Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 030856
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
356 AM EST TUE MAR 3 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 451 PM EST MON MAR 2 2015

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW OVER N AMERICA.
FEATURES OF INTEREST FOR THE SHORT TERM FCST ARE A NRN STREAM
SHORTWAVE DROPPING THRU ALBERTA/SASKATCHEWAN AND THE SRN STREAM TROF
OVER CA/NV...IN PARTICULAR THE SHORTWAVE OVER SRN CA/SRN NV WHERE
CONVECTION IS NOTED. THESE TWO WAVES WILL BRING A WIDESPREAD
SYNOPTIC SNOW TO THE AREA TUE. ABUNDANT SUNSHINE HAS BEEN THE RULE
ACROSS THE AREA THIS AFTN UNDER DRY AIR MASS ASSOCIATED WITH SFC
HIGH OVER THE MID MISSISSIPPI VALLEY AND WRN GREAT LAKES REGION.
SUNSHINE WORKING ON THE FORESTED TERRAIN OF UPPER MI HAS RESULTED IN
TEMPS RISING WELL INTO THE 20S OVER MOST OF THE AREA. COOLEST
CONDITIONS (AROUND 20F) ARE OVER THE FAR E...CLOSER TO THE DEPARTING
850MB THERMAL TROF...AND AT MANY LOCATIONS ALONG LAKE SUPERIOR WHERE
LAKE/ICE BREEZE HAS DEVELOPED.

LATEST MODEL RUNS CONTINUE TO SHOW THE 2 AFOREMENTIONED SHORTWAVES
REMAINING UNPHASED AS THEY AFFECT THE AREA TUE. THE SRN WAVE WILL
ACCELERATE OUT OF THE SW INTO THE DOWNSTREAM CONFLUENT FLOW...AND IT
WILL BE THE DRIVER OF THE SNOW THAT SPREADS INTO THE UPPER LAKES. IT
APPEARS 1 MAIN STREAK OF PCPN OR AT LEAST MORE ORGANIZED/HEAVIER
PCPN WILL DEVELOP TONIGHT TO THE SW. THIS PCPN WILL STREAK NE ACROSS
SD INTO CNTRL MN IN ASSOCIATION WITH A COUPLED UPPER JET
STRUCTURE/ENHANCED UPPER DIVERGENCE FROM LEFT EXIT OF 150KT JET
TRANSLATING OUT OF THE SRN ROCKIES AND THE RIGHT ENTRANCE OF 125KT
JET STREAK OVER ND INTO NRN ONTARIO. MORE PCPN WILL BEGIN TO GET
ORGANIZED FARTHER E LATE IN THE NIGHT AS MID LEVEL FRONTOGENESIS AND
BROADER WAA/ISENTROPIC ASCENT BEGIN TO SATURATE DRIER AIR AT THE
LOWER LEVELS. MODELS ARE NEARLY IDENTICAL IN TIMING THE PCPN INTO
WRN AND SRN UPPER MI IN THE 08-12Z TIME FRAME...AND STARTING ACROSS
THE N AND E AROUND OR SHORTLY AFTER 12Z. SO...LITTLE ADJUSTMENT WILL
BE REQUIRED WITH ONSET TIMING. ACCUMULATIONS AROUND ONE HALF INCH
MAY OCCUR ALONG THE WI BORDER BY 12Z.

ON TUE...THE BEST UPPER DIVERGENCE ASSOCIATED WITH A WEAKENING
COUPLED UPPER JET STRUCTURE QUICKLY SHIFTS NE ACROSS NE MN/WRN LAKE
SUPERIOR INTO NRN ONTARIO. MEANWHILE...WAA/ISENTROPIC
ASCENT/FRONTOGENETICALLY FORCED PCPN WILL QUICKLY EXPAND/INCREASE IN
INTENSITY AS AIR MASS SATURATES AND DEEP LAYER FORCING PROVIDED BY
SHORTWAVE ARRIVES. ON THE 285K SFC (ROUGHLY 700-750MB)...MIXING
RATIOS AROUND 2.5G/KG ARE AVBL...SUGGESTING SOMETHING AROUND 3
INCHES OF SNOW FOR 6-9HRS OF ASCENT. HOWEVER...GIVEN THE OTHER
FACTORS AT PLAY...A WIDESPREAD FAIRLY UNIFORM 3-5 INCH SNOW IS
EXPECTED ACROSS THE ENTIRE FCST AREA TUE...WHICH FALLS NICELY INLINE
WITH THE CONSENSUS QPF NUMBERS FROM THE MODELS CONVERTED TO SNOW
USING A 15 TO 1 OR SO SNOW RATIO. WITH SOUTHERLY LOW-LEVEL FLOW UP
LAKE MICHIGAN FOR SEVERAL HRS AND AIR MASS JUST COLD ENOUGH TO
SUPPORT ENHANCEMENT...THERE SHOULD BE SOME BOOST TO SNOW TOTALS
DOWNWIND OF LAKE MICHIGAN THOUGH ICE COVER WILL LIMIT THE
ENHANCEMENT OVER WHAT IT COULD BE. THAT AREA IS MORE LIKELY TO SEE
ACCUMULATIONS CLOSER TO 5 INCHES THAN 3...AND NOT OUT OF THE
QUESTION THAT SOME 6 INCH AMOUNTS COULD OCCUR. FORCING QUICKLY
SHIFTS E TUE AFTN...RESULTING IN SNOW RAPIDLY DIMINISHING W TO E
DURING THE MID AND LATE AFTN HRS. IN FACT...IT MAY END COMPLETELY
OVER PORTIONS OF THE WEST LATE IN THE AFTN. WITH SNOW RATIO LIKELY
UNDER 20 TO 1...THIS SYSTEM WILL ACHIEVE THE WETTER SNOW TYPE ADVY
CRITERIA OF AN AVG SNOWFALL OF AT LEAST 3IN/12HR OVER THE ENTIRE
FCST AREA. SO...ADVY WILL BE HOISTED ACROSS THE BOARD.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 356 AM EST TUE MAR 3 2015

