Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 311141
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
641 AM EST SAT JAN 31 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EST SAT JAN 31 2015

A WEAK SHORTWAVE TROUGH ALOFT PRECEDING A SFC TROUGH/COLD FRONT NOW
JUST NW OF LAKE SUPERIOR HAS BEEN DRIVING LIGHT SNOW ACROSS MUCH OF
THE AREA TONIGHT. THE PRECIP IS COMING TO AN END FROM NW TO SE AS
THE SHORTWAVE MOVES OUT...AND LES IS NOT A FACTOR GIVEN THE SWLY LOW
LEVEL WINDS AHEAD OF THE SFC TROUGH /MORE OF A WLY WIND OVER NRN
LAKE MICHIGAN. THE COLD FRONT WILL MOVE INTO NWRN UPPER MI BY 12Z
THIS MORNING...MOVING TO SERN UPPER MI BY 18Z TODAY. LOW LEVEL WINDS
WILL VEER TO A NLY DIRECTION BY 00Z SUN AS 850MB TEMPS DROP TO AS
LOW AS -20C. LOW LEVEL WINDS WILL CONTINUE TO VEER TONIGHT TO THE NE
AS A SFC RIDGE PUSHES INTO PARTS OF ONTARIO N OF LAKE SUPERIOR.
THINK THAT RELATIVELY MINOR LES AMOUNTS WILL RESULT IN THE N-NW WIND
SNOWBELTS TODAY...TRANSITIONING TO THE NE WIND SNOWBELTS TONIGHT.
THE SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SFC RIDGE TO THE N
WILL RESULT IN LAKE INDUCED EQUILIBRIUM LEVELS OF 4500-5000FT. EVEN
WITH THE DRY AIR TO THE N AND ABOVE THE BOUNDARY LAYER...THINK THAT
DECENT SNOW RATIOS OF 20-25 TO 1 WILL RESULT OVER THE NE WIND
SNOWBELTS TONIGHT GIVEN FAIRLY WEAK LOW LEVEL WINDS TO REDUCE SNOW
FLAKE FRACTURING AND SINCE THE DGZ WILL BE IN THE BOUNDARY LAYER.
STILL...NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS /NORTH
CENTRAL WILL SEE THE MOST SNOW TONIGHT OF 1-3 INCHES/ AS
ANTICYCLONIC FLOW AND DRY AIR WILL BE LIMITING FACTORS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 531 AM EST SAT JAN 31 2015

THE UPPER GREAT LAKES WILL BE IN A COLD PATTERN FOR MUCH OF THE
EXTENDED PORTION OF THE FCST FEATURING A W COAST RIDGE AND CNTL/ERN
TROF. THE RESULTING NW FLOW INTO THE GREAT LAKES WILL RESULT IN A
STEADY FEED OF CANADIAN AIR. EXPECT TEMPS BLO TO MUCH BLO NORMAL AT
TIMES THROUGH MUCH OF THE PERIOD. AS FOR PCPN...THIS IS TYPICALLY A
DRY PATTERN FOR THE UPPER LAKES WITH LITTLE IN THE WAY OF SYNOPTIC
PCPN EXPECTED. THE COLD WILL HOWEVER LEAD TO PERSISTENT LES OFF LAKE
SUPERIOR. MOST THE LES WILL BE ON THE LIGHT SIDE...BUT THERE MAY BE
THE OCCASIONAL BOOST WITH THE PASSAGE OF SHORTWAVES PROVIDING SOME
ENHANCEMENT.

BEGINNING SUN AND SUN NIGHT...ARRIVAL OF NW FLOW SHORTWAVE DIVING
THROUGH THE PLAINS WILL PHASE WITH REMNANT OF CLOSED LOW CURRENTLY
OVER THE SW CONUS. THIS WILL DEEPEN SFC LOW OVER SRN IL ON SUNDAY
WHICH IS PROGGED TO MOVE EAST INTO THE OHIO VALLEY BY SUN EVENING.
MODELS CONSISTENT IN SHOWING THAT PCPN FROM THIS DEVELOPING SYSTEM
WILL MISS UPPER MI TO THE SOUTH. 00Z NAM AND LOCAL WRF-ARW MODELS
INDICATE THE POTENTIAL FOR A LAND BREEZE TO PUSH OUT OVER LAKE
SUPERIOR FROM AROUND MUNISING EASTWARD LATE SAT NIGHT/SUN MORNING AS
PRES GRADIENT/WINDS SLACKEN. IF THIS HAPPENS...A MESOLOW COULD SPIN
UP OVER SCNTRL LAKE SUPERIOR AND LEAD TO SOME HEAVIER SNOW NEAR THE
SHORE BTWN MARQUETTE AND MUNISING ON SUNDAY...DEPENDING ON THE
CIRCULATION STRUCTURE. OTHERWISE...LIGHT NNE WINDS IN ANTICYCLONIC
FLOW ALONG WITH ABSENCE OF DGZ GIVEN COLD AIRMASS (850 MB TEMPS OF -
20C OR COLDER) AND INVERSION HGTS AROUND 3 KFT SHOULD LEAD TO SMALL
SNOWFLAKE SIZE AND LIGHT LES ACCUMULATION MAINLY OVER WRN AND NCNTRL
PORTIONS OF THE CWA SUNDAY. BACKING WINDS AS SFC HIGH CENTER SAGS SW
OF THE AREA ALONG WITH DEVELOPING LAND BREEZE CIRCULATIONS COULD
AGAIN LEAD TO LOCALIZED CONVERGENCE AND THE POTENTIAL OF A MESOLOW
FORMING OVER SCNTRL LAKE SUPERIOR SUN NIGHT AS LOCAL MESOSCALE
MODELS SUGGEST. GIVEN THAT WINDS WILL CONTINUE TO BACK WEST LATE SUN
NIGHT INTO EARLY MONDAY...IT REMAINS UNCLEAR THAT IF ANY MESOLOW
FORMS THAT IT WILL IMPACT LAND AREAS. IT MAY JUST STAY OUT OVER LAKE
SUPERIOR...BUT NONETHELESS THIS WILL BE SOMETHING TO WATCH.
REGARDLESS...EXPECT SOME VERY LIGHT LES ACCUMULATION FOR NW
SNOWBELTS NEAR LAKE SUPERIOR.

