423  
FXUS63 KMQT 241127  
AFDMQT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MARQUETTE MI  
727 AM EDT MON SEP 24 2018  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 508 AM EDT MON SEP 24 2018  
 
WV IMAGERY AND RAP ANALYSIS INDICATED A SHORTWAVE TROUGH MOVING  
THROUGH THE NORTHERN ROCKIES AND NW PLAINS WITH MID-UPPER LEVEL  
RIDGE DEVELOPING DOWNSTREAM OVER THE GREAT LAKES REGION. BETWEEN  
THESE FEATURES A BAROCLINIC ZONE/FRONTAL BOUNDARY HAS SET UP OVER  
THE PLAINS STATES. ACROSS UPPER MI PLENTY OF LOW CLOUDS PERSIST  
ALONG WITH MID-CLOUD COVER IN ADVANCE OF FRONTAL SYSTEM MOVING IN  
FROM THE PLAINS. UPSLOPE EASTERLY FLOW CONTINUES TO SUPPORT PATCHY  
FOG OVER PORTIONS OF THE KEWEENAW PENINSULA EARLY THIS MORNING.  
 
TODAY, EXPECT ANY REMAINING LOW CLOUDS OR FOG TO GRADUALLY DISSIPATE  
DURING THE LATE MORNING HOURS AS LOW LEVEL MIXING INCREASES, AND SFC-  
850 MB WARM FRONT PUSHES WELL NORTH INTO ONTARIO. SUNSHINE AND WAA  
WITH GUSTY SOUTHERLY WINDS TO AROUND 25 MPH WILL HELP PUSH TEMPS  
INTO THE UPPER 60S TO LOW 70S, ESPECIALLY WEST HALF WHERE DOWNSLOPE  
FLOW PREVAILS NEAR LAKE SUPERIOR. SOUTHERLY WINDS WILL ALSO SUPPORT  
HIGH SWIM RISK THROUGH 18Z FOR SOUTHERN SCHOOLCRAFT COUNTY SO ISSUED  
A BEACH HAZARDS STATEMENT.  
 
TONIGHT, MODELS TRENDING EVEN SLOWER WITH ARRIVAL OF FRONT AND  
ASSOCIATED SHOWERS AS FRONTAL BOUNDARY BECOMES ORIENTED CLOSER TO  
PARALLEL WITH THE SW FLOW ALOFT. SHOWERS NOT EXPECTED TO REACH INTO  
WESTERN COUNTIES UNTIL LATE EVENING/MIDNIGHT AND THEN INTO CENTRAL  
COUNTIES LATE TONIGHT OR TOWARD DAYBREAK. SHOWERS SHOULD BE  
WEAKENING RAPIDLY AS THEY MOVE INTO CENTRAL COUNTIES AS UPPER LEVEL  
SUPPORT WANES ALONG THE FRONT. MODEL SOUNDINGS NOT REALLY SHOWING  
MUCH INSTABILITY TO SUPPORT THUNDER SO TOOK IT OUT OF THE WESTERN  
ZONES. EXPECT LOWS IN THE LOWER 50S WEST TO UPPER 50S SOUTH CENTRAL  
AND EAST.  
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 348 AM EDT MON SEP 24 2018  
 
RIDGING/POSITIVE HEIGHT ANOMALIES THAT EXTENDED FROM THE ALEUTIANS  
TOWARD THE NORTH POLE AT THE MIDDLE OF LAST WEEK HAVE MIGRATED TO  
THE NE PACIFIC. DURING THE WEEK, THIS RIDGE WILL STRENGTHEN WITH A  
HUGE POSITIVE HEIGHT ANOMALY (350+DM AT 500MB) DEVELOPING OVER AK BY  
THE WEEKEND. THIS WILL FORCE DEVELOPMENT OF A DEEP TROF DOWNSTREAM,  
CENTERED OVER CENTRAL CANADA, AND AN ACCOMPANYING BUILD UP OF  
UNSEASONABLY COLD AIR FOR SO EARLY IN THE SEASON IN THAT AREA AS THE  
WEEK PROGRESSES. WITH THE HEIGHT ANOMALY OVER AK CLOSING OFF A MID-  
LEVEL ANTICYCLONE, FLOW WILL TEND TO UNDERCUT IT, AND THIS WILL  
PROBABLY WORK TO PREVENT THE UNSEASONABLY COLD AIR BUILDING TO THE  
NW FROM FULLY DUMPING INTO THE UPPER LAKES LATE THIS WEEK INTO EARLY  
NEXT WEEK. IN THE MEANTIME, TEMPS THIS WEEK ON THE WHOLE WILL END UP  
BLO NORMAL AS THE SOUTHERN EDGE OF BUILDING COLD AIR TO THE N  
BRUSHES THE AREA DUE TO THE PASSAGE OF SEVERAL SHORTWAVES. TODAY  
WILL BE THE WARMEST DAY OF THE WEEK. AS THE TROF DEEPENS ACROSS MUCH  
OF CANADA THIS WEEK, SEVERAL SHORTWAVES WILL SWING AROUND THE TROF  
AND AFFECT THE UPPER LAKES. THE FIRST MON NIGHT/TUE MORNING, A  
SECOND FOLLOWING QUICKLY LATE TUE/EARLY WED, A THIRD LATE THU/THU  
NIGHT, A FOURTH WEAK WAVE ON SAT, AND A FIFTH LATE SUN/EARLY MON.  
EACH WAVE WILL BRING SOME SHRA TO AT LEAST PARTS OF THE FCST AREA.  
FROM A STANDPOINT OF PCPN AMOUNTS, IT APPEARS THE SECOND WAVE WILL  
PROBABLY PRODUCE THE GREATEST RAINFALL, OCCURRING TUE AFTN/EVENING.  
THE SYSTEM EARLY NEXT WEEK WILL LIKELY BE A SIGNIFICANT PCPN  
PRODUCER DUE TO THE STRONG TEMP CONTRAST THAT WILL BE PRESENT AT  
THAT TIME ACROSS THE CONUS/SOUTHERN CANADA. HOWEVER, AT 6-7 DAYS  
OUT, IT'S UNCERTAIN WHERE THE CORRIDOR OF HEAVIEST PCPN WILL OCCUR.  
 
