Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 080050
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
750 PM EST Wed Dec 7 2016

.NEAR TERM...(Tonight)
Issued at 403 PM EST Wed Dec 7 2016

...Lake convection to ramp up tonight...

High Impact Weather Potential: Snow shower coverage increasing this
evening across the tip of the mitt/northwest Lower...and into
eastern Upper late tonight and into Thursday morning.

Pattern Synopsis/Forecast: Afternoon surface analysis shows 998mb
surface low along the southwest shore of James Bay...with a couple
of surface troughs extending to the west and south of this low...
along with a pretty decent pressure gradient across the upper
Midwest/northern Plains and Manitoba.  1040+mb surface ridge
associated with invading Arctic air mass edging down the
northern/central high Plains banked up against the Rocky Mountains.
Southwest boundary layer flow across Lake Michigan this afternoon
has been pushing snow showers through the Straits and tip of the
mitt counties...there is also some synoptically driven light snow
across central upper.  Broad upper troughing in place this afternoon
across much of North America this afternoon...closed low within this
trough over far northern Lake Superior.

Upper low will continue to pull away to the northeast tonight...
which opens the door to much colder air spilling across the Great
Lakes over the coming days.  Surface trough that extends to the west
of the James Bay low will start to pivot southeast tonight...and
move into Michigan/Wisconsin on Thursday.

Primary Forecast Concerns: Snow...and more snow.  Main event should
start to ramp up tonight...expecting coverage of westerly flow LES
to increase off Lake Michigan this evening and continue into the
overnight hours...initially along/north of the M-32 corridor then
expanding south of the Leelanau Peninsula. Generally like a swath of
2-4 inches of snow tonight from Leelanau/ Antrim/Otsego counties and
north...with 1-3 inches along and west of US-131/south of M-72. Much
of eastern Upper will be fairly quiet this evening...but overnight
looking for a narrow but more intense band of snow aligned along the
southward moving surface trough to drop south off Lake Superior and
across much of the Upper Peninsula...perhaps arriving in time to
impact the morning commute.

&&

.SHORT TERM...(Thursday and Friday)
Issued at 403 PM EST Wed Dec 7 2016

...First big lake snow event of the season Thursday/Friday...

High Impact Weather Potential: Lake snow squalls and gusty winds.

Pattern Synopsis/Forecast: Surface trough will continue to drop
southeast across the upper Lakes Thursday...which will serve to veer
boundary layer winds around to more of a north/northwest direction.
This in turn will strengthen cold advection across the region
especially going into Thursday night/Friday.

Primary Forecast Concerns: More snow.  Surface trough rotating
across the forecast area during the day Thursday should result in a
transition from westerly lake effect snow (with some enhancement
along surface trough)...to north/northwest oriented multi-band
convection with a long effective fetch off Lake Superior (and
possibly off Lake Nipigon as well).  May take some time for things
to get organized during the day with shifting winds so snowfall may
tend to get "fanned out" for a time...but by mid/late afternoon
anticipating organized bands to really get going.  Current thinking
on Thursday daytime snowfall totals of 2-6 inches across the "Big 5"
counties of Charlevoix/Otsego/Crawford/Kalkaska/Antrim (heavier
amounts more likely over the latter two)...and anywhere from 1-4
inches across eastern Upper and the remainder of northwest Lower.
Accumulations of lighter/fluffier snow should also begin to increase
the threat for blowing snow issues especially in open areas near
Lake Michigan.

Based on snowfall totals from Thursday through Friday afternoon...
have made some adjustments to ongoing headlines. Have added
Charlevoix/Missaukee counties to the Winter Storm Warning...and
Roscommon county to the Winter Weather Advisory.

JPB

Thursday night through Saturday night...The cold, snowy and wintry
pattern which began earlier in the week, will continue across the
Great Lakes region.

The deep 500mb upper trough centered on the eastern Great Lakes and
New England Thursday...will push east allowing the upper flow to
flatten and become more zonal Friday and into the weekend. 850mb
temperatures in this upper pattern will remain nearly steady between
-14c and -16c through Saturday. At the surface, the strong storm
system which moved over Ontario Wed, will continue to exit northeast
across Quebec and into the north Atlantic Friday. Cyclonic flow on
the backside of this exiting storm system will linger over the Great
Lakes through Friday, before weakening Saturday. A narrow area of
high pressure will push over the region Saturday, in advance of yet
another storm system organizing in the Plains and lifting north into
the region by Sunday.

