Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 250656
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
256 AM EDT MON MAY 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 255 AM EDT MON MAY 25 2015

NAM HAS A CLOSED 500 MB LOW AND TROUGH MOVING INTO THE NORTHERN
PLAINS THIS MORNING WITH A RIDGE OVER THE ERN U.S. POKING INTO THE
UPPER GREAT LAKES. THERE IS ALSO A STRONG SHORTWAVE OVER MISSOURI
THAT WILL HEAD NORTH TODAY AND MOVE THROUGH THE UPPER GREAT LAKES
THIS AFTERNOON.

NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER
MOISTURE THROUGH THE CWA TODAY BEFORE THE Q-VECTOR CONVERGENCE MOVES
OUT TONIGHT...BUT THE DEEPER MOISTURE REMAINS OVER THE AREA.
GFS...ECMWF AND CANADIAN SHOW ABOUT THE SAME THING AND WILL DO A
BLEND OF THEIR FORECASTS WHICH FOR THE MOST PART DID NOT CHANGE MUCH
FROM THE GOING FORECAST. DID BUMP UP WINDS THIS AFTERNOON AS THERE
IS A HINT OF STRONGER SOUTHWEST WINDS ACROSS THE SOUTHERN CWA AS A
SFC LOW MOVES ACROSS WESTERN LAKE SUPERIOR. WITH THE SFC LOW MOVING
A BIT FURTHER WEST...HEAVIER PCPN WILL BE FOCUSED MORE TO THE NORTH
AND WEST OF NORTHERN AND WESTERN U.P. WITH LIGHTER AMOUNTS ACROSS
THE SOUTH AND CENTRAL AND CUT QPF AMOUNTS THERE A BIT.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 358 PM EDT SUN MAY 24 2015

IN THE UPPER LEVELS...TROUGH OVER THE WESTERN CONUS LIFTS ACROSS THE
NORTHERN PLAINS AND UPPER GREAT LAKES EARLY THIS WEEK AS ADDITIONAL
TROUGHING MOVES OVER NORTHWEST CONUS. BY LATE IN THE WEEK...NW CONUS
TROUGH MOVES EAST AND MERGES WITH DEEPER TROUGH MOVING FM CNTRL
CANADA OVER THE GREAT LAKES. AT THE SFC...LOW PRESSURE SYSTEM OVER
LK SUPERIOR ON MONDAY NIGHT WILL DRAG A TROUGH ACROSS UPPER LAKES ON
TUESDAY AS IT MOVES TO QUEBEC. MOST RAIN WILL BE DONE BY 00Z TUESDAY
AS DRY SLOT MOVES IN FM THE SOUTH IN WAKE OF SHORTWAVE AND SFC LOW
MOVING THROUGH. TRACK OF SFC LOW STILL UNCERTAIN...BUT SEEMS IT WILL
BE SOMEWHERE OVER CNTRL OR EASTERN LK SUPERIOR...COMPARED TO FARTHER
WEST TRACK MODELS WERE PREVIOUSLY INDICATING. RESULT WILL BE TO KEEP
EASTERLY COMPONENT WIND OVER THE KEWEENAW INTO THE EVENING AND THUS
A BETTER CHANCE OF FOG OR EVEN SOME DRIZZLE. SSW-SW WINDS ELSEWHERE
WILL LIMIT MOST OF THE FOG VCNTY OF LAKE MICHIGAN SHORE.

NEXT BETTER CHANCES OF RAIN ARRIVE LATER IN THE DAY ON TUESDAY AS
MODELS INDICATE SHORTWAVES CURRENTLY OVER FAR SOUTHERN CA AND IN THE
VCNTY OF UPPER LOW CENTER OVER INTERMOUNTAIN WEST COMBINE TO LIFT
ACROSS UPPER GREAT LAKES. MAY EVEN BE STRONG ENOUGH SYSTEM TO HELP
DEVELOP A SFC LOW PRESSURE. HEAVIEST QPF WILL BE ALONG AND WEST OF
H85-H7 LOWS...WHICH IS NOT QUITE CLEAR. GFS FAVORS FAR WESTERN UPR
MICHIGAN WHILE GEM-NH AND ECMWF ARE MORE OVER CNTRL UPR MICHIGAN.
ELEVATED INSTABILITY PRESENT WITH MUCAPES OF AT LEAST 300 J/KG ECMWF
OR UP OVER 1000J/KG AS THIS WAVE LIFTS THROUGH...SO DID INCLUDE TSRA
MENTION ON TUE/TUE NIGHT. IF FARTHER WEST TRACK VERIFIES...POTENTIAL
IS THERE FOR SFC BASED TSRA TUE AFTN INTO TUE EVENING. MAX TEMPS ON
TUESDAY AHEAD OF THE SYSTEM SHOULD BE ABLE TO REACH 70S INLAND WEST.
HOWEVER...EAST WINDS CLOSER TO LK SUPERIOR AND SOUTH WINDS CLOSER TO
LK MICHIGAN WILL KEEP IT COOLEST IN THOSE AREAS DUE TO ONSHORE FLOW
AND ALSO LINGERING FOG AND LOW CLOUDS.