BEGINNING TUE/TUE NIGHT...AT 12Z TUE, COLD FRONT ASSOCIATED WITH THE  
FIRST SHORTWAVE WILL EXTEND ROUGHLY FROM EASTERN LAKE SUPERIOR  
ACROSS CENTRAL UPPER MI AND WILL BE ACCOMPANIED BY ISOLD/SCT -SHRA.  
RAPID APPROACH OF THE SECOND SHORTWAVE INTO THE UPPER MISSISSIPPI  
VALLEY/WESTERN GREAT LAKES BY EVENING WILL BEGIN TO SPIN UP A SFC  
WAVE ALONG THE COLD FRONT WHICH WILL HAVE DRIFTED TO FAR SE UPPER MI  
OR NORTHERN LAKE MI BY THAT TIME. STRENGTHENING BAND OF MID-LEVEL  
FGEN AS WELL AS INCREASING UPPER DIVERGENCE WITHIN RIGHT ENTRANCE OF  
UPPER JET STREAK EXTENDING FROM NW WI TO JAMES BAY WILL SUPPORT  
INCREASING PCPN ON THE COLD SIDE OF THE SFC COLD FRONT DURING THE  
AFTN/EVENING. OVERALL, MODELS OVER THE LAST COUPLE OF DAYS HAVE  
TRENDED A BIT HEAVIER/NW WITH THIS PCPN THAT WILL STREAK ACROSS  
ROUGHLY THE E HALF OF UPPER MI. HOWEVER, THE 00Z ECWMF IS MORE  
VIGOROUS WITH THE SHORTWAVE AND THUS FARTHER NW WITH SFC LOW WHICH  
IT TRACKS ACROSS FAR S CENTRAL AND EASTERN UPPER MI. RESULT IS A MDT  
RAINFALL ACROSS MUCH OF THE FCST AREA WITH 0.5-1 INCH RAINFALL  
AMOUNTS ACROSS A WIDE SWATH OF W AND CENTRAL UPPER MI. GIVEN RECENT  
MODEL TRENDS, FCST INCORPORATED SOME OF THE 00Z ECMWF. WITH A LITTLE  
INSTABILITY AND DECENT FORCING, INCLUDED SLIGHT CHC THUNDER S  
CENTRAL AND SE FCST AREA. THIS BAND OF PCPN WILL QUICKLY EXIT BY  
MIDNIGHT TUE NIGHT. WITH 850MB TEMPS FALLING TO AROUND 0C TUE NIGHT,  
THERE COULD BE SOME LAKE EFFECT -SHRA, BUT RECENT LARGE WAVE ACTION  
ON THE LAKE HAS MIXED/COOLED WATERS WITH THE 3 MID LAKE BUOYS  
SHOWING WATER TEMPS ALREADY DOWN TO 52F, 45F, 45F FROM W TO E. WHILE  
THERE ARE CERTAINLY AREAS OF WARMER WATER, CONDITIONS WILL BE  
MARGINAL FOR ANY LAKE EFFECT -SHRA TO DEVELOP TUE NIGHT.  
 
