303  
FXUS63 KMQT 292351  
AFDMQT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MARQUETTE MI  
751 PM EDT SAT APR 29 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH SUNDAY)  
ISSUED AT 342 PM EDT SAT APR 29 2017  
 
THE MAIN WEATHER CONCERNS DURING THIS TIME PERIOD WILL BE AN  
APPROACHING LOW PRESSURE SYSTEM FROM THE SOUTHWEST, INTRODUCING A  
CHANCE OF RAIN VERY LATE TONIGHT THROUGH SUNDAY.  
 
TONIGHT: LOW PRESSURE OVER THE SOUTHERN PLAINS IS EXPECTED TO SLOWLY  
LIFT NORTHWARD TOWARD THE UPPER GREAT LAKES REGION THROUGH THIS TIME  
PERIOD. AS THIS HAPPENS, THE SURFACE LOW AND UPPER LEVEL 500MB LOW  
ARE BOTH EXPECTED TO INTENSIFY. THE MAIN IMPACT THAT THIS WILL HAVE  
ON THE U.P. TONIGHT, WILL BE A STEADY INCREASE IN MOISTURE FLOW INTO  
THE AREA. INITIALLY, HIGH CLOUDS WILL BE ON THE INCREASE THIS  
EVENING AND THEN STEADILY INCREASE IN DEPTH THROUGH THE OVERNIGHT  
HOURS. ISENTROPIC UPGLIDE WILL SLOWLY INCREASE ACROSS FAR SOUTH  
CENTRAL PORTIONS OF THE U.P. OVERNIGHT, WHICH MAY GIVE A FEW RAIN  
SHOWERS. THE PRECIPITATION WILL LIKELY HAVE TROUBLE LIFTING TOO FAR  
TO THE NORTH AS DRY HIGH PRESSURE REMAINS IN PLACE OVER SOUTHERN  
HUDSON BAY, HELPING TO CONTINUE PUMPING LOW TO MID LEVEL DRY AIR  
INTO THE AREA. IN FACT, MODELS CONTINUE TO TREND A BIT SLOWER WITH  
THE ONSET OF THE PRECIPITATION.  
 
SUNDAY: THIS SYSTEM WILL CONTINUE NORTHWARD, REACHING SOUTHWEST IOWA  
BY 00Z MONDAY. AGAIN, THE MAIN CONCERN WILL BE THE CONTINUED/STEADY  
INCREASE IN MOISTURE ACROSS THE AREA AS THE HIGH OVER SOUTHERN  
HUDSON BAY CONTINUES TO SHIFT TO THE EAST AND THE LOW SLOWLY  
APPROACHES. A MAJORITY OF THE SYSTEM FORCING WILL REMAIN TO THE  
SOUTH OF THE U.P. THROUGH LATE SUNDAY AFTERNOON; HOWEVER, THE  
ISENTROPIC UPGLIDE WILL CONTINUE TO STEADILY INCREASE THROUGHOUT THE  
DAY. THIS WILL LEAD TO AT LEAST SCATTERED RAIN SHOWERS BUILDING  
ACROSS MAINLY THE SOUTH HALF OF THE AREA, WITH CLOUD COVER  
INCREASING ACROSS THE NORTH HALF. PRECIPITATION TOTALS THROUGH  
SUNDAY AFTERNOON WILL BE BETWEEN A TENTH TO A QUARTER OF AN INCH  
SOUTH HALF WITH A TENTH OR LESS NORTH HALF.  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 342 PM EDT SAT APR 29 2017  
 
THE ACTIVE WX PATTERN THAT HAS DOMINATED MOST OF APR WL CONTINUE  
INTO MAY. MAIN FOCUS FOR EARLY THIS COMING WEEK WL BE THE IMPACT OF  
A SLOW MOVING, NEGATIVELY TILTED CLOSED LO LIFTING NEWD FM THE SRN  
PLAINS INTO THE WRN GREAT LKS ON MON. ALTHOUGH THE BULK OF THE  
HEAVIER PCPN IS LIKELY TO FALL AS RAIN THRU MON IN THE STRONG WAA  
AHEAD OF THE APRCHG LO, THERE COULD BE SOME SN OVER MAINLY THE HIER  
TERRAIN OF THE NW HALF MON NGT INTO TUE AS SOME COLDER LLVL AIR  
ARRIVES IN THE CYC NW FLOW BEHIND THE DEPARTING CLOSED LO. THE UPR  
PATTERN WL THEN CHANGE TO ONE FEATURING A NW FLOW ALF BTWN A BLDG  
RDG IN THE ROCKIES/WRN PLAINS AND LINGERING TROFFING OVER THE E.  
WHILE DISTURBANCES EMBEDDED IN THE NW FLOW ALF COULD BRING SOME  
SHOWERS TO UPR MI LATER THIS COMING WEEK, THE PRIMARY RESULT OF THIS  
PATTERN CHANGE WL BE A DRYING TREND FOR UPR MI.  
 
