FXUS63 KMQT 022328 CCA
AFDMQT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
625 PM EST WED DEC 2 2009

UPDATED FOR 00Z TAF ISSUANCE

.SYNOPSIS... /ISSUED AT 450 PM EST/

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE ERN 
PACIFIC INTO NW CANADA. DOWNSTREAM...A TROF IS DEEPENING SWD INTO 
THE CNTRL CONUS. ONE SHORTWAVE WAS SHEARING NE ACROSS LAKE 
SUPERIOR/ONTARIO. ANOTHER SHORTWAVE WAS DROPPING S THRU THE DAKOTAS. 
THE MOST SIGNIFICANT SHORTWAVE WAS OVER THE LWR MISSISSIPPI VALLEY. 
AS IT HEADS NE ON THE FRONT SIDE OF DEEPENING CNTRL CONUS TROF... 
THIS SYSTEM WILL PASS WELL E OF THE AREA. AT THE SFC...LOW PRES HAS 
MOVED E OF LAKE SUPERIOR...ALLOWING COLDER AIR TO FILTER INTO THE 
UPPER GREAT LAKES. ALTHOUGH THERE HAVE BEEN A FEW BANDS OF HEAVIER 
SNOW...AVBL WEBCAMS OVER WRN UPPER MI SUGGEST LES HAS GENERALLY BEEN 
LIGHT TODAY DUE TO AN INITIAL LOW INVERSION. MORNING TAMDAR SOUNDING 
FROM FLIGHT OUT OF THUNDER BAY ONTARIO SHOWED INVERSION BASED AT 
900MB (AROUND 3.2KFT) WITH TEMP OF -9C.

&&

.SHORT TERM (TONIGHT AND THU)... /ISSUED AT 450 PM EST/

LES...SNOW AMOUNTS AND HEADLINES WILL BE THE CONCERNS THRU THE SHORT 
TERM AND INTO THE LONG TERM PORTION OF THIS FCST. BOUNDARY LAYER 
WINDS WILL VEER NNE THIS EVENING THRU THE NIGHT. THIS WILL FOCUS 
MAIN LES INTO FAR WRN UPPER MI AND INCREASINGLY INTO NCNTRL UPPER MI 
AS AIRMASS CONTINUES TO COOL. ALTHOUGH FCST SOUNDINGS AND EARLY AFTN 
TAMDAR SOUNDING FROM KSAW SUGGEST THERE SHOULDN'T BE ANY DENDRITIC 
SNOW GROWTH OVER NCNTRL UPPER MI (SNOW GROWTH ZONE IS IN THE DRY AIR 
ABOVE INVERSION)...LARGER SNOWFLAKES HAVE STILL BEEN OBSERVED THIS 
AFTN HERE AT THE OFFICE. SHOULD THIS CONTINUE TO BE THE CASE 
TONIGHT...ADVY AMOUNTS MAY BE REACHED IN PARTS OF MARQUETTE COUNTY. 
FOR NOW...KEPT AMOUNTS SUB ADVY GIVEN AGREEMENT FROM ALL THE MODELS 
INCLUDING LOCAL HIGH RES WRF THAT SNOW SHOULD BE KEPT IN CHECK BASED 
ON FCST SOUNDINGS. LES SHOULD GRADUALLY DEVELOP EWD INTO THE ERN 
FCST AREA TONIGHT AS AIRMASS SLOWLY COOLS. TO THE W...ADVY WILL 
REMAIN UP FOR THE FAR W (GOGEBIC/ONTONAGON COUNTIES). HOWEVER... 
DEFINITELY HAVE SOME CONCERN FOR LOCALLY HVY LES THAT MAY PUSH 
AMOUNTS OVER WARNING CRITERIA IN A FEW SPOTS. THAT CONCERN IS DUE TO 
PRECONDITIONING FROM LAKE NIPIGON. VIS SATELLITE IMAGERY TODAY HAS 
SHOWN GOOD BANDING OFF LAKE NIPIGON THOUGH THERE HAS BEEN SOME 
DECREASE RECENTLY DUE TO DAYTIME HEATING AND DEVELOPING MIXED LAYER 
IN UPSTREAM AIRMASS HEADING ACROSS THE LAKE. WITH LOSS OF DAYTIME 
HEATING...PRECONDITIONING WILL BECOME AN INCREASINGLY FAVORABLE 
ENHANCEMENT FACTOR. TRAJECTORIES INDICATE THIS PRECONDITIONED AIR 
WILL STREAM S ACROSS WRN LAKE SUPERIOR INTO GOGEBIC/ONTONAGON 
COUNTIES TONIGHT. SO...THE WILDCARD IS THE POSSIBLE DEVELOPMENT OF 
ONE OR MORE DOMINANT LES BANDS WITHIN THE CORRIDOR DOWNWIND OF LAKE 
NIPIGON. INCOMING 18Z LOCAL HIGH RES WRF RUN IS SHOWING A LITTLE 
STRONGER SIGNAL FOR THIS TO OCCUR. WILL BE SOMETHING TO MONITOR 
CLOSELY DURING THE EVENING. FOR NOW...KEPT 24HR AMOUNTS JUST SHY OF 
WARNING CRITERIA. ACROSS THE KEWEENAW PENINSULA...LES SHOULD BE 
LIGHTER SINCE WINDS VEER TO A LESS FAVORABLE NNE DIRECTION. EXPECT 
SUB ADVY AMOUNTS THERE TONIGHT. 

