Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 031743
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
143 PM EDT WED JUN 3 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 444 AM EDT WED JUN 3 2015

THE HIGH PRESSURE RIDGE THAT HAS BEEN LEADING TO SUNNY SKIES OVER
THE LAST FEW DAYS IS SLIDING TO THE EAST THROUGH THE CENTRAL GREAT
LAKES REGION. THIS WILL LEAD TO TODAY BEING THE TRANSITION DAY FROM
THE DRY CONDITIONS TO THE MORE UNSETTLED WEATHER THAT WILL CONTINUE
INTO FRIDAY MORNING. WATER VAPOR IMAGERY LOOP SHOWS THE SHORTWAVE
THAT MOVED THROUGH THE DAKOTAS ON TUESDAY AND LED TO THE DEVELOPMENT
OF THE SHOWERS AND THUNDERSTORMS IS NOW MOVING EAST-NORTHEAST
THROUGH NORTHERN MINNESOTA AND ALONG AND JUST EAST OF A SURFACE
TROUGH STRETCHING FROM A LOW IN EASTERN COLORADO TO HUDSON BAY. THAT
CONVECTION HAS BEEN NEARING WESTERN LAKE SUPERIOR OVER THE LAST HOUR
AND SHOULD SEE AT LEAST SHOWERS CONTINUING EAST OVER THE NORTHWEST
PART OF THE LAKE EARLY THIS MORNING. THESE SHOWERS/THUNDERSTORMS ARE
TIED TO THE SHORTWAVE AND THE NOSE OF THE 850MB WARM AIR
ADVECTION...WITH THE NOSE OF THE 500 J/KG OF MUCAPE MAINLY OVER
NORTHERN MINNESOTA. THE INSTABILITY DROPS OFF FAIRLY QUICKLY TO THE
EAST AND EXPECT THE THUNDER POTENTIAL TO DIMINISH QUICKLY TO THE
EAST TOO...ALTHOUGH THE MID LEVEL LAPSE RATES HAVE BEEN NOSING UP
TOWARDS 6.5-7C/KM OVER THE FAR WESTERN U.P.. MEANWHILE...FARTHER TO
THE SOUTHWEST...AND MCS IS DROPPING SOUTHEAST ACROSS CENTRAL
NEBRASKA AND APPEARS TO BE WEAKENING OVER TH LAST HOUR. BACK TO
UPPER MICHIGAN...PARTS OF THE AREA ARE SEEING SOME MID/HIGH CLOUDS
STREAMING EAST-NORTHEAST AHEAD OF THE MN SHOWERS. WITH A TIGHTENING
PRESSURE GRADIENT BETWEEN THE DEPARTING HIGH AND THE SURFACE TROUGH
TO THE NORTHWEST...THE SOUTHERLY WINDS HAVE KEPT UP THROUGH THE
NIGHT AND HAS AIDED TEMPERATURES IN THE WESTERN U.P. REMAINING IN
THE 50S AND EVEN SOME LOWER 60S AT 4AM. OVER THE EASTERN U.P. WHERE
THE HIGH HAS A GREATER INFLUENCE...LIGHTER WINDS HAVE ALLOWED
TEMPERATURES TO FALL INTO THE LOWER 40S AND EVEN A COUPLE UPPER 30S.
BELOW THE HIGH CLOUDS...LOW LEVEL DRY AIR STILL IN PLACE WITH THE
00Z KGRB SOUNDING SHOWING A PWAT VALUE OF 0.39IN WHILE THE 00Z KMPX
SOUNDING SHOWS THE INCREASING MOISTURE THAT THE AREA WILL SEE OVER
THE NEXT 24HRS (PWAT OF 0.96IN).

