Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 240914
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
414 AM EST WED DEC 24 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 259 PM EST TUE DEC 23 2014

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER EASTERN IOWA
THIS MORNING. THE NAM TAKES THE CLOSED 500 MB LOW NORTHEAST TODAY
AND ACROSS THE U.P. THIS AFTERNOON. A 500 MB TROUGH REMAINS OVER THE
AREA THROUGH WED. NAM SHOWS A NEW 500 MB CLOSED LOW FORMING IN THIS
TROUGH OVER SW MISSOURI 12Z WED THAT HEADS NORTHEAST TO SOUTHERN
LAKE MICHIGAN BY 00Z THU.

NAM...GFS AND ECMWF SHOW STRONG 850-500 MB Q-VECTOR CONVERGENCE THIS
AFTERNOON MOVING OUT OF THE CWA BY THIS EVENING. ALL MODELS TRY TO
SHOW SOME Q-VECTOR CONVERGENCE RETURNING TO THE EASTERN CWA BY 00Z
THU. GFS IS THE FURTHEST NORTH WITH THIS SECOND SYSTEM WITH THE
NAM...ECMWF AND CANADIAN FURTHER SOUTH WITH THE SFC LOW OVER
SOUTHERN LOWER MICHIGAN WITH THE GFS HAVING THE LOW OVER NORTHERN
LOWER MICHIGAN. GFS IS THE ONLY MODEL THAT FAR NORTH AND WEST WITH
THE HEAVIEST PCPN AND DID NOT USE. 12Z ECMWF CAME UP FURTHER EAST
WITH NEXT STORM...SO AFTER THE SNOW WINDS DOWN THIS
AFTERNOON...LIGHT SNOW...DRIZZLE...FREEZING DRIZZLE WILL CONTINUE
OVERNIGHT. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES. HEAVIEST SNOW HAS MOVED OUT AND CUT BACK POPS THIS
AFTERNOON. DID KEEP HIGHEST POPS IN THE NORTHERLY LAKE EFFECT SNOW
BELTS WITH SOME LAKE ENHANCEMENT AND UPSLOPE HELPING TO AID IN THE
SNOW AND KEPT HEAVIER AMOUNTS OF QPF IN. MIXED PCPN OF RAIN AND SNOW
WILL CONTINUE ACROSS THE SOUTHERN AND EASTERN CWA TONIGHT AND ALSO
FOR WED. OVERALL...ONLY MAJOR CHANGE WAS TO SPEED UP DIMINISHING
POPS THIS AFTERNOON AND EVENING AND DID NOT CHANGE PCPN TYPES.

.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 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1238 AM EST WED DEC 24 2014

EXPECT LIFR TO OCCASIONAL VLIFR CONDITIONS OVERNIGHT TO SLOWLY
IMPROVE TO IFR BY LATE WED MORNING/EARLY AFTERNOON AND THEN TO MVFR
BY EARLY CHRISTMAS MORNING AS WINDS BACK FROM N TO A MORE WNW
DIRECTION BRINGING DRIER AIR/LOWER DEWPOINTS BACK INTO THE REGION.
&&

.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...07
LONG TERM...KC
AVIATION...VOSS
MARINE...KC




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