Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 310844
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
344 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...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 424 PM EST FRI JAN 30 2015

COLD WEATHER PATTERN IN STORE FOR MUCH OF EXTENDED. TEMPS WILL BE
MUCH BLO NORMAL...ESPECIALLY FOR DAYTIME HIGHS. NORMAL HIGHS FOR
FIRST PORTION OF FEBRUARY ARE IN THE LOWER TO MIDDLE 20S...AND THERE
WILL BE A FEW DAYS NEXT WEEK WHERE HIGHS STAY BLO 10 ABOVE. TROUGHING
ALOFT EXPANDS FM NORTHERN CANADA OVER GREAT LAKES AND MOST OF THE
EASTERN CONUS AS RIDGING TEMPORARILY BUILDS OVER THE WEST COAST. LEAD
SHOT OF ARCTIC AIR DROPS OVER GREAT LAKES SECOND HALF OF THE WEEKEND
WITH H85/5KFT AGL TEMPS BLO -20C/-3F. ANOTHER STRONGER PUSH OF COLDER
AIR IS DUE IN THE MIDDLE OF THE WEEK AS H85 TEMPS DROP TO AT LEAST
-25C/-13F. COULD BE A WIDESPREAD SNOW JUST AHEAD OF THAT REINFORCING
COLD FRONT TUESDAY NIGHT INTO WEDNESDAY. SINCE THE RIDGING OVER THE
WEST COAST IS NOT THAT SHARP...WESTERN RIDGE AND EASTERN TROUGH
PATTERN BREAKS DOWN BY NEXT WEEKEND WITH TEMPS MODERATING BACK TOWARD
NORMAL...POSSIBLY ABOVE...BY NEXT WEEKEND.

COLD FRONT MOVES EAST OF THE AREA ON SATURDAY NIGHT. ARCTIC HIGH
PRESSURE BUILDS FM THE CANADIAN PRAIRIES TO THE NORTHERN PLAINS.
RIDGING EXTENDS NORTH OF LK SUPERIOR WITH CONFLUENT FLOW ALOFT.
SOUNDINGS INDICATE INVERSIONS 4 TO POSSIBLY 6 KFT WITH DELTA T/S
INCREASING FM AROUND 18C SATURDAY EVENING TO 25C BY SUNDAY MORNING.
MAJORITY OF DGZ NOT WITHIN LAKE CONVECTIVE LAYER...SO SNOWFLAKE SIZE
AND THUS SLR/AMOUNTS WILL BE HELD DOWN TO AROUND 20:1 OR EVEN LOWER.
LOW-LEVEL WINDS START OUT NNW-N ON SATURDAY EVENING AND TURN TO NNE
BY SUNDAY AS RIDGING EXPANDS NORTH OF LK SUPERIOR. SETUP FAVORS LES
WITH MAINLY LIGHT ACCUMS FOR FAR WEST CWA AND OVER THE NCNTRL CWA.
SOUNDINGS INDICATE POSSIBLE WEAK LAKE ENHANCED SETUP AS SWATH OF H7-
H5 MOISTURE MOVES ACROSS SATURDAY EVENING INTO SUNDAY MORNING.
EXTENT OF DRYING BTWN THE MID-LEVEL MOISTURE AND LAKE CONVECTIVE
LAYER MAY BE TOO MUCH TO OVERCOME THOUGH AS LIFT ALOFT IS WEAK. LOW-
LEVEL CONVERGENCE VCNTY OF NORTH CENTRAL UPR MICHIGAN MAY MAKE UP
FOR OVERALL MARGINAL SETUP FOR LES...BUT EVEN SO...DO NOT EXPECT
MORE THAN A FEW INCHES OF SNOW SATURDAY NIGHT INTO SUNDAY FOR
FAVORED AREAS. WINDS ARE NOT VERY STRONG...SO SNOW SHOWERS MAY TRY
TO STAY CONFINED TOWARD THE SHORE INSTEAD OF SETTING UP OVER THE
HIGHER TERRAIN.

