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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