764  
FXUS63 KMQT 231144  
AFDMQT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MARQUETTE MI  
744 AM EDT WED MAY 23 2018  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 438 AM EDT WED MAY 23 2018  
 
QUIET START TO THE DAY WITH SOME CIRRUS OVER WESTERN UPPER MICHIGAN  
AND SOME STRATUS AND PATCHY FOG ON LK MICHIGAN. TEMPS INLAND OVER  
UPPER MICHIGAN ARE IN THE 40S. TEMPS NEAR LK SUPERIOR ARE STAYING UP  
IN THE 50S, EVEN NEAR 60F AROUND MARQUETTE, DUE TO SOUTHERLY RETURN  
FLOW BETWEEN HIGH PRESSURE OVER SOUTHERN LK MICHIGAN/LOWER MI AND  
WEAK FRONT DROPPING OVER NORTHERN LK SUPERIOR. CLOSEST PRECIP IN THE  
FORM OF T-STORMS IS OCCURRING OVER SOUTHWEST MN INTO NORTHERN IA.  
STORMS ARE FIRING IN AREA OF FOCUSED H85 WARM AIR ADVECTION ON EDGE  
OF ELEVATED MIXED LAYER AND HIGHER MUCAPE. SFC WARM FRONT IS STILL  
SOUTHWEST OF THIS ELEVATED ACTIVITY. ANOTHER AREA OF T-STORMS ARE  
OVER SD CLOSER TO MAIN TROUGH ALOFT AND SHORTWAVES LIFTING ACROSS  
THE NORTHERN PLAINS.  
 
FOR UPPER MICHIGAN TODAY, TEMPS ALOFT LOOK WARMER THAN TUE BY 1-2C  
SO EXPECT HIGHS WELL INTO THE 80S INLAND AND UPPER 60S/NEAR 70F  
ALONG LK SUPERIOR. COOLEST TEMPS TODAY NEAR LK MICHIGAN BUT EVEN  
THERE SHOULD GET MID 60S. COULD BE SOME FOG AFFECTING IMMEDIATE  
SHORE OF LK MICHIGAN EAST SIDE OF GARDEN PENINSULA EASTWARD. LOOKING  
AT ANOTHER DAY OF ELEVATED FIRE WEATHER CONCERNS WITH MIN RH DIPPING  
TO AROUND 20 PCT INLAND. WINDS GUSTING TO 10-15 MPH ALONG LAKE  
BREEZES THIS AFTN LOOK TOO LIGHT TO JUSTIFY ANY KIND OF SPECIAL  
WEATHER STATEMENT. THIS SHOULD BE THE LAST DAY UNTIL NEXT WEEK OF  
SEEING PERSISTENT LOW RH BLO 25 PCT.  
 
