Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 271000
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
500 AM EST SAT DEC 27 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 337 PM EST FRI DEC 26 2014

AN ELONGATED SURFACE TROUGH STRETCHING FROM A 1007MB LOW IN THE
TEXAS PANHANDLE NORTHEAST THROUGH MISSOURI AND INTO EASTERN UPPER
MICHIGAN WILL BE A CONTRIBUTING FEATURE TO THE WEATHER IN THE SHORT
TERM. PRESENTLY...SKIES ARE CLOUDS ACROSS UPPER MICHIGAN WITH
TEMPERATURES IN THE UPPER 20S AND LOWER 30S. THERE ARE LIGHT SNOW
SHOWERS OVER WESTERN AND NORTH CENTRAL UPPER MICHIGAN TIED A THIN
POCKET OF MID LEVEL FGEN. AS THE TROUGH CONTINUES TO SAG SOUTHEAST
ACROSS THE CWA...STARTING TO SEE A SLIGHT INCREASE IN THE LIGHT LOW
LEVEL NORTHERLY FLOW AND IN TURN LIGHT LAKE/TERRAIN ENHANCEMENT AT
KIWD.

UPSTREAM...A SHORTWAVE ROUNDING THE THE BASE OF THE UPPER TROUGH IN
NEW MEXICO WILL LIFT NORTHEAST TONIGHT AND ACROSS SOUTHEASTERN
UPPER MICHIGAN ON SATURDAY. AS THIS OCCURS...A SURFACE LOW WILL
DEVELOP IN MISSOURI ALONG THE TROUGH TONIGHT AND QUICKLY MOVE
NORTHEAST THROUGH FAR NORTHERN LOWER MICHIGAN AROUND 18Z ON
SATURDAY AND THEN INTO QUEBEC SATURDAY EVENING. THERE LOOKS TO BE
TWO WAVES OF PRECIPITATION AS THESE FEATURES LIFT NORTHEAST THROUGH
THE AREA...WITH THE HEAVIEST PRECIPITATION AFFECTING CENTRAL/EASTERN
UPPER MICHIGAN. THE FIRST WAVE WILL ARRIVE AFTER MIDNIGHT
TONIGHT...WITH AN INITIAL WEAK SHORTWAVE...BROAD MID LEVEL WARM
AIR ADVECTION AND ISENTROPIC ASCENT (ON 285-295K SFCS). THIS BEST
FORCING LOOKS TO BE OVER CENTRAL AND WEST-CENTRAL UPPER MICHIGAN
AND WILL FOCUS THE HIGHEST POPS AND QPF THERE. THEN THE SECOND WAVE
WILL ARRIVE WITH THE FORCING FROM THE SHORTWAVE AND SURFACE LOW
MOVING THROUGH THE REGION TOMORROW MORNING THROUGH EARLY AFTERNOON.
SECOND WAVE WILL HAVE THE FORCING (INCLUDING 900-750MB FGEN) MORE
OVER THE SOUTHEAST THIRD OF THE CWA AND CLOSER TO LAKE MICHIGAN AND
TREND HIGHER QPF IN THAT AREA. ALL TOLD...MODELS ARE IN DECENT
AGREEMENT ON QPF AMOUNTS GREATER THAN 0.25IN SOUTHEAST OF A LINE
FROM BARAGA TO MARENISCO AND 0.33-0.4 INCH SOUTHEAST OF A LINE FROM
THE HURON MOUNTAINS TO IRON RIVER. DO HAVE A LITTLE BIT OF A CONCERN
ON THE WESTWARD TREND IN SOME OF THE 12Z RUNS WITH THE INITIAL WAVE
BRINGING THE SNOW MORE OVER THE WESTERN CWA AND THE EVENING SHIFT
WILL NEED TO KEEP AN EYE ON THE TRENDS.

