000
FXUS63 KAPX 181742
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1242 PM EST Mon Feb 18 2019

.UPDATE...
Issued at 1042 AM EST Mon Feb 18 2019

Large area of Canadian high pressure continues to slowly build
into the region this morning. Still getting some lake induced
clouds and flurries rotating off the big waters, primarily
impacting northeast lower Michigan and the Leelanau Peninsula with
convective layer flow remaining a bit east of north. Definitely
not a big deal for sure. Plenty of sunshine across a good chunk of
the remainder of northern Michigan. These overall trends will
continue as we head through this afternoon, with a slowly backing
wind field bringing more lake clouds and flurries into northwest
lower Michigan with time. Temperatures will remain well below
normal, with afternoon highs in the teens and lower 20s.

&&

.NEAR TERM...(Today through Tonight)
Issued at 317 AM EST Mon Feb 18 2019

...Fairly quiet, but cold temps tonight...

High impact weather potential...none.

Low pressure is over n central PA, moving ne. This low will
weaken today as secondary development occurs off the east coast.
Associated snow swath over the southern Great Lakes is moving east
and slowly diminishing. That will exit, and in its wake a large
area of high pressure will move from s central Canada into the
Great Lakes thru tonight.

Very light snow is occurring down by OSC/Gladwin. Expect that to
gradually exit over the next few hours, with little if anything left
after 7 am. Cloud cover elsewhere largely consists of mid and high
clouds, and there are a number of thin spots, especially north of a
TVC-APN line. Cloud cover will substantially erode from n to s,
especially after sunrise. Eastern upper MI should be mostly sunny by
late morning, and most of northern lower will do the same during the
afternoon. The lakes will provide some exceptions, though. Our
initial 1000-850mb winds are from the ne, pushing lake clouds into
ne lower MI (where higher synoptic clouds are present). However, as
the surface low departs and loses influence, the fetch backs to
north by midday, and nw/nnw by late afternoon. That will support
partly to mostly cloudy skies near/w of M-37 in nw lower MI this
afternoon. We also currently see lake clouds and snow showers in the
immediate MQT area on ne winds. with 850mb temps around -16C. Those
will gradually get shoved eastward, with increasing clouds in
western Chip/Mack Cos this afternoon, along with a chance of snow
showers.

1000-850mb winds back a little further to the wnw as we move thru
tonight. The arrival of surface high pressure and a drier airmass
will limit lake effect potential. A chance of snow showers continues
to be justified in western Chippewa Co. In nw lower, ice cover on
Lake MI will help limit snow showers to primarily Leelanau/Benzie/
Manistee/Gd Traverse Cos. Partly to mostly cloudy skies will hold in
those areas, while we are partly cloudy to mostly clear
elsewhere.

Max temps today in the teens to lower 20s. Will go sharply below
guidance min temps tonight, especially away from Lk MI, where lows
of -5 to -15f will be common.

&&

.SHORT TERM...(Tuesday through Wednesday Night)
Issued at 317 AM EST Mon Feb 18 2019

High Impact Weather Potential...Widespread accumulating snow Wed
into Wed night. Possibly some minor ice accumulation south of M-72
Wed afternoon-evening due to freezing drizzle.

Pattern Synopsis/Forecast...Anomalous ~1040 mb surface high will sit
overhead Tuesday morning, with its center drifting east of Lower
Michigan by late afternoon. Generally fair weather expected through
this timeframe with subtle warm air and moisture advection
developing behind the departing high heading into Tuesday night.
Attention then turns to a developing low over the Middle Mississippi
Valley Wednesday morning that will lift through the Great Lakes
region Wednesday night. This system will bring the next round of
widespread accumulating snowfall to northern Michigan.

Primary Forecast Concerns...Diminishing light lake effect potential
on Tuesday. Snow timing/amounts on Wednesday.