SUN NGT/MON...THE NEGATIVELY TILTED CLOSED UPR LO IN THE SRN BRANCH  
FLOW IS PROGGED TO MOVE FROM NEAR KANSAS CITY AT 00Z MON TO THE  
MI/WI BORDER BY 00Z TUE. IN GENERAL, THE MODELS HAVE CONTINUED TO  
TREND TOWARD A BIT FARTHER W TRACK FOR THIS FEATURE, NOT SURPRISING  
CONSIDERING THE UPR RDGING PRESENT JUST OFF THE SE CONUS. THE  
ARRIVAL OF A CCB/TROWAL WITH VIGOROUS ISENTROPIC ASCENT BEST SHOWN  
ON THE 300K SFC (H725-8) THAT LIFTS PWAT TO 1-1.25 INCHES UNDER  
DPVA/DIFFLUENT FLOW ALF AHEAD OF THE APRCHG CLOSED LO WL BRING A  
PERIOD OF AT LEAST BRIEFLY HEAVY PCPN TO THE AREA ON SUN NGT.  
ALTHOUGH SOME RECENT MODEL RUNS, ESPECIALLY THE 00Z AND 12Z CNDN  
MODELS, INDICATE THE PCPN COULD BE AT LEAST MIXED WITH SN OVER  
MAINLY THE NW HALF WITH H85 TEMPS AS LO AS -2C TO -4C, THE MODEL  
TREND TOWARD A FARTHER W TRACK AND VIGOROUS WAA SUPPORTS THE WARMER  
SCENARIOS/RAIN AS THE PRIMARY PTYPE BEST ILLUSTRATED BY THE  
CONSISTENTLY WARMER ECMWF AND RECENT GFS RUNS. HOWEVER, AS THE PCPN  
BEGINS ON SUN EVNG, EVAPORATIVE COOLING OF THE LINGERING LLVL DRY  
AIR COULD RESULT IN A MIX WITH SOME SN OVER THE HIER TERRAIN OF THE  
NW CWA. SINCE THE CLOSED LO HAS TRENDED TO MOVE A BIT FARTHER TO THE  
E, THE MORE RECENT MODELS SHOW MORE AGGRESSIVE MID-LVL DRY SLOTTING  
WRAPPING ARND THE APRCHG CLOSED LO ARRIVING FM THE SE EARLIER AND AS  
SOON AS LATE SUN NGT OVER THE SE CWA, RESULTING IN DIMINISHED SHOWER  
INTENSITY INTO MON. SHOWER COVERAGE WILL PROBABLY INCREASE AGAIN ON  
MON AS THE CLOSED LO/DEEP CYC FLOW/BACKWASH MSTR UNDER THE LOWER  
HGTS ARRIVE FM THE SW AND THE DRY SLOT SHIFTS TO THE NE. ALTHOUGH  
DAYTIME MAX TEMPS ON MON WL BE WARM ENUF TO SUPPORT RAIN, THE  
READINGS WL BE COOL FOR LATE APR. SOME COLDER LLVL AIR IN THE NW  
FLOW BEHIND THE PASSING LO PRES COULD ARRIVE OVER THE FAR W NEAR  
IRONWOOD LATE IN THE DAY ON MON TO AT LEAST CAUSE THE PCPN TO MIX  
WITH SN THERE.  
 
MON INTO TUE NGT...ALTHOUGH THE INTENSE DYNAMIC SUPPORT WILL  
DIMINISH AS THE DEEP CLOSED LO EXITS SLOWLY TO THE NE, LINGERING  
SHARP CYC FLOW SHIFTING TO THE NW/PERSISTENT LO-MID LVL MSTR IN ITS  
WAKE WL MAINTAIN AT LEAST HI CHC/LIKELY POPS INTO TUE. THE ARRIVAL  
OF SOME DRIER AIR AND WEAKENING CYC FLOW ON TUE NGT UNDER STEADILY  
RISING HGTS AHEAD OF APRCHG SFC HI PRES WL THEN CAUSE DIMINISHING  
POPS. WITH THE WSHFT TO THE NW AND ARRIVAL OF SOME COLDER AIR, THE  
SHOWERS WILL AT LEAST MIX WITH SOME SNOW, ESPECIALLY OVER THE HIER  
TERRAIN OF THE NW HALF, WHERE THERE COULD BE SOME SN ACCUMS ON MON  
NGT INTO TUE MRNG. TUE MAX TEMPS WL RUN WELL BLO NORMAL.  
 
