Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 031127
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
627 AM EST Sat Dec 3 2016

.NEAR TERM...(Today and tonight)
Issued at 223 AM EST Sat Dec 3 2016

...Mixed rain and snow showers continue...

High Impact Weather Potential: None

Pattern Synopsis/Forecast: Cool, moist, weakly cyclonic flow
continues across the area, with the region caught between slowly
departing trough and approaching Upper Mississippi Valley ridge.
Elongated vort shear axis along this demarcation, briefly
responsible for an uptick in lake effect showers last evening,
continues to rotate off to the east. Just enough lower level
moisture and over-water instability remains, however, to continue to
produce some very light lake effect showers in favored northwest
flow areas. Much like the last few nights, what form those showers
have taken has been predicated by distance from the big waters and
elevation, with a rain/snow mix across interior regions and all
liquid closer to the lake shores.

Large scale features slowly progress east today and tonight, with
that upstream ridge and associated surface high building directly
overhead by this evening. Lake processes will continue to slowly
abate as a result, although per the usual, will be stubborn to
completely come to an end.

Primary Forecast Concerns: Addressing lingering lake induced rain
and snow showers, especially today. Cloud and temperature trends
today and tonight.

Details: Never easy ending lake effect around these parts, and that
definitely looks to be the case heading through today. Northwest to
west/northwest flow remains, becoming increasingly light through
the day. Stout subsidence inversion forms, centered just above 6kft.
Moisture profiles remain pretty decent below this inversion, and h8
temperatures actually cool a smidge this morning. Those light winds
will definitely put a kibosh on good heat/moisture transfer from the
lakes, and should gradually confine better shower chances closer to
the lake shores. Upshot to the above...expect light lake showers to
continue, likely becoming increasingly scattered with time. Trends
from previous days continue, with rain near the big waters, and a
rain/snow mix across interior areas. May see a dusting of snow yet
this morning, and will need to be on the lookout for some black ice
potential as temperatures likely fall to below freezing for a few
hours before rising back up into the mid 30s to lower 40s this
afternoon. Otherwise, that stout inversion looks to really lock in
the overcast, even away from the favored lake zones.

Winds quicky back around to southwest tonight as center of surface
high builds east of the region. Very light flow will continue to
help negate much lake contribution, although actual thermal fields
and lower level moisture change little overnight. Top of inversion
straddles -10c, looking just cold enough to allow at least a few
light lake showers to continue. Definitely think inherited scattered
wording is the way to go, trending pop orientation to those favored
by southwest winds. Just cant see much help with the overcast as
that moisture rich low level environment remains below that
inversion.

&&

.SHORT TERM...(Sunday through Monday night)
Issued at 223 AM EST Sat Dec 3 2016

...Light snow Sunday afternoon and evening...

High Impact Weather Potential: Accumulating snow possible Sunday
afternoon-Sunday evening. Minimal impact from strictly a snow amount
vantage point, but will be the most widespread wintry weather in two
weeks with slick travel possible in spots.

Pattern Forecast: Upper-level ridging is progged to be present
Saturday night with return flow ongoing ahead of a well-defined
shortwave set to cross the area Sunday evening. Weak ridging builds
in behind Sunday`s system to start next week before low pressure is
expected to move from the northern Plains through southern Ontario
resulting in lowering heights over the northern Great Lakes.

Primary Forecast Concerns: The primary forecast concern lies around
the Sunday afternoon -evening timeframe as the aforementioned
shortwave makes its approach locally. Fairly decent guidance
agreement in terms of overall strength and timing at this hour with
the expectation that any synoptically driven precip will hold off
until the afternoon hours across the majority of northern Michigan,
coinciding with the best pocket of QG forcing arriving mid-afternoon
into the evening. The only exception may be far southwestern
sections (generally west of M-37), which may see a bit of shower
activity sneak in just prior to the midday hours. Still expecting a
rain/snow mix for coastal counties with mainly snow inland as precip
arrives, before a transition to all snow past sunset Sunday evening.
Raw QPF output on the order of 0.14 - 0.18 inches along with pockets
of stronger forcing coinciding with the DGZ and low-mid level temps
supportive of snow-to-liquid ratios of 9-11:1 increasing to 14-15:1
should allow 1-3 inches of accumulation, highest across interior
sections of northern Lower and eastern Upper. Again, while not
necessarily impactful snow amounts, it`s expected to be the most
widespread wintry event in two weeks or so with slick travel
possible in spots.

As the system continues to quickly race northeast Sunday night, flow
begins to veer more westerly. Despite a quick departure of deep
layer moisture and synoptic support, would expect to see a bit of
westerly lake effect shower activity continue as over-lake
instability (delta T`s of 13-15 C) will likely overcome the lack of
any lingering synoptic support. Shower activity perhaps most
prevalent across the tip of the mitt where a westerly wind includes
a fetch that still encompasses an ice-free Green Bay & Little
Traverse Bay.

.LONG TERM...(Tuesday through Friday)
Issued at 223 AM EST Sat Dec 3 2016

Upper ridge axis will shift east of the area on Tuesday as a broad
trough digs south into the nation`s mid-section midweek. This will
kick off an active winter weather pattern across northern Michigan
as a surge of colder air and persistent W/NW low level flow leads to
an extended period of lake effect snow. Tuesday will be dry until a
cold front pushes through in the afternoon and evening. Models have
been wavering on how far north a system will track through the
Ohio Valley on Tuesday, and it is still within the realm of
possibility that this system will brush the APX forecast area.
Thermal profiles will allow for mainly rain until Tuesday night when
the initial shot of colder air arrives behind the cold front.

Wednesday morning the lake effect snow machine will start to ramp up
as 850 mb temperatures steadily plummet from their initial readings
of around -6 to -8C while winds increase out of the west. Forecast
soundings become more favorable for efficient lake effect snow going
into Thursday and Friday as low level lapse rates steepen and
negative omega becomes coincident with the dendritic growth zone.
During this timeframe, 850 mb temperatures will drop to around -10
to -15C. Also of note for Wednesday night into Thursday is the
potential for synoptic-scale snow contribution from another system
progged to pass through the Ohio Valley. There remains low
confidence in local impacts from this system, however, as models
continue to flip flop on its track and strength. The 03.00Z ECMWF is
back to a somewhat organized cyclone with QPF extending north of the
APX area, while the GFS does not depict an organized cyclone and
keeps the brunt of the QPF just south of our area.

Temperatures will start out above normal on Tuesday with highs
around 40. They will then take a quick downward turn with highs by
Thursday and Friday in the mid 20s to around 30.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 626 AM EST Sat Dec 3 2016

MVFR/low end VFR conditions to persist through this taf period in
weak lake effect regime. No vis restriction expected. Light winds
through the duration.

&&

.MARINE...
Issued at 223 AM EST Sat Dec 3 2016

No marine issues as northwest winds will continue to decrease in
speed today, becoming light and variable tonight. Winds become
south and southwest Sunday into Sunday night, increasing in speed
and become a bit gusty in the process. Borderline SCA conditions
look possible for a brief time Sunday night, particularly across
northern Lake Michigan.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...MSB
SHORT TERM...MJG
LONG TERM...MEK
AVIATION...MSB
MARINE...MSB



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