THE FORECAST FOR THE SHORT TERM IS TRICKY...AS IT LARGELY DEPENDS ON
SUBTLE WAVES LIFTING OUT OF THE WESTERN CONUS TROUGH AND UPSTREAM
CONVECTION ALONG THE SURFACE TROUGH. ALTHOUGH THE FINER DETAILS ARE
MUDDLED BY THE POTENTIAL UPSTREAM CONVECTION...THE GENERAL IDEA OF
SOME SHOWERS AND MAYBE THUNDERSTORMS AFFECTING THE WESTERN U.P.
LATER TODAY AND INTO TONIGHT SEEMS REASONABLE AS THE SURFACE TROUGH
SLOWLY DROPS ACROSS THE AREA. THE SHOWERS/THUNDERSTORMS IN NORTHERN
MINNESOTA ARE EXPECTED TO SLOWLY WEAKEN AND DIMINISH THROUGH THE
MORNING HOURS AS THE 850MB WARM AIR ADVECTION WEAKENS WHILE SHIFTING
EAST INTO THE UPPER GREAT LAKES REGION. HAVE CONTINUED TO SHOW SOME
SLIGHT/CHANCE POPS OVER NORTHWEST LAKE SUPERIOR AND EDGING INTO THE
WESTERN U.P. THROUGH THE DAY. EXPECT THE REST OF THE AREA TO SEE
INCREASING CLOUDS THROUGH THE DAY...AS THE LOW LEVEL DRY AIR HOLDS
OFF THE PRECIPITATION. WITH SOME FILTERED SUNSHINE...SHOULD SEE
ANOTHER DAY WITH NORMAL TO ABOVE NORMAL HIGHS AND HAVE VALUES IN THE
70S FOR ALL BUT THE IMMEDIATE LAKE MICHIGAN SHORELINE. IT WILL GET A
LITTLE GUSTY OVER THE EAST TODAY...WITH A DEEPER MIXING. HAVE GUSTS
TO 20KTS MAINLY FROM KSAW/KIMT EASTWARD AND COULD EVEN SEE SOME
OCCASIONAL HIGHER GUSTS TOWARDS KP53/KERY.

FOR LATER THIS AFTERNOON AND INTO TONIGHT...A LOT OF THE FORECAST
DEPENDS ON THE CONVECTION UPSTREAM IN CENTRAL/SOUTHERN MINNESOTA AND
HOW THAT EVOLVES AS THE SURFACE TROUGH DROPS ACROSS THE AREA.
UNFORTUNATELY WITH THE LIMITED FORCING AND VARYING SOLUTIONS ON WEAK
SHORTWAVES PULLING OUT OF THE WESTERN TROUGH...LEADS TO LOW
CONFIDENCE ON THE SECOND HALF OF THE SHORT TERM FORECAST. WILL
FOLLOW THE IDEA THAT THE LOW LEVEL SOUTHWESTERLY FLOW AND THE
SURFACE TROUGH DROPPING ACROSS THE AREA WILL LEAD TO SCATTERED
SHOWERS MOVING THROUGH THE AREA TONIGHT. HAVE THE HIGHEST POPS OVER
THE WESTERN HALF OF THE CWA...CLOSER TO THE TROUGH AXIS. WITH THE
NOSE OF THE MUCAPE VALUES OVER 250 J/KG MOVING INTO THE WESTERN U.P.
WILL HAVE THE HIGHEST THUNDER CHANCES IN THAT AREA AND THEN DIMINISH
THEM NORTH AND EAST. WITH LIMITED INSTABILITY AND SHEAR...WOULD NOT
EXPECT ANY SEVERE THUNDERSTORMS...BUT IF THEY CAN MOVE INTO THE
WESTERN U.P. ALONG THE WISCONSIN BORDER...COULD SEE SOME BRIEF HEAVY
RAIN.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 515 AM EDT WED JUN 3 2015

DURING THE LONG TERM...THERE WILL BE 2 PERIODS OF TROF AMPLIFICATION
INTO THE GREAT LAKES/NE CONUS AND ERN CANADA. THE FIRST WILL AFFECT
THE UPPER LAKES THU. THE SECOND WILL BE A BIT MORE AMPLIFIED AND
SLOWER MOVING THANKS TO A STRONGER POSITIVE HEIGHT ANOMALY
TEMPORARILY DEVELOPING IN SW CANADA. THIS SECOND TROF WILL AFFECT
THE UPPER LAKES LATE WEEKEND THRU THE FIRST HALF OF NEXT WEEK.
OVERALL...THESE CHANGES WILL PROBABLY RESULT IN TEMPS NOT STRAYING
TOO FAR FROM NORMAL...THOUGH THERE SHOULD BE A TENDENCY FOR TEMPS TO
BE ON THE COOLER SIDE OF NORMAL ON MOST DAYS. AS FOR PCPN...THE 2
PERIODS OF TROF AMPLIFICATION INTO THE UPPER LAKES WILL BRING THE
POTENTIAL OF SHRA (TODAY THRU THU NIGHT AND THEN DURING THE LAST
HALF OF THIS WEEKEND). PCPN CHANCES DURING THE FIRST HALF OF NEXT
WEEK WILL DEPEND ON THE DEGREE OF TROF AMPLIFICATION AND WHETHER
SHORTWAVES WILL BE DIVING SE THRU THE AREA. WARM SEASON NW FLOW IS
NOTORIOUS FOR GENERATING ISOLD TO SCT CONVECTION WITH EVEN THE
SUBTLEST OF SHORTWAVES.

