Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290912
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
412 AM EST THU JAN 29 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 444 PM EST WED JAN 28 2015

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A PAIR OF SHORTWAVES TO
THE W AND NW. ONE IS MOVING OUT OF WY/CO INTO THE WRN PLAINS AND THE
OTHER IS MOVING FROM SRN SASKATCHEWAN INTO SRN MANITOBA. AHEAD OF
THESE FEATURES...A RIBBON OF STRENGTHENING WAA/ISENTROPIC ASCENT IS
SPREADING ESE ACROSS NRN ONTARIO AND THE UPPER GREAT LAKES
UNDERNEATH RIGHT ENTRANCE OF UPPER JET CURVING FROM NRN ONTARIO DOWN
THRU THE CNTRL APPALACHIANS. REGIONAL RADARS SHOW A STREAK OF RADAR
RETURNS EXTENDING ESE FROM SE MANITOBA ACROSS ADJACENT NRN ONTARIO
AND OVER LAKE SUPERIOR/ERN UPPER MI. THE ASCENT HAS BEEN SUFFICIENT
TO ERODE DRY AIR AT THE LOWER LEVELS AND ALLOW SOME -SN TO REACH THE
GROUND FROM THE TIP OF THE KEWEENAW INTO THE NCNTRL AND ERN FCST
AREA.

PAIR OF SHORTWAVES WILL CONTINUE MOVING ESE TONIGHT WITH THE NRN
STREAM WAVE THE MORE IMPORTANT FEATURE FOR THE WEATHER HERE. AS THE
WAVE APPROACHES...ISENTROPIC ASCENT ON THE 295K SFC INCREASES
TONIGHT...MOST NOTABLY OVER THE E HALF OF UPPER MI. WHILE IT WILL BE
TOO WARM FOR ANY LAKE ENHANCEMENT OFF LAKE MICHIGAN...THE FLOW OFF
THE LAKE WILL STILL AID THE MOISTENING OF THE LOW LEVELS. OVER THE
W...THE WINDOW OF COLUMN MOISTENING IS SHORTER BEFORE THE ISENTROPIC
ASCENT DEPARTS OVERNIGHT. THUS...PCPN AMOUNTS TONIGHT WILL BE
LIGHTEST OVER THE W AND GREATER OVER THE E. 295K SFC SHOWS MIXING
RATIOS OF 3-4G/KG AVBL...SUGGESTING THE POTENTIAL FOR 3-4INCHES OF
SNOW FOR THE ROUGHLY 6HRS OF ASCENT EXPECTED. 4 INCHES IS LIKELY TOO
HIGH SINCE SNOW TO WATER RATIOS SHOULD BE ON THE LOWER SIDE. AS IT
IS...WILL PROBABLY BE CLOSE TO ADVY THRESHOLD OVER THE FAR E...
MAINLY LUCE COUNTY...AS 12HR SNOW ACCUMULATIONS FROM LATE EVENING TO
LATE THU MORNING WILL BE NEAR 3 INCHES. SNOW ACCUMULATIONS WILL BE
STEADILY LIGHTER TO THE W...DOWN TO LESS THAN 1 INCH FAR W AND ALONG
THE WI BORDER. LATE TONIGHT INTO THU MORNING...FCST SOUNDINGS
SUPPORT THE POTENTIAL FOR SOME -FZDZ AS MID LEVEL MOISTURE/SYNOPTIC
SNOW EXIT...LEAVING A LOW LEVEL MOIST LAYER THAT HAS TEMPS HIGHER
THAN -10C. WILL INCLUDE MENTION OF -FZDZ WHERE WINDS WILL BE
UPSLOPING.

