Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 210747
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
347 AM EDT SUN AUG 21 2016

.SHORT TERM...(Today and tonight)
Issued at 344 AM EDT Sun Aug 21 2016

High impact weather potential: Lake effect rain showers in
westerly flow, and potential thundershowers primarily around the
GTV Bay region. Advisory level wind gusts possible this morning
for the immediate lakeshore of Chippewa county.

Pattern synopsis and forecast:

Sharp upper level trough moving in early this morning with a cold
front already east of nrn Michigan. The main precipitation ended
awhile back, but quickly crashing H8 temperatures into the single
digits and lake water temperatures 22-24C has resulted in the
development of lake effect rain showers in increasing westerly flow.
These light rains were primarily tied to the interior higher terrain.
Looking upstream, there is a sfc trough dropping SE across central
upper, associated with sfc low pressure just north of the Sault.
Deeper moisture along this sfc trough was approaching Green Bay and
nrn Lake Michigan, and was associated with additional rain showers.

Heading into the dawn hours and through morning, this sfc trough and
deeper moisture overspread nrn Michigan, and lake effect rains will
be more common across westerly flow regimes. More cyclonic low level
winds and steeper lapse rates aloft will not only result in the
additional rains, but also there outside chance at some embedded
thunder. Sfc based CAPES will range from a few hundred j/kg to as
much as 1000j/kg closer to Manistee in the GTV Bay region. Directly
along the sfc trough, there is even a slight chance at early season
waterspouts. Certainly our first sampling of a more fall-like air
mass with gusty winds and high temperatures in the mid and upper
60s most locales with lower 70s in downsloping regimes of NE lower.
The greatest coverage of rain showers will be this morning after
dawn, and in the interior higher terrain. Also, the the strongest
winds will be coming in off Lake Superior shortly after dawn, and
it`s not out of the question that the immediate shoreline areas in
Chippewa county could see some gusts as high as 45 mph. Will keep
the wind advisory this morning for there.

Other light rain showers are expected to develop diurnally in the
afternoon for portions of NE lower. These showers will decay into
the evening as the deeper moisture will have departed, but air mass
temperatures will remain cold enough for at least the potential for
isolated showers to impact areas downwind of Lake Michigan. Warming
at 700mb really shuts down the instability however, especially
across eastern upper where rains are not expected tonight. Anything
still pestering NW lower will end by midnight. Air mass dries
through the night with the sky eventually being a bit more clear
than cloudy. Pretty chilly lows tonight in the upper half of the 40s
for many areas, but immediately downwind of Lakes Superior and
Michigan will hold in the mid to upper 50s.

.LONG TERM...(Monday through Saturday)
Issued at 344 AM EDT Sun Aug 21 2016

(8/22)Monday...For the most part, the only moisture in the region is
the 700-500 mb moisture associated with the warm advection wing
north of Upper Michigan during the afternoon. The lower levels
continue to have moisture levels less than 50% (850 mb and the sfc).
So will continue the dry forecast for the daylight hours. Models
still want to produce light rain in Upper Michigan overnight as a
500 mb jet streak (about 35 knots) moves through E Upper and there
is decent warm advection in Upper Michigan during from the sfc
return slow. Models seem to moisture up, the 850 mb level by 06z
over the eastern end of the upper peninsula which continues through
12z/Tue. However, the models make the precipitation out to be pretty
spotty, so would expect sprinkles, and a few light rain showers, so
have low pops.

(8/23)Tuesday...However, the warm sector finally arrives and the 500
mb ridge axis begins to amplify, lifting the 500 mb jet north of the
Lake Superior, which continues through the night. So will expect
that the day and the night will be dry.

Extended (Wednesday through Saturday)...Models are beginning to show
a train of waves that will move through the Upper Great Lakes every
few days. This will exhibit a deep 500 mb trough, at least compared
to most of the summer, and followed by some decent ridging keeping
the region dry for a day or two. This trending toward a new pattern
may be signaling that the previous pattern of the summer has
changed. In fact looking at the CIPS Analog page, the precipitation
and temperatures look to show that the trends will flip/flop through
not just 6-8 days, but 9-11 and 12-14 days as well. Will see how
this plays out, but seems reasonable given what has been happening
at the end of this last week, and the beginning of the next.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1110 PM EDT Sat Aug 20 2016

Early season lake processes soon to ramp up as shot of
unseasonably cold air follows passing cold front. Slug of upstream
moisture and passing waves will only help the cause, supporting a
long duration mvfr stcu/cu deck across the taf locations through
today. Light showers will also impact western taf locations, with
small drop size perhaps allowing brief reductions in visibility.
Conditions begin to improve later Sunday into Sunday night.

Winds will increase and become increasingly gusty out of the west
to northwest, with gusts easily exceeding 20 knots at times. These
winds will also begin to subside later Sunday.


&&

.MARINE...
Issued at 344 AM EDT Sun Aug 21 2016

...Gales, lake effect rains and slight chance for waterspouts
today...

Nrn Michigan is getting an early shot of fall behind the passage of
a strong cold front last evening. Colder westerly winds and waves
have increased significantly overnight with speeds well into
advisory levels and periodic gales. Current gale warnings and
advisories will remain as is, but there may be less chance at gales
south of Sleeping Bear Point. Lake effect rain showers will pick up
through the morning as a sfc trough pushes through, resulting in the
additional slight chance for a waterspout. Overall it will be a
rather unfavorable day to be out on the big water. Both wind speeds
and lake effect will wane later in the day, and outside of some
remnant advisory level gusts in Whitefish Bay and nrn Lake Huron,
headlines will be falling off this evening.

Lighter winds for Monday in higher pressure, but winds ramp up again
Monday night and through midweek as a another low pressure system
and cold front develop into western Lake Superior and the upper
Mississippi valley. This is looking more likely to result in
additional marine headlines, as there will still be some overall
shallow instability over the Lakes.

&&

.APX Watches/Warnings/Advisories...
MI...BEACH HAZARDS STATEMENT through this afternoon for MIZ016-019-
     020-025-031.

     WIND ADVISORY until 11 AM EDT this morning for MIZ008.

LH...GALE WARNING until 11 PM EDT this evening for LHZ346>349.

     SMALL CRAFT ADVISORY until 11 PM EDT this evening for LHZ345.

LM...GALE WARNING until noon EDT today for LMZ323-342-344>346.

     SMALL CRAFT ADVISORY until 6 PM EDT this evening for LMZ341.

LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ322.

     GALE WARNING until 8 PM EDT this evening for LSZ321.

&&

$$

SHORT TERM...Dickson
LONG TERM...JSL
AVIATION...MSB
MARINE...Dickson



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