FXUS63 KMQT 060522 AAC
AFDMQT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
1222 AM EST SUN DEC 6 2009

UPDATED FOR 06Z AVIATION DISCUSSION

.UPDATE... /ISSUED AT 1028 PM EST/

OPTED TO CONTINUE LAKE EFFECT SNOW WARNING FOR NRN HOUGHTON COUNTY 
UNTIL 10Z. COOP OBSERVER AT ATLANTIC MINE AROUND 8PM STILL HAD HVY 
SNOW AT A RATE AROUND 2IN/HR. SFC OBS INDICATE CONVERGENCE ZONE 
SUPPORTING DOMINATE BAND IS STILL HOLDING ON FROM E OF THE APOSTLES 
TO JUST N OF ONTONAGON AND THEN INTO NRN HOUGHTON COUNTY... 
APPARENTLY JUST W OR SW OF HOUGHTON. IT CERTAINLY LOOKS LIKE THIS 
DOMINATE BAND WILL SLOWLY DIMINISH OVERNIGHT AS CONVERGENCE WEAKENS 
AND WINDS BECOME MORE NW OVER ALL OF WRN LAKE SUPERIOR PER LATEST 
MODEL DATA. HOWEVER...ALL MODELS HAVE BEEN TOO QUICK TO MOVE 
BAND/WEAKEN CONVERGENCE SO FAR THIS EVENING. SO...WILL EXTEND 
WARNING TO 10Z...BUT EMPHASIZE HEAVIEST SNOW S OF HOUGHTON AND 
SHIFTING TOWARD THE TWIN LAKES AREA. ADVY WILL REMAIN UP FOR 
ONTONAGON WITH EMPHASIS ON NRN PART OF COUNTY.  

TO THE E...MESOLOW MOVED ACROSS ERN LAKE SUPERIOR LATE AFTN/EARLY 
EVENING WITH IMPRESSIVE LES BANDING AROUND CIRCULATION. HEAVIER SNOW 
BANDS WITH THE LOW HAVE BEEN AFFECTING FAR ERN ALGER COUNTY AROUND 
GRAND MARAIS AND ALSO ROUGHLY THE NE THIRD OF LUCE COUNTY. WOULD NOT 
BE SURPRISED IF SNOW ACCUMULATIONS HAVE REACHED 3 OR 4 INCHES IN A 
SPOT OR TWO WHERE BANDS HAVE BEEN MOST PERSISTENT. CONSIDERED ADVY 
BUT BANDS ARE BECOMING MORE DISORGANIZED AND ARE SHIFTING E AS A 
PUSH OF WRLY WINDS IS OCCURRING AHEAD OF NEXT SFC TROF DROPPING S 
ACROSS THE LAKE AND ALSO NOW THAT THE LINGERING AFFECTS OF MESOLOW 
ARE WEAKENING. THERE MAY BE A BREAK FOR A WHILE OVERNIGHT BEFORE 
ANOTHER DOMINANT BAND POSSIBLY SETS UP ALONG THE NEXT TROF. IF 
SO...LES SHOULD PICK UP AGAIN OVER THE NE FCST AREA LATE IN THE 
NIGHT/EARLY SUN MORNING. 