SIGNS OF THIS CHANGE TO A MORE WARM, HUMID SUMMERLIKE PATTERN BEGIN  
TO SHOW UP TONIGHT, THOUGH AS IT ALWAYS SEEMS, MODEL FORCASTS OF  
CONVECTION SHOW LITTLE AGREEMENT, EVEN LESS THAN 24 HOURS OUT. ALOFT  
TONIGHT WE ARE IN REGION OF BUILDING HEIGHTS AS MAIN TROUGH ALOFT IS  
STILL WELL TO THE WEST OVER THE ROCKIES AND JUST BEGINNING TO AFFECT  
THE NORTHERN PLAINS, BUT THERE SHOULD BE SIGNIFICANT WARM AND MOIST  
ADVECTION ONGOING IN LOW LEVELS AHEAD OF STRENGTHENING PLAINS SFC-  
H85 TROUGH. SIMILAR TO WHAT IS OCCURRING THIS MORNING TO THE  
SOUTHWEST OVER IA AND MN, EXPECT SHRA/T-STORMS TO DEVELOP ON NOSE OF  
LOW-LEVEL JET/MOISTURE TRANSPORT AND ON EDGE OF RESERVOIR OF  
ELEVATED INSTABILITY WITH 1-6KM MUCAPES OF AT LEAST 1000 J/KG  
FORECAST. DIFFERENCES IN THE MODELS TIE INTO HOW FAR EAST THIS  
MOISTURE/INSTABILITY GRADIENT REACH. NAM SEEMS TOO AGGRESSIVE WITH  
ITS LOW-LEVEL JET AND IN ITS RESULTING CLUSTER OF ELEVATED T-STORMS  
OVER MUCH OF THE WEST HALF OF UPPER MICHIGAN BY 12Z THU. INSTEAD  
LIKE THE GEM/ECMWF IDEA OF SHOWING SIMILAR IDEA TO NAM BUT JUST  
SHIFTED MORE OVER MAINLY MN INTO FAR WESTERN LK SUPERIOR. GFS SEEMS  
TOO MUTED WITH OVERALL DEVELOPING OF SHRA/T-STORMS GIVEN INSTABILITY  
THAT IS BUILDING OVER THE PLAINS CURRENTLY. AS ALWAYS WILL HAVE TO  
WATCH FOR CONVECTIVELY INDUCED SHORTWAVES THAT COULD TRIGGER  
ACTIVITY AS FAR EAST AS NAM INDICATE, BUT FOR NOW WILL BRING LOW  
CHANCE POPS INTO WESTERN UPPER MICHIGAN LATE TONIGHT. EFFECTIVE  
SHEAR LATE TONIGHT IS WEAK UNDER 15 KTS, SO MAYBE LOOKING AT SMALL  
HAIL AS UPDRAFTS WILL NOT BE ABLE TO PERSIST TOO LONG.  
 
LOW TEMPERATURES TONIGHT WILL BE IN THE 40S TO 50S, BUT GIVEN THE  
WARMTH ALREADY SEEN THIS MORNING, FORECAST LOWS IN THE LOW TO MID  
50S ALONG LK SUPERIOR MAY END UP BEING TOO COOL SINCE THE PRESSURE  
PATTERN IS PRETTY SIMILAR WITH EVEN A STRONGER SOUTH WIND.  
   
