FXUS63 KMQT 102325 AAA
AFDMQT

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
625 PM EST THU DEC 10 2009

UPDATED FOR 00Z TAF ISSUANCE

.SYNOPSIS /ISSUED AT 430 PM/...

COLD AIRMASS CONTINUES TO SETTLE FM THE NORTHERN PLAINS INTO THE 
GREAT LAKES. TEMPS HAVE REMAINED BLO ZERO OVR THE DAKOTAS INTO WRN 
MN WHILE OVR UPR MI...READINGS HAVE STAYED STEADY IN THE LWR SINGLE 
DIGITS IN THE FAR SW TO THE LWR-MID TEENS ELSEWHERE. MQT VWP AND 
RADAR LOOP POINTS TO DOMINANT BAND OF SNOW FM SOUTHERN PORTIONS OF 
KEWEENAW PENINSULA TOWARD PICTURED ROCKS/GRAND MARAIS AND INTO 
NORTHERN HALF OF LUCE COUNTY. SNOWFALL AMOUNTS BENEATH THIS BAND 
HAVE EXCEEDED 6" IN AREAS SOUTH OF GRAND MARAIS. VIS SATELLITE 
INDICATES NW FLOW MULTIPLE BANDED SNOW SHOWERS ALONG REST OF LK 
SUPERIOR...WITH GREATEST COVERAGE IN EXTREME NORTHERN ONTONAGON 
COUNTY. SKIES HAVE CLEARED OVR INTERIOR SW UPR MI INTO NRN WI. 

&&

.SHORT TERM (TONIGHT AND FRIDAY)...

WRLY FLOW LK EFFECT AND LOW WIND CHILLS ARE THE MAIN ISSUES.

STRONGEST LK EFFECT THROUGH THE PERIOD COMPLETELY DEPENDENT UPON 
LOW-LEVEL WINDS AS MOISTURE/INSTABILITY REMAIN FAIRLY STEADY STATE. 
ITS NOT A BIG SURPRISE THAT LOCAL LK EFFECT GUIDANCE WITH INVERSION 
UP TOWARD 10KFT AND TEMPS AT TOP OF INVERSION BLO -20C INDICATES 
SIGNIFICANT 12 HR SNOW AMOUNTS. WINDS SHOULD CONTINUE TO SLOWLY BACK 
THROUGH THE NIGHT...BUT WITHOUT LACK OF STRONG SHORTWAVE/SFC TROUGH 
IN THE AREA...LOCATION OF DOMINANT BAND IS HIGHLY DEPENDENT ON 
MESOSCALE AFFECTS. SINCE SUCH COLD AIR IS ENTRENCHED OVR THE AREA 
FOLLOWED RUC13/NAM GUIDANCE AS IT INDICATED THE STRONGEST LAND 
BREEZE SETTING UP. RESULT WAS A DOMINANT BAND OF SNOW IN THE HIGHER 
TERRAIN FM TWIN LAKES TO HOUGHTON/CALUMET SHIFTING ACROSS THE REST 
OF THE KEWEENAW ON FRIDAY. IN THE EAST...BAND OF HEAVY SNOW LOOKS TO 
HANG ALONG THE SHORE FROM GRAND MARAIS TO TWO HEART MUCH OF THE 
NIGHT BEFORE WINDS BACK SW ENOUGH TO KICK THE BAND OUT INTO EASTERN 
LK SUPERIOR. TREND TO EXIT THE SNOW WAS A BIT SLOWER...SO HAVE 
EXTENDED THE LK EFFECT WARNING FOR ALGER/NRN LUCE THROUGH 12Z ON 
FRIDAY. IN THE DOMINANT BAND...SNOWFALL RATES UP TO 2 INCHES PER 
HOUR SEEM LIKELY. WENT FOR TOTAL SNOW AMOUNTS TONIGHT THEN AGAIN ON 
FRIDAY OF UP TO 10 INCHES EACH TIME FRAME IN THE CONVERGENCE BAND 
AREA...WITH A GENERAL 3-5 INCHES FOR OTHER AREAS FAVORED BY WNW FLOW 
MULTIBAND SNOW SHOWERS.