&&

.SHORT TERM...TONIGHT AND SUNDAY /ISSUED AT 440 PM EST/

MAIN FORECAST CONCERNS TONIGHT ARE ONGOING LES OVER THE KEWEENAW AND 
THE EVENTUAL STARTUP OF LES OVER NORTHWEST LES BELTS INCLUDING AREAS 
EAST OF MUNISING. DOMINANT BAND OVER LAKE SUPERIOR MOVED ONSHORE 
THIS MORNING AS FORECASTED. HOWEVER PERSISTENT SOUTHERLY FLOW OVER 
NORTHERN HOUGHTON COUNTY ALLOWED BAND TO LINGER LONGER THAN 
EXPECTED...ESPECIALLY NEAR AREAS LIKE ATLANTIC MINE AND SOUTH RANGE. 
IN THESE AREAS 6 INCHES OF SNOW FELL FROM 10AM THROUGH 2PM. BECAUSE 
OF THIS...UPGRADED ADVISORY TO A WARNING AS ANOTHER 2 INCHES OF SNOW 
SEEMED VERY REALISTIC. OPTED TO PUT UP A LES ADVSY FOR 
ONTONAGON...MAINLY NORTH OF M-38 WHERE DOMINANT BAND MOVED ONSHORE. 
500MB S/W WILL PUSH THROUGH THE FA TONIGHT...ALLOWING WINDS TO GO 
PREDOMINANTLY NORTHWEST AND ALLOWING LIGHT LAKE EFFECT TO ESTABLISH 
ITSELF OVER THE FAR WESTERN ZONES. AS OF NOW SNOW HEADLINES ARE DONE 
BY 5AM SUNDAY...BUT COULD BE CANCELLED SOONER AS LIGHTER SNOW 
DEVELOPS. EAST OF MUNISING...WIND FLOW FAVORS EASTERN ALGER AND 
NORTHERN LUCE COUNTIES. THROUGH TOMORROW UP TO 7 INCHES OF SNOW IS 
POSSIBLE...GENERALLY IN GRAND MARAIS AND NORTH OF PINE STUMP JCT. 
LATEST NAM SHOWS A MORE WESTERLY FLOW OVER THE EAST WHICH WOULD KEEP 
HEAVIER SNOW OFFSHORE AND INTO CANADA. 

IN ADDITION TO LES...LIGHT SYNOPTIC SNOW IS POSSIBLE OVER THE FAR 
SOUTHERN CWA AS THE MID LEVEL S/W WORKS OVER THE AREA. OVERALL 
MOISTURE ISN/T VERY IMPRESSIVE THOUGH WEAK DYNAMICS SCRAPE SOUTHERN 
ZONES WARRANTING CHC POPS AFTER 06Z ENDING MID SUNDAY MORNING.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

SUNDAY NIGHT INTO MONDAY...MODELS WERE IN GOOD AGREEMENT WITH THE 
TRACK/STRENGTH OF THE SHORTWAVE AND ASSOCIATED QPF. THE STRONGEST 
UPPER LEVEL DIV AND 700-300 QVECTOR CONV REMAINS FAR ENOUGH 
SOUTH...THROUGH WI SO THAT LIGHT SNOW WILL ONLY BRUSH THE FAR SOUTH 
(NEAR MNM.). WITH 850 MB TEMPS STILL NEAR -14C...SOME LES WILL 
LINGER SUN NIGHT FOR LOCATIONS FAVORED BY WNW FLOW. HOWEVER...WITH A 
WEAK LOW LEVEL RIDGING AND GENERALLY LIGHT BNDRY LYR WINDS AOA 10 
KT. CONFIDENCE IS LOWER WITH LOCATION OF ANY HIGHER SNOWFALL 
AMOUNTS WILL MOVE ONSHORE. THE NAM HINTS THAT A SHORELINE PARALLEL 
BAND COULD DEVELOP NEAR W UPPER MI AND MOVE IN ON MON. IF THE BAND 
MOVES STEADILY INLAND...SNOWFALL AMOUNTS WOULD BE FAIRLY LIGHT EVEN 
WITH A BRIEF PERIOD OF HEAVIER SHSN. BY LATE MOND INTO MON 
EVENING...THE GFS AND NAM SUGGEST LOW LEVEL CONV MAY FOCUS NEAR 
MARQUETTE AS WINDS BRIEFLY VEER NRLY IN THE WAKE OF THE LOW MOVING 
TO LAKE HURON. AGAIN...WITH ONLY A BRIEF PERIOD OF FAVORABLE WIND 
FLOW OVERALL SNOW AMOUNTS SHOULD ONLY AMOUNT TO A FEW INCHES. 

TUE INTO THU...ALTHOUGH THE GLOBAL MODELS HAVE BEEN INCONSISTENT 
WITH THE PATH OF THE MAJOR STORM SYSTEM EMERGING FROM THE SRN 
ROCKIES AND PLAINS THE LAST FEW DAYS...THE 12Z GFS/ECMWF/CMC AND GFS 
ENS MEAN WERE IN BETTER AGREEMENT IN TRACKING THE SFC LOW FROM ABOUT 
W CNTRL IN (12Z/WED) TO SRN LAKE HURON (00Z/THU). THE BROAD AREA OF 
STRONG DYNAMICS WITH THE NEG TILT TROUGH SHOULD BRING LIGHT TO 
MODERATE SYNOPTIC SNOW TO MOST OF THE CWA. WITH 850 MB TEMPS FROM 
-8C TO -11C DROPPING TO -12C TO -14C (00Z THU GFS/ECMWF) SIGNIFICANT 
LAKE ENHANCED/EFFECT SNOW COULD BRING HEAVY SNOW TO THE NORTH HALF 
OF UPPER MICHIGAN ALONG WITH SIGNFIFCANT BLSN. 