LONG TERM
 
(THURSDAY THROUGH TUESDAY)  
ISSUED AT 459 AM EDT WED MAY 23 2018  
 
MEAN WESTERN CANADA RIDGE/EASTERN CANADA TROF THAT HAS DOMINATED FOR  
SOME TIME WILL PROGRESS DOWNSTREAM AND BREAKDOWN OVER THE NEXT  
SEVERAL DAYS AS MEAN TROFFING TENDS TO BECOME ESTABLISHED FROM THE  
GULF OF AK INTO WESTERN CANADA/PACIFIC NW. THIS WILL SUPPORT A  
CHANGE IN THE WEATHER FOR THE UPPER GREAT LAKES LATE WEEK THRU THE  
MEMORIAL DAY HOLIDAY WEEKEND. UNDERNEATH THE CURRENT WESTERN CANADA  
RIDGE, A SOUTHERN STREAM TROF IS OVER THE WESTERN CONUS. WITH THE  
FLOW TO THE N IN CANADA BECOMING PROGRESSIVE AND ANOTHER SHORTWAVE  
TROF MOVING OFF THE N PACIFIC TOWARD THE SW CONUS, THE CURRENT  
WESTERN CONUS TROF WILL GET KICKED NE THEN EASTWARD ALONG THE  
U.S./CANADA BORDER REGION, BRINGING AN UNSETTLED PERIOD OF WEATHER  
TO UPPER MI LATE WEEK THRU THE WEEKEND. WITH LARGE PORTIONS OF WEST  
AND CENTRAL UPPER MI ONLY RECEIVING LESS THAN 25PCT OF NORMAL  
RAINFALL OVER THE LAST 30 DAYS, WIDESPREAD DECENT RAINFALL IS  
NEEDED. THAT PROBABLY WON'T HAPPEN, BUT AT LEAST THE POTENTIAL IS  
THERE FOR SOME AREAS TO RECEIVE MUCH NEEDED RAINFALL WITH SCT  
SHOWERS AND THUNDERSTORMS THU THRU SUN, AN UNFORTUNATE SETUP FOR  
THOSE PLANNING OUTDOOR ACTIVITIES DURING THE HOLIDAY WEEKEND AFTER  
HAVING WEEKS OF MOSTLY DRY WEATHER PREVAILING. WITH SHORTWAVE  
SLIPPING E OF THE AREA SUN, DRY WEATHER SHOULD RETURN FOR MEMORIAL  
DAY. THE SHORTWAVE TROF THAT KICKS THE CURRENT TROF OUT OF THE  
WESTERN CONUS TO THE UPPER LAKES WILL ESTABLISH A NEW WESTERN CONUS  
TROF THIS WEEKEND. WITH THE AFOREMENTIONED TROFFING SETTING UP OFF  
THE GULF OF AK INTO WESTERN N AMERICA NEXT WEEK, THIS WESTERN CONUS  
TROF SHOULD EVENTUALLY GET FORCED NE LIKE ITS PREDECESSOR, PROVIDING  
UPPER MI WITH ANOTHER OPPORTUNITY OF SHRA/TSRA AT SOME POINT DURING  
THE LAST HALF OF NEXT WEEK. AS FOR TEMPS, WITH THE DEPARTURE OF THE  
EASTERN CANADA TROF, THE MECHANISM FOR SENDING COOLER AIR INTO THE  
UPPER LAKES WILL BE GONE. OVERALL, THE UPCOMING 7-10 DAY PERIOD  
LOOKS SOLIDLY ABOVE NORMAL, THOUGH THE TYPICAL COOLER BY THE LAKE  
WILL OCCUR FREQUENTLY. MANY DAYS WILL SEE MORE SUMMERLIKE DWPTS  
READINGS AS WELL.  
 
BEGINNING THU, SW FLOW WILL BRING 850MB THETA-E ADVECTION ACROSS THE  
FCST AREA. THE SHARP 850MB INSTABILITY GRADIENT NOTED WITHIN THE  
THETA-E ADVECTION REGIME SHOULD BE A KEY LOCATION FOR ELEVATED  
CONVECTION POTENTIAL THRU THE MORNING, AND CHC POPS WILL FOLLOW  
ALONG IN THIS GRADIENT ZONE. WHILE 1000-1500/KG OF CAPE IS AVBL FOR  
THE POTENTIAL ELEVATED STORMS, EFFECTIVE DEEP LAYER SHEAR IS BLO  
25KT. SO, NOT EXPECTING ANY SVR STORMS. STRONGER STORMS MAY PRODUCE  
SOME SMALL HAIL. WHETHER ANY SFC BASED STORMS MANAGE TO DEVELOP IN  
THE AFTN REMAINS TO BE SEEN. IF SOME MORNING STORMS DO OCCUR, ANY  
BOUNDARY GENERATED BY THAT CONVECTION COULD PROVIDE A FOCUSING FOR  
POSSIBLE REDEVELOPMENT. OTHERWISE, THERE'S NOT MUCH TO GENERATE  
CONVECTION. AWAY FROM SOUTHERLY FLOW OFF LAKE MI, TEMPS WILL RISE  
INTO THE 80S. WITH DWPTS RISING THRU THE 50S, IT WILL BEGIN TO FEEL  
MUCH MORE SUMMERLIKE.  
 
WITH 850MB FLOW ORIENTED MORE ANTICYCLONICALLY THU NIGHT AND WITH  
THE 850MB INSTABILITY GRADIENT SHIFTED N AND NE OF THE AREA, NOT  
CONVINCED THERE WILL BE MUCH CONVECTION AROUND. ONLY SCHC/LOW CHC  
POPS WERE UTILIZED. CERTAINLY COULD END UP BEING A DRY NIGHT ACROSS  
THE BOARD. WILL BE A WARM NIGHT W AND N CENTRAL WITH MINS ABOVE 60F.  
WILL BE COOLER TOWARD LAKE MI, PROBABLY 40S LAKESIDE E OF THE GARDEN  
PENINSULA.  
 
