667  
FXUS63 KMQT 170334  
AFDMQT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MARQUETTE MI  
1034 PM EST SAT DEC 16 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH SUNDAY)  
ISSUED AT 413 PM EST SAT DEC 16 2017  
 
WV IMAGERY AND RAP ANALYSIS INDICATED CONFLUENT WNW MID/UPPER LEVEL  
FLOW THROUGH NRN ONTARIO AND THE NRN GREAT LAKES. LIGHT ERLY FLOW  
PREVAILED BETWEEN HIGH PSRESSURE OVER NRN ONTARIO AND A TROUGH AND  
FRONT FROM THE CNTRL PLAINS THROUGH THE SRN GREAT LAKES. VIS LOOP  
SHOWED A SMALL CLEAR AREA OVER CNTRL UPPER MICHIGAN BUT WITH LOW/MID  
CLOUDS MOVING IN FROM THE WEST WITH INCREASING 280K ISENTROPIC LIFT.  
 
TONIGHT, LINGERING EAST FLOW OFF OF LAKE MICHIGAN WITH 850 MB TEMPS  
AROUND -8C MAY SUPPORT SOME LIGHT LAKE EFFECT PCPN. WITH MARGINAL  
MOISTURE TO -10C FOR ICE NUCLEI, FREEZING DRIZZLE WILL ALSO BE  
POSSIBLE FROM NEAR MNM TO ESC. OTHERWISE, VEERING WINDS TO SRLY OVER  
LAKE SUPERIOR WILL KEEP ANY PCPN OFF SHORE. FAVORABLE RADIATIONAL  
COOLING OVER THE EAST SHOULD ALLOW TEMPS TO DROP NEAR ZERO.  
OTHERWISE, CLOUDS WILL KEEP TEMPS MAINLY IN THE 10 TO 15 RANGE.  
 
SUNDAY, THERE MAY BE SOME LINGERING LIGHT PCPN EAST NEAR LAKE  
MICHIGAN. PCPN ASSOCIATED WITH A SHORTWAV TROUGH MOVING THROUGH NRN  
ONTARIO, WILL REMAIN NORTH OF THE CWA. EVEN WITH CONSIDERABLE  
CLOUDS, WAA WILL PUSH TEMPS INTO THE MID 20 TO AROUND 30.  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 337 PM EST SAT DEC 16 2017  
 
MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON: A BROAD TROUGH SWEEPING  
ACROSS SOUTHERN CANADA WILL BRUSH THE CWA MONDAY NIGHT INTO TUESDAY.  
SOME LIGHT SNOW SHOWERS WILL ACCOMPANY THIS TROUGH ACROSS MAINLY THE  
NORTHERN CWA LATE MONDAY EVENING INTO EARLY TUESDAY MORNING. COLDER  
AIR ALOFT THAT WOULD BE SUFFICIENT FOR LES WILL LAG THE MAIN TROUGH  
AXIS, SO MORE PROMINENT LES WILL HOLD OFF UNTIL A SECONDARY SURFACE  
TROUGH CROSSES THE WEST TUESDAY AFTERNOON AND THE EAST TUESDAY  
EVENING. THOUGH LES WILL BE GENERALLY WEAK EARLY TUESDAY, GUSTY  
W/WNW WINDS TO 45MPH ACROSS MAINLY THE KEWEENAW PENINSULA COMBINED  
WITH A LOOSE SNOWPACK MAY CREATE INTERMITTENT WHITEOUT CONDITIONS  
TUESDAY INTO TUESDAY EVENING. THE SAME WILL LIKELY HOLD TRUE NEAR  
LAKE SUPERIOR EAST OF MUNISING TUESDAY AFTERNOON AND EVENING. A  
PERIOD OF MODERATE LAKE EFFECT SNOW FOR THE W TO NW WIND SNOW BELTS  
IS THEN EXPECTED TUESDAY NIGHT BEFORE DIMINISHING FROM WEST TO EAST  
ON WEDNESDAY.  
 