AS FOR SNOW RATIOS...MUCH OF THE MID LEVEL FORCING IS WITHIN THE
DGZ AND A LOT OF THE SNOW RATIO WILL DEPEND ON THE BOTTOM 10KFT OF
THE ATMOSPHERE. NEAR LAKE MICHIGAN...BELOW 10KFT THE TEMPERATURES
ARE ABOVE -10C WHICH WOULD SUPPORT AGGREGATION AND LOWER SNOW
RATIOS (CLOSER TO 10-1). BUT A LITTLE FARTHER
NORTHWEST...TEMPERATURES ARE A LITTLE COOLER AND ENDS UP KEEPING
MORE OF THE CLOUD LAYER ALONG THE BOTTOM OF THE DGZ. THIS WOULD KEEP
RATIOS A LITTLE HIGHER AND IN THE 13-15 TO 1 RANGE. USING THOSE
VALUES GIVES SNOWFALL AMOUNTS THROUGH SATURDAY OF 1-3 INCHES OVER
KEWEENAW/HOUGHTON/ONTONAGON COUNTIES...WITH A GENERAL 3-5 OVER THE
REST OF THE AREA. 09Z SREF MEAN VALUES ARE GENERALLY IN THE 3-4
INCH RANGE FOR MUCH OF CENTRAL/EASTERN UPPER MICHIGAN WHICH
MATCHES WELL WITH THE GOING FORECAST. DO HAVE THE HIGHEST AMOUNTS
OVER THE NORTH CENTRAL DUE TO WEAK TERRAIN/LAKE ENHANCEMENT THAT
WILL ADD ABOUT A HALF INCH OF SNOW TO AREAS FAVORED BY
NORTH-NORTHEAST WINDS.

WITH THOSE SNOWFALL AMOUNTS...HAVE ISSUED AN ADVISORY FOR
BARAGA/IRON COUNTIES EASTWARD. ALTHOUGH THOSE TOTALS ARE OVER AN 18
HOUR PERIOD...THINK MOST LOCATIONS WILL BE ON THE EDGE OF OUR
3IN/12HR CRITERIA. PLUS...WITH IT BEING ON THE TAIL END OF THE
HOLIDAY TRAVEL PERIOD...THOUGHT THE MODERATE SNOW OVER THE
SOUTHEAST DURING THE MID MORNING THROUGH EARLY AFTERNOON
HOURS WARRANTED THE ADVISORY. AS MENTIONED PREVIOUS...WILL NEED TO
WATCH THE NORTHWEST EDGE OF THE ADVISORY AS CURRENT SNOWFALL AMOUNTS
OVER SOUTHEAST ONTONAGON/HOUGHTON COUNTIES NEAR ADVISORY CRITERIA
AND ANY SHIFT TO THE NORTHWEST MAY CAUSE THEM TO BE ADDED TO IT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 458 AM EST SAT DEC 27 2014

WILL START OUT 12Z SUNDAY WITH A COLD FRONT DRAPED ACROSS THE FAR W
CWA. THIS WILL BE THE FOCUS FOR LIGHT TO POTENTIALLY MODERATE SNOW
SHOWERS FROM AROUND ONTONAGON UP THROUGH THE KEWEENAW PENINSULA. AS
NOTED IN THE PREVIOUS DISCUSSION...A LES ADVISORY BY BE NEEDED FOR
ONTONAGON AND HOUGHTON COUNTIES. CURRENTLY FORECASTING 3-5IN OF NEW
SNOW IN THIS AREA OVERNIGHT THROUGH SUNDAY EVENING. WILL HOLD OFF ON
ISSUING ANYTHING AS ONTONAGON AND S HOUGHTON HAVE BEEN INCLUDED IN
THE INITIAL WINTER WX ADVISORY FOR TODAY.

WITH COOLER AIR SLIDING IN...LOOK FOR SNOW RATIOS TO BE ON THE
INCREASE...RANGING FROM AROUND 20-23:1 THROUGH MUCH OF THIS PERIOD.
THE SFC TROUGH WILL SLOWLY EXIT AS STRONG AND COLD HIGH PRESSURE
PUSHES FROM FAR NW CANADA SUNDAY TO BRITISH COLUMBIA/ALBERTA ON
MONDAY...WITH A SIZABLE RIDGE EXTENDING INTO THE UPPER GREAT LAKES.

THE LOWERING INVERSION HEIGHTS /AROUND 850MB AT IWD/ WILL START TO
BECOME A CONCERN FOR MODERATE/HEAVY SNOWFALL DEVELOPMENT FROM 00Z
MONDAY ON ACROSS THE CWA. STILL EXPECTING 12HR SNOW TOTALS OF 1-3IN
WHERE THE BEST CONVERGENCE DEVELOPS WITH PLENTY OF MOISTURE STILL
STUCK IN OUR STEADY NW FLOW INTO TUESDAY.

