Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 241154
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
654 AM 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 THROUGH TUESDAY)
ISSUED AT 408 AM EST WED DEC 24 2014

LONGER RANGE MODELS INDICATE A SPLIT FLOW PATTERN WILL DOMINATE
NAMERICA INTO EARLY NEXT WEEK WITH AN UPR TROF IN BOTH BRANCHES
CENTERED OVER THE PLAINS. SINCE THE MODELS INDICATE THERE WL NO
PHASING BTWN THE SRN AND NRN BRANCH FLOWS...LOOKS LIKE THERE WL BE
NO MAJOR WINTER STORMS FOR UPR MI DURING THIS TIME. INITIAL FCST
CONCERN WL ON POTENTIAL FOR SOME LIGHT SN MAINLY ON FRI IN ADVANCE
OF A SRN BRANCH SHRTWV LIFTING NEWD INTO THE GREAT LKS. FOCUS THEN
SHIFTS ON INFLUX OF COLDER AIR AND THE INCREASING POTENTIAL FOR LES
AS THE NRN BRANCH FLOW BECOMES THE DOMINANT INFLUENCE OVER THE UPR
LKS. ABOVE NORMAL TEMPS THRU THE END OF THIS WEEK WL TREND BLO
NORMAL EARLY NEXT WEEK AS MANY OF THE MODELS SHOW H85 TEMPS FALLING
AOB -20C NEXT TUE.

XMAS DAY...UPR MI WL BE DOMINATED BY RISING H5 HGTS UP 100M BTWN
25/12Z AND 26/00Z IN ADVANCE OF A SRN BRANCH UPR RDG BLDG INTO WRN
GREAT LKS IN THE WAKE OF DEPARTING LO PRES. ALTHOUGH THERE MAY BE
SOME LINGERING SN SHOWERS NEAR LK SUP IN THE MRNG...THE COVERAGE AND
INTENSITY OF WHICH WL BE LIMITED BY H85 TEMPS NO LOWER THAN -6C TO
-7C...THE BULK OF THE DAY SHOULD BE DRY AS A WEAK SFC HI PRES RDG/
AREA OF ACYC FLOW MOVES INTO THE AREA. BUT AS THE FLOW SHIFTS TOWARD
THE SW IN ADVANCE OF A SRN BRANCH SHRTWV LIFTING NEWD THRU THE
PLAINS...MODELS INDICATE INCRSG ISENTROPIC ASCENT/MID LVL RH. SOME
OF THE MODELS GENERATE SOME PCPN NEAR THE WI BORDER LATE IN THE DAY.
BUT LINGERING DRY AIR BLO THE INCRSG MID LVL RH FAVORS THE DRIER 00Z
NAM/12Z ECMWF FCSTS...SO WL MAINTAIN GOING DRY FCST. WITH H85 TEMPS
RISING TO WITHIN A FEW DEGREES...EXPECT TEMPS TO RUN WELL ABV NORMAL
AND IN THE 30S AT MOST PLACES.

THU NGT...BAND OF HIER WAA MID LVL RH IS FCST TO SHIFT N ACRS UPR
MI. ALTHOUGH THERE ARE QUESTIONS AS TO WHETHER LINGERING LLVL DRY
AIR WL LIMIT ACCOMPANYING PCPN...CLOSER APRCH OF SRN BRANCH SHRTWV
WITHIN THE SW FLOW ALF AND ASSOCIATED DPVA/INCRSG DEEP LYR QVECTOR
CNVGC JUSTIFY SOME LO CHCS POPS MAINLY OVER THE NW HALF OF THE
CWA...WHERE AN APRCH COLD FNT ATTENDANT TO A NRN BRANCH DISTURBANCE
CROSSING NW ONTARIO MAY ADD SOME LIFT. EXPECT TEMPS TO REMAIN WELL
ABV NORMAL IN THE LIGHT SW FLOW AHEAD OF THIS FNT.