BEGINNING THU...SFC COLD FRONT WILL BE SETTLING S ACROSS UPPER MI AS
A SHORTWAVE TRACKS ALONG VCNTY OF MN/ONTARIO BORDER TOWARD FAR NRN
LAKE SUPERIOR. ADDITIONAL SHORTWAVE ENERGY WILL BE TRACKING ACROSS
SRN MN/WI. GEM CONVECTIVELY SPINS UP A WAVE...AND THIS RESULTS IN
SOMEWHAT STRONGER SRLY FLOW OVERTOP THE SOUTHWARD MOVING COLD FRONT
OVER UPPER MI. THIS IN TURN PRODUCES A MORE SIGNIFICANT POST FRONTAL
RAINFALL BAND OVER WRN AND NRN UPPER MI THU. SEEMS LIKE A LOW
PROBABILITY. IN ANY EVENT...THE POTENTIAL FOR AT LEAST SOME
INSTABILITY BUILD UP ALONG/AHEAD OF FRONT SUGGESTS SCT SHRA/TSRA
(CHC POPS) FOR THU. UPPER MI WILL BE ON THE SRN EDGE OF A BAND OF
STRONGER DEEP LAYER SHEAR...SO IF CLOUDS BREAK ENOUGH TO ALLOW A
MORE SIGNIFICANT INCREASE IN INSTABILITY THAN CURRENTLY EXPECTED...
THERE COULD BE SOME STRONGER STORMS...PERHAPS ISOLD SVR.

AS SFC HIGH PRES BUILDS ACROSS NRN ONTARIO THU NIGHT/FRI...COLD
FRONT SHOULD SETTLE FAR ENOUGH S BY FRI TO ALLOW FOR A DRY DAY AFTER
LINGERING SHRA DIMINISH THU NIGHT. HOWEVER...WITH FCST SOUNDINGS
INDICATING SATURATED LOW-LEVELS THU NIGHT/FRI MORNING...UPSLOPE -DZ
COULD BECOME AN ISSUE UNDER N TO NE FLOW OFF LAKE SUPERIOR. MAY HAVE
SOME FOG TO DEAL WITH AS WELL...ESPECIALLY IF FOG BECOMES WIDESPREAD
OVER LAKE SUPERIOR OVER THE NEXT 24-36HRS. WILL BE QUITE A BIT
COOLER ALONG LAKE SUPERIOR FRI WITH N TO NE WINDS OFF THE LAKE.

LOOKS LIKE DRY WEATHER SHOULD BE THE RULE FOR FRI NIGHT INTO SAT AS
SFC HIGH PRES DRIFTS SE THRU ONTARIO.

BUILDING RIDGE/POSITIVE HEIGHT ANOMALY IN SW CANADA WILL BEGIN TO
FORCE INCREASED TROFFING DOWNSTREAM INTO THE GREAT LAKES FOR
SUN/MON. THE ECMWF IS FASTER BRINGING THE LEAD SHORTWAVE ENERGY INTO
THE AREA THAN THE GFS. ECMWF THEN GOES ON TO BECOME STRONGER WITH
THIS WAVE AS WELL...CLOSING OFF A MID LEVEL LOW OVER NE LAKE
SUPERIOR SUN NIGHT...BUT THE 00Z RUN HAS BACKED OFF JUST A BIT ON
THIS STRONGER SOLUTION. AS A RESULT...THE ECMWF BRINGS PCPN INTO THE
AREA SAT AFTN WITH A GOOD SOAKING RAINFALL SAT NIGHT/SUN AS IT
TRACKS SFC LOW PRES ACROSS WI AND INTO NRN LWR MI. WHETHER OR NOT
THE STRONGER SOLUTION WORKS OUT...GEM/GFS ALSO SUPPORT A PERIOD OF
PCPN AT SOME POINT SAT NIGHT/SUN. GIVEN UNCERTAINTY IN
TIMING/STRENGTH...WILL ONLY GO AS HIGH AS CHC POPS SAT NIGHT/SUN.