THE COLDEST AIR LOOKS TO SWING IN TUESDAY NIGHT...ON THE ORDER OF
-21 TO -24C. IF WINDS BECOME MORE WESTERLY AND THE INTERIOR W HALF
CLEARS OUT...THIS COULD BE A VERY CHILLY NIGHT. CURRENTLY CALLING
FOR -5 TO -10F LOWS BY DAYBREAK WEDNESDAY UNDER A PARTLY CLOUDY SKY.

THERE MAY BE A BRIEF REPRISE FROM THE STEADY NW TO WNW WINDS
WEDNESDAY INTO WEDNESDAY NIGHT. POPS/WX MAY NEED TO BE DIMINISHED
FROM THE CURRENT FCST FOR WEDNESDAY NIGHT IF THIS TREND HOLDS UP.
THERE IS PLENTY OF DISCREPANCIES BETWEEN THE AVAILABLE GUIDANCE AT
THIS POINT...VARYING FROM -20C 850MB AIR OVERHEAD ON GUSTY NW WINDS
/UP TO 40KTS AT 850MB/ FROM THE 27/00Z GFS...AND MORE W-WSW WINDS
WITH -12C 850MB TEMPERATURES OFF THE 26/12Z ECMWF. WILL KEEP GOING
WITH A GENERAL BLEND BETWEEN THE CONSENSUS AND OUR PREVIOUS FORECAST
BEYOND THIS POINT GIVEN THE MODERATE TO LOWER CONFIDENCE.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1223 AM EST SAT DEC 27 2014

MVFR CIGS WILL GIVE WAY TO IFR/LIFR CONDITIONS BY LATE TONIGHT OR
EARLY SATURDAY AS LOW PRESSURE OVER SE IA LIFTS NORTHEAST TO NORTHERN
LOWER MI SAT AFTERNOON. THE LOW PRESSURE SYSTEM WILL BRING LIGHT TO
OCCASIONALLY MODERATE SNOWFALL ACROSS WEST-CENTRAL UPPER MICHIGAN
OVERNIGHT THROUGH SATURDAY MORNING. HAVE SHOWN LOWERING
CEILINGS/VISIBILITIES AS THIS SNOW MOVES THROUGH...WITH THE WORST
CONDITIONS AT KIWD AND ESPECIALLY KSAW...WHERE CONDITIONS WILL FALL
TO OR REMAIN LIFR. THE LOW AND HEAVIER SNOW WILL QUICKLY DEPART
SATURDAY AFTERNOON AND LEAD TO IMPROVING CONDITIONS TO MVFR THE
AFTERNOON AND TO VFR SAT EVENING.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 337 PM EST FRI DEC 26 2014

EXPECT GENERALLY LIGHT WINDS OVER LAKE SUPERIOR TONIGHT INTO
SATURDAY MORNING AS A WEAK PRESSURE GRADIENT IS IN PLACE DUE TO A
SURFACE TROUGH STALLED OVER THE MACKINAC STRAITS. BUT AS A LOW
LIFTS NORTHEAST ALONG THE TROUGH FROM THE CENTRAL PLAINS ON
SATURDAY AND MOVES INTO QUEBEC BY SATURDAY NIGHT...NORTHWEST WINDS
WILL BE ON THE INCREASE SATURDAY AFTERNOON AND EVENING WITH GUSTS
UP TO 30KTS. BEHIND THE LOW...A WEAK SURFACE TROUGH WILL REMAIN IN
PLACE ON SUNDAY AND KEEP WEST-NORTHWEST WINDS UP TO 25KTS IN PLACE.
A HIGH PRESSURE RIDGE BUILDING INTO THE AREA ON MONDAY FROM A
STRONG HIGH IN THE NORTHERN/CENTRAL PLAINS WILL LEAD TO NORTHWEST
TO NORTHERLY WINDS UP TO 25-30KTS THROUGH TUESDAY. AN APPROACHING
TROUGH FROM A LOW OVER HUDSON BAY ON TUESDAY NIGHT WILL LEAD TO A
TIGHTER PRESSURE GRADIENT AND WESTERLY GALES TO 35-40KTS LATE
TUESDAY NIGHT INTO WEDNESDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ006-
     007-014-085.

  WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
     FOR MIZ004-005-010>013.

  WINTER WEATHER ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON
     FOR MIZ002-009-084.

LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...KF
AVIATION...JLB
MARINE...SRF





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