COLD FRONT PASSES ACROSS UPPER MI THU MORNING. DESPITE INCREASING
WIND FIELDS...INITIAL CAA IS WEAK AS THERMAL GRADIENT IS DISPLACED
OFF TO THE NW...BUT CAA INCREASES QUICKLY IN THE AFTN. 850MB TEMPS
AROUND -10C IN THE MORNING WILL FALL TO NEAR -20C BY 00Z FRI...AND
THIS WILL RESULT IN FALLING SFC TEMPS...ESPECIALLY IN THE AFTN. LAST
OF THE SYNOPTIC SNOW WILL END OVER THE E IN THE MORNING.
OTHERWISE...THERE MAY NOT BE TOO MUCH IN THE WAY OF PCPN (-SN/-FZDZ)
DURING THE MORNING AWAY FROM AREAS THAT SEE UPSLOPING UNDER NW
WINDS. AS COLDER AIR ARRIVES IN THE AFTN...NW/NNW FLOW LES WILL
INCREASE IN COVERAGE WITH DGZ DROPPING INTO THE CONVECTIVE LAYER.
STRONG SUBSIDENCE/DEEP LAYER QVECTOR DIVERGENCE WILL LIMIT LES
INTENSITY. SO FOR THE MOST PART...EXPECT ACCUMULATIONS MOSTLY AROUND
1 INCH IN THE AFTN. STRONG WINDS WILL DISPLACE LES A LITTLE FARTHER
INLAND THAN NORMAL. SPEAKING OF WINDS...FAVORABLE POSTIONING OF PRES
RISE/FALL COUPLET WILL RESULT IN AN ADDITIVE ISALLOBARIC WIND
COMPONENT. COMBINED WITH 925MB WINDS INCREASING TO AROUND
40KT...CONDITIONS WILL BECOME BLUSTERY ACROSS THE AREA. ALONG THE
LAKE SUPERIOR SHORE AROUND THE TIP OF THE KEWEENAW AND FROM BIG BAY
EASTWARD...WINDS WILL PROBABLY GUST TO 35 TO 45 MPH IN THE AFTN.
DEPENDING ON HOW QUICKLY LES INCREASES IN THE AFTN...BLSN COULD
BECOME A SIGNIFICANT ISSUE NEAR THE LAKE.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 411 AM EST THU JAN 29 2015

FCST FOCUS IN THE MEDIUM AND EXTENDED RANGE WL BE ON THE IMPACT OF
SEVERAL CLIPPER TYPE SHRTWVS THAT ARE FCST TO MOVE THRU A MEAN UPR
TROF IN ERN NAMERICA. UNDER THE PERSISTENT NW FLOW ALOFT...EXPECT
BLO TO WELL BLO NORMAL TEMPS TO DOMINATE DURING THIS TIME WITH A
STEADY FEED OF CNDN AIR. WITH THE COLD AIR SURGES...LES WL BE AN
OBVIOUS CONCERN.

FRI...SFC HI PRES IS FCST TO SHIFT FM OVER MN TOWARD THE OH RIVER
VALLEY BE 00Z SAT. AS NW WINDS IN THE MRNG BACK TO THE W AND THEN
THE SW LATE...LINGERING LES OVER THE W WL BECOME CONFINED TO OVER
THE KEWEENAW AND END OVER THE E EXCEPT NEAR THE SHORE E OF GRAND
MARAIS TOWARD 00Z SAT. ALTHOUGH THE LK CLDS WL BE SHIFTING
OFFSHORE...MORE MID/HI CLDS IN ADVANCE OF ANOTHER SHRTWV MOVING SE
WITHIN THE NW FLOW ALF WL BE PUSHING INTO THE UPR LKS.