SHORTWAVE SWINGING ACROSS THE AREA ON FRI WILL PROVIDE THE FORCING  
FOR SCT SHRA/TSRA DEVELOPMENT. MLCAPES INCREASE TO 1000-1500J/KG,  
BUT WITH DEEP LAYER SHEAR AOB 25KT, WELL-ORGANIZED SVR CONVECTION IS  
NOT EXPECTED. IF ANY SVR STORMS MANAGE TO DEVELOP, THEY WOULD BE  
OVER THE WESTERN FCST AREA AND SHORT-LIVED/ISOLATED. WILL BE A VERY  
WARM DAY WITH HIGHS WELL INTO THE 80S AWAY FROM SOUTHERLY FLOW OFF  
LAKE MI.  
 
ANOTHER SHORTWAVE WILL MOVE ACROSS THE AREA ON SAT, AND MLCAPE WILL  
PROBABLY END UP SIMILAR TO FRI IN THE 1000-1500J/KG. THERE ARE HINTS  
THAT DEEP LAYER SHEAR MAY BE UP AROUND 30KT, THOUGH MODELS DON'T  
AGREE ON THAT ASPECT. IF SO, THERE WOULD BE A SLIGHTLY BETTER CHC OF  
ISOLD SVR STORMS SAT AFTN.  
 
WHETHER ANY SHRA/TSRA LINGER INTO SUN WILL DEPEND ON PROGRESS OF  
COLD FRONT THRU THE UPPER LAKES. THE DRIER ECMWF SCENARIO IS  
PROBABLY MORE LIKELY WITH EARLIER FROPA, BUT UNTIL THERE IS BETTER  
MODEL AGREEMENT, WILL LINGER CHC/SCHC POPS ON SUN.  
 
BUILDING MID-LEVEL RIDGE INTO THE UPPER MISSISSIPPI VALLEY/WESTERN  
GREAT LAKES SHOULD SUPPORT DRY WEATHER FOR MEMORIAL DAY AND TUE.  
WITH ASSOCIATED SFC HIGH PRES SETTING UP OVER THE AREA, LAKE BREEZES  
WILL PROVIDE COOLING NEAR THE GREAT LAKES WHILE INTERIOR LOCATIONS  
STILL RISE ABOVE 80F.  
 
SOME SHRA MAY ARRIVE WED, DEPENDING ON TIMING OF THE TROF LIFTING  
OUT OF THE WESTERN CONUS AS DISCUSSED ABOVE.  

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)  
ISSUED AT 743 AM EDT WED MAY 23 2018  
 
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL TAF SITES THROUGH THE  
FORECAST PERIOD. JUST A SMALL CHANCE IWD WILL SEE ISOLD SHOWERS  
AND T-STORMS AROUND DAYBREAK ON THU. WENT WITH VCSH FOR NOW. WILL  
SEE LAKE BREEZES DEVELOP AT ALL SITES THIS AFTERNOON BUT WINDS  
SHOULD REMAIN LIGHT AT 10 KTS OR LESS.  
 

 
   
MARINE
 
(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)  
ISSUED AT 438 AM EDT WED MAY 23 2018  
 
WINDS ARE EXPECTED TO STAY BELOW 20 KNOTS THROUGH THE ENTIRE  
FORECAST PERIOD. EXPECT AREAS OF FOG TO DEVELOP LATE THIS WEEK INTO  
THE WEEKEND AS SOME RAINFALL OCCURS OVER THE LAKE AND A HUMID AIR  
MASS ARRIVES OVER THE AREA. COULD BE LOOKING AT DENSE FOG AT  
TIMES.  

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

 
 

 
 
SHORT TERM...JLA  
LONG TERM...ROLFSON  
AVIATION...JLA  
MARINE...JLA  
 
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