Model soundings showing conditions favorable for continued lake
induced snows over northwest Lower and east Upper Michigan through
Saturday. 925-850mb winds will remain locked in from the northwest
Thursday night through Friday afternoon with inversion heights
remaining over 6k feet. 925-850mb winds trend west Saturday before
southwest Saturday evening (inversion heights remaining around 6k
feet). NCAR ensemble 12hr max accumulated snow forecasts, show two
significant snow bands Friday into early Saturday with connections
to Lake Superior...focusing heavy snows around Grayling, Kalkaska,
Mancelona, Alba, Fife Lake. Snowfall totals in these areas from
Thursday through Friday afternoon likely to exceed 10 inches.

For locations away from the influences of Lake Michigan and
Lake Superior, mainly between Alpena to Saginaw Bay...will diminish
snow chances Friday through Saturday as cyclonic flow continually
weakens on the backside of the exiting storm system.

SWR

.LONG TERM...(Friday night through Wednesday)
Issued at 403 PM EST Wed Dec 7 2016

High Impact Weather Potential: Additional snow accumulations with
synoptic system Sunday (perhaps Monday if it slows down) and
continued lake effect afterward into mid-week. Gusty winds and cold
temperatures mid-week may bring single digit, perhaps some negative,
wind chills.

Active weather will continue through the extended period. The first
issue will be a system coming through in the Sunday/Monday
timeframe. This has the potential to bring a few more inches of snow
accumulation to the area. There is a good deal of uncertainty with
this system right now, with a lot of divergence in speed, track, and
strength among guidance. The track has been slowly converging
towards a SE MI passage, will see if that continues. The magnitude
of H5 troughing is also quite different at this point, with more
aggressive troughing resulting in a much deeper low from the Euro.
Either way, we are looking at picking up at least a few more inches
Sunday/Monday, with more significant totals not out of the
question this point.

H8 temps will continue to drop, with some of the coldest air of the
season paying a visit mid-week. This will result in continued lake
effect behind the aforementioned synoptic system, bringing further
accumulations. As the coldest air moves in, high temperatures could
struggle to get out of the teens by mid-week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 744 PM EST Wed Dec 7 2016

Conditions becoming predominantly MVFR.

Lake effect snow conditions steadily improve tonight through
Thursday as the coldest air of the season overspreads the northern
lakes region. Initially, heaviest snows will impact the tip of the
mitt areas (PLN) tonight. But veering winds toward west and
eventually northwest will push heavier lake snow showers down
toward TVC and MBL on Thursday. Potential for a period of heavy
snow showers at TVC Thursday morning as secondary cold front
swings down through northern Michigan.

&&

.MARINE...
Issued at 403 PM EST Wed Dec 7 2016

Gale Warnings to remain up on Lake Michigan sans the Seul Choix
Point to the Bridge zone which has been put into a Small Craft
Advisory. Advisories on Lake Huron and in the Lake Superior zones
have been extended through the day Thursday.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING from midnight tonight to 3 PM EST Friday
     for MIZ019>021-025>027-031>033.
     WINTER WEATHER ADVISORY from midnight tonight to 3 PM EST Friday
     for MIZ016-017-022-028-034.
     LAKE EFFECT SNOW ADVISORY from midnight tonight to 3 PM EST
     Friday for MIZ008.
LH...SMALL CRAFT ADVISORY until 5 PM EST Thursday for LHZ348-349.
     GALE WARNING until 7 AM EST Thursday for LHZ345>347.
LM...SMALL CRAFT ADVISORY until 5 PM EST Thursday for LMZ341.
     GALE WARNING until 7 AM EST Thursday for LMZ323-342-344>346.
LS...SMALL CRAFT ADVISORY until 7 AM EST Friday for LSZ321-322.
&&

$$

NEAR TERM...JPB
SHORT TERM...JPB/SWR
LONG TERM...ALM
AVIATION...TBA
MARINE...JPB


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