NW FLOW SETS UP FOR MON/TUE AS TROF DEEPENS OVER THE GREAT LAKES AND
SHIFTS E. THERE IS DECENT AGREEMENT ON A SHORTWAVE DROPPING THRU THE
UPPER LAKES IN THE NW FLOW ON MON. THIS WARRANTS AT LEAST A MENTION
OF SCHC/CHC POPS...HIGHEST IN THE INTERIOR WHERE SOME INSTABILITY IS
LIKELY TO DEVELOP DURING THE DAY. COULD BE A SIMILAR SET UP ON TUE
IF THE TROF IS SLOWER TO SHIFT E AS THE GFS INDICATES.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 143 PM EDT WED JUN 3 2015

UPPER LEVEL ENERGY WILL DRIVE THE DEVELOPMENT OF SHOWERS AND
POSSIBLY THUNDERSTORMS THIS EVENING THROUGH THURSDAY. WHILE
CONFIDENCE IS QUITE LOW DUE TO UNCERTAINTY WITH THE DEVELOPMENT OF
CONVECTION...THE BEST GUESS IS TO HAVE BEST RAIN CHANCES TONIGHT AT
KIWD AND KCMX...WITH THE MAIN FOCUS ON THURSDAY AT KSAW. WITH THE
LOW CONFIDENCE...DECIDED TO LEAVE THUNDER OUT OF THE TAFS FOR NOW.
LOW LEVEL MOISTURE AND FLOW OFF THE GREAT LAKES SHOULD LEAD TO IFR
CONDITIONS THURSDAY.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 444 AM EDT WED JUN 3 2015

SOUTH TO SOUTHWEST WINDS WILL AFFECT CENTRAL/EASTERN LAKE SUPERIOR
TODAY...AS THE AREA IS BETWEEN A DEPARTING HIGH AND A TROUGH RUNNING
FROM THE DAKOTAS TO HUDSON BAY. WITH THE COLDER LAKE SUPERIOR WATER
TEMPERATURES...EXPECT THE MARINE LAYER TO KEEP THE WINDS IN THE
10-20KT RANGE...ALTHOUGH HIGHER PLATFORMS CLOSER TO THE SOUTHERN
SHORE OF LAKE SUPERIOR MAY SEE GUSTS TO 25-30KTS THROUGH MID
DAY. AS THE SURFACE TROUGH SLOWLY DRIFTS SOUTHEAST ACROSS LAKE
SUPERIOR TONIGHT...EXPECT THE WINDS TO DIMINISH BELOW 15KTS. THE
TROUGH WILL CONTINUE TO SAG SOUTHEAST THURSDAY INTO THURSDAY
NIGHT...LEADING TO NORTHEAST WINDS INCREASING TO 15-20KTS AHEAD
OF AN APPROACHING HIGH IN CENTRAL CANADA. THIS HIGH WILL STRETCH A
RIDGE OVER THE UPPER GREAT LAKES FRIDAY AND SATURDAY AS IT MOVES
INTO SOUTHERN QUEBEC.

FINALLY...WITH SOME RAIN EXPECTED OVER WESTERN LAKE SUPERIOR AND
INCREASING DEWPOINTS...THERE IS THE POTENTIAL FOR FOG OVER THE
WESTERN HALF OF LAKE SUPERIOR LATER TODAY INTO THURSDAY. CONFIDENCE
IS LOW IN THE LOCATION AND THICKNESS...SO WILL JUST HAVE
PATCHY/AREAS OF FOG IN THE FORECAST.
&&

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

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...TITUS
MARINE...SRF



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