Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 181539
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1039 AM EST Thu Jan 18 2018

.UPDATE...
Issued at 1038 AM EST Thu Jan 18 2018

...Slowly warming with light precipitation chances...

High Impact Weather Potential...None expected through this afternoon.

Primary Forecast Concern...Cloud cover along with precipitation
development over Upper Michigan.

Pattern Synopsis/Forecast...The Great Lakes will be between systems
today, with a weakly organized boundary stretching over Ontario
associated with a system in Quebec, while a large area of high
pressure remains centered south of the Ohio Valley. At upper levels,
a short wave dropping out of central Canada will push across
northern Michigan this afternoon before exiting east this evening.
850/700MB and 500/300mb qvectors showing convergence increasing over
northern Michigan into this afternoon in response to the upper wave
and Ontario boundary sinking southward toward Lake Superior. However
precipitation chances and amounts will be limited across the region
today, as model soundings and mstr progs show extremely dry
conditions in mid levels (Pw values under 0.25). There is some
concern for freezing drizzle today, with mstr trapped in lowest
levels in a vertical temperature profile between 0c and -10c.
Though, abundant upper lvl mstr and ice crystal seeding from aloft,
should still trend most pcpn type today toward light snow.

Overall will continue with current line of thinking and mention low
chances of snow over east Upper and the Straits region into this
afternoon.

&&

.NEAR TERM...(Today through Tonight)
Issued at 302 AM EST Thu Jan 18 2018

...A bit milder yet today...

High impact weather potential: Minimal.

Pattern synopsis/forecast: Flat-topped mid level ridge axis building
overhead at this early hour as core of coldest temperature anomalies
and deep troughing now rotate well off to our northeast. Sharp
shortwave trough digging rapidly southeast across southern Manitoba.
Despite its rather healthy looking appearance on water vapor
imagery, distinct lack of any appreciable deep layer moisture
preventing much more than a few light snow showers attached to this
feature. Otherwise, early evening very strong winds have subsided
just a bit as pressure gradient has relaxed some, but still seeing
wind gusts in excess of 25 mph, especially along the Lake Michigan
coast. Those winds have kept temperatures from falling much
overnight, this despite plenty of clear skies this evening.

Pattern remains very progressive, with current overhead ridging
giving way to that fast moving wave by later today, with ridging
returning by Friday morning as that wave races off to the east.

Primary forecast concerns/challenges: Cloud trends and addressing
potential for flurries or even a bit of freezing drizzle.

Details: Challenging forecast with regards to cloud trends today.
Some guidance remains insistent of an expanding stratus shield
quickly this morning as moisture rapidly increases below very strong
H9 centered inversion. Temperatures at inversion height are just
cool enough to support some weak lake moisture contribution, at
least adding some merit to the stratus idea. However, those same
models have stratus already forming upstream ahead of that
approaching shortwave, and this has not happened yet as several
degree surface dewpoint depressions remain. Definitely not sold on
this aggressive stratus idea (would actually like to see some start
to form). That lake contribution just may tip the scales to stratus
development this morning however, but will definitely not go as
aggressive as some guidance would suggest. Now, if this cloud deck
does materialize, moisture appears just deep enough to kick off a
few flurries, or even a bit of freezing drizzle as moisture column
straddles ice nuclei activation temperatures. Arrival of that
Manitoba wave does bring a bit of enhanced moisture along with it
this afternoon, perhaps enough to kick off a few more flurries/very
light snow showers, especially across eastern upper Michigan.
Pressure gradient does slowly relax today, so not expecting near the
gustiness experienced yesterday. Still a bit breezy, enough so to
make afternoon temperatures up near 30 degrees feel a touch more
chilly.

While shortwave trough departs rapidly this evening, that challenging
and low confidence cloud forecast remains with guidance derived
soundings still showing plentiful low level moisture remaining. And,
just like today, not sold on this idea. Will let a consensus blend
ride for now, featuring mostly cloudy skies. Overnight lows will be
several degrees above normal, with readings mostly in the lower and
middle 20s.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 302 AM EST Thu Jan 18 2018

...Moderating temperatures...