WIND CHILLS ARE THE OTHER ISSUE TONIGHT. EXPECT TEMPS TO FALL OFF IN 
THE 5 TO 10 BELOW ZERO RANGE LATER TONIGHT INTO EARLY FRIDAY MORNING.
WINDS ON THE SOUTHERN FLANK OF THE STRONGER BAND OF SNOW SHOULD BE 
FAIRLY GUSTY...WITH GUSTS TO 30 MPH ALONG THE SOUTH SHORE OF LK 
SUPERIOR. EVEN INLAND...WINDS REMAINING IN THE 10-15 MPH RANGE 
RESULT IN WIND CHILL READINGS FALLING TO 15-30 BLO SET UP OVR THE 
INTERIOR WRN U.P...MAINLY WEST OF MQT-ESC. WIND CHILLS STAY ON THE 
CHILLY SIDE INTO MIDDAY FRIDAY. CURRENT WIND CHILL ADVY UP THROUGH 
LATE MORNING LOOKS GOOD.

&&    

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

FRIDAY NIGHT...AS A SHORTWAVE TROUGH MOVES THROUGH NW ONTARIO AND 
HEIGHTS RISE OVER THE UPPER GREAT LAKES WITH A TRANSITION TO MORE 
ZONAL FLOW...WINDS WILL BACK FROM WRLY TO SW. SO...THE AREA OF 
FAVORABLE LOW LEVEL CONV INTO THE KEWEENAW WILL SHIFT NORTHWARD AND 
SHOULD BE NORTH OF KP59 BY 12Z. ADDITIONAL SNOW AMOUNTS OF 3 TO 7 
INCHES WILL BE POSSIBLE...MAINLY JUST OVER THE NRN PENINSULA FROM 
CALUMET INTO KEWEENAW COUNTY. EXPECT SNOW/WATER RATIO TO REMAIN 
FAIRLY HIGH...AOA 25/1 BUT SOME WIND WITH BLOWING AND DRIFTING THE 
SNOW MAY BE MORE COMPACT.

SATURDAY INTO SATURDAY NIGHT....WAA DEVELOPS AS A WEAK TROUGH 
APPROACHES WITH SW WINDS KEEPING ANY LES NORTH OF THE CWA. THE NAM 
AND GFS LOW LEVEL WINDS AND FCST AREA OF LOW LEVEL CONV WOULD KEEP 
ANY LES OFF OF LAKE MICHIGAN MAINLY EAST OF THE CWA. INSTABILITY FOR 
LES ALSO DECREASES WITH 850 MB TEMPS CLIMBING FROM -8C TO -12C. WEAK 
ISENTROPIC ASCENT OVER THE AREA MAY PRODUCE A FEW FLURRIES OR LIGHT 
SNOW SHOWERS BUT WITH VERY LIMITED MOISTURE AVAILABLE LITTLE OR NO 
ACCUMULATION IS EXPECTED. OTHERWISE...TEMPERATURES SHOULD MODERATE 
BACK TO MAX READINGS INTO THE LOWER 20S. 

SUNDAY INTO MONDAY...WAA CONTINUES INTO SUNDAY WITH A MAINLY ZONAL 
PATTERN. AS THE POLAR VORTEX EDGES INTO CENTRAL CANADA A MID LEVEL 
TROUGH WILL DEVELOP INTO THE PLAINS. THE ECMWF WAS LESS AGGRESSIVE 
IN LOWERING HEIGHTS INTO THE CONUS COMPARED TO THE GFS. AS A 
RESUL...THE GFS WAS MORE AGGRESSIVE WITH THE SFC LOW DEVELOPMENT AND 
SPREAD OF LIGHT PCPN INTO THE AREA. FOR NOW ONLY CHANCE POPS WERE 
INCLUDED FOR SYNOPTIC PCPN BUT WITH ANOTHER ROUND OF COLD AIR MOVING 
IN ON NW WINDS LES WILL AGAIN DEVELOP BY LATE MONDAY. 