LOW PRESSURE SYSTEM OR TROUGH SHOULD BE EAST OF UPPER LAKES BY WED.
COULD BE WEAKER WAVE ALOFT MOVING THROUGH THAT INTERACTS WITH SOME
AFTN HEATING TO PRODUCE ISOLD SHRA OR EVEN TSRA...MAINLY WEST. GEM-
NH AND ECMWF HINTING AT THIS...SO KEEP SLIGHT CHANCES EVEN THOUGH
GFS FAVORS DRY CONDITIONS. LIGHTER WEST WINDS WILL ONLY BE LOCALLY
ONSHORE...SO MOST AREAS SHOULD WARM WELL INTO THE 70S AS H85 TEMPS
CLIMB INTO THE LOWER TEENS C.

TROUGH ALOFT SETTLES OVER UPR LAKES ON THURSDAY WHILE MORE ORGANIZED
AREA OF LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS AS THE
SHORTWAVE TROUGH MOVES EAST FM THE NORTHWEST CONUS. SFC LOW AND
TROUGH WILL EDGE ACROSS UPPER MISSISSIPPI RIVER VALLEY ON THURSDAY
THEN SLIDE OVER THE UPPER GREAT LAKES FRIDAY INTO FRIDAY NIGHT. THE
TROUGH WILL THEN BE SHOVED SOUTH OVER THE LOWER GREAT LAKES AND OHIO
VALLEY BY NEXT WEEKEND AS CANADIAN HIGH PRESSURE BUILDS OVER THE
NORTHERN PLAINS AND UPR GREAT LAKES. BEST SHOT OF SHRA AND POSSIBLE
TSRA ARRIVES FOR THURSDAY NIGHT OVER THE WEST THEN OVER ALL OF CWA
ON FRIDAY AS THE UPPER AND SFC COLD FRONT SWEEP THROUGH. MODELS ALL
HAVE THE GENERAL IDEA OF COLD FRONTAL PASSAGE...BUT VARY ON WHEN
PASSAGE OCCURS. GFS IS QUICKEST WITH MOST OF AREA DRY BY FRIDAY
AFTN. ECMWF AND GEM-NH ARE SLOWER...BRINGING THE FRONT THROUGH ON
FRIDAY OR EVEN FRIDAY NIGHT. NO MATTER WHICH SOLUTION IS
PREFERRED...APPEARS COOL AND DRY CONDITIONS ARE ON THE WAY NEXT
WEEKEND AS HIGH PRESSURE BUILDS OVERHEAD.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 111 AM EDT MON MAY 25 2015

SHOWERS WILL CONTINUE TO LIFT N ACROSS UPPER MI OVERNIGHT...
BRINGING DETERIORATING CONDITIONS. EXPECT KIWD/KCMX/KSAW TO FALL
TO LIFR OVERNIGHT. LIFR CONDITIONS WILL THEN PERSIST INTO THIS
AFTN. SOME IMPROVEMENT COULD OCCUR MID TO LATE AFTN AT KIWD/KSAW AS
WINDS SHIFT TO THE WSW BEHIND FROPA. IMPROVEMENT IS MORE
LIKELY TO OCCUR AT KSAW AS WINDS WILL HAVE A DOWNSLOPE COMPONENT.
MAY SEE IMPROVEMENT TO VFR THERE IN THE EVENING...PERHAPS EARLIER.
MEANWHILE...MOIST EASTERLY UPSLOPE FLOW OFF OF LAKE SUPERIOR INTO
THE KEWEENAW PENINSULA MAY RESULT IN VIS DROPPING TO VLIFR AT KCMX
THIS MORNING...BUT THERE IS LOW CONFIDENCE IN SUCH A LOW VIS
WITH RAIN PREVAILING. BETTER POTENTIAL FOR VLIFR WILL BE LATE THIS
AFTN/EVENING AS PCPN DIMINISHES OR ENDS WITH WINDS SHIFTING TO AN
UPSLOPE WESTERLY DIRECTION.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 255 AM EDT MON MAY 25 2015

LIGHT WINDS INCREASE TODAY AS A LOW PRESSURE SYSTEM MOVES ACROSS
WESTERN LAKE SUPERIOR.  EAST WINDS MAY REACH 25 KTS...STRONGEST OVER
WESTERN LAKE SUPERIOR AND ALSO NORTHERN LAKE MICHIGAN AND THE BAY OF
GREEN BAY. LOW SLIDES OVERHEAD ON MONDAY NIGHT SO THE WINDS WILL
DIMINISH. WINDS THE REST OF THE FORECAST PERIOD ARE EXPECTED TO STAY
AT OR BELOW 20 KTS. FOG WILL LINGER THROUGH WEDNESDAY MORNING AND
MAY BE DENSE AT TIMES. ONCE IT IS EVIDENT HOW EXPANSIVE THE FOG
IS...A DENSE FOG ADVISORY MAY BE NEEDED.
&&

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

$$

SHORT TERM...07
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...07



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