Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 270351
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1151 PM EDT FRI AUG 26 2016

.UPDATE...
Issued at 1022 PM EDT Fri Aug 26 2016

Mid and upper level clouds continue to filter into the area as
top-down moisture advection increases well ahead of upstream wave.
Deepest moisture/forcing still aways off, evident by areas of
showers back across the corn belt. Simple trends suggest a
continued increase in clouds overnight, with extrapolation of
moisture advection/upper jet forcing suggesting some of those
showers maybe making a run into our southwest areas by sunrise.
Still think much of the area remains dry, waiting until Saturday
morning for more widespread shower activity to arrive.

&&

.SHORT TERM...(This evening and overnight)
Issued at 311 PM EDT Fri Aug 26 2016

High pressure remains centered over the Upper Mississippi Valley and
the Great Lakes region this afternoon. Tail end of a secondary cold
front is making its way thru Central Upper Michigan...still
producing a small area of showers and low clouds across Upper
Michigan. Scattered to broken diurnal CU continues to develop across
much of our CWA thanks to cooler air aloft in the wake of
yesterday`s cold front. In addition...some relatively dense cirrus
is streaming into our CWA as upper level moisture increases well in
advance of an developing area of low pressure over the Central and
Southern Plains. Temps have warmed into the low to mid 70s across
our entire CWA...certainly cooler than the last several days and
less humid as well.

Secondary cold front will clip our northern CWA as we head into late
afternoon/early evening as will the associated scattered showers and
area of low clouds along and ahead of the boundary. Diurnal CU will
maintain thru the remainder of the afternoon...but will diminish as
we approach sunset with loss of diurnal heating/instability. Dense
cirrus will likely continue to stream into our CWA thru the
evening...tending to lower as mid level moisture/clouds begin to
increase overnight.

Latest short term models are a bit more aggressive with developing
precip across our SW CWA very late tonight. Think this may be a bit
too soon as low level flow shifts to the E/SE ahead of the
developing low. This is a rather dry low level flow for our area and
will likely not immediately aid in low level moistening an already
dry low level atmosphere overhead. Thus...will keep the forecast dry
thru tonight...with precip chances holding off until after 12z.
Chances of showers and thunderstorms should quickly increase from SW
to NE thereafter as deeper moisture and some weak instability lift
into our area ahead of the low. Wind fields remain weak...and
instability unimpressive...so strong to svr storms are not
anticipated.

Expect another cool night across the Northwoods...with overnight
lows cooling into the 50s. High temps on Saturday will warm into the
70s.

.LONG TERM...(Saturday through Friday)
Issued at 311 PM EDT Fri Aug 26 2016

High impact weather potential: Scattered thunderstorms possible
Saturday night.

Pattern synopsis/Expected evolution: Rather zonal mid-upper level
flow today with high pressure anchored at the surface will give way
to gradually increasing heights aloft ahead of a digging shortwave
set to race from the northern Plains toward the western Great Lakes
by Saturday night. This will result in increasing shower/storm
chances from Saturday morning through Saturday night. Zonal flow
returns to start the work week; however, another wave is set to trek
through southern Canada (just north of the Sault`s International
Bridge), ultimately renewing scattered precip chances late Monday
night-Tuesday.

Saturday night-Sunday: At the start of the period (Saturday night),
a 90+ kt 250 mb jet streak is draped from the Atlantic Ocean through
central Quebec, Ontario and into the central U.P. leaving portions
of northern Michigan with divergence aloft as we sit under the right
entrance region. A coinciding, well-defined wave is centered over
western Ontario at the same time, aiding to increase large scale
forcing, albeit not overly strong, across the Great Lakes. An
associated weak cold front is expected to be draped over eastern WI,
gradually pushing eastward with time. Will continue inherited PoPs
area-wide through the overnight hours, hedging toward the highest
chances north of M-72. As the evening wears on, deep layer moisture
begins to wane from west to east, hinted at by decreasing PW values
(still approaching 1.50 inches east of I-75, but tapering to the
west). While guidance has come into better agreement over the past
24 hours of the overall evolution of the system, raw QPF output
varies wildly amongst members. Certainly some locations will likely
receive beneficial rainfall, but still have concerns that Saturday
night won`t be the provider of that to a widespread area of northern
Michigan with overall shower/storm coverage lacking. 0-1 km MLCAPE
values of a few hundred J/kg and bulk shear values of 30-40 kts may
promote an isolated stronger thunderstorm or two across the area
ahead of the front; however confidence remains low.

Guidance continues to be in fairly good agreement come Sunday
morning that nearly all appreciable precip has exited/is exciting
the CWA as forcing wanes in the wake of mid-level troughing becoming
centered directly overhead. Weak upper-level ridging and associated
high pressure usher in cooler/drier air throughout the day Sunday
with peeks of sunshine expected to prevail by late in the day.

Monday: Little in the way of consequence expected as high pressure
briefly makes another appearance over the Great Lakes. Mostly sunny
skies, light winds and late-season warmth will be the rule. Highs
topping out in the low-mid 80s across northern Lower, slightly
cooler in the U.P.

Extended (Monday night through Friday)...

Occasional precip chances continue into the extended with the first
threat arriving late Mon night-Tue associated with a weak mid-level
wave and cold front expected to cross the area. Perhaps a larger
story in the extended is the fact that guidance hints at longwave
ridging building over the heart of the country late in the week/next
weekend. Details are unclear as to where the ridge axis may set up,
but sensible weather could vary from summertime heat to a ring-of-
fire pattern with northern MI sitting on the northeastern periphery
of aforementioned ridging.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1148 PM EDT Fri Aug 26 2016

Rather challenging forecast remains, especially heading through
into early this morning through today/early evening. Still just
some passing high and mid clouds for the next few ours. Changes
begin from southwest to northeast toward morning, as upstream
areas of showers makes a run into our area. Definitely not sure on
exact timing or areal extent of these showers (with even a rumble
of thunder or two possible). Will trend pessimistically, bringing
in showers and an mvfr cloud deck across the taf sites through
the morning...lasting through the day. Even some hints of ifr
producing stratus heading through the afternoon. Will wait on
introducing this idea, waiting on actual shower trends. Light and
variable winds this will trend light southeasterly Saturday.

&&

.MARINE...
Issued at 311 PM EDT Fri Aug 26 2016

Winds and waves will remain below SCA criteria for all nearshore
areas through Sunday. High pressure will shift east out Michigan by
late tonight...giving way to increasing chances of showers and
storms by Saturday ahead of low pressure lifting NE out of the
Central Plains and into the Western Great Lakes region.


&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...MSB
SHORT TERM...MLR
LONG TERM...Gillen
AVIATION...MSB
MARINE...MLR


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