WEDNESDAY NIGHT THROUGH SATURDAY: THOUGH THERE REMAINS A LOT OF  
UNCERTAINTY IN THE FORECAST DURING THE SECOND HALF OF THE WEEK, THE  
MAIN MESSAGE IS THAT MORE ACTIVE WEATHER WITH ACCUMULATING SNOW WILL  
AFFECT AT LEAST PORTIONS OF THE WESTERN GREAT LAKES WEDNESDAY NIGHT  
THROUGH FRIDAY.  
 
A POTENT MID-LEVEL TROUGH MOVING ONTO THE NW CONUS TUESDAY NIGHT  
WILL BECOME STRETCHED ACROSS THE CENTRAL CONUS BY THURSDAY  
AFTERNOON. THE EXTREME POSITIVE TILT WITH THE NORTHERN PORTIONS OF  
THIS TROUGH COMPLICATE THE FORECAST ACROSS THE UPPER GREAT LAKES BY  
WEDNESDAY NIGHT. SOMEWHAT DISORGANIZED LEE CYCLOGENESIS IN THE  
PLAINS WILL SPREAD A SHIELD OF WAA PRECIP ACROSS THE REGION  
WEDNESDAY EVENING INTO THURSDAY. GUIDANCE HAS BEEN QUITE  
INCONSISTENT ON THE PLACEMENT OF THE GENERALLY NARROW SWATH OF  
PRECIP, WITH THE GFS SWITCHING FROM THE NORTHERN-MOST SOLUTION  
YESTERDAY TO A MUCH MORE OPEN SOUTHERN TRACK WITH TODAY'S 12Z  
GUIDANCE. THE GEFS AND OTHER LONG-RANGE GUIDANCE ONLY INCREASE  
UNCERTAINTY WITH A WIDE DISTRIBUTION OF SOLUTIONS. WITH THAT SAID,  
THERE IS A RELATIVELY HIGH CHANCE OF AT LEAST SOME ACCUMULATING SNOW  
ACROSS THE CWA WITH THIS SYSTEM WEDNESDAY NIGHT INTO THURSDAY.  
 
BY FRIDAY AND SATURDAY, MODEL DISAGREEMENTS GROW SUBSTANTIALLY, WITH  
SOME SOLUTIONS SUGGESTING CHANCES OF AN ORGANIZED SYSTEM BRINGING  
ACCUMULATING SNOW ACROSS THE REGION AS THE UPPER TROUGH RECEIVES A  
RE-ENFORCING SHOT OF ENERGY FROM THE NORTH. AGAIN, WITH SIGNIFICANT  
UNCERTAINTY THIS FAR OUT, THOSE WITH HOLIDAY TRAVEL PLANS SHOULD  
CONTINUE TO MONITOR FORECAST UPDATES.  

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)  
ISSUED AT 1034 PM EST SAT DEC 16 2017  
 
MVFR CONDITIONS WILL CONTINUE FOR MOST OF THIS FORECAST PERIOD AT  
ALL SITES AS SRLY LOW LEVEL FLOW AS INCREASING MOISTURE ADVECTION  
DEVELOPS.  

 
   
MARINE
 
(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)  
ISSUED AT 413 PM EST SAT DEC 16 2017  
 
SOUTHWESTERLY WINDS WILL INCREASE LATE MONDAY TO 20 TO 30 KNOTS  
BEFORE VEERING TO NORTHWESTERLY GALES TO 35-45 KNOTS LATE MON NIGHT  
THROUGH TUE NIGHT. WITH INCREASING WAVE HEIGHTS, FREEZING SPRAY IS  
POSSIBLE TUESDAY NIGHT INTO WEDNESDAY.  

 
   
MQT WATCHES/WARNINGS/ADVISORIES
 
 
UPPER MICHIGAN...  
NONE.  
LAKE SUPERIOR...  
NONE.  
LAKE MICHIGAN...  
NONE.  

 
 

 
 
SHORT TERM...JLB  
LONG TERM...KLUBER  
AVIATION...07  
MARINE...JLB  
 
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