ALTHOUGH A SUBTLE SHORTWAVE PASSING WED MAY GENERATE ISOLD -SHRA,  
FOR MOST OF THE AREA, DRY WEATHER WILL PREVAIL WED INTO WED NIGHT.  
NEXT MORE SIGNIFICANT SHORTWAVE WILL AMPLIFY TOWARD THE UPPER  
MISSISSIPPI VALLEY/UPPER LAKES ON THU. ASSOCIATED SFC LOW WILL TRACK  
FROM SOUTHERN MANITOBA WED EVENING ACROSS NORTHERN ONTARIO THRU THU.  
AT LEAST SCT -SHRA WILL ACCOMPANY THE COLD FRONT ACROSS THE FCST  
AREA ON THU UNDER DECENT DEEP LAYER FORCING/70-80M HEIGHT FALLS AT  
500MB. BEHIND THE COLD FRONT, CYCLONIC FLOW AND FAIRLY DEEP MOISTURE  
WITH 850MB TEMPS FALLING TO AT LEAST 0C WILL SUPPORT SOME LAKE  
ENHANCED -SHRA FOR W TO NW FLOW FAVORED AREAS THU NIGHT INTO FRI  
MORNING. SOME LAKE EFFECT -SHRA MAY LINGER ON INTO SAT FOR W WIND  
FAVORED LOCATIONS IF CONSENSUS OF 850MB TEMPS OF -4C WORKS OUT.  
 
LATER SUN INTO MON, SHORTWAVE ORIGINATING IN THE FLOW UNDERCUTTING  
THE STRONG MID-LEVEL HIGH OVER AK WILL STREAK ENE ACROSS THE CONUS.  
WHILE THIS WAVE IS NOT PARTICULARLY STRONG AS CURRENTLY DEPICTED IN  
MEDIUM RANGE GUIDANCE DUE TO ITS PROGRESSION THRU A MORE CONFLUENT  
FLOW REGIME, THE STRONG THERMAL CONTRAST ACROSS THE CONUS AND  
SOUTHERN CANADA MAY MAKE THIS A MDT/HVY PCPN PRODUCER AS IT REACHES  
THE GREAT LAKES. TRACK OF THE SFC WAVE IS UNCERTAIN GIVEN THAT WE'RE  
6-7 DAYS OUT IN THE FCST, BUT IT APPEARS UPPER MI WILL BE AFFECTED  
BY AT LEAST SOME OF THE PCPN ASSOCIATED WITH THE WAVE AT SOME POINT  
SUN/MON.  

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 719 AM EDT MON SEP 24 2018  
 
ABUNDANT LOW-LEVEL MOISTURE AND UPSLOPE WINDS WILL SUPPORT IFR/LIFR  
CONDITIONS AT KCMX FOR THE NEXT FEW HOURS BEFORE QUICKLY IMPROVING  
TO VFR LATE MORNING. VFR CONDITIONS WILL CONTINUE AT BOTH IWD AND  
CMX THROUGH LATE EVENING/EARLY OVERNIGHT AND THEN RAIN AND MVFR  
CONDITIONS MOVE IN FOR LATE TONIGHT. MVFR CONDITIONS AT KSAW WILL  
IMPROVE TO VFR BY NOON BEFORE MVFR/IFR CONDITIONS RETURN LATE  
TONIGHT. GUSTY SOUTH WINDS TO 20-25 KNOTS ARE EXPECTED TODAY AT  
ALL SITES.
 
   
MARINE
 
(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)  
ISSUED AT 508 AM EDT MON SEP 24 2018  
 
ANOTHER COLD FRONT APPROACHES FROM THE WEST TODAY, AND THIS WILL  
KEEP SOUTHERLY WINDS MOSTLY IN THE 20-30KT RANGE OVER THE EAST  
HALF. NOT OUT OF THE QUESTION THAT THERE COULD BE SOME GALE FORCE  
GUSTS OVER FAR NORTHERN SECTIONS OF THE LAKE BUT SHOULD BE  
GENERALLY IN CANADIAN WATERS. WITH PASSAGE OF THE COLD FRONT  
TONIGHT/TUE MORNING, WINDS WILL SHIFT TO THE NW AT 15-25KT FOR  
TUE, STRONGEST OVER THE E HALF OF THE LAKE. MAY BE ABLE TO SLIP IN  
A DAY WITH WINDS MOSTLY UNDER 20KT ON WED BEFORE THE NEXT LOW  
PRES SYSTEM MOVING E TOWARD NORTHERN ONTARIO BRINGS STRONGER WINDS  
OF 20-30KT AGAIN ON THU.  

 
   
MQT WATCHES/WARNINGS/ADVISORIES
 
 
UPPER MICHIGAN...  
BEACH HAZARDS STATEMENT UNTIL 2 PM EDT THIS AFTERNOON FOR MIZ014.  
 
LAKE SUPERIOR...  
NONE.  
LAKE MICHIGAN...  
NONE.  

 
 

 
 
SHORT TERM...VOSS  
LONG TERM...ROLFSON  
AVIATION...VOSS  
MARINE...VOSS  
 
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