FXUS63 KMQT 230525 AAA
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1225 AM EST WED DEC 23 2009

UPDATED AVIATION DISCUSSION FOR 06Z TAFS 

.SYNOPSIS...

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER THE LOWER 
GREAT LAKES REGION WITH ANOTHER CLOSED LOW OVER THE PACIFIC NW WITH 
A BROAD 500 MB RIDGE ACROSS THE PLAINS.
&&

.SHORT TERM THROUGH 00Z THU...

FOR THIS SHORT TERM FORECAST...THE QUIET WEATHER WILL CONTINUE AS 
THE RIDGE PUSHES EAST INTO THE UPPER GREAT LAKES REGION THROUGH WED.
MORE ACTIVE WEATHER ARRIVES LATER IN THE FORECAST WITH THE WINTER 
STORM FOR CHRISTMAS EVE AND DAY. LAKE EFFECT SNOW SHOWERS OR 
FLURRIES WILL CONTINUE TONIGHT OVER THE FAR NORTH WITH A NORTH TO 
NORTHEAST WIND WHICH WILL START TO BRING LAKE EFFECT SNOW SHOWERS 
BACK TO AREAS NEAR LAKE SUPERIOR AS LAKE TEMPERATURES ARE AROUND 4C 
AND 850 MB TEMPERATURES ARE AROUND -10C. LAKE EFFECT SHOULD BE NO 
MORE THAN FLURRIES OR LIGHT SNOW SHOWERS AT BEST. WHERE THE SKY 
REMAINS CLEAR TONIGHT...TEMPERATURES WILL AGAIN DROP QUICKLY AND 
WENT BELOW GUIDANCE IN MOST PLACES AS IDEAL RADIATIONAL COOLING 
CONDITIONS SET UP WITH SNOW COVER AND LIGHT WINDS. LOWS TONIGHT WILL 
BE TRICKY WITH QUITE A RANGE IN TEMPERATURES WITH CLOUDS NEAR THE 
LAKE KEEPING TEMPERATURES IN CHECK. DROPPED LOW AWAY FROM THE LAKE 
AND KEPT ABOUT THE SAME FOR PLACES NEAR THE LAKE. FOR WED...KEPT 
TEMPERATURES PRETTY CLOSE TO WHAT OCCURRED TODAY WITH UPPER 20S TO 
AROUND 30 IN MOST PLACES.

.LONG TERM (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)...

MAIN FOCUS IS POTENTIAL WINTER STORM FOR CHRISTMAS EVE THROUGH 
CHRISTMAS DAY. 

STORM OVERVIEW...MEDIUM RANGE MODELS CONTINUE TO TREND FARTHER WEST 
WITH THE CYCLONE. PRIMARY REASON IS THAT NORTHERN STREAM SHORTWAVE 
CURRENTLY DIGGING INTO FAR WESTERN ALBERTA CANADA IS FCST TO PHASE 
WITH THE MORE WELL ADVERTISED TROUGH DROPPING TOWARD THE FOUR 
CORNERS AREA. PHASING SET TO OCCUR LATE THU INTO EARLY CHRISTMAS 
DAY...WITH RESULTING 990MB SFC LOW DEVELOPING OVR MO BY 12Z FRI
AND ONLY MOVING TO SRN WI BY 12Z SAT...WHILE IT BEGINS TO WEAKEN.
HPC PREFERS THIS TRACK WHICH IS SIMILAR TO GFS/ECMWF GUIDANCE.
NAM/SREF FAVORS SLIGHTLY FARTHER WEST TRACK...INTO ECNTRL MN
THROUGH SAT. EXPECT SURGE OF PCPN TIED TO THE WARM AIR ADVECTION
AHEAD OF THE CYCLONE TO COME INTO THE UPR LAKES AS EARLY AS THU
MORNING. INITIALLY...PCPN WILL BE HAMPERED BY FEED OF DRY LOW-
LEVEL AIR (BLO 5KFT) WITH ERLY WINDS FLOWING OFF OF ONTARIO.
EVENTUALLY...MOISTURE ADVECTION ALLOWS FOR SATURATION OVR THE SW
CWA AND SPREADING TO THE CNTRL CWA BY THU EVENING...AND INTO THE
FAR ERN CWA AND ERN UPR MI TOWARD DAYBREAK FRIDAY. HEAVIEST QPF
THU/THU NIGHT IN REGION OF DIVERGENCE ALOFT...H9-H7 FGEN...AND
ISENTROPIC LIFT WITH OVR 4G/KG AVAILABLE ON THE 290K SFC
(850-750MB) OVR NW WI INTO WRN LK SUPERIOR AND INTO THE FAR SWRN
CWA. LIGHTER QPF AMOUNTS THE FARTHER NORTH AND EAST YOU
GO...LIKELY DUE TO THE LINGERING DRY AIR SHOWING UP BLO H85 AND
LACK OF SIGNIFICANT ISENTROPIC LIFT TO OVERCOME THE DRY AIR. ARRIVAL
OF WARM AIR IN THE 850-800MB LAYER WITH TEMPS ABOVE 0C ALLOWS SLUG
OF QPF TO SWING ACROSS REST OF UPR MI LATE THU NIGHT INTO FRIDAY
MORNING. AFTERWARDS...MID LEVEL DRY SLOT PLOWS NORTH...LIKELY
TURNING PCPN TO MORE OF A DRIZZLE IN THE AFTN. WITH THE WARM AIR
AROUND...DENSE FOG MAY ALSO BECOME AN ISSUE INTO FRIDAY NIGHT.

