Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 241955
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
255 PM EST WED DEC 24 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 441 AM EST WED DEC 24 2014

WV LOOP AND 00Z RAOBS SHOW SHARP MID CONUS TROUGH WITH PRIMARY
SHORTWAVE ROUNDING BASE OF TROUGH OVER LOWER MISSISSIPPI RIVER
VALLEY WITH ASSOCIATED SFC LOW FORMING OVER ALABAMA/TENNESSEE AND
TROUGH EXTENDING NORTH TO WESTERN OHIO VALLEY. LOW PRESSURE WILL
QUICKLY BECOME ORGANIZED INTO A STRONG LOW PRESSURE SYSTEM BUT IT
APPEARS THAT A MORE EASTERN TRACK WILL MATERIALIZE. THUS...THOUGH
SOME LGT SLUSHY SNOW ACCUMS ARE EXPECTED ON NORTHWEST EDGE OF SFC-H85
LOWS VCNTY OF LUCE COUNTY LATE THIS AFTN INTO THE EVENING...BIGGEST
IMPACT FM THE SYSTEM WILL STAY EAST/SOUTHEAST OF OUR CWA OVER LOWER
MICHIGAN. DO NOT EXPECT ENOUGH SNOW IN LUCE COUNTY LATE THIS AFTN
INTO TONIGHT TO JUSTIFY THE NEED FOR AN ADVISORY.

WHAT IS LEFT OVER THE REST OF THE CWA TODAY INTO TONIGHT IS LOW
PRESSURE TROUGH THAT IS REMNANT FROM FILLING LOW PRESSURE SYSTEM
THAT BROUGHT SNOW TO THE AREA ON TUESDAY. PLENTY OF LOW-LEVEL
MOISTURE BENEATH THE TROUGH WITH LOW CLOUDS AND DENSE FOG AT TIMES.
MOST PERSISTENT FOG WAS OVER LUCE COUNTY CLOSER TO OCCLUDED FRONT
MOVING INTO EASTERN UPR MICHIGAN AND WHERE DWPNTS IN THE MID 30S
WERE COMMON. FOG HAS ALSO BEEN PRETTY DENSE IN THE UPSLOPE AREAS OF
MARQUETTE COUNTY AS WELL.

UPSLOPE FLOW CONTINUES THROUGH THE DAY...FAVORING HIGHER TERRAIN OF
WESTERN AND NCNTRL UPR MICHIGAN. FORECAST SOUNDINGS WOULD SUGGEST
FZDZ/DZ SHOULD BE ONGOING EARLY THIS MORNING...BUT THAT HAS REALLY
NOT OCCURRED IN THE STRONG SUBSIDENCE IN WAKE OF THE SHORTWAVE THAT
MOVED THROUGH ON TUESDAY. WEAK RIBBON OF HIGHER PV/SHEARED SHORTWAVE
AND SOME H85-H7/H7-H5 Q-VECTOR CONVERGENCE IS EXPECTED TO LIFT OVER
THE WEST HALF OF UPR MICHIGAN FM DAYBREAK THROUGH EARLY AFTN.
SOUNDINGS AND VARIOUS HIGH-RES GUIDANCE POINT TO SIGNAL OF INCREASING
LIFT IN THE MOIST LAYER THAT IS AROUND AT PRESENT AND ADDITIONAL
MOISTURE H85-H75 CONTRIBUTED FM THE SHORTWAVE...WHICH SHOULD INCREASE
CHANCES OF SEEING SNOW VERSUS DZ/FZDZ. IR SATELLITE SHOWING THAT AREA
OF MOISTURE IS ALREADY MOVING INTO WESTERN UPR MICHIGAN WITH CLOUD
TOPS OF -10C TO -13C. WILL PUSH POPS TO 30-40 PCT FOR SNOW
SHOWERS...ESPECIALLY IN THE UPSLOPE AREAS. DID KEEP MENTION OF
DZ/FZDZ OVER LOWER ELEVATIONS OF NCNTRL AND ALSO FARTHER EAST OVER
REST OF CWA /DUE TO LESS MID-LEVEL MOISTURE/ AS THIS WEAK LIFT MOVES
THROUGH AND INTERACTS WITH THE LOW- LEVEL MOISTURE /TEMPS WARMER THAN
-7C/.

