Area Forecast Discussion
Issued by NWS Gaylord, MI

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710
FXUS63 KAPX 091125
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
625 AM EST Fri Dec 9 2016

.NEAR TERM...(Today and Tonight)
Issued at 343 AM EST Fri Dec 9 2016

...Prolonged accumulating lake effect snow event continues...

High Impact Weather Potential...Accumulating lake effect snow.

Pattern Synopsis/Forecast...NW low level flow lake effect snow event
continues across Northern Michigan early this morning. Deep cyclonic
flow remains over the entire Great Lakes region...but a look
upstream shows upper level ridging has reached the Upper Mississippi
Valley with the surface ridge axis extending thru the Plains states
attm. Back in Northern Michigan...some of the heavier lake snow
bands have generally been producing around 1 inch an hour snowfall.
However...banding has been wavering a bit throughout the night...
resulting in a more even distribution of snow accumulation across
the region. Main dominant band currently extends from Central Upper
Michigan per KMQT base ref images thru Northern Lake Michigan into
Antrim county attm under the direction of NW low level winds. Winds
will change very little thru the morning and into early afternoon...
with inversion heights holding around 7-8 kft. 850-700 mb RH will
hold around 90 pct...and certainly over-lake instability will remain
more than sufficient for sustained lake effect snow shower
production. By late afternoon/early evening...low level winds begin
to gradually back toward a more W/NW trajectory and then hold there
for the remainder of the night.

Primary Forecast Concerns...Additional snowfall potential remains
the primary focus thru tonight...with shifting wind direction
playing a large role in the evolution of snowfall amounts and POPS.
With relatively consistent NW low level winds holding thru early
afternoon...locations along and west of US-131 will remain the
target for highest POPs and greatest additional snowfall amounts.
These areas will likely receive another 4 to 8 inches of additional
snowfall thru early afternoon...which certainly justifies
maintaining the ongoing Winter Storm Warning for these areas.
Locations just outside of this area with in an Advisory...including
Chippewa county...will receive another 2 to 4 inches thru early
afternoon. Thus...will keep all Advisories in tact as well. Backing
winds to the W/NW during mid to late afternoon will certainly shift
lake snow bands northward and slightly further east into far
Northern Lower Michigan. At that point...headlines will need to be
reassessed and likely adjusted as it appears lake effect snow
production will continue thru tonight and into Saturday.

&&

.SHORT TERM...(Saturday through Sunday)
Issued at 343 AM EST Fri Dec 9 2016

...Continuing Lake effect...

High Impact Weather Potential...Continuing lake effect in the NW and
WNW flow regions will make traveling difficult from TVC to MGN,
especially near ACB, GLR, and GOV.

Pattern Synopsis/Forecast...Saturday, the lake aggregate trough at
the sfc, begins to fill as sfc high pressure begins to build into
the forecast area, more. At 500 mb, the flat flow will continue a
steady train of shortwaves to move over the region, with the next
sfc low moving into the Central Plains on Sunday, turning the winds
to the southeast and warming temperatures a bit more. The current
track looks to keep the forecast area in the cold air so that snow
is expected.

Main concern is the LES potential on Saturday, especially the
morning as the winds shift from the NW to the WNW and then W by the
end of the day. This would put a bull`s eye in Antrim county through
that shift. At this point it looks like moderate amounts of snow
during the transition. After that the winds become WSW and SW, with
the moisture beginning to cut off for a bit before the next system
moves into S Lower and S Lake Huron by 12z/Mon.

.LONG TERM...(Monday through Thursday)
Issued at 343 AM EST Fri Dec 9 2016

With the retreating low on Monday morning, and the flat flow at
500 mb, the 850 mb and sfc temperatures fall Monday and Tuesday,
with the 850 mb temperatures ending up in the -20c or colder range
through Wednesday. Thursday, the 850 mb temperatures start to warm
up a bit, but not enough to stop the LES machine. wind directions
and the moisture in the 850- 700 mb layer will have to be watched
to determine the snow amounts. The GFS and ECMWF have different
wind regimes and moisture profiles so it could be minor or
moderate.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 625 AM EST Fri Dec 9 2016

Lake effect snow showers will continue to impact much of Northern
Lower Michigan thru Saturday morning. Focus of heavier snow bands
will gradually shift from TVC and MBL northward to PLN later this
afternoon and tonight as low level winds shift from the NW to
W/NW. Conditions will drop to MVFR/IFR within heavier snow bands.
Wind speeds will generally be 10 to 15 kts today with a few higher
gusts possible...diminishing to below 10 kts tonight.

&&

.MARINE...
Issued at 343 AM EST Fri Dec 9 2016

SCA winds and waves will linger for nearshore areas from Manistee
to Grand Traverse Light this morning. NW low level flow lake
effect snow showers will continue to stream into most of our area
thru Saturday night as cold air and low level moisture remain in
place across the Great Lakes region.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING until 3 PM EST this afternoon for
     MIZ019>021-025>027-031>033.
     WINTER WEATHER ADVISORY until 3 PM EST this afternoon for MIZ016-
     017-022-028-034.
     WINTER WEATHER ADVISORY until noon EST today for MIZ018-024.
     LAKE EFFECT SNOW ADVISORY until 3 PM EST this afternoon for
     MIZ008.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 11 AM EST this morning for LMZ344>346.
LS...NONE.
&&

$$

NEAR TERM...MLR
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...MLR
MARINE...MLR



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