A SHORTWAVE AND SFC TROUGH WILL SHIFT ACROSS THE CWA ON WED/WED
EVENING WITH 850MB TEMPS AS COLD AS -27C. LOW LEVEL WINDS WILL BE
OUT OF THE WNW THROUGH THE AFTERNOON BUT WILL VEER AROUND TO THE NW
BEHIND THE TROUGH WED EVENING. MORNING AND EARLY AFTERNOON WINDS
GUSTING TO 30-40MPH ALONG THE LAKE SUPERIOR SHORE WILL LEAD TO
BLOWING SNOW AND SIGNIFICANTLY REDUCED VISIBILITIES OVER THE
KEWEENAW AND EAST OF MUNISING DUE TO THE MORE WNW WIND
DIRECTIONS...BUT WINDS WILL DECREASE IN THE LATE AFTERNOON AND
EVENING. OF COURSE...LES WILL RESULT EVEN WITH A MOSTLY ICE COVERED
LAKE SUPERIOR...ESPECIALLY WITH THE SHORTWAVE COMING THROUGH. LES
WILL DIMINISH WED NIGHT INTO THU AS A SFC RIDGE MOVES IN FROM THE W
WHILE WINDS BACK. GENERALLY HAVE 1-2 INCHES IN WNW WIND SNOWBELTS ON
WED...WITH AROUND ANOTHER INCH WED NIGHT INTO THU.

FOR FRI THROUGH NEXT MON...SEVERAL SHORTWAVES MAY MOVE THROUGH THE
REGION DURING THIS TIME. A STRONGER SHORTWAVE LOOKS TO MOVE THROUGH
ON SUN/SUN NIGHT...BUT THE OTHER WILL BE PRETTY WEAK. PRECIPITATION
FORECAST CONFIDENCE IS QUITE LOW GIVEN UNCERTAINTIES WITH THE
SHORTWAVES. THAT BEING SAID...ISOLATED TO SCATTERED LES IS POSSIBLE
IN W-NW WINDS SO WILL INCLUDE THAT IN THE FORECAST. TEMPS DO LOOK TO
MODERATE...AND SHOULD REACH NORMAL VALUES THIS WEEKEND. LOOKING EVEN
FARTHER AHEAD...MODELS CONTINUE TO SHOW THE W COAST RIDGE SHIFTING E
INTO THE CENTRAL CONUS MID TO LATE NEXT WEEK...WHICH WOULD BRING
ABOVE NORMAL TEMPS AND START MELTING THE SNOWPACK.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1149 PM EST MON MAR 2 2015

VFR CONDITIONS WILL GIVE WAY TO MVFR CONDITIONS LATE TONIGHT AT KIWD
(AROUND 10Z) AND AT KCMX/KSAW AROUND 12Z AS INCREASING MOISTURE IN A SW
FLOW WILL LEAD TO SNOW DEVELOPMENT. BY MID TO LATE MORNING...ALL
TERMINALS SHOULD SEE IFR CONDITIONS. EXPECT IMPROVEMENT TO MVFR AT
ALL TERMINALS LATE AFTERNOON/EVENING (BTWN 20-22Z) WITH DRIER
CONDITIONS AND DEVELOPING W WINDS IN WAKE OF LOW PRES TROF/COLD
FROPA. W WINDS GUSTING AS HIGH AS 30 MPH AT KCMX COULD LEAD TO SOME
BLSN AND POSSIBLY BRIEF IFR CONDITIONS TUE EVENING. EXPECT KSAW TO
SEE VFR CONDITIONS DEVELOPING TUE EVENING IN DOWNSLOPE WNW FLOW.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 451 PM EST MON MAR 2 2015

GENERALLY LIGHT WINDS CURRENTLY ACROSS LAKE SUPERIOR WILL BECOME S
AND RAMP UP TONIGHT AND TUE TO 15-25KT IN ADVANCE OF AN APPROACHING
LO PRES TROF. ONCE THE TROF PASSES TO THE E TUE NIGHT...TIGHTENING
PRES GRADIENT AND STRONG COLD AIR ADVECTION AHEAD OF ARCTIC HIGH
PRES MOVING INTO THE NORTHERN PLAINS WILL LIKELY BRING A PERIOD OF
NW GALES INTO WED...MAINLY ACROSS CNTRL AND ERN LAKE SUPERIOR. AFTER
WED...NO GALE FORCE WINDS ARE EXPECTED THRU THE REMAINDER OF THE
WEEK. LATEST OFFICIAL ICE CONCENTRATION ON LAKE SUPERIOR IS AROUND
94 PCT. EVEN WITH STRONG WINDS AT TIMES THIS WEEK...THE HIGHER ICE
COVERAGE SHOULD PERSIST AS TEMPERATURES STAY BELOW FREEZING.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ THIS MORNING TO
     7 PM EST /6 PM CST/ THIS EVENING FOR MIZ001>007-009>014-084-
     085.

LAKE SUPERIOR...
  GALE WARNING FROM 1 AM TO 7 PM EST WEDNESDAY FOR LSZ267.

  GALE WARNING FROM 10 PM THIS EVENING TO 7 PM EST WEDNESDAY FOR
     LSZ266.

  GALE WARNING FROM 10 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
     LSZ265.

  GALE WARNING FROM 10 PM THIS EVENING TO 1 PM EST WEDNESDAY FOR
     LSZ264.

LAKE MICHIGAN...
NONE.
&&

$$

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



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