THU-SAT...COLD ENOUGH AIR REMAINS FOR LES TO CONTINUE THROUGH THE 
PERIOD. NW TO WNW FLOW IS EXPECTED TO BACK WRLY THU AND REMAIN 
MAINLY WRLY INTO SAT. 

&&

.AVIATION /FOR THE 06Z TAF ISSUANCE/...

SFC TROF/MAIN BAND OF LOW-LEVEL CONVERGENCE APPEARS TO HAVE DRIFTED 
S OF KCMX. AS A RESULT...NW-SE ORIENTED LES BANDS WILL SET UP AND 
AFFECT KCMX WITH PREVAILING CONDITIONS PROBABLY SETTLING INTO THE 
IFR CATEGORY. AS IS THE CASE WITH LAKE EFFECT SHSN...CONDITIONS WILL 
STILL BE VARIABLE AS BANDS TRANSIT THE AREA...BUT THERE SHOULD BE 
LESS FREQUENT AND SHORTER DURATION VARIATION FROM THE EXPECTED IFR 
PREVAILING CONDITIONS OVERNIGHT INTO THE MORNING HRS. INVERSION MAY 
LOWER A BIT DURING THE DAY...AND THIS SHOULD LEAD TO A WEAKENING OF 
SHSN...RESULTING IN CONDITIONS IMPROVING TO MVFR.

AT KSAW...CONDITIONS WILL PROBABLY REMAIN VFR THRU THIS FCST PERIOD. 
A DOWNSLOPING WRLY WIND DIRECTION OVERNIGHT SUPPORTS VFR CONDITIONS. 
WITH A NW WIND DURING THE DAY...EXPECT STRATOCU AND MAYBE SOME 
FLURRIES OFF LAKE SUPERIOR...BUT THERE SHOULD STILL BE SUFFICIENT 
DOWNSLOPE COMPONENT TO KEEP CIGS VFR. 

&&

.MARINE... /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/ 

LAKE INDUCED TROUGHING/CONVERGENCE WILL RESULT IN LOCALLY HIGHER 
WIND SPEEDS INTO THE 20-25 KT RANGE TODAY...MAINLY OVER THE SOUTHERN 
HALF OF THE LAKE. OTHERWISE...WINDS THROUGH SUN REMAIN 20 KTS OR 
LESS AS WEAK TROUGH DRIFTS ACROSS THE UPPER GREAT LAKES. THERE IS 
STILL THE POTENTIAL FOR A STRONG LOW PRESSURE SYSTEM TO AFFECT MUCH 
OF GREAT LAKES REGION TUE AND WED OF NEXT WEEK...ALTHOUGH 
SIGNIFICANT UNCERTAINTY REMAINS WITH THE EXACT TRACK OF SYSTEM. KEPT 
MARGINAL GALES IN THE FORECAST FOR PARTS OF THE FORECAST WED AND 
THU. THE LOW PRESSURE SYSTEM MOVES QUICKLY TO THE NORTHEAST ON 
THURSDAY...WHILE HIGH SURFACE HIGH PRESSURE BUILDS OVER THE MIDWEST. 
THIS WILL PUT LAKE SUPERIOR UNDER NORTHWESTERLY FLOW ON THURSDAY.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...

UPPER MICHIGAN...
  LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST SUNDAY FOR MIZ002.
  LAKE EFFECT SNOW WARNING UNTIL 5 AM EST SUNDAY FOR MIZ003. 

LAKE SUPERIOR...NONE.

LAKE MICHIGAN...NONE.

&&

$$

UPDATE...ROLFSON
SHORT TERM...DJP
LONG TERM...JLB
AVIATION...ROLFSON
MARINE...JT