DESPITE THE ARRIVAL OF THE ARCTIC AIR...WINDS SHOULD NOT BE TOO
STRONG...LIMITING THE OVERALL IMPACT. TEMPS SATURDAY NIGHT SHOULD
FALL WELL BLO ZERO OVER THE EAST WITH DRAINAGE FLOW OFF ONTARIO.
OTHERWISE...NE FLOW AND WEALTH OF STRATUS OFF LK SUPERIOR BENEATH A
SUBSIDENCE INVERSION WILL RESTRICT TEMPS FM FALLING BLO ZERO.
STRATUS SHOULD STAY IN PLACE FOR MUCH OF SUNDAY...EXCEPT OVER THE
FAR EAST. HIGHS ON SUNDAY WILL STAY IN THE SINGLE DIGITS AND MAY
JUST STRUGGLE ABOVE ZERO IN THE FAR EAST CWA. ARRIVAL OF ANOTHER
SHORTWAVE FM THE NORTHWEST ACROSS THE PLAINS WILL BRING A SWATH OF
SNOW TO AS CLOSE AS NORTHERN WI LATE SATURDAY NIGHT. THAT SYSTEM
PHASES WITH ANOTHER MOVING OUT OF THE REMNANT OF CURRENT SOUTHWEST
CONUS LOW TO PROVIDE WIDESPREAD SNOW ON SUNDAY ALONG DEVELOPING SFC
LOW OVER MAINLY SOUTHERN PORTIONS OF WISCONSIN AND MICHIGAN. LOOKS
LIKE UPR MICHIGAN WILL MISS THIS STORM SYSTEM. EXPECT LINGERING
WEAKENING LES FOR SNOW BELTS TO EAST OF MARQUETTE AND POSSIBLY OVER
THE NORTHWEST CWA. LES WILL CONTINUE TO DRIFT MAINLY OFFSHORE ON
SUNDAY NIGHT AS WINDS IN BLYR SLOWLY BACK TO THE WEST ON EDGE OF
HIGH PRESSURE SINKING OVER THE MIDDLE MISSISSIPPI RIVER VALLEY.
CHILLY TEMPS FOR SUNDAY NIGHT WELL BLO ZERO...ESPECIALLY IN THE WEST
INTERIOR AND ALSO EAST CWA WITH CONTINUATION OF LOW-LEVEL FLOW OFF
ONTARIO. SINCE WINDS ARE LIGHT AND CALM...NO WIND CHILL ISSUES ARE
EXPECTED.

LES DRIFTS FARTHER EAST TO SNOW BELTS EAST OF MUNISING AND LIKELY
INCREASES ON THE KEWEENAW AS WINDS BECOME MORE CONVERGENT FM THE
WEST. SETUP THEN MAY BECOME FAVORABLE FOR MODERATE TO POSSIBLY HEAVY
LAKE ENHANCED SNOW FOR NORTHERN KEWEENAW LATE MONDAY INTO TUESDAY
MORNING AS WSW FLOW RESULTS IN STRONG CONVERGENCE BAND TO FORM WHILE
SHORTWAVE WITH ADDITIONAL MID-LEVEL LIFT AND MOISTURE SLIDES ACROSS.
SOUNDINGS INDCIATE THAT INVERSIONS REACH MORE TOWARD 8KFT WITH
INVERSION TOP TEMPS NEARING -24C. POTENTIAL FOR HEAVY SNOW WITH
RATES OVER 1 INCH PER HOUR WILL GREATLY DEPEND ON WHERE SHARPEST
CONVERGENCE ALLIGNS. TOUGH TO TELL THAT AT THIS POINT WHERE THAT
OCCURS...BUT WORTH AN HWO MENTION AS THIS TYPE OF LES PATTERN CAN
RESULT IN A LOT OF SNOW IN JUST A FEW HOURS.