Conditions will be supportive Tuesday morning for some lingering
lake effect along the Lake Michigan shoreline from Manistee to the
Leelanau Peninsula. Light ambient wind fields Monday night will lead
to land breeze development and enhanced convergence just offshore,
where a dominant band is expected to hug the lakeshore through at
least mid-morning Tuesday. As the high drifts east during the day,
developing southwest flow will drive the band farther inland as it
begins to gradually dissipate in the face of increasing warm air
advection and falling inversion heights. Offshore SSW flow near
Whitefish Bay should preclude any lake effect up that way. Limited
moisture and inversion heights at or below 4000 feet should limit
overall strength of the lake effect, so overall impacts should be
low with little to no accumulation. The only concern would be if the
band lingers in one place Tuesday morning along the shoreline before
diurnal winds give the weakening band some forward momentum.

Main focus of the period revolves around Wednesday`s system.
Increasing isentropic lift and upper level difluence will spread
across northern Michigan during the day ahead of the approaching
system. At the same time, moisture return will be decent as we tap
into some Gulf moisture by afternoon. The exact track the surface
low will take is still far from certain, as evidenced by the 18.00Z
NAM being a significant outlier, taking it well north into eastern
Upper. For now will discount that solution and take a general
consensus of other guidance, which favors the low lifting northeast
through the Lower Peninsula. Snow looks to arrive around or shortly
after 7am Wed south of Grand Traverse Bay, spreading northeast
across the remainder of the forecast area by the noon hour. The dry
slot looks to gradually encroach from the south Wed afternoon into
the evening, kicking off a south to north diminishing trend Wed
night, with remaining system snow exiting the Tip of the Mitt and
eastern Upper by daybreak Thursday. Due to lingering uncertainties
with regard to storm track, still too early to pin down precise
snowfall amounts. However, there is a consistent signal among
various guidance for the heavier QPF (up to a third of an inch) to
lay out across the Tip of the Mitt and eastern Upper. With snowfall
ratios generally in the 10-15:1 range, looks like we could be
dealing with advisory level snowfall of about 3 to 5 inches north of
M-72 between 7am Wed - 7am Thu. Lesser amounts of 1 to 3 inches as
you go south of M-72, as that area could see some freezing drizzle
(up to a tenth of an inch of icing) mix in Wed afternoon-evening as
the dry slot works into the area. This far out these forecast
snow/ice amounts are preliminary and will be subject to later
refining, of course, but overall model trends have been fairly
consistent over the last 24 hours, so forecast confidence is medium
at this time. The good news is winds don`t look too strong to cause
blowing/drifting problems with this system, with gusts generally
around 20 mph or less.

.LONG TERM...(Thursday through Sunday)
Issued at 317 AM EST Mon Feb 18 2019

High Impact Weather Potential...Minimal at this time.

As our snow system departs Thursday morning, slightly colder air in
its wake will wrap around back into eastern Upper and northwest
Lower to generate a period of lake effect. However, overlake
instability appears marginal with H8 temperatures only dropping to
around -10 to -11C and inversion heights generally 3000 feet or
less. Conditions will slowly become less favorable with time through
Friday. A weak wave is progged to push through on Saturday, bringing
a chance of snow, perhaps mixed with rain in some areas as temps
climb into the mid 30s. Sunday looks potentially much more
interesting as models are trying to latch onto a more robust system
lifting into the Great Lakes. Very low confidence in storm track,
but medium-range guidance shows a fairly intense developing surface
low lifting somewhere through the region. This would have the
potential to produce significant wintry precip somewhere across the
region (much too early to tell where, as we don`t yet know the
system`s track) and likely gusty winds.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1240 PM EST Mon Feb 18 2019

While nothing too significant is expected, MVFR to low end VFR
producing lake clouds and snow showers will continue to impact
KTVC and KMBL through much of this taf period. Current MVFR
producing overcast at KAPN should scatter out shortly, leaving
them and KPLN dominated by VFR conditions under a few passing high
clouds. Light winds through the period.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
&&

$$

UPDATE...MB
NEAR TERM...JZ
SHORT TERM...MK
LONG TERM...MK
AVIATION...MB

NWS APX Office Area Forecast Discussion