PTYPE AND IMPACTS...SOUNDINGS FM BOTH NAM/GFS AND THICKNESSES SHOW 
MOSTLY A PTYPE OF SNOW FOR FAR WRN UPR MI THROUGH THU NIGHT AND EVEN 
INTO FRIDAY. SNOW-WATER RATIOS WILL BE A BIT HIGHER FM FAR WRN CWA 
INTO NW WI AND MN AS BLYR TEMPS STAY BLO 32 AND SOUNDINGS SHOW A BIT 
BETTER SNOW GROWTH. SINCE THE QPF IS PROGGED HEAVIER IN THESE AREAS 
CLOSER TO SFC TROUGH EXTENDING N FM MAIN CYCLONE...AND PTYPE SHOULD 
STAY MOSTLY SNOW...THINK TOTAL SNOW ACCUMS COULD SATISFY WARNING 
CRITERIA THU/FRI. HAVE ISSUED A WINTER STORM WATCH FOR GOGEBIC...
ONTONAGON...AND IRON COUNTIES.

PICTURE NOT NEAR AS CLEAR OVR CNTRL AND ERN CWA...AT LEAST FOR THU 
NIGHT INTO FRIDAY. SOUNDINGS AT MQT...IMT...ESC...ERY AND PARTIAL 
THICKNESS APPROACH SUGGEST ALMOST ALL PTYPES ARE POSSIBLE BTWN 06Z 
AND 18Z FRI. WARM LAYER ALOFT WITH H85 TEMPS UP TO +2C BY 12Z FRI 
POINT TO FZRA POTENTIAL WHERE SFC TEMPS ARE STILL BLO FREEZING. BEST 
CHANCE FOR ANY ICING WOULD BE OVR THE CNTRL AND ERN CWA AWAY FM LK 
SUPERIOR AND LK MICHIGAN. IF MAINLY FZRA OCCURS...VERSUS SNOW... 
COULD FLIRT WITH QUARTER-INCH CRITERIA FOR ICE STORM WARNING. RIGHT 
NOW THOUGH...THINK THAT MOST OF THE PCPN THU NIGHT OVR THE CNTRL AND 
EAST WILL FALL AS SNOW WITH A CHANGEOVER TO FZRA/RA LATE IN THE 
NIGHT AS WARM AIR ALOFT ARRIVES BUT AS HEAVIER PCPN TAPERS OFF. 
SNOW-WATER RATIOS WILL BE LUCKY TO REACH 10:1...SO TOTAL SNOW 
AMOUNTS AWAY FM THE WEST WILL PROBABLY STAY IN THE ADVY CRITERIA 
(3-5" IN 12 HR). SEEMS VERY PROBABLE ADVYS WILL BE NEEDED FOR THIS 
EVENT FOR THE CNTRL AND ERN CWA. QUITE A BIT LESS QPF THAN THE WRN 
CWA THOUGH...SO DID NOT GO WITH A WATCH FOR THESE AREAS.

