682
FXUS63 KMQT 202342 AAA
AFDMQT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
640 PM EST FRI NOV 20 2009
UPDATED FOR AVIATION DISCUSSION FOR 00Z TAF ISSUANCE
SHORT TERM (THROUGH 00Z SUN)
/ISSUED AT 343 PM EST/
UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER THE LOWER
GREAT LAKES AND RIDGING OVER THE CENTRAL AND NORTHERN ROCKIES AND
TROUGHING INTO THE GREAT BEND REGION OF TEXAS AND THE SOUTHERN
ROCKIES AND A TROUGH OFF THE WEST COAST. IT CONTINUES TO LOOK PRETTY
QUIET AND WARM FOR A WHILE LONGER. THE TROUGH OFF THE WEST COAST
WILL MOVE EAST INTO THE ROCKIES AND THIS WILL PUSH UP A RIDGE INTO
THE UPPER GREAT LAKES THIS PERIOD.
MAIN FORECAST PROBLEM TONIGHT WILL BE FOG AND HOW MUCH OF IT AND
WHEN IT FORMS. LOOKS GOOD FOR FOG TONIGHT WITH LIGHT WINDS. ONLY
PROBLEM IS NAM WHICH IS MODEL I FOLLOWED IS SHOWING SOME LIGHT
WESTERLY WINDS. LOW LEVEL MOISTURE REMAINS AROUND HERE AS IT DOES
NOT GET SCOURED OUT...SO FOG LOOKS GOOD. WILL GO WITH PATCHY TO
AREAS OF FOG TONIGHT AND FORM A LITTLE EARLIER AS CLOUDS WILL
CONTINUE TO DECREASE AND WILL HAVE LIGHT WINDS. THINK FOG WILL FORM
IN THE EVENING AND WILL CONTINUE THROUGH MID MORNING ANYWAY. DID NOT
MAKE TOO MANY CHANGES TO GOING TEMPERATURES OR TO WEATHER OTHERWISE.
LONG TERM (SAT NIGHT THROUGH NEXT FRI)
/ISSUED AT 343 PM EST/
HIGHER HEIGHTS ASSOCIATED WITH RIDGE OVR THE GREAT LAKES ONLY SLOWLY
FALL INTO SUNDAY AS TROUGH MOVES INTO NORTHERN PLAINS AND CNTRL
CANADA. GFS/NAM/ECMWF TRENDED SLOWER WITH ARRIVAL OF LOW-LEVEL MOIST
ADVECTION...KEEPING MAJORITY OF ANY WARM AIR ADVECTION QPF TO THE
WEST OF UPR MI THROUGH SUN AFTN. PREV FCST WAS IN GOOD SHAPE AND
MADE FEW CHANGES. TRIMMED EAST EXTENT OF POPS SUN NIGHT AS RIBBON OF
HIER H85 DWPNTS AND CONVERGENCE PERSISTS OVR WRN UPR MI INTO WRN LK
SUPERIOR. DUE TO THE MOISTURE ADVECTION...SOUNDINGS ACROSS UPR MI
INDICATE ABUNDANT CLOUD COVER IN THE H9-H8 LAYER...SO TEMPS SHOULD
REMAIN IN THE MID-UPR 30S. PCPN CHANCES ON MONDAY LOOK PRETTY MEAGER
AS UPR LAKES ARE BTWN TROUGH EXITING TOWARD HUDSON BAY AND ANOTHER
TROUGH FORMING OVR THE CENTRAL CONUS. KEPT SKIES MAINLY CLOUDY AS
MOISTURE COULD BECOME TRAPPED BENEATH INVERSION.
OVERALL...UPPER LEVEL PATTERN EARLY NEXT WEEK BEGINS WITH A RIDGE
OVR THE EASTERN CONUS AND A DEVELOPING TROUGH IN THE NW CONUS. TO
START OFF...GFS REMAINS IN OPPOSITION TO UKMET/CANADIAN/ECMWF...AS
WELL AS THE ENSEMBLES FM THE CANADIAN/GEFS/ECMWF. SO...DESPITE THE
GFS CONSISTENTLY SHOWING LEAD SHORTWAVE SWEEPING ACROSS UPR LAKES
TUE AND HEADING INTO NORTHERN NEW ENGLAND AND EASTERN CANADA BY
WED...HAVE DISCOUNTED ITS OUTLIER SOLUTION AS RIDGE OVR THE EASTERN
CONUS SHOULD HOLD FIRM. INSTEAD PREFER SOLUTION SHOWN BY MAJORITY
OF GUIDANCE WITH A CLOSED OFF TROUGH MOVING INTO THE CNTRL PLAINS BY
TUE MORNING...THEN SLOWLY GRINDING INTO THE UPR LAKES WED INTO
THANKSGIVING DAY. IT IS INTERESTING THAT ALTHOUGH THE GFS IS VERY
DIFFERENT FM OTHER GUIDANCE FOR EARLY IN THE WEEK...IT ACTUALLY DOES
COME BACK INTO SOME AGREEMENT BY LATE WEEK AS IT SHOWS GENERAL
TROUGHING/COLDER AIR OVR THE UPR LAKES.