OTHER THAN SOME SLIGHT COOLING ACROSS ERN LAKE SUPERIOR...THERE 
ISN'T MUCH CHANGE WITH MOISTURE AND TEMP PROFILES THU. NRLY WINDS IN 
THE MORNING WILL GRADUALLY BACK NW THRU THE DAY...CAUSING A SLOW 
SHIFTING OF LES. THIS WILL RESULT IN MORE PERSISTENT LES AFFECTING  
MORE OF WRN UPPER MI. THERE WILL ALSO BE A SLOW SHIFTING OF LES OUT 
OF MARQUETTE/BARAGA COUNTIES INTO ALGER/LUCE. AS WINDS SHIFT...ANY 
OF THE MORE SIGNIFICANT LES BANDS ORIGINATING FROM LAKE NIPIGON 
PRECONDITIONING WILL ALSO SHIFT INTO THE KEWEENAW PENINSULA. MAY 
NEED AN ADVY HEADLINE THERE THU DEPENDING ON HOW THINGS EVOLVE 
TONIGHT OVER GOGEBIC/ONTONAGON COUNTIES.

.LONG TERM (THU NIGHT THRU WED)...

.THURSDAY NIGHT THROUGH FRIDAY NIGHT...THIS FORECAST PERIOD BEGINS 
WITH LES ONGOING ACROSS TYPICAL NORTHWEST SNOW BELTS. BY FRIDAY 
NIGHT AS PBL FLOW BECOMES WESTERLY AND THEN SOUTHWESTERLY...EXPECT 
LES TO SHIFT OFFSHORE AND IMPACT THE CANADIAN SHORELINES OF
EASTERN LAKE SUPERIOR. MAIN CHANGES TO THE GOING FORECAST WERE TO
REFINE AREAS WHERE LES CAN BE ANTICIPATED GIVEN THIS BACKING WIND
PROFILE AND ADJUST CORRESPONDING QPF/SNOW TOTALS. MAIN DIFFERENCE
IN GUIDANCE IS HOW QUICKLY WINDS BACK TO THE WEST ON
FRIDAY NIGHT...EFFECTIVELY ENDING LES OVER THE EASTERN ZONES NEAR
LAKE SUPERIOR. GFS TRIES TO HANG ONTO LES OVER FAR NORTHERN
LUCE/CHIPPEWA COUNTIES...OPTED TO END SNOW HERE AFTER 06Z
SATURDAY. NOT CONVINCED LES SNOWFALL WARNING TOTALS WILL BE SEEN
DURING THIS EVENT. CURRENT GRIDS INDICATE AROUND 7-10 INCHES IS
POSSIBLE OVER NORTHWEST SNOW BELTS USING A 25:1 SNOW RATIO WHICH
MIGHT BE HIGHER THAN WE WILL ACTUALLY SEE. BUFKIT PROFILES WOULD
SUGGEST A SLIGHTLY LOWER SLR OF 18-20:1...WHICH WOULD ONLY
DIMINISH FORECASTED SNOW TOTALS.