FRI NGT/SAT...SHRTWV EMBEDDED IN THE NW FLOW ALOFT WL BE MOVING INTO
NW MN AT 00Z SAT AND IS THEN FCST TO SLIDE SE THRU NCENTRAL WI BY
12Z SAT AND THEN ACROSS LOWER MI ON SAT. AT THE SAME TIME...ANOTHER
STRONGER SHRTWV WL BE MOVNG FM CENTRAL CANADA INTO FAR NW ONTARIO BY
12Z SAT BEFORE MOVING TO JUST S OF JAMES BAY BY 00Z SUN. UPR MI WL
BE IMPACTED MAINLY BY THE WEAKER SRN DISTURBANCE. ALTHOUGH A BAND OF
RELATIVELY WEAK QVECTOR CNVGC IS FCST TO SLIDE ACROSS UPR MI ON FRI
NGT INTO SAT MRNG ON THE CYC SIDE OF THIS SRN SHRTWV...ACCOMPANYING
ISENTROPIC ASCENT/MSTR INFLOW IS FCST TO BE RELATIVELY WEAK. SO WL
FCST ONLY CHC POPS OVER MOST OF THE CWA AND MAINLY BTWN 03Z SAT AND
15-18Z SAT...WHEN THE FORCING ACCOMPANYING THE SRN SHRTWV AND A COLD
FNT ATTENDANT TO THE NRN SHRTWV ARE FCST TO EXIT THE ERN CWA AND
GIVE WAY TO SOME VIGOROUS DEEP LYR QVECTOR DVGC. MAINTAINED SOME
LIKELY POPS OVER THE NRN TIER OF THE CWA CLOSE TO THE STRONGER NRN
SHRTWV AND WHERE SHARPER LLVL CNVGC WL ACCOMPANY THE SAT COLD FROPA.
THE COLDEST 00Z GFS/12Z ECMWF RUNS SHOW H85 TEMPS IN THE WAKE OF THE
SAT COLD FROPA PLUNGING AS LO AS -25C BY 00Z SUN...BUT QUICK
TRANSITION TO A MORE DIFFLUENT/ACYC H925 N FLOW AND INVRN BASE
FALLING TO H85-875 WL TEND TO LIMIT LES INTENSITY. RELATIVELY
MODERATE TEMPS INTO SAT MRNG WL FALL THRU THE AFTN AS THE COLDER AIR
SURGES INTO THE AREA IN THE STEADY N FLOW AHEAD OF ARCTIC HI PRES
BLDG SEWD IN SCENTRAL CANADA.

SAT NGT THRU SUN NGT...UPR MI WL REMAIN DOMINATED BY A COLD N
BACKING WNW LLVL FLOW OF ARCTIC AIR ASSOCIATED WITH ARCTIC HI PRES
MOVING FM OVER ALBERTA/SASKATCHEWAN AT 00Z SUN INTO THE UPR MS RIVER
VALLEY BY 12Z MON. EXPECT TEMPS TO RUN WELL BLO NORMAL AND LES TO
CONTINUE NEAR LK SUP WITH H85 TEMPS FCST TO REMAIN NOT FAR FM -22C
TO -25C. SAT NGT COULD BE PARTICULARLY CHILLY OVER THE E WITH THE N
H925 FLOW ALLOWING SOME DRAINAGE OF COLD AIR INTO THAT AREA OFF
ONTARIO. ALTHOUGH FCST ACYC NATURE OF THE H925 FLOW AND NEAR ABSENCE
OF THE DGZ ASSOCIATED WITH THE VERY LO H85 TEMPS WL LIMIT LES
AMOUNTS...SOME OF THE MODELS HINT THERE MAY BE SOME ENHANCED CNVGC
ALONG A LK INDUCED TROF STRETCHING FM THE KEWEENAW TOWARD WHITEFISH
PT THAT WL INTENSIFY AS THE LARGER PRES GRADIENT RELAXES AND A
SHRTWV EMBEDDED IN THE NW FLOW APRCHS ON SUN/SUN NGT. RAISED POPS
WELL ABOVE THE CONSENSUS TO LIKELY ALONG THIS AXIS.

MON...LES ALONG THE LK INDUCED TROF WL BEGIN TO DIMINISH/SHIFT OUT
INTO LK SUP WITH THE APRCH OF A SFC RDG AXIS EXTENDING N FM THE HI
CENTER SHIFTING TOWARD THE OH VALLEY AND THE ASSOCIATED BACKING LLVL
FLOW. BUT THE MORE W WIND COMPONENT WL MEAN LESS LK MODERATION AND
PERSISTENT WELL BLO NORMAL SFC TEMPS EVEN AS THE H85 TEMPS MODERATE
A BIT FASTER.

