Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 270942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

//DISCUSSION...UPDATED 06Z...

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
335 PM CST

A STALLED WEST-EAST FRONTAL BOUNDARY STRETCHED ACROSS NORTHERN LAKE
MICHIGAN WILL GET A GOOD PUSH SOUTH TONIGHT AS COLDER AIR SURGES IN
BEHIND DEPARTING LOW PRESSURE OVER CENTRAL ILLINOIS.  HIGH PRESSURE
OVER THE SOUTHERN CANADIAN PRAIRIE PROVINCES WILL HELP DRIVE THE
COLDER AIR SOUTH. WINDS WILL INCREASE QUICKLY BEHIND THE FRONT EARLY
THURSDAY FROM NORTH TO SOUTH... WITH A BRIEF PERIOD OF GALE FORCE
GUSTS IS EXPECTED. HIGH PRESSURE RIDGING THEN QUICKLY BUILDS EAST
ACROSS THE LAKE THURSDAY NIGHT ALLOWING WINDS AND WAVES TO THEN
QUICKLY SUBSIDE.  WINDS AND WAVES THEN QUICKLY INCREASE AGAIN FRIDAY
AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE HIGH AND AHEAD OF
DEEPENING LOW PRESSURE OVER THE PLAINS.

THIS LOW PRESSURE AREA WILL MOVE TO THE U.P. OF MICHIGAN BY EARLY
SUNDAY.  A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE EAST ACROSS
THE LAKE DURING THE DAY SUNDAY... WITH BRISK NORTHWEST FLOW
INTENSIFYING BEHIND THE FRONT INTO MONDAY.

ED F

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL MIDNIGHT
     FRIDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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