FXUS63 KMQT 300527 AAB
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1227 AM EST MON NOV 30 2009
.SHORT TERM /TONIGHT AND MONDAY/...
OUR MAIN LOW AND ASSOCIATED FGEN/UPPER LEVEL DEFORMATION ZONE HAS
SHIFTED EAST OF THE AREA. STILL...PLENTY OF MOISTURE REMAINS
ENTRENCHED ACROSS ALL OF MN...WI...MI...AND ONTARIO. A STRAIGHT
EXTRAPOLATION OF THE CURRENT BREAK IN CLOUDS ACROSS FAR NORTHWESTERN
MN WOULD BRING THE CLEARING LINE TO WESTERN LAKE SUPERIOR SHORTLY
AFTER 08Z. HOWEVER...AN APPROACHING SFC TROUGH FROM CENTRAL ONTARIO
MAY NOT ALLOW FOR SUCH A RAPID CLEARING OVERNIGHT...PARTICULARLY
ACROSS THE EAST HALF OF UPPER MICHIGAN WHERE FAVORABLE NORTHWESTERLY
FLOW OFF LAKE SUPERIOR WILL COMBINE WITH 850MB TEMPS AROUND
-8C...AND LINGERING LOW LEVEL MOISTURE. AS STATED...850MB
TEMPERATURES WILL BOTTOM OUT AROUND -8C BETWEEN 00Z AND 06Z
TONIGHT...BEFORE WARMING ONLY SLIGHTLY TO AROUND -6.5 BY 00Z
TUESDAY. THIS WILL STILL BE COLD ENOUGH FOR SOME LAKE ENHANCEMENT AS
WINDS GO FROM NNW LATE THIS AFTERNOON TO NEARLY W BY DAYBREAK
MONDAY. THE MAIN RESULT FOR UPPER MICHIGAN WILL BE DIMINISHING LAKE
ENHANCED CLOUDS/PRECIPITATION ACROSS FAR WESTERN UPPER MICHIGAN
UNTIL THE WEAK SURFACE TROUGH ENTERS THE PICTURE MONDAY AFTERNOON.
EVEN THOUGH COOL AIR REMAINS ALOFT...TEMPERATURES CLOSER TO THE
SURFACE MAY WARM UP JUST ENOUGH FOR RAIN SHOWERS TO MIX BACK IN
DURING THE AFTERNOON HOURS.
&&
LONG TERM...MONDAY NIGHT THROUGH SUNDAY
MONDAY NIGHT...LAKE ENHANCED SNOW DURING THE EVENING WITH DEEP
MOISTURE AND 850 MB TEMPS TO NEAR -8C WILL GIVE WAY TO SUBSIDENCE
AND DRYING OVERNIGHT IN THE WAKE OF THE MID LEVEL TROUGH. SO...NMRS
SNOW SHOWERS FOR AREAS FAVORED BY CYCLONIC WNW FLOW WILL DIMINISH
OVERNIGHT. WITH ONLY MARGINAL INSTABILITY AND SHIFTING WIND
FIELDS...EXPECT ANY ACCUMULATIONS WILL AMOUNT TO ONLY AN INCH OR
LESS. FCST LOW LEVEL THICKNESS AND WET-BULB ZERO HEIGHTS FALL ENOUGH
SO THAT ANY RAIN MIX OVER THE ERN CWA SHOULD BE MINIMAL..
TUESDAY INTO TUESDAY NIGHT...THE DEVELOPING WAA PATTERN AHEAD OF THE
SHORTWAVE AND LOW MOVING THROUGH SRN MANITOBA WILL BRING MAINLY
CLOUDY SKIES WITH TEMPERATURES CLIMBING INTO THE MID 30S NORTH AND
NEAR 40 SOUTH. THE 00Z/12Z/29 ECMWF AND 12Z//29 NAM WERE FASTER WITH
THE SHORTWAVE AND LOW THAN THE 12Z/29 GFS WITH A TRACK FARTHER TO
THE NORTH. GOING WITH THE PREFERRED NON GFS SCENARIO...EXPECT THE
BULK OF ANY PCPN WITH THE LOW TO REMAIN NORTH OF THE CWA.