FRI INTO SAT...THE COLD FNT ASSOCIATED WITH THE NRN BRANCH SHRTWV
SHEARING OUT IN NW ONTARIO WITHIN THE CONFLUENCE ZN BTWN THE
SEPARATE BRANCHES IS FCST TO PASS NW-SE THRU THE CWA. THE 00Z GFS IS
IN THE MINORITY SHOWING ANOTHER STRONGER SRN BRANCH SHRTWV/AREA OF
FAIRLY SHARP DEEP LYR QVECTOR CNVGC RIDING NEWD PARALLEL TO THE FNT
AND INITIATING ANOTHER LARGER AREA OF SOMEWHAT HEAVIER PCPN OVER THE
CWA FRI NGT INTO SAT. CONSIDERING THE SHARP CONFLUENCE BTWN THE NRN
AND SRN BRANCH FLOWS...PREFER THE MORE SHEARED OUT...WEAKER FORCING
DEPICTED BY THE NON GFS CAMP. THE NEW 00Z ECMWF DOES LIFT A SHRTWV
TO THE NE...BUT THIS MODEL WEAKENS THIS DISTURBANCE AS IT MOVES THRU
THE UPR CONFLUENCE. SO WL CARRY NO MORE THAN CHC POPS DURING THIS
TIME. THE BEST CHC FOR SOME SN WL BE IN AREAS NEAR LK SUP WITH
UPSLOPE NNW FLOW DVLPG IN THE WAKE OF THE FROPA...BUT ABSENCE OF CYC
FLOW IN THE WAKE OF THE FROPA /IN FACT MOST OF THE MODELS SHOW A
QUICK TRANSITION TO ACYC NW FLOW/ AND ONLY SLOW ARRIVAL OF COLDER
AIR THAT IS FCST TO DEPRESS H85 TEMPS TO ONLY -12C TO -14C BY LATE
SAT OVER THE NW WL LIMIT LES. SFC TEMPS SHOULD AT LEAST RETURN TO
NEAR NORMAL ON SAT.

SAT NGT THRU TUE...AS ARCTIC HI PRES BUILDS OVER WRN CANADA TO THE E
OF RDG ALONG THE W COAST...COLDER AIR IS PROGGED TO STEADILY SAG
INTO THE UPR LKS IN THE NNW FLOW TO THE E OF THE HI. BY TUE...MOST
OF THE LONGER RANGE MODELS SHOW H85 TEMPS NEAR -20C. SINCE THIS
EXPANDING COLD AIR WL SUPPRESS THE MORE ACTIVE SRN BRANCH FLOW TO
THE S...EXPECT GENERALLY DRY WX WITH THE EXCEPTION OF LES NEAR LK
SUP. BUMPED UP POPS FOR SN SHOWERS ABOVE THE CONENSUS IN AREAS MOST
LIKELY TO SEE THE LES.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 652 AM EST WED DEC 24 2014

AT KIWD AND KCMX...EXPECT MAINLY IFR CONDITIONS INTO THIS EVENING
DUE TO LOW CIGS. A WEAK TROUGH MAY BRING SOME LGT SNOW THIS EVENING
TO KCMX WITH VSBY POSSIBLY DOWN TO IFR RANGE FOR A FEW HOURS. EXPECT
BOTH SITES TO IMPROVE TO MVFR OVERNIGHT TONIGHT AS DRIER AIR MOVES
INTO THE AREA. AT KSAW...VLIFR CONDITIONS IN FOG WILL SLOWLY IMPROVE
THIS MORNING. YET...EXPECT MAINLY IFR CONDITIONS TO LINGER INTO THE
EVENING DUE TO PERSISTING LOW CLOUDS. A PERIOD OF IFR VSBY IS
POSSIBLE FOR A FEW HOURS THIS EVENING IN LGT SNOW AND DRIZZLE AS A
WEAK TROUGH AFFECTS THE AREA...BUT WILL JUST GO WITH MVFR VSBY ATTM.
OTHERWISE...EXPCECT THE IFR CIGS TO IMPROVE TO MVFR LATE TONIGHT. A
GOOD FLYING OUTLOOK FOR CHRISTMAS AT ALL SITES WITH HIGHER MVFR OR
VFR CIGS WITH MINIMAL RESTRICTIONS TO VSBY. &&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 408 AM EST WED DEC 24 2014

EXPECT N WINDS UP TO 20 KTS TODAY TO INCREASE UP TO 25-30 KTS OVER
THE E HALF OF THE LAKE AND THEN BACK TO THE NW TONIGHT AS A RAPIDLY
DEEPENING LO PRES MOVES NNE ACROSS LAKE HURON AND THEN TO NEAR JAMES
BAY BY THU MORNING. AS THE LO MOVES AWAY AND A HI PRES RIDGE MOVES
IN FROM THE W ON XMAS DAY...THE WINDS WILL BACK FURTHER TO THE SW
AND DIMINISH TO UNDER 20 KTS BY THU NIGHT. AS A COLD FRONT CROSSES
THE LAKE ON FRI/FRI NIGHT...THE WINDS WILL VEER TO THE NNW BUT
REMAIN UNDER 20 KTS. NW WINDS UP TO 20 TO 25 KTS WILL THEN BE THE
RULE AT TIMES THIS WEEKEND AS COLDER AIR ARRIVES AND RESULTS IN
GREATER DESTABILIZATION OVER THE RELATIVELY WARM LAKE WATERS.
&&

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

$$

SHORT TERM...JLA
LONG TERM...KC
AVIATION...JLA
MARINE...KC




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