Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 160830
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
330 AM EST TUE DEC 16 2014

.UPDATE...
ISSUED AT 825 PM EST MON DEC 15 2014

SINCE THE LATEST SHORT TERM GUIDANCE HAS TENDED TO SLOW THE INFLUX
OF COLDER AIR...RAISED FCST MIN TEMPS A FEW DEGREES AND SLOWED THE
CHANGE TO SN BY A FEW HRS. SINCE VSBYS ARE SLOWLY COMING UP AT MANY
PLACES...ALSO LET THE DENSE FOG ADVYS EXPIRE AT 01Z. DID ISSUE AN
SPS FOR LINGERING DENSE FOG PATCHES...WHICH WL LAST LONGEST OVER THE
E HALF OF THE CWA WITH A LATER COLD FROPA/MORE PERSISTENT S WIND OFF
LK MI.
&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 311 PM EST MON DEC 15 2014

UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER THE CENTRAL
PLAINS AND A NORTHERN TROUGH OVER SOUTH CENTRAL CANADA THIS MORNING.
THERE IS ALSO RIDGING OVER THE ERN U.S. AND THE ROCKIES. THE CLOSED
LOW AND THE TROUGH TRY TO MERGE INTO ONE SYSTEM AS THE LOW HEADS
NORTHEAST AND THE TROUGH DIGS SOUTHEAST TODAY. THE NORTHERN STREAM
SYSTEM TAKES OVER AS THE STRONGER SYSTEM TUE AFTERNOON. NAM...GFS
AND ECMWF SHOW 850-500 MB Q-VECTOR CONVERGENCE REMAINING OVER THE
AREA THROUGH TUE AFTERNOON.

DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. COLDER AIR
COMES IN TONIGHT WHICH WILL START TO GET RID OF THE FOG...SO WILL
LET DENSE FOG ADVISORY EXPIRE AT 8 PM. FOLLOWED A BLEND OF THE
ECMWF...GFS AND NAM FOR THIS FORECAST FOR PCPN TYPES AND WAS NOT
MUCH DIFFERENT FROM GOING FORECAST AND SNOW DOES NOT REALLY GET
STARTED ACROSS THE WEST UNTIL AFTER MIDNIGHT. DID NOT WORRY TOO MUCH
ABOUT SLEET OR FREEZING RAIN AS THIS DID NOT LOOK LIKE IT WOULD LAST
VERY LONG AT ALL AND KEPT THE PCPN GOING FROM RAIN TO SNOW FOR THIS
FORECAST. BROUGHT THE COLD AIR IN A LITTLE SLOWER THAN PREVIOUS
FORECAST AND DID NOT MAKE TOO MANY CHANGES TO THE GOING TEMPERATURES
AND DID NOT MAKE TOO MANY CHANGES TO POPS OR QPF AMOUNTS EITHER.
SNOW AMOUNTS LOOK TO BE 1-4 INCHES ON TUESDAY WITH THE SNOW REALLY
STARTING UP LATE IN THE AFTERNOON. AMOUNTS LOOK TO BE LIGHT UNTIL
THEN AND WILL NOT GO WITH ANY ADVISORIES AT THIS TIME.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 330 AM EST TUE DEC 16 2014

