Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 250440

Area Forecast Discussion
National Weather Service Gaylord MI
1140 PM EST Fri Nov 24 2017

Issued at 945 PM EST Fri Nov 24 2017

...Colder air arrives overnight through Saturday...

Evening satellite/surface analysis reveals a short wave trough
sliding across the upper Midwest into the western Great
Lakes. Associated surface low pressure is over NE Ontario with a
trailing cold front just swinging through eastern upper Michigan
at this hour...and crossing northern Lake Michigan. Attending
batch of rainfall along and just behind the surface front now
making steady progress eastward...already across eastern upper
Michigan (where it`s been wet all day) and just reaching the NW
lower Michigan shore.

No big changes planned to the going forecast. Cold front/attending
rainfall will swing eastward across the CWA over the next several
hours. Most areas will see something...although best precip chances
will be across eastern upper and northwest lower Michigan. Cold
advection proceeds gradually behind the front with temps dropping
into the mid 30s to around 40 for most by morning. Just gets cold
enough to begin to see a lake response toward morning...still mainly
rain with some mixiness in eastern upper and the high terrain of
northern lower MI. Better lake effect precip chances and gradual
changeover to mainly snow come on Saturday.


.NEAR TERM...(Tonight through Saturday)
Issued at 251 PM EST Fri Nov 24 2017

...Showers tonight...turning cooler with rain/snow for Saturday...

High impact weather potential...Lingering gales on some of the big
waters into this evening.

Pattern synopsis/forecast...Very mild late November day across the
northwoods, courtesy of deep and gusty southwest flow ahead of a
developing cold front punching into western Wisconsin. Widespread
readings in the 40s and 50s, with even some areas near Lake Michigan
pushing 60 degrees. Very dry low levels partially overcome by that
strong waa, still resulting in some sprinkles/very light showers,
particularly for areas north of the big bridge. Most concentrated
area of showers remains in post-frontal environment across northwest
Wisconsin and central Minnesota.

Pattern remains very progressive, with upstream shortwave and its
attendant cold front set to sweep across the area overnight,
bringing their band of mostly light showers along with them. System
backside cold air advection is not overly impressive (as evident by
readings in the upper 30s and lower 40s back across southern Canada
and the Dakota`s), but should be enough to drum up a bit of a lake
response Saturday.

Primary forecast concerns/challenges: Temperature and cloud trends
through the forecast. Timing of rain showers through tonight and
additional rain/snow chances Saturday.

Details: As mentioned, upstream wave and cold front will remain
quick movers, set to slide across our area this evening, exiting
stage right well before sunrise Saturday. Forced ascent along
narrow/focused moisture axis expected to drive an area of mostly
light rain showers from northwest to southeast as the front passes.
Moisture will be thinning with time, so expect the best bet for
measurable rain to remain across the northwest half of the region
this evening. "Best" post-frontal cold air advection looks delayed
by a few hours, so northwest flow lake processes may take a bit to
organize. Lake processes expected to increase Saturday morning
through early afternoon as H8 temps fall to near -10c (give or take
a few degrees) and secondary subtle mid level wave arrives. Limiting
factors for significant lake induced showers are many, most notably
a very shallow convective boundary layer...largely below 5kft...and
moisture that barely reaches the favored dendritic growth layer. So
while no doubt lake driven precip will develop, expect organization
and intensity to remain limited. Add in a marginally cold low level
environment that will support a rain/snow mixture, at least
initially, and largely suspect any snow amounts will remain well
under an inch.


.SHORT TERM...(Saturday night through Monday)
Issued at 251 PM EST Fri Nov 24 2017

...Mild Temperatures Return...

Perhaps some lingering northwest flow lake effect snow showers
Saturday evening across eastern upper and northwest lower but with
little to no accumulation. There will also be a slight chance for
rain or snow showers across eastern upper Sunday as a short
wave/weak front move by. Otherwise...fairly quiet weather is
expected during this period. In fact there is a general warm
advection pattern shaping up leading to more mild daytime
temperatures. Highs both days ranging from the middle 30s north to
the middle 40s south. Lows mainly in the 20s to lower 30s.

.LONG TERM...(Monday night through Friday)
Issued at 251 PM EST Fri Nov 24 2017

Much like we have been seeing recently, the extended will be marked
with above normal temperatures and occasional systems passing
overhead. While clippers will continue to pass to our north, a late
week system moving out of the plains will be the best chance at more
wide spread precipitation if it gets far enough north. Have
increased high temperatures Tuesday over the blend, as we could once
again reach into the 50s ahead of a cold front.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1139 PM EST Fri Nov 24 2017

Sharp cold front just working into NW lower Michigan and will
bring a period of light rainfall to the terminal sites over the
next several hours. This will also bring a quick transition from
VFR to MVFR and possible IFR conditions as we go through the
overnight hours. Lake effect showers will follow later overnight
and persist through much of the day Saturday as temperatures turn
progressively colder.

Winds have weakened in the last few hours and LLWS conditions have
eased. But gustier surface winds will again develop behind the
front overnight and persist through Saturday.


Issued at 251 PM EST Fri Nov 24 2017

Gale producing southwest winds will swing around to
northwest later tonight, decreasing in speed just a bit in the
process. Still expecting widespread small craft advisory conditions
on all the big waters right through Saturday. Winds further decrease
Saturday night before becoming gusty southwest again on Sunday ahead
of the next weak cold front.


LH...SMALL CRAFT ADVISORY until 11 PM EST Saturday for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 11 PM EST Saturday for LMZ323-341-342-
LS...SMALL CRAFT ADVISORY until 11 PM EST Saturday for LSZ321-322.


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