ON INTO TUESDAY...LOW PRESSURE SYSTEM WILL BE ADVANCING ACROSS THE
NORTHERN PLAINS. AREA OF H7-H5 Q-VECTOR CONVERGENCE TO THE NORTH AND
EAST OF THE LOW AND AREA OF DIVERGENCE IN RIGHT ENTRANCE REGION OF
JET STREAK SLIDING OVER THE UPPER GREAT LAKES SHOULD SPREAD AN AREA
OF LGT SNOW WEST TO EAST ACROSS THE WESTERN GREAT LAKES. WENT WITH
LOW POPS AWAY FM LAKE EFFECT AREAS...ESPECIALLY AS THE ECMWF KEEPS
MOST WIDESRPEAD QPF SOUTH OF UPR MICHIGAN. LOW PRESSURE SYSTEM
SHOULD BE JUST EAST OF UPR MICHIGAN WEDNESDAY MORNING WITH STRONGER
COLD FRONT POISED TO SWEEP ACROSS. EXPECT NW FLOW LAKE EFFECT TO
RAMP UP WEDENSDAY AFTN AS NEW SURGE OF COLD AIR RETURN TO THE AREA.
ECMWF/GFS VARYING ON HOW COLD IT GETS AT H85. BLEND OF 12Z RUNS
SUGGEST H85 TEMPS END UP AROUND -27C/-17F WHICH WITH LAKE TEMPS IN
ICE FREE AREAS AROUND 2C/35F YIELDS PLENTY OF OVER-WATER
INSTABILITY. ALSO...COMPARED TO THE RECENT LAKE EFFECT EVENTS...THE
FORECAST SOUNDINGS INDICATE INVERSIONS MAY CLIMB TOWARD 8KFT. DUE TO
THE COLD AIR...SLR/S WILL BE LOWER...BUT WHATEVER LES OCCURS WILL BE
EFFICIENT AT REDUCING VSBY. SEEMS THAT SOME HAZARDS FOR THE SNOW AND
BLSN MAY BE NEEDED AND LOW VSBY AFFECT WOULD ONLY BE ENHANCED DUE TO
THE ICE COVER NEAR THE SHORELINE OF LK SUPERIOR. WILL MENTION THIS
IN THE HWO.

WILL BE AROUND WIND CHILL ADVISORY CRITERIA FOR AT LEAST WESTERN CWA
LATE WEDNESDAY NIGHT INTO THURSDAY MORNING AS TEMPS DROP TOWARD 10
BELOW AND WINDS ARE AT LEAST 5-10 MPH FM THE NW. ELSEWHERE...NW FLOW
OFF LK SUPERIOR WILL MODERATE TEMPS AND KEEP WIND CHILLS ABOVE 20
BELOW. LES DIMINISHES AND EVENTUALLY ENDS BY NEXT FRIDAY AS WINDS
BACK SW WITH HIGH PRESSURE DROPPING ACROSS THE CENTRAL PLAINS. COLD
FOR ALL ON FRIDAY MORNING WITH MOST AREAS BLO ZERO...BUT WINDS SHOULD
BE LIGHT ENOUGH TO RESTRICT WIND CHILL ISSUES AT THAT TIME.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1146 PM EST FRI JAN 30 2015

A TROUGH OVER NW MN WILL CROSS CENTRAL LAKE SUPERIOR BY 12Z. LOOK
FOR -SN TO PICK UP IN INTENSITY ALONG AND BEHIND THE FRONT AND
CONDITIONS AT SAW AND IWD WILL BE MVFR AND STAY THERE THROUGH THE
REST OF THE FORECAST PERIOD. LES AND GUSTY WINDS PRODUCING BLSN AND
LOWER VSBY INTO IFR CATEGORY IS EXPECTED AT CMX OVERNIGHT BEFORE
GOING TO MVFR BY AFTERNOON.
&&

.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...JLA
AVIATION...07
MARINE...TITUS



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