BY LATE TODAY AS THE CNTRL GREAT LAKES SYSTEM REACHES NEAR THE THUMB
OF LOWER MICHIGAN...LARGER SCALE FORCING SEEN IN TERMS OF H85-H5
Q-VECTOR CONVERGENCE FOCUSES MORE OVER FAR EASTERN CWA WHILE
SUBSIDENCE DEVELOPS OVER REST OF CWA. COULD SEE DZ/FZDZ RETURN TO
AREAS OF WEST HALF OF CWA...ESPECIALLY UPSLOPE AREAS. INTO TONIGHT
AS THE SYSTEM SNOW AFFECTS FAR EAST CWA VCNTY OF LUCE COUNTY...HINTS
PRESENT THAT INVERTED TROUGH TAKES SHAPE TO THE WEST AND
NORTHWEST...ESSENTIALLY LAYING OUT ALONG THE SOUTH SHORE OF LK
SUPERIOR IN THE EVENING. COOLER AIR BEGINS TO WORK IN FM THE NNW IN
WAKE OF THE SFC TROUGHING OVER THE AREA TO START THE DAY THAT MOVES
EAST AND WRAPPED UP SFC LOW AROUND 980MB OVER EASTERN PORTIONS OF
LK HURON AND GEORGIAN BAY. DUE TO THE INVERTED SFC TROUGH AND
INCREASED MOISTURE AND COLD AIR ADVECTION...WENT FOR SCATTERED POPS
IN THE EVENING ALONG LK SUPERIOR. WNW WINDS WILL BECOME WINDY OVER
THE EAST CWA OVERNIGHT TONIGHT WITH BLYR WINDS 20-25 KTS ON PERIPHERY
OF THE STRONG LOW...SO HAVE KEPT MENTION OF BLSN.

TROUGHING FADES QUICKLY OVERNIGHT AS THE LOW PRESSURE SYSTEM MOVES
TOWARD WESTERN QUEBEC WHILE DEEPENING FURTHER AND SFC RIDGE BEGINS
TO MOVE INTO THE WESTERN GREAT LAKES. SOUNDINGS SHOW TEMPS ONLY
AROUND -8C AT TOP OF INVERSION 900-850MB BY LATE TONIGHT. UNLIKE THE
EVENING WHEN THERE WAS SOME SYNOPTIC SUPPORT AROUND...THERE WILL NOT
BE OVERNIGHT...AND -8C IS NOT GOOD ENOUGH FOR LES GIVEN WATER TEMPS
2-4C. IMAGINE THE SNOW SHOWERS WILL TREND DOWN TO FLURRIES PRETTY
QUICKLY...MOST PREVALENT OVER THE HIGHER TERRAIN OF NORTHWEST UPR
MICHIGAN. DESPITE THE COOLING TEMPS...TODAY AND TONIGHT WILL REMAIN
MILD FOR CHRISTMASTIME IN UPR MICHIGAN WITH READINGS TODAY IN THE
LOW-MID 30S AND TONIGHT IN THE UPR 20S TO AROUND 30 DEGREES.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 255 PM EST WED DEC 24 2014

NAM SHOWS A CLOSED 500 MB LOW OVER UTAH 00Z FRI THAT MOVES ACROSS
THE 4 CORNERS REGION AND OUT INTO THE WESTERN HIGH PLAINS 00Z SAT.
THIS LOW GETS EJECTED OUT AND COMBINES WITH A TROUGH THAT DIGS
SOUTHEAST FROM SOUTH CENTRAL CANADA AND THIS TROUGH MOVES INTO THE
UPPER GREAT LAKES ON SAT.

NAM...GFS AND ECMWF SHOW WEAK 850-500 MB Q-VECTOR CONVERGENCE 00Z
FRI THROUGH 18Z FRI. LOOKED LIKE THERE WOULD BE SOME WEAK PCPN BAND
HANGING AROUND THE AREA FOR THU NIGHT AND FRI AND PUT IN SOME SLIGHT
CHANCE TO LOW CHANCE POPS TO COVER THIS WITH THE CHANCE POPS ACROSS
THE NORTHERN CWA WITH SOME LAKE ENHANCEMENT THROWN IN. HAVE CHANCE
POPS IN FOR LATE FRI AND SAT MORNING WITH A DISTURBANCE PASSING
THROUGH AND LOOKED LIKE THERE COULD BE SOME LAKE ENHANCEMENT WITH
THIS AS WELL. OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE GOING
FORECAST FOR TEMPERATURES OR WEATHER AND LOOKS LIKE ALL THE PCPN
WILL BE SNOW.

IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER MOST
OF THE U.S. 12Z SUN WITH COLDER AIR POISED TO COME IN AT 850 MB WITH
-14C TO -17C OVER THE AREA WHICH IS COLD ENOUGH FOR LAKE EFFECT
SNOW. PATTERN CHANGES LITTLE FOR 12Z MON. COLDER AIR COMES IN 12Z
TUE WITH 850 MB TEMPERATURES DROPPING TO -18C TO -20C WITH A 500 MB
TROUGH DIGGING INTO THE ROCKIES. THIS DEEP 500 MB TROUGH MOVES INTO
THE UPPER GREAT LAKES 12Z WED WITH 850 MB TEMPERATURES DROPPING TO
-25C BY 00Z THU. TEMPERATURES LOOK TO GO BELOW NORMAL AGAIN WITH
LAKE EFFECT SNOW THROUGH THIS PERIOD AND HAVE THE HIGHEST POPS IN
NORTHWEST LAKE EFFECT SNOW BELTS.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 129 PM EST WED DEC 24 2014

CONTINUE TO TRACK A SFC LOW SHIFTING ACROSS SE MI AND INTO LAKE
HURON TODAY. WHILE MOST OF THE PRECIP AND HEAVIER SNOW IS WELL TO
THE E...LAKE ENHANCED -SHSN /AND EVEN SOME DZ AT SAW/ WILL REMAIN.

LIGHT N WINDS ARE KEEPING IWD IN THE MVFR-IFR RANGE. LOOK FOR IFR
CEILINGS TO WIN OUT THROUGH THE EVENING HOURS. BY LATE EVENING MORE
NW WINDS WILL TAKE HOLD AS THE SFC LOW EXITS ACROSS S ONTARIO AND
INTO QUEBEC...AND CONDITIONS WILL MORE RAPIDLY IMPROVE BACK TO MVFR
BETWEEN 06-12Z THURSDAY.

LOOK FOR SLOWER IMPROVEMENT AT CMX...GIVEN THE MORE FAVORABLE
UPSLOPE WIND DIRECTION...WITH MVFR CEILINGS RETURNING 12-15Z
THURSDAY. FCST IS A BIT TRICKIER AT SAW...WHERE MUCH OF THE DEEP
MOISTURE PULLS OUT SHORTLY AFTER 00Z THURSDAY. HOWEVER...CLOSER TO
THE EXITING LOW MVFR MAY BE HARD TO FIND PRIOR TO 12Z THURSDAY.
CONDITIONS AT ALL 3 SITES WILL CONTINUE TO IMPROVE THROUGH THE
DAY...WITH WINDS OUT OF THE W AROUND 10KTS /POSSIBLY GUSTING TO
AROUND 15KTS AT CMX/.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 129 PM EST WED DEC 24 2014

A LOW OVER S LAKE HURON WILL PUSH NNE AS IT DEEPENS ACROSS CENTRAL
QUEBEC BY THURSDAY AFTERNOON. AS A RESULT...N-NNW WINDS MAY GUST 30
TO NEAR 35KTS OVER E LAKE SUPERIOR OVERNIGHT TONIGHT.

A BRIEF RIDGE WILL BUILD OVER S LAKE SUPERIOR THURSDAY. A LOW ACROSS
E COLORADO THURSDAY AFTERNOON WILL SWING AN ELONGATED TROUGH UP
ACROSS IOWA AND LAKE SUPERIOR FRIDAY...WHICH WILL SLOWLY EXIT E LAKE
SUPERIOR/LAKE MICHIGAN FRIDAY NIGHT...AND S ONTARIO ON SATURDAY.
LOOK FOR A SMALL TROUGH TO PUSH ACROSS LAKE SUPERIOR SATURDAY NIGHT.
THIS WILL BE QUICKLY REPLACED BY A RIDGE BUILDING ACROSS LAKE
SUPERIOR ON MONDAY...EXTENDING FROM LARGE/STRONG/COLD HIGH PRESSURE
ACROSS MUCH OF SOUTHWESTERN CANADA. LOOK FOR THE RETURN OF FREEZING
SRAY AND POSSIBLY HEAVY FREEZING SPRAY WITH STRONGER WINDS AS MUCH
COOLER AIR SETTLES ACROSS THE UPPER GREAT LAKES FROM SATURDAY ON.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...JLA
LONG TERM...07
AVIATION...KF
MARINE...KF





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