Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 162328

Area Forecast Discussion
National Weather Service Gaylord MI
728 PM EDT Sun Apr 16 2017

.NEAR TERM...(Tonight through Monday)
Issued at 301 PM EDT Sun Apr 16 2017

High impact weather potential: None.

Pattern synopsis and forecast:

One cold front was slowly trying to exit the far SE CWA this
afternoon with a large wedge of drier air/clearing behind it, seen
on satellite working eastward. Meanwhile, while a secondary cold
front with notably drier sfc air behind it, but large area of
stratus extending through much of Ontario, is also slowly sinking
into eastern upper. Aloft, a shortwave in fast westerly flow is
working across western Lake Superior. The stronger forcing is north
in southern Ontario, but this wave was able to help spark off a few
diurnally driven showers where skies cleared out, across NE
Wisconsin and central upper Michigan. Some sun was penetrating areas
along and south of M-72, and a few showers have also popped off in
decent cumulus field on the departing front near Saginaw Bay.
Further upstream, behind the aforementioned shortwave, was a little
closed off upper low and it`s associated showers, within quite steep
mid level lapse rates of 7-7.5c/km.

The current batch of showers in central upper Michigan/NE Wisconsin,
will cross into nrn lake Michigan late this afternoon, and make a