HOWEVER...CAA IN THE WAKE OF THE LOW WITH STRONG WRLY FLOW WILL
RESULT IN SOME LES INTO WRN UPPER MI BY LATE TUE NIGHT.
WEDNESDAY INTO THURSDAY...NW TO N FLOW CAA AND AN AMPLIFYING MID
LEVEL PATTERN WILL BRING IN SIGNIFICANTLY COLDER AIR WITH 850 MB
TEMPS DROPPING TO AROUND -11C BY 00Z/THU AND -BY 12Z/THU...PER
GFS/ECMWF...GIVING LAKE-H8 DELTA/T TO AROUND 18C. WITH DEEP MOISTURE
AND FAVORABLE INVERSION HEIGHTS AOA 7K FT...MODERATE TO HEAVY
ACCUMULATIONS ARE EXPECTED. THE GFS/ECMWF VEER WINDS FROM WNW TO NNW
WHICH WOULD IMPACT N CNTRL UPPER MI. HOWEVER...EXPECT LAKE INDUCED
TROF POSITION WOULD LIKELY FOCUS BETTER LES INTO W UPPER MI AND
LOCATIONS E OF MARQUETTE.
FRI-SUN...FCST LEANS MORE TOWARD THE ECMWF/CANADIAN SCENARIO WHICH
WAS LESS PROGRESSIVE RESULTING A LONGER PERIOD OF LES POTENTIAL.
SO...EXPECT NW FLOW LAKE EFFECT SNOW TO CONTINUE THROUGH SATURDAY
WITH WINDS GRADUALLY BACKING MORE WRLY FROM FRI INTO SAT. BY
SUN...SIGNIFICANT UNCERTAINTY WITH POTENTIAL FOR RIDGE MOVING IN AND
SHUTTING OFF LES. FOR NOW...WITH LITTLE SUPPORT FROM OTHER GLOBAL
MODELS OR GFS ENSEMBLE...DISREGARDED 12Z GFS SCENARIO OF SIGNIFICANT
WIDESPREAD SNOW INTO THE REGION.
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
AT CMX...LAKE EFFECT MOISTURE SHOULD CONTINUE AS WINDS STAY FROM THE
WEST AND THIS WILL HELP KEEP A MVFR CIG AT THIS SITE THROUGH THIS
FORECAST. LITTLE CLIPPER TYPE SYSTEM WILL BRING SOME MVFR VIS SNOW
TO CMX MON EVENING. AT SAW...VFR CONDITIONS WILL CONTINUE UNTIL
CLIPPER TYEP SYSTEM CLOUDS AND SNOW ARRIVE IN THE AFTERNOON OR EARLY
EVENING.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
LOW PRESSURE ACROSS LAKE ONTARIO WILL SHIFT INTO THE NEW ENGLAND
STATES OVERNIGHT...AS A RIDGE OF HIGH PRESSURE SLIDES OVER THE UPPER
GREAT LAKES. ON MONDAY...EXPECT A TROUGH TO MOVE SOUTHEASTWARD
ACROSS LAKE SUPERIOR. A WEAK RIDGE OF HIGH PRESSURE MOVE ACROSS LAKE
SUPERIOR TUESDAY BEFORE LOW PRESSURE SLIDES IN FROM THE CANADIAN
PRAIRIES TUESDAY EVENING...AND TO QUEBEC BY WEDNESDAY EVENING. THE
POTENTIAL REMAINS FOR WESTERN GALES TO 35 KNOTS ACROSS EASTERN LAKE
SUPERIOR WEDNESDAY. OTHERWISE FOR WEDNESDAY AND THURSDAY...A
STRONGER LOW IS EXPECTED TO MOVE FROM THE MISSISSIPPI DELTA REGION
TO THE NEW ENGLAND STATES. THIS WILL KEEP AN ELONGATED AREA OF HIGH
PRESSURE...AND NORTHERLY WINDS...STUCK ACROSS THE PLAINS STATES
THROUGH FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KF
LONG TERM...JLB
AVIATION...07
MARINE...KF