TUE THROUGH THU...WITH A NEGATIVE NAO PATTERN PREVAILING...IT WILL 
BE DIFFICULT TO DISPLACE THE BATCH OF COLDER AIR OVER ERN CANADA 
AND THE GREAT LAKES. EVEN THOUGH THE ECMWF REMAINS MORE FLAT WITH 
THE PATTERN...ENOUGH COLD AIR LINGERS OVER THE REGION WITH 850 MB 
TEMPS DOWN TO AT LEAST -15C FOR LES TO CONTINUE FOR LOCATIONS 
FAVORED BY NW FLOW. GREATER UNCERTAINTY WITH THE PATTERN APPARENT BY 
THU AS THE ECMWF WAS MORE EAGER TO PUSH THE MID LEVEL TROUGH AND 
COLD AIR TO THE EAST.

&&

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

LOCATION OF SHARP AXIS OF LLVL CONVERGENCE/ACCOMPANYING HEAVY LES 
BAND STRETCHING ACROSS WRN LK SUP ACROSS THE KEWEENAW WL DETERMINE 
WX AT CMX. ALTHOUGH THIS HEAVIER BAND IS LIKELY TO REMAIN JUST S OF 
CMX DURING THE NGT...RECENT OBS SUG IFR/OCNL LIFR CONDITIONS WL 
PREVAIL. SINCE BULK OF NUMERICAL GUIDANCE HINTS THE WIND MAY VEER A 
BIT LATER THIS EVNG...THERE MAY BE A SLGT IMPROVEMENT TO MVFR VSBY 
FOR A TIME. BUT AS FLOW BACKS AGAIN LATE TNGT/FRI MRNG...EXPECT THE 
BAND TO DRIFT N ACROSS CMX WITH VLIFR CONDITIONS. WITH CONTINUED 
BACKING FLOW...THE HEAVIER BAND WL DRIFT JUST TO THE N ON FRI AFTN 
WITH IMPROVING CONDITIONS WITH VERY DRY ARCTIC AIR OVERSPREADING THE 
SITE. NOTE SUBTLE CHANGES IN OBS VS FCST WIND DIRECTION WOULD HAVE 
SIGNIFICANT CHANGES IN BAND PLACEMENT/CONDITIONS.

THE FCST IS MUCH LESS OF A CHALLENGE AT SAW WITH VFR CONDITIONS 
PREDOMINATING THIS FCST PERIOD IN LLVL DOWNSLOPING WLY FLOW OF DRY 
ARCTIC AIR THAT WILL KEEP LES BANDS WELL N OF THAT LOCATION. 

&&

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

W GALES THROUGH FRIDAY...MAINLY OVER EASTERN LAKE SUPERIOR ON THE 
SOUTHERN FLANK OF LAKE INDUCED LOW PRESSURE TROUGH. ELSEWHERE... 
WINDS TO 30 KTS PERSIST ALONG WITH FREEZING SPRAY. WINDS REMAIN BLO 
25 KTS THIS WEEKEND...BUT STRONGER WINDS TO 30 KTS MAY ARRIVE EARLY 
NEXT WEEK AS ANOTHER ARCTIC AIRMASS MOVES INTO THE UPPER GREAT LAKES.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR MIZ002-084.

  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR MIZ001-003.

  WIND CHILL ADVISORY FROM 10 PM EST /9 PM CST/ THIS EVENING TO 11   
     AM EST /10 AM CST/ FRIDAY FOR MIZ002-004-005-009>013.

  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR MIZ006-007.

LAKE SUPERIOR...
  GALE WARNING UNTIL 7 PM EST FRIDAY FOR LSZ266-267.

LAKE MICHIGAN...NONE.

&&

$$

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