High Impact Weather Potential: Minimal.

Pattern Forecast: Upper level heights rise across northern Michigan
as early as Friday morning before flow becomes rather zonal as early
as Friday evening thanks to a shortwave sliding eastward across
southern Canada. Surface high pressure anchored well to our south
will nose into the area through the majority of the forecast period
with above normal temperatures and little in the way of sensible
weather expected.

Primary Forecast Concerns/Challenges: Perhaps a brief wintry
mix across eastern upper Friday afternoon.

The only threat for precip through the Friday-Saturday time frame
will arrive Friday afternoon, primarily across sections of eastern
upper Michigan as the southern periphery of shortwave troughing
skirts the area. Forecast soundings from ANJ suggest a lack of
appreciable moisture through the column, but perhaps just enough for
rain/snow showers to develop. Warm nose and associated rather dry
layer depicted between 700-900 mb lends uncertainty to how much
precip will actually reach the ground and in what form it will take,
especially with sub freezing temps below the boundary layer before
warming to a couple degrees on either side of freezing at the
surface. Gut feeling is that any precip will be scattered in nature
and feature more a wintry mix of sleet and perhaps even freezing
rain. The window Friday afternoon for precip remains fairly minimal,
so substantial impacts are not expected, but even just a bit of
freezing rain/drizzle can create headaches, especially on
untreated/secondary roadways.Elsewhere, dry weather is expected with
above normal temperatures. Friday`s high varying from the low-mid
30s across the aforementioned problem area in eastern upper to the
upper 30s across northern lower.

Tightening pressure gradient will yield strengthening west-
southwesterly winds Friday evening through the first half of
Saturday as the system bringing the wintry mix chances to eastern
upper progresses eastward across southern Ontario. Gusts upwards of
25 mph expected to common across northern Michigan during this time.

The gradient relaxes Saturday; however, southwesterly return flow
continues ahead of the next system beginning to take shape across
the Plains (talked about more below). The result will be
temperatures boosted by a couple more degrees area wide with highs
topping out in the upper 30s across the far north to the low 40s
elsewhere...some 15 or so degrees above normal.

.LONG TERM...(Saturday night through Wednesday)
Issued at 302 AM EST Thu Jan 18 2018

High impact weather potential: Storm system Sunday into early next
week...perhaps bringing a messy wintry mix to portions of northern
Michigan.

Focus continues to revolve around the Sunday through monday
timeframe as strengthening low pressure is expected to eject lee of
the Rockies late Saturday before progressing northeastward toward
the Great Lakes Sunday into Monday. While some guidance differences
continue with respect to the strength and track of the system, the
consensus would suggest low pressure center tracking from southwest
WI through eastern upper MI during the day Monday into Monday night.

Isentropically driven precip starting Sunday may initially pose the
biggest impact prior to strong warm advection taking over by late
Sunday night. As was alluded to by the prior shift, 1035 mb high
pressure over Hudson Bay may result in a prolonged period of E/ESE
winds across northern Michigan and a greater potential for icing,
especially across the northern half of the forecast area. Low level
temps get a boost by late Sunday night into Monday, especially
across northern lower where warm air advection is expected to be
firmly underway and any wintry precip transitioning to rain. Tight
thermal gradient may linger across eastern upper...perhaps posing
additional problems with mixed precip through Monday. Cooler air
pours back into the region during the Monday night-Tuesday time
frame with a period of lake effect snow possible through the end of
the forecast period.

Worth monitoring over the coming days as any subtle changes to the
system`s track can pose meaningful implications on p-type and
resultant impacts.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 610 AM EST Thu Jan 18 2018

MVFR producing stratus starting to develop across northern
Michigan early this morning. Minor lake contributions should
support further development across the taf sites through this
morning. May see cigs scatter out a bit this afternoon, with more
MVFR producing stratus expected to return tonight. No significant
precipitation expected.


&&

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

$$

UPDATE...SR
NEAR TERM...MB
SHORT TERM...MG
LONG TERM...MG
AVIATION...MB


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