Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 242333
AFDMQT

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

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 339 PM EST WED DEC 24 2014

TAKING A LOOK AT THE OVERALL PATTERN...A 500MB LOW OVER N CENTRAL
CANADA EXTENDING A TROUGH DOWN THROUGH WI AND IL. BY 00Z THIS TROUGH
WILL BECOME NEGATIVELY TILTED QUICKLY EJECTING ACROSS LAKE MI...AND
LAKE HURON BY 06Z. BY THURSDAY THE UPPER GREAT LAKES WILL BE STUCK
IN ZONAL FLOW IN BETWEEN THE CANADIAN LOW AND HIGH PRESSURE OFF THE
COAST OF FLORIDA.

THE SFC LOW OVER FAR SE LOWER MI WILL CONTINUE TO BE MONITORED...AS
IT KEEPS A TROUGH SET UP ACROSS OUR CWA THROUGH THE EVENING HOURS.
AS A RIDGE BRIEFLY BUILDS OVER W LAKE SUPERIOR AND ALONG THE WI
BORDER FROM THE PLAINS STATES THIS EVENING...LOOK FOR SLOWLY
IMPROVING CONDITIONS W. THE STEADY N WINDS ENHANCING SNOW OVER THE
FAR W WILL BECOME MORE OUT OF THE W...CUTTING OF LAKE ENHANCEMENT
FOR GOGEBIC AND IRON COUNTIES BY 06Z THURSDAY /SFC-925-850MB WINDS
TURN OUT OF THE W AT IWD BY 06Z/. TEMPERATURES ARE MARGINAL FOR ANY
SIGNIFICANT SNOW ACCUMULATIONS...WITH 850MB TEMPS RUNNING AROUND -5
TO -7C OVER THE FAR W THROUGH DAYBREAK THURSDAY.

FZDZ/DZ COULD EXTEND INTO THE EVENING HOURS BEFORE THE LOWER LEVEL
MOISTURE PULLS OUT OVER THE W HALF OF THE CWA...GIVEN NO REAL ICE
CRYSTALS FOUND IN THE SOUNDINGS. STILL HAVE A SLIGHT CHANCE OF
DRIZZLE OR MAINLY FREEZING DRIZZLE OVER THE E HALF /PRIMARILY ALONG
LAKE SUPERIOR OVERNIGHT. OVER THE W...SFC TEMPS MAY EVEN FALL INTO
THE UPPER 20S...FROM THE STEADY LOW TO MID 30S THAT WE HAVE BEEN
EXPERIENCING FOR THE LAST COUPLE OF DAYS.

WINDS WILL RETURN TO THE SW THURSDAY AS THE SFC RIDGE SLIDES
OVERHEAD BY 18Z. THIS WILL HELP PUSH THE LAST OF ANY LINGERING SNOW
SHOWERS OR DRIZZLE OFF INTO LAKE SUPERIOR...AS THE SFC LOW EXITS
INTO CENTRAL QUEBEC. QUICKENED UP THE APPROACH OF LIGHT SNOW
ASSOCIATED WITH THE NEARING SFC THROUGH EXTENDING AT 00Z FROM THE
MAIN LOW OVER CO/KS/OK/TX THROUGH FAR W LAKE SUPERIOR AND UP INTO
CENTRAL QUEBEC.

.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 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 630 PM EST WED DEC 24 2014

A SURFACE RIDGE MOVING INTO UPPER MICHIGAN TONIGHT BEHIND A STRONG
LOW PRESSURE SYSTEM LIFTING NORTHEAST OUT OF LAKE HURON WILL LEAD
TO GRADUALLY BACKING LOW LEVEL WINDS AND AN INFUSION OF DRIER LOW
LEVEL AIR. UNFORTUNATELY...MODELS CONTINUE TO DIFFER IN HOW QUICKLY
AND IF THE LOW CLOUDS WILL PULL OUT OF THE TAF SITES (LIKE THEY
HAVE OVER THE LAST COUPLE WEEKS). THIS LEADS TO A LOWER CONFIDENCE
CEILING FORECAST...ESPECIALLY HEADING INTO THE SECOND HALF OF THE
TAF PERIOD.

FOR TONIGHT...EXPECT LAKE ENHANCED LIGHT SNOW SHOWERS TO FOLLOW THE
BACKING LOW LEVEL WINDS AND WEAKEN THROUGH THE NIGHT AS THE DRIER
AIR MOVES IN. THERE ARE SOME CONCERNS FOR THE AMOUNT OF ICE CRYSTALS
PRESENT FOR SNOW...SO THERE MAY BE PERIODS OF LIGHT DRIZZLE OR
FREEZING DRIZZLE AWAY FROM ANY OF THE STRONGER SHOWERS. BUT WITH THE
DRIER AND WARMER AIR MOVING IN...WOULD EXPECT THE SHOWER POTENTIAL
TO DIMINISH AND THE CEILINGS TO TREND TOWARDS HIGHER MVFR VALUES.

WITH THE SURFACE RIDGE MOVING THROUGH TOMORROW MORNING...EXPECT
WINDS TO TURN MORE WESTERLY OR EVEN SOUTHWESTERLY. THIS WOULD LEAD
TO DOWNSLOPING AT KSAW AND WOULD NOT BE SURPRISED TO SEE THEM
SCATTER OUT AND GO TO VFR CONDITIONS FOR A PERIOD. AT
KCMX/KIWD...THERE IS THAT POTENTIAL TO OCCUR LATE TONIGHT INTO THE
FIRST PART OF TOMORROW MORNING...BEFORE ADDITIONAL LOW LEVEL
MOISTURE MOVES INTO THE AREA. WITH THE AMOUNT OF HIGH END IFR AND
LOW MVFR CEILINGS UPSTREAM...HAVE A TOUGH TIME TRENDING THEIR
FORECAST AWAY FROM MVFR...SO WILL KEEP THEM RIGHT AROUND THE
MVFR/VFR THRESHOLD TOWARDS THE AFTERNOON. FINALLY...A WEAK
DISTURBANCE ARRIVING LATE IN THE PERIOD TOWARDS THE WISCONSIN BORDER
MAY BRING A FEW SHOWERS TO KIWD AND HAVE ADDED A VCSH FOR THAT
POTENTIAL.
&&

.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
SPRAY 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...KF
LONG TERM...07
AVIATION...SRF
MARINE...KF





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