THE UPPER LOW WILL BE OVER THE GREAT LAKES REGION AT 12Z
WEDNESDAY...WHILE THE 1006MB SURFACE LOW IS LOCATED OVER FAR
SOUTHEAST ONTARIO. A MID LEVEL TROUGH WILL BE STRETCHING WEST
ACROSS UPPER MICHIGAN AND WILL BE THE PRIMARY FOCUS FOR THE LIGHT
TO OCCASIONALLY MODERATE SNOW OVER MUCH OF UPPER MICHIGAN. THE
STRONGEST SNOW SHOWERS WILL BE OCCURRING OVER THE WESTERN AND NORTH
CENTRAL U.P. WHERE NORTH-NORTHWEST WINDS AND 850MB TEMPS AROUND
-14C WILL LEAD TO LAKE AND TERRAIN ENHANCEMENT. THESE FAVORABLE
CONDITIONS WILL REMAIN FOR THE MORNING HOURS...BUT THEN THE MID
LEVEL TROUGH WILL DROP SOUTH THROUGH UPPER MICHIGAN WEDNESDAY
AFTERNOON...LEADING TO WINDS SHIFTING TO THE NORTH-NORTHEAST AND
BRINGING WARMER 850MB AIR OVER THE AREA. THUS...SHOULD SEE THE
INTENSITY OF THE LAKE ENHANCEMENT DIMINISHING THROUGH THE AFTERNOON
AND INTO THE EVENING HOURS. IT WILL LIKELY LINGER THE LONGEST OVER
THE NORTH CENTRAL DUE TO THE FAVORABLE WIND DIRECTION. WITH MUCH OF
THE FORCING BELOW THE DGZ...WOULD EXPECT THE SNOW RATIOS FOR MUCH OF
THE AREA TO BE IN THE 12-15 TO 1 RANGE. THE ONE AREA WHERE VALUES
COULD BE A LITTLE HIGHER WOULD BE OVER THE WEST...WHERE THE LOW
LEVEL TEMPERATURES ARE A LITTLE COLDER AND PUTTING MORE OF THE CLOUD
IN THE DGZ. BUT EVEN THEN...A LOT OF THE LAKE ENHANCED FORCING IS AT
OR BELOW THE DGZ...WHICH WOULD SUPPORT RIMING OF ANY DENDRITES AND
IN TURN RATIOS IN THE 15-17 TO ONE RANGE. ALL IN ALL...ADDITIONAL
SNOWFALL AMOUNTS ON WEDNESDAY WILL BE IN THE 1-3 INCH
RANGE...HIGHEST IN THE TERRAIN/LAKE ENHANCED AREA OF NORTH CENTRAL
UPPER MICHIGAN.

WITH THE DRIER/WARMER AIR QUICKLY DIVE INTO THE REGION WEDNESDAY
NIGHT...WILL BRING AN END TO THE SNOW SHOWERS FROM NORTH TO SOUTH
THROUGH THE NIGHT. THIS TRANSITION IS SEVERAL HOURS FASTER THAN
SHOWN 24HRS AGO IN THE MODELS AND HAVE SHOWN THAT FASTER END IN THE
POPS. THAT WARMER/DRIER AIR IS ASSOCIATED WITH AN UPPER RIDGE AND
SURFACE HIGH SHIFTING OVER THE UPPER GREAT LAKES REGION. THESE
FEATURES WILL REMAIN IN PLACE THROUGH AT LEAST FRIDAY. THERE ARE
SOME HINTS OF MOISTURE AROUND 925MB BEING TRAPPED BELOW THE
SUBSIDENCE INVERSION ON THURSDAY. WILL HOLD ONTO MOSTLY CLOUDY SKIES
IN THE MORNING IN THE NORTH-NORTHEAST WIND FAVORED AREAS AND THEN
TRANSITION TO PARTLY CLOUDY IN THE AFTERNOON AS THE SFC-925MB
DELTA-T VALUES BECOME MORE MARGINAL.

MODELS CONTINUE TO DIFFER WITH THE EVOLUTION OF BOTH
UPSTREAM/DOWNSTREAM FEATURES WHICH LEADS TO A LITTLE LOWER
CONFIDENCE IN THE WEEKEND FORECAST. THE FIRST FEATURE THAT THEY
DIFFER ON IS A SHORTWAVE PULLING OUT OF THE SOUTHERN PLAINS AND OFF
THE MID ATLANTIC COAST. THE 12Z GEM/ECMWF DEVELOP A STRONGER LOW
WITH A MUCH MORE AMPLIFIED TROUGH...WHILE THE 00Z GFS IS MUCH WEAKER
WITH THE LOW AND FLATTER WITH THE WAVE. LOOKING AT THE ENSEMBLE
MEANS/MEMBERS...THE 12Z ECMWF MEMBERS ARE REMARKABLY CONSISTENT IN
THE EVOLUTION OF THE LOW OFF THE MID ATLANTIC STATES. BUT WHERE
THINGS DIFFER IS WITH THE HANDLING OF THE NEXT WEAK SHORTWAVE MOVING
THROUGH THE NORTHERN STREAM FLOW SATURDAY INTO SUNDAY. WHILE THE 12Z
GEM/ECMWF OPERATIONAL RUNS HOLD ONTO AN UPPER RIDGE OVER THE UPPER
MISSISSIPPI VALLEY DURING THIS TIME...THE ENSEMBLE MEANS MORE
CLOSELY RESEMBLE THE GFS IN THE IDEA OF A WEAK UPPER TROUGH MOVING
THROUGH THE UPPER MISSISSIPPI VALLEY AND THEN THE UPPER GREAT LAKES
THIS WEEKEND. BASED OFF THE 12Z ENSEMBLE MEANS AND THE 00Z
GEM/ECMWF OPERATIONAL RUNS COMING IN MORE IN LINE WITH THAT
IDEA...WILL FOLLOW THAT FOR THIS FORECAST. BUT EVEN WITH THAT WEAK
UPPER TROUGH MOVING THROUGH...THE SURFACE HIGH WILL BE PERSISTENT
AND SHOULD LEAD TO DRY CONDITIONS. 850MB TEMPS LOOK TO BE AROUND
-6C...WHICH IS EVEN MARGINAL FOR LAKE EFFECT CLOUDS IF THERE WAS
ENOUGH MOISTURE PRESENT...SO WILL GO WITH A DRY FORECAST AND PARTLY
CLOUDY SKIES ON SATURDAY AND MOSTLY CLOUDY ON SUNDAY. HIGHS THURSDAY
WILL START OUT NEAR NORMAL THEN SLOWLY WARM TO SLIGHTLY ABOVE NORMAL
VALUES (UPPER 20S AND LOWER 30S) FOR THE WEEKEND.