DAYS 4-7...AFFECTS OF THE CHRISTMAS STORM LINGER RIGHT THROUGH EARLY 
NEXT WEEK. ECMWF HAS TRENDED TOWARD IDEA OF STALLING OUT THE LATE 
WEEK UPR LOW AND ONLY SLOWLY DRIFTING IT THROUGH THE GREAT LAKES 
SUN-TUE. GFS REMAINS MOST PROGRESSIVE IN EXITING THE TROUGH AND 
DIGGING IN ANOTHER TROUGH FM CNTRL CANADA. EVEN THE GFS DOES SHOW A 
SLIGHTLY SLOWER TREND WITH THE EXITING OF THE CYCLONE. 12Z RUN 
CONTINUES THIS TREND. UKMET/CANADIAN AND A MAJORITY OF ENSEMBLES FM 
BOTH THOSE MODELS ALSO SUPPORT UPR LOW GRINDING THROUGH THE GREAT 
LAKES. EVEN WITH THE LOW IN THE AREA...THE COLD AIR DIMINISHES BY 
MON-TUE AS THE LOW CONTINUES TO WEAKEN. DETAILS...SHAKY AT 
BEST...INCLUDE POTENTIAL FOR WIDESPREAD SNOW IN DECAYING DEFORMATION 
AXIS SAT INTO SUN...ESPECIALLY FAR WRN CWA INTO THE KEWEENAW. 
OVERALL...SNOW AMOUNTS WITH THIS FEATURE WOULD BE LIGHT TO MODERATE 
BUT FAVORABLE ERLY FLOW ACROSS KEWEENAW AND ENOUGH LAKE INDUCED 
INSTABILITY MAY LEAD TO LAKE ENHANCEMENT. WEAK LK EFFECT REMAINS 
POSSIBLE THROUGH EARLY NEXT WEEK WITH LOW-LEVEL NW FLOW BUT ONLY 
WEAK OVER WATER INSTABILITY. TEMPS SHOULD ACTUALLY STAY AT OR A BIT 
ABOVE NORMAL THROUGH EARLY NEXT WEEK AS PUSH OF COLDER AIR SHOWN ON 
YDY MODELS IS NOW NOT NEARLY AS AGGRESSIVE.
&&

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

SOME MVFR CLOUDS OVER LAKE SUPERIOR AND FAR WESTERN UPPER MICHIGAN 
WILL CONTINUE TO WRAP BACK ACROSS CMX AND SAW OVERNIGHT. 
OTHERWISE...WINDS WILL BECOME MORE ENE AND STRENGTHEN...STILL LESS 
THAN OR EQUAL TO 10KTS THROUGH THE PERIOD. AT CMX THE RESULT WILL BE 
UPSLOPE CONDITIONS...WITH A BETTER CHANCE OF THOSE MVFR CEIGS COMING 
BACK INTO PLAY. IT SHOULD TAKE A FEW HOURS LONGER AT SAW...WITH HIGH 
CLOUDS BEGINNING TO STREAM ACROSS DURING THE LATE AFTERNOON AND 
EARLY EVENING HOURS AT BOTH SITES...WITH TE LOWER LEVELS DRYING OUT 
A BIT AFTER 00Z AS WINDS BECOME MORE OFFSHORE.

&&

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

WINDS WILL REMAIN LIGHT UNDER 25 KNOTS UNTIL GALES ARRIVE FOR THU 
WITH APPROACH OF THE STRONG LOW PRESSURE SYSTEM FROM THE SOUTH. 
FOLLOWED THE GFS/ECMWF SOLUTION WHICH BRINGS THE LOW UP NORTH AND 
THEN SLOWS IT DOWN OVER OUR AREA AND WEAKENS IT WITH TIME...SO 
STRONGEST WINDS LOOK TO BE THROUGH FRI BEFORE THE LOW AND PRESSURE 
GRADIENT WEAKEN ENOUGH FOR WINDS TO GO BELOW GALES.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY 
     EVENING FOR MIZ002-009-010.

LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

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