE HIGH IS
FOCUSED OVER THE SOUTHERN PLAINS...WITH A RIDGE EXTENDING THROUGH
THE MID MISSOURI VALLEY NORTH AND THROUGH MUCH OF THE UPPER
MISSISSIPPI VALLEY AS WELL. THERE IS A WEAK SURFACE TROUGH WHICH
IS HEADING EAST OF THE LOCAL AREA EARLY THIS MORNING. AHEAD OF THE
UPPER LOW AND IN WEAKLY CONVERGENT LOW LEVELS...A FEW ECHOES STILL
CONTINUING SUGGESTIVE OF SOME PASSING FLURRIES...WITH SOME LAKE
ENHANCEMENT OUT OVER THE OPEN WATERS.

THE LEADING SHORTWAVE WILL PASS EAST THIS MORNING WHICH SHOULD BRING
AN END TO MOST OF THE FLURRY ACTIVITY...WITH SOME LAKE EFFECT SNOW
SHOWERS LARGELY IMPACTING LOCATIONS IN SOUTHWEST MICHIGAN. THIS IS
ALSO SUPPORTED BY A DISTINCT CLEARING LINE IN 11-3.9 MICRON
SATELLITE IMAGERY. THE SURFACE RIDGE MOVES OVERHEAD THIS MORNING
WHICH WILL PROMOTE A PERIOD OF CLEARING SKIES...BUT IT WILL QUICKLY
TRANSLATE EASTWARD. THIS IS DUE TO A SECONDARY SHORTWAVE/CLIPPER IN
NW FLOW THAT WILL INCREASE CLOUD COVER AGAIN THIS AFTERNOON. IN
SPITE OF SOME SUNSHINE THIS MORNING...IT WILL BE A COLDER DAY WITH
HIGHS IN THE UPPER 20S TO LOW 30S. SINCE WE STAY ON THE NORTHERN
FRINGE OF THE RIDGE...WEST WINDS REMAIN ELEVATED MAKING IT FEEL A
BIT COLDER.

THIS SECONDARY WAVE AND ASSOCIATED WEAK SURFACE TROUGH MAY BRING A
FEW FLURRIES AND SOME CLOUDS TONIGHT...BUT IMPACTS WILL BE MINOR.
THE UP AND DOWN CONTINUES FRIDAY AS SURFACE RIDGING BUILDS
IN...ONLY TO BE FOLLOWED BY A SIMILAR INCREASE IN CLOUDS AND A
POSSIBLY SLIGHTLY STRONGER SHORTWAVE FRIDAY NIGHT. MODEL GUIDANCE
DEPICTS THAT ENERGY IN THIS TROUGH WILL NOT REMAIN
CONSOLIDATED...BUT BECOME SPLIT WITH SOME PASSING THROUGH
WISCONSIN WHILE A PORTION OF THE FORCING SHIFTS ALONG THE BASE OF
THE TROUGH AXIS FRIDAY NIGHT. WITH THIS IN MIND...MOST GUIDANCE
KEEPS THE LOCAL AREA DRY WITH BETTER CHANCES FOR SNOW SHOWERS
NORTH. THE NAM DOES DRIVE SOME OF THE SOUTHERN ENERGY THOUGH NE
ILLINOIS AND NW INDIANA...BUT AT THIS POINT HAVE HELD TO A GLOBAL
CONSENSUS FOR MOSTLY DRY CONDITIONS BUT WILL CARRY FLURRIES. AND
JUST LIKE CLOCKWORK...THE PATTERN REPEATS ITSELF SATURDAY NIGHT
INTO EARLY SUNDAY WITH HIGH PRESSURE RETURNING.

KMD

&&

.LONG TERM...
334 AM CST

SUNDAY THROUGH THURSDAY...

THE UP AND DOWN PARADE WILL TAKE A TURN SUNDAY INTO THE COMING
WEEK AS A MASSIVE RIDGE BUILDS ACROSS THE WEST. DOWNSTREAM
TROUGHING WILL LEAD TO AT LEAST A COUPLE DAY INTRUSION OF CANADIAN
AIR. SEVERAL PERIODS OF LIGHT SNOW APPEAR ON TAP FOR
SUNDAY...MONDAY...AND POSSIBLY TUESDAY. IT WILL GENERALLY BE ON
THE CLOUDIER SIDE AND BREEZY AS WELL INITIALLY...MAKING IT FEEL A
BIT MORE UNCOMFORTABLE. THE GFS IS MORE AGGRESSIVE WITH THE
COOLING...SNOW SHOWER COVERAGE...AND WIND SPEEDS THAN THE ECMWF AT
THIS POINT...BUT THE THEME IS FOR COLDER CONDITIONS WITH POSSIBLE
LIGHT SNOW AS ENSEMBLES INDICATE DECENT CONFIDENCE IN THIS DEEP
EASTERN CONUS TROUGH EVOLUTION DESPITE DISAGREEING SOME ON ITS
STRENGTH AND BREAKDOWN.

KMD

&&

.AVIATION...
FOR THE 12Z TAFS...

RELATIVELY QUIET WEATHER EXPECTED ACROSS THE REGION TODAY AS HIGH
PRESSURE MOVES OVERHEAD THROUGH THE AFTERNOON. BACK EDGE OF
DEPARTING MVFR STRATUS WILL CLEAR THE CHICAGO TERMINALS BY MID
MORNING WITH VFR CONDITIONS EXPECTED THE REMAINDER OF THE DAY.
ONCE THE RIDGE AXIS PASSES OVERHEAD THIS AFTERNOON...EXPECT WINDS
TO BACK TO THE SOUTHWEST BY THIS EVENING. A WEAK TROUGH WILL MOVE
ACROSS THE REGION LATE THIS EVENING AND OVERNIGHT BRINGING SOME
MID LEVEL CLOUD COVER...THEN WINDS VEER BACK TO THE NORTHWEST
BEHIND THE TROUGH.

BMD

&&

.MARINE...
300 AM CST

AREA OF LOW PRESSURE THAT BROUGHT MODERATELY STRONG WINDS TO THE
GREAT LAKES WILL CONTINUE TO DEPART TOWARDS THE CANADIAN MARITIME
PROVINCES TODAY WHILE HIGH PRESSURE BUILDS OVER THE WESTERN GREAT
LAKES. THIS WILL ALLOW WINDS TO CONTINUE TO DIMINISH AND FOR WAVES
TO SUBSIDE. WILL ALLOW THE SMALL CRAFT ADVISORY FOR THE INDIANA
NEARSHORE WATERS TO EXPIRE THIS MORNING AS CONDITIONS IMPROVE.
LOOKING AHEAD...A SERIES OF INCREASINGLY DEEP LOWS WILL TRAVERSE
THE REGION TONIGHT THROUGH EARLY NEXT WEEK. A WEAK TROUGH WILL
MOVE ACROSS LAKE MICHIGAN TONIGHT WITH ANOTHER WEAK LOW TRAVERSING
THE REGION SATURDAY. YET ANOTHER LOW IS EXPECTED TO DROP ACROSS
THE WESTERN LAKES LATE SUNDAY INTO MONDAY. FOR NOW EXPECT SOUTH TO
SOUTHEAST WINDS TO INCREASE TO AROUND 30 KT AHEAD OF THE LOW WITH
SIMILAR MAGNITUDE NORTH TO NORTHWEST WINDS BEHIND THE LOW ON
TUESDAY.

BMD

&&

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

$$

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