HEADING INTO NEXT WEEK...ECMWF/GEM/GFS ENSEMBLE MEANS HAVE BEEN
CONSISTENT FOR THE LAST SEVERAL DAYS TO A WEEK ON AN UPPER TROUGH
DROPPING SOUTHEAST FROM THE GULF OF ALASKA AND INTO THE NORTHERN
CONUS. THIS WILL LEAD TO A COOLER PERIOD AROUND CHRISTMAS AND
LIKELY REMAINING FOR THE END OF DECEMBER. ALTHOUGH IT IS STILL 8-9
DAYS OUT...THE CONSISTENCY IN THE ENSEMBLE MODELS ON THIS IDEA
IS WORTH MENTIONING. THEY CONTINUE TO SHOW A CANADIAN LOW TO DROP
THROUGH ONTARIO OR THE UPPER GREAT LAKES REGION ON THE 24TH OR
25TH. WHILE SNOW AMOUNTS ARE UNFORECASTABLE AT THIS TIME...AT
LEAST LIGHT SNOW IS EXPECTED DURING THAT BUSY HOLIDAY TRAVEL PERIOD.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1237 AM EST TUE DEC 16 2014

ALTHOUGH IFR CONDITIONS WL PREDOMINATE AT THE SITES EARLY THIS MRNG
AS AREA OF LARGER SCALE PCPN MOVES OVHD AND COLDER AIR MOVES INTO
THE UPR LKS BEHIND SLOW MOVING COLD FNT... WEAK UPSLOPE FLOW AT CMX
MAY ALLOW FOR SOME MVFR CONDITIONS THERE EARLY IN THE PERIOD. LATER
ARRIVAL OF THE FNT AND MORE SHALLOW NATURE OF THE COLD AIR INFLOW WL
LEAD TO THE POTENTIAL FOR SOME VLIFR CONDITIONS AT SAW UNTIL
SUNRISE. THEN CYC...GUSTY N FLOW THRU TODAY WL LEAD TO WIDESPREAD
-SN/PREDOMINANT IFR CONDITIONS. SOME HEAVIER SN MAY IMPACT THE SITES
TNGT AS ANOTHER DISTURBANCE SLIDES SE THRU THE UPR LKS...LEADING TO
A PERSISTENCE OF IFR TO LIFR CONDITIONS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 311 PM EST MON DEC 15 2014

COLDER AIR WILL MOVE INTO THE AREA THIS EVENING REDUCING THE FOG.
EXPECT N-NW WINDS OF 20-30KTS LATE THIS EVENING INTO EARLY TUESDAY
EVENING. A FEW GALE FORCE GUSTS TO 35KTS WILL BE POSSIBLE AND THIS
WILL BE THE STRONGEST WIND FORECAST FOR THE ENTIRE FORECAST. NO
GALES SEEN ANYTIME SOON OTHERWISE.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
  DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR LMZ221-248-
     250.

&&

$$

UPDATE...KC
SHORT TERM...07
LONG TERM...SRF
AVIATION...KC
MARINE...07





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