DETAILS...INCLUDING TIMING OF WHEN MORE WIDESPREAD PCPN OCCURS
AND THE ALL IMPORTANT PTYPE QUESTION...REMAIN FAR FROM CERTAIN.
GOING WITH THE PREFERRED ECMWF/CANADIAN IDEA...THE MAJORITY OF
SIGNIFICANT PCPN OCCURS WED INTO WED NIGHT AND PERHAPS EVEN
LINGERING INTO THANKSGIVING. AGAIN...GFS SOLN WOULD BE 18-24 HR
EARLIER THAN THIS. INITIAL PCPN INTO WED WOULD BE MAINLY RAIN
AS THE UPR LOW/SFC LOWS AND SLUG OF WARMER AIR LIFT TOWARD UPR
MICHIGAN. CANADIAN IS EVEN A BIT FARTHER WEST...SUGGESTING MORE
RAIN THAN SNOW. BY WED NIGHT INTO THU...MAJORITY OF PCPN WOULD
TRANSITION TO SNOW AS SFC LOW AND LOW-LEVEL WARM AIR HEADS TO THE
EAST...ALLOWING FOR COLDEST AIRMASS SEEN SO FAR THIS FALL (H85
TEMPS FALLING BLO -10C)...TO SURGE INTO THE UPR LAKES. WILL CONTINUE
TO MENTION THE POTENTIAL OF A MODERATE STRENGTH SYSTEM IN THE
HAZARDOUS WEATHER OUTLOOK AS IT COULD AFFECT THE HOLIDAY TRAVEL
BEFORE THANKSGIVING.
MAIN RESULT FOR THANKSGIVING INTO FRI IS COOLER TEMPERATURES THAN
HAVE BEEN SEEN MOST OF NOVEMBER AND THE CHANCE OF SYNOPTIC SNOW ON
THU TRANSITIONING TO LK EFFECT SNOW SHOWERS LATER THU INTO FRI...
MAINLY IN AREAS FAVORED BY NW FLOW CLOSE TO LK SUPERIOR. BOUT OF
COLDER TEMPS LOOKS BRIEF THOUGH WITH TEMPS BEGINNING TO REBOUND NEXT
WEEKEND AS UPPER LEVEL RIDGING ARRIVES.
AVIATION /FOR THE 00Z TAF ISSUANCE/
QUITE A BIT OF UNCERTAINTY EXISTS IN THE FCST TONIGHT AT KCMX/KSAW.
BOUNDARY LAYER MOISTURE REMAINS HIGH AS IT WAS NOT ABLE TO MIX OUT
DURING THE AFTN...AND THAT BRINGS A POTENTIAL OF RADIATIONAL FOG
DEVELOPMENT TONIGHT UNDER CLEAR SKIES. LIGHT WRLY WINDS ARE
ADVECTING DRIER AIR INTO UPPER MI...BUT WITH SUCH LIGHT FLOW...IT'S
UNCERTAIN IF THE DRYING WILL BE SUFFICIENT TO PREVENT DENSE FOG FROM
DEVELOPING. KCMX PROBABLY HAS THE BEST CHC OF AVOIDING SIGNIFICANT
FOG WITH DRIER AIR IN CLOSER PROXIMITY. DID NOT GO ANY LOWER THAN
MVFR VIS THERE TONIGHT. AT KSAW...FOG SHOULD BE MORE SIGNIFICANT...
BUT WITH LIGHT WRLY WINDS...WHICH IS A DOWNSLOPING DIRECTION...IT IS
UNCERTAIN HOW LOW VIS MAY GO. MAINTAINED PREVIOUS FCST OF LOWERING
VIS TO IFR THIS EVENING...BUT OPTED TO DROP VIS FURTHER TO LIFR LATE
IN THE NIGHT SINCE W WINDS WILL BE SO LIGHT. AFTER ANY MORNING
FOG...VFR CONDITIONS WILL BE THE RULE AT KCMX/KSAW SAT UNDER DEEP
DRY AIRMASS.
MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/
WINDS WILL REMAIN BELOW 25 KNOTS THROUGH THIS FORECAST PERIOD AS
HIGH PRESSURE MOVES IN AND KEEPS SYSTEMS OUT OF THE AREA. WINDS WILL
START TO INCREASE WED AS A STORM SYSTEM COMES UP FROM THE SOUTH.
MQT WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...07
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...07
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