TUE/WED...THE LONGER RANGE GUIDANCE HINTS ANOTHER CLIPPER TYPE
DISTURBANCE WL PASS THRU THE UPR LKS ON TUE...WITH H85 TEMPS
REBOUNDING TO NEAR -15C IN THE WAA BTWN THIS FEATURE AND HI PRES
MOVING INTO THE MID ATLANTIC. BUT ANOTHER ARCTIC SURGE LOOKS TO
FOLLOW ON WED AS THE SHRTWV PASSAGE REAMPLIFIES THE ERN TROF AND THE
NW FLOW IN ADVANCE OF THE NEXT CNDN HI SINKING INTO THE NRN PLAINS
ADVECTS H85 TEMPS AS LO AS -25 TO -28C INTO THE UPR LKS.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1154 PM EST WED JAN 28 2015

DISTURBANCE APPROACHING TONIGHT WILL BRING SOME -SN/DETERIORATING
CONDITIONS. ALL TERMINALS WILL LIKELY FALL TO IFR WITH A FEW HRS OF
LIFR POSSIBLE OVERNIGHT. THERE MAY BE A LITTLE
-FZDZ LATE TONIGHT AT KIWD. PASSAGE OF COLD FRONT
EARLY THU MORNING WILL BRING INCREASING...GUSTY NW
WINDS...ESPECIALLY AT THE MORE EXPOSED KCMX TERMINAL.
OTHERWISE...EXPECT IMPROVEMENT TO MVFR AT ALL TERMINALS.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 355 AM EST THU JAN 29 2015

LOW PRESSURE SYSTEM NEAR N LAKE SUPERIOR THIS MORNING WILL MOVE INTO
QUEBEC THIS AFTERNOON WHILE ANOTHER LOW NEAR CHICAGO SHIFTS EAST
INTO NEW ENGLAND ON FRIDAY MORNING. MEANWHILE...A HIGH OVER S
CENTRAL CANADA WILL MOVE SE INTO MN ON FRIDAY. IN BETWEEN THE
EXITING LOW AND NEARING HIGH...STRONG N-NNW GALES GUSTING 35 TO
AROUND 40KTS WILL DEVELOP THIS AFTERNOON OVER MAINLY CENTRAL AND E
LAKE SUPERIOR. LOOK FOR WINDS TO SLOWLY DIMINISH LATE THIS EVENING
AND OVERNIGHT...WITH GUSTS REMAINING 25-30KTS THROUGH DAYBREAK
FRIDAY. GIVEN THE STRONG WINDS...AND COLDER AIR SURGING IN...HEAVY
FREEZING SPRAY WILL BE POSSIBLE OVER THIS SAME AREA INTO EARLY
FRIDAY MORNING. WINDS WILL THEN QUICKLY DIMINISH AND REMAIN LESS
THAN 30KTS THROUGH FRIDAY NIGHT.

AS THIS HIGH DRIFTS INTO THE OH RIVER VALLEY ON SATURDAY...A TROUGH
WILL SLIDE ACROSS THE UPPER GREAT LAKES. A FEW N TO NW GUSTS OF 30
TO NEAR 35KTS WILL BE POSSIBLE SATURDAY AFTERNOON AND EVENING.
EXPECT HIGH PRESSURE OVER CENTRAL CANADA ON SATURDAY TO MOVE SE INTO
THE N PLAINS ON SUNDAY...AND THE MID MS RIVER VALLEY ON MONDAY.
WINDS SHOULD DIMINISH FOR A TIME SUN BEFORE INCREASING AGAIN MONDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING FROM 1 PM THIS AFTERNOON TO 7 AM
     EST FRIDAY FOR LSZ264-266-267.

  GALE WARNING FROM 1 PM THIS AFTERNOON TO 4 AM EST FRIDAY FOR
     LSZ267.

  GALE WARNING FROM 10 AM THIS MORNING TO 4 AM EST FRIDAY FOR
     LSZ265-266.

  GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ263-264.

  HEAVY FREEZING SPRAY WARNING FROM 1 PM THIS AFTERNOON TO 1 AM
     EST FRIDAY FOR LSZ263.

LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...ROLFSON
LONG TERM...KC
AVIATION...07
MARINE...KF



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