AT THIS POINT IT LOOKS LIKE THE SNOW WILL FALL OVER A PERIOD OF 36
TO 48 HOURS...SO EVEN THOUGH WE MAY SEE STORM TOTAL VALUES OVER A
FOOT IN THE NORTHWEST SNOWBELTS...IT WON/T FALL OVER A SHORT
ENOUGH PERIOD TO MEET WARNING CRITERIA. HOWEVER COULD ENVISION
ADVISORIES BEING NEEDED FOR THURSDAY NIGHT INTO FRIDAY AS COLDEST
AIR CROSSES LAKE SUPERIOR AND HEAVIER BANDS DEVELOP.

NAM/GFS/UKMET/GEM AGREE ON THE GENERAL SYNOPTIC PATTERN FOR
SATURDAY INTO SATURDAY NIGHT WITH SURFACE RIDGING OVER THE SOUTHERN
CONUS BUILDING NORTH INTO THE LOWER LAKES AND LOW PRESSURE OVER
SOUTHERN HUDSON BAY. THIS SETS UP A PERIOD OF CONVERGENT
SOUTHWESTERLY FLOW OVER WESTERN LAKE SUPERIOR. IN THIS PATTERN THE
POTENTIAL EXISTS FOR A DOMINANT SOUTHWEST-NORTHEAST ORIENTED BAND
ALONG THE WESTERN SHORELINES OF THE KEWEENAW PENINSULA...MAINLY
IMPACTING AREAS OF KEWEENAW COUNTY. WILL ALSO HAVE TO KEEP AN EYE
ON LAKE MICHIGAN LES POTENTIAL OVER EASTERN UPPER MICHIGAN WHICH
AT THIS POINT LOOKS TO OCCUR NEAR AND SOUTH OF THE BRIDGE.

FOR SUNDAY AND MONDAY THE PATTERNS IS A BIT UP IN THE AIR. LATEST
FORECAST LEANS TOWARDS AN IDEA OF LES RE-ESTABLISHING ITSELF FOR
NORTH-NORTHWEST SNOW BELTS AS A S/W TRACKS TO THE SOUTHEAST OF
LAKE SUPERIOR. STILL COLD ENOUGH AIR IN PLACE AS 850MB
TEMPERATURES RANGE IN THE -10 TO -12C RANGE. THROUGHOUT THE
EXTENED FORECAST TEMPERATURES LOOK NEAR TO SLIGHTLY BELOW NORMAL.

&&

.AVIATION /FOR THE 00Z TAF ISSUANCE/...

AS COLDER AIR MOVES OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR 
THIS FCST PERIOD...EXPECT PERIODS OF LES AT BOTH SITES. WITH A N 
WIND TNGT...THE WORST PREDOMINANT IFR VSBY/MVFR CIGS SHOULD IMPACT 
SAW GIVEN LONG FETCH ACROSS THE OPEN WATERS OF CENTRAL LAKE SUPERIOR 
INTO THAT SITE. SINCE THE AIR IS ONLY MARGINALLY COLD FOR LES THIS 
EVNG...THERE WL LIKELY BE TIMES OF VFR VSBY EARLY IN THE FCST PERIOD 
AT SAW EVEN WITH THE FAVORABLE WIND DIRECTION. THE N WIND IS LESS 
FAVORABLE AT CMX...SO PLAN ON PREDOMINANT VFR VSBY/MVFR CIGS THERE 
INTO THU MORNING. AS THE WIND BACKS TO NW ON THU AFTN...THE HEAVIER 
LES WILL IMPACT CMX INSTEAD OF SAW. LOOK FOR PREDOMINANT IFR VSBYS 
AT CMX THEN...WITH THE VSBY AT SAW TRENDING TO VFR WITH DOWNSLOPING 
FLOW/LESS LAKE MOISTENING.

&&

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

PRES GRADIENT BTWN LOW PRES LIFTING NE INTO NEW ENGLAND AND HIGH 
PRES SETTLING S INTO THE WRN PLAINS WILL KEEP NRLY WINDS GENERALLY 
IN THE 15-30KT RANGE ACROSS LAKE SUPERIOR TONIGHT THRU THU NIGHT. 
WINDS WILL DIMINISH FRI AND THEN WINDS OVER THE WEEKEND SHOULD BE 
UNDER 20KT AS A LOW PRES TROF SLOWLY DRIFTS SE ACROSS THE UPPER 
GREAT LAKES.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ FRIDAY 
     FOR MIZ002-009.

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

$$

SHORT TERM...ROLFSON
LONG TERM....PEARSON
AVIATION...KC
MARINE...ROLFSON