Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KMQT 262038
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
338 PM EST FRI DEC 26 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...(SATURDAY THROUGH THURSDAY)
ISSUED AT 510 AM EST FRI DEC 26 2014

WILL START OFF SATURDAY MORNING IN THE MIDDLE OF WET SNOW FALLING
ACROSS CENTRAL AND EASTERN UPPER MI. ADDITIONAL DAYTIME
ACCUMULATIONS AT THIS POINT LOOK BE BE 1 TO 3IN. CONFIDENCE IS
GROWING...WITH THE OPERATIONAL MODEL RUNS INDICATING THE SFC LOW
ALONG THE WI/IL BORDER AT 12Z SATURDAY LIFTING ACROSS N LOWER/FAR E
UPPER MI BY 18Z...AND THEN JUST N OF GEORGIAN BY BY 00Z SUNDAY. THE
26/00Z RUN OF THE ECMWF WAS ORIGINALLY FARTHER W...SLOWER...AND
DEEPER...BUT HAS COME GENERALLY IN LINE WITH THE 26/00Z
NAM/GFS/CANADIAN. AS NOTED IN THE SHORT TERM DISCUSSION THE NEEDED
FOR A WINTER WX HEADLINE OF SOME SORT MAY BE NEEDED. A WINTER WX
ADVISORY MAY COVER IT /3-6IN IN A 12 HOUR PERIOD/. THE 18-24 HOUR
DURATION OF THIS EVENT MAKES IT VERY BORDERLINE.

HIGH PRESSURE OVER THE PLAINS STATES WILL TAKE LITTLE TIME TO SLIDE
IN BEHIND THE EXITING LOW SATURDAY EVENING ALONG THE WI
BORDER...HELPING TO GIVE THE AREA A BREAKER BETWEEN THE EXITING
SYNOPTIC SNOW AND THE DEVELOPMENT OF LAKE EFFECT SHOWERS.

W SFC-850MB FLOW AT 00Z SUNDAY UNDER 850MB TEMPS AROUND -11C WILL
REMAIN LESS THAN IDEAL AND VARYING IN DIRECTION AT THE LOW LEVELS
UNTIL COOLER AIR ARRIVES LATE SUNDAY AFTERNOON INTO SUNDAY EVENING.
LOOK FOR SNOW RATIOS TO RETURN TO 20:1 OR MORE FROM SUNDAY MORNING
ON. STILL WITH A SFC TROUGH LINGERING ACROSS S LAKE SUPERIOR SUNDAY
MORNING...THE FOCUS FOR SNOW SHOWERS WILL REMAIN.

OTHERWISE...THE MAIN STORY FOR THIS PERIOD WILL BE THE PROLONGED
PERIOD OF MAINLY NW WINDS LATE SUNDAY THROUGH AT LEAST MONDAY
EVENING...THANKS IN PART TO THE LARGER/COOL HIGH PRESSURE AREA
BUILDING IN FROM NW CANADA. DURING THIS TIME 850MB TEMPS SHOULD BE
AROUND -17C TO -21C. LOOK FOR ADDITIONAL SNOW OF 1-2 IN TO LOCALLY 3
WHERE THE WIND FOCUSES NEAR LAKE SUPERIOR.

THE LARGE HIGH SHOULD SINK INTO THE CENTRAL AND S PLAINS BY
WEDNESDAY. THIS WILL LEAVE THE UPPER GREAT LAKES BETWEEN THIS HIGH
AND A NEARING LOW FROM ONTARIO TUESDAY NIGHT INTO EARLY WEDNESDAY.
AS NOTED...BLOWING SNOW COULD BE A CONCERN ALONG LAKE SUPERIOR AS
WINDS INCREASE WITH THE INCREASED PRESSURE GRADIENT. THE LOW TO THE
N SHOULD SLIP ACROSS S ONTARIO AND NE LAKE SUPERIOR WEDNESDAY
AFTERNOON...LEAVING ANOTHER TROUGH ACROSS LAKE SUPERIOR FOR THE REST
OF THIS FCST PERIOD. WILL BE DIFFICULT TO HAVE AREAS DRY FOR ANY
PROLONGED PERIOD ACROSS THE KEWEENAW PENINSULA...OR E OF MUNISING
ALONG LAKE SUPERIOR.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1252 PM EST FRI DEC 26 2014

A WEAK SURFACE TROUGH SLOWLY SAGGING SOUTHEAST ACROSS UPPER
MICHIGAN HAS BEEN LEADING TO MVFR CEILINGS OVER MUCH OF THE AREA
AND SOME SNOW SHOWERS. THE STRONGEST SNOW SHOWERS AND LOWEST
CEILINGS ARE NEAR IRONWOOD...WHERE WINDS HAVE TURNED TO A
FAVORABLE LAKE ENHANCED SNOW DIRECTION TO GO WITH SOME SYNOPTIC
SNOW MOVING THROUGH THAT AREA. WOULD EXPECT SIMILAR SNOW TO OCCUR
AT KCMX/KSAW THIS AFTERNOON AS WINDS TURN OFF LAKE SUPERIOR.

ATTENTION THEN TURNS TO THE LOW PRESSURE SYSTEM THAT WILL DEVELOP
IN THE CENTRAL PLAINS THIS AFTERNOON AND LIFT NORTHEAST THROUGH FAR
NORTHERN LOWER MICHIGAN. THIS WILL SPREAD LIGHT TO OCCASIONALLY
MODERATE SNOWFALL ACROSS WEST-CENTRAL UPPER MICHIGAN TONIGHT AND
THEN CENTRAL/EASTERN UPPER MICHIGAN 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 LIFR. THIS LOW WILL QUICKLY DEPART SATURDAY AFTERNOON
AND LEAD TO IMPROVING CONDITIONS JUST AFTER THE TAF PERIOD.
&&

.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 FROM 4 AM TO 7 PM EST SATURDAY FOR
     MIZ006-007-014-085.

  WINTER WEATHER ADVISORY FROM 1 AM EST /MIDNIGHT CST/ TO 4 PM EST
     /3 PM CST/ SATURDAY FOR MIZ004-005-010-011.

  WINTER WEATHER ADVISORY FROM 4 AM EST /3 AM CST/ TO 4 PM EST /3
     PM CST/ SATURDAY FOR MIZ012-013.

  WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST
     SATURDAY FOR MIZ009.

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

$$

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





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.