MON...LES WILL BEGIN TO SHIFT OUT OVER LAKE SUPERIOR AS WINDS BACK
DUE TO HIGH PRES SHIFTING FROM THE MID MISSISSIPPI VALLEY TO THE
OHIO VALLEY. BY MON AFTN...LES MAY ONLY BE AFFECTING THE KEWEENAW
AND THE FAR ERN SHORELINE AREAS OF THE CWA. MODELS SHOW A SHORTWAVE
DIVING SE THROUGH THE NRN PLAINS MON AND THEN INTO THE LOWER MIDWEST
MON NIGHT. MUCH OF FORCING AND MOISTURE ASSOC WITH THIS WAVE LOOKS
LIKE WILL STAY SOUTH AND NOT AFFECT UPPER MI.

TUE-THU...MEDIUM RANGE GUIDANCE CONTINUES TO SHOW A STRONG SHORTWAVE
DIVING SE OUT OF CANADA INTO THE UPPER LAKES FOR THE MIDDLE OF THE
WEEK. MODELS TRENDING FARTHER SOUTH WITH MOISTURE AND LIFT ASSOC
WITH THIS SYSTEM SO NOW IT LOOKS LIKE WIDESPREAD SNOW MAY STAY
MAINLY SOUTH OF THE FCST AREA TUE INTO TUE NIGHT. BEHIND THE
SHORTWAVE...MODELS INDICATE A VERY COLD SURGE OF ARCTIC AIR WITH
850MB TEMPS OF -25 TO -28C MOVING OVER THE AREA WED INTO EARLY THU.
WITH DGZ DRIVEN BELOW LAKE SURFACE...INVERSIONS AT OR BLO 5KFT
SETTING UP BEHIND SHORTWAVE AND LARGE SCALE LOW-LVL ANTICYCLONIC FLOW
...LES ACCUMULATIONS SHOULD BE LIGHT WED INTO THU. ALTHOUGH
ACCUMULATION SHOULD BE LIGHT...THE VERY COLD AIR AIRMASS WILL RESULT
IN SMALL SNOWFLAKES THAT ARE VERY EFFECTIVE AT REDUCING VISIBILITY.
LOWEST TEMPS OF THE WEEK SHOULD OCCUR WED INTO THU TIME FRAME AND
WIND CHILL ADVISORY MAY BE MET FOR SOME OF THE COUNTIES IN THE CWA.

MODELS SUGGEST TEMPS SHOULD MODERATE BY FRI AS AMPLIFIED WRN RDG/ERN
TROF PATTERN SHOWS SIGNS OF BREAKING DOWN.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 639 AM EST SAT JAN 31 2015

A COLD FRONT WILL SWEEP ACROSS THE AREA THIS MORNING...WITH LIGHT
SNOW AND LOWER CIGS ALONG AND BEHIND THE FRONT. NW WINDS IMMEDIATELY
BEHIND THE FRONT WILL LEAD TO INCREASED LAKE EFFECT SNOW AND
CLOUDS...BUT WINDS WILL TURN NORTHERLY LATE THIS AFTERNOON THEN
NORTHEASTERLY THIS EVENING. THEREFORE...THE WORST CONDITIONS WILL BE
AT KIWD AND KCMX INTO THIS AFTERNOON BEFORE TRANSITIONING TO KSAW
THIS AFTERNOON/EVENING AND CONTINUING THROUGH TONIGHT. AS WINDS
BECOME NORTHEASTERLY TONIGHT...CONDITIONS AT KIWD MAY IMPROVE MORE
THAN FORECASTED...DEPENDING ON EXACT WIND DIRECTION.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM EST SAT JAN 31 2015

A COLD FRONT CROSSING LAKE SUPERIOR TODAY WILL BRING IN ANOTHER
SURGE OF STRONG WINDS...POSSIBLY WITH SOME GUSTS REACHING 35KTS THIS
AFTERNOON AND EVENING. CANCELED THE GALE WATCH AS IT IS ONLY A
MARGINAL SETUP FOR GALES AND ONLY A FEW GALE GUSTS ARE EXPECTED.
WINDS BECOME LIGHT BY SUNDAY AS HIGH PRESSURE DRIFTS ACROSS. WINDS
INCREASE FM THE WSW ON MONDAY NIGHT AHEAD OF ANOTHER LOW PRESSURE
AND COLD FRONT THAT SWEEP OVER THE AREA ON TUESDAY NIGHT AND
WEDNESDAY. BEHIND THAT FRONT...ANOTHER PERIOD OF GALES AND HEAVY
FREEZING SPRAY IS EXPECTED INTO THURSDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING FROM NOON TODAY TO 5 AM EST SUNDAY
     FOR LSZ264-266-267.

LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...TITUS
LONG TERM...VOSS
AVIATION...TITUS
MARINE...TITUS



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