WED THRU SAT...UPR MI WL BE DOMINATED BY A NW FLOW ALOFT AHEAD OF A  
BLDG UPR RDG IN THE ROCKIES/WRN PLAINS. WHILE DISTURBANCES DIGGING  
INTO THE GREAT LKS UNDER THIS FLOW COULD BRING SOME CLDS AND PERHAPS  
A FEW SHOWERS ESPECIALLY ON THU INTO FRI, OVERALL DRYNESS OF THE  
AIRMASS AND TIMING UNCERTAINTY WL LIMIT FCST POPS. THERE IS SOME  
DISAGREEMENT AMONG THE LONGER RANGE GUIDANCE ON THE AMPLITUDE OF THE  
BLDG RDG AND UPR TROFFING THAT WL PREVAIL TO THE E. THE MODELS THAT  
SHOW A HIER AMPLITUDE FLOW INDICATE COOLER WX WL PERSIST INTO THE  
WEEKEND UNDER A MORE PERSISTENT NNW FLOW ALF. ON THE OTHER HAND, THE  
GUIDANCE FEATURING A LOWER AMPLITUDE/MORE PROGRESSIVE FLOW HINT THE  
UPR RDG WL BUILD INTO THE WRN GREAT LKS TOWARD THE WEEKEND, WHICH  
WOULD RESULT IN DRY/ WARMER WX.  

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)  
ISSUED AT 745 PM EDT SAT APR 29 2017  
 
VFR CONDITIONS WILL PREVAIL INTO LATE SUNDAY AFTERNOON; HOWEVER,  
THERE MAY BE LOWER CLOUDS INTO THE MVFR RANGE THAT TRY TO BUILD INTO  
THE KSAW TAF SITE TOWARD THE VERY END OF THE TAF PERIOD AS A SHIELD  
OF RAIN MOVES NORTHWARD INTO THE AREA.  

 
   
MARINE
 
(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)  
ISSUED AT 342 PM EDT SAT APR 29 2017  
 
HIGH PRESSURE WILL REMAIN IN PLACE ACROSS LAKE SUPERIOR THROUGH  
TONIGHT, KEEPING WINDS LIGHT NORTHEAST IN THE EVENING, TURNING  
EASTERLY OVERNIGHT. WINDS WILL REMAIN AT OR LESS THAN 15 TO 20  
KNOTS. SUNDAY, LOW PRESSURE WILL APPROACH THE UPPER GREAT LAKES FROM  
THE SOUTHWEST ALLOWING THE PRESSURE GRADIENT TO TIGHTEN ONCE AGAIN.  
THIS WILL ALLOW WINDS TO INCREAST TO 20 TO 30 KNOTS OVER MUCH OF  
LAKE SUPERIOR, WITH THE STRONGEST GUSTS EXPECTED OVER THE WEST HALF  
OF THE LAKE DUE TO TERRAIN ENHANCEMENTS ON A FAVORED NORHTEAST WIND.  
AS THE PRES GRADIENT TIGHTENS OVER THE UPPER LAKES ON SUN NIGHT  
AHEAD OF DEEP LO PRES APPROACHING FROM THE SW, NE WINDS WILL  
INCREASE TO GALE FORCE OVER AT LEAST PORTIONS OF THE W AND CENTRAL  
LAKE. EXPECT THE STRONGEST GALES UP TO 40 KTS OVER THE W, WHERE THE  
TERRAIN WILL FUNNEL THE NE FLOW AND FURTHER ENHANCE THE WIND SPEEDS.  
ISSUED GALE WARNINGS FOR THE AREAS TO BE IMPACTED. AS THE PRES  
GRADIENT BEGINS TO WEAKEN ON MON NIGHT INTO TUE BEHIND THE DEPARTING  
LO PRES, WINDS WILL DIMINISH AND BACK TOWARD THE N AHEAD OF  
APPROACHING HI PRES THAT WILL BUILD OVER THE UPPER LAKES ON WED AND  
FURTHER REDUCE WIND SPEEDS UNDER 20 KTS THRU THU.  

 
   
MQT WATCHES/WARNINGS/ADVISORIES
 
 
UPPER MICHIGAN...  
NONE.  
LAKE SUPERIOR...  
GALE WARNING FROM 2 AM TO 2 PM EDT MONDAY FOR LSZ265-266.  
 
GALE WARNING FROM 8 PM EDT /7 PM CDT/ SUNDAY TO 5 PM EDT /4 PM  
CDT/ MONDAY FOR LSZ162.  
 
GALE WARNING FROM 2 AM TO 8 PM EDT MONDAY FOR LSZ263-264.  
 
LAKE MICHIGAN...  
GALE WARNING FROM 2 PM SUNDAY TO 8 AM EDT MONDAY FOR LMZ221-248-  
250.  
 

 
 

 
 
SHORT TERM...KEC  
LONG TERM...KC  
AVIATION...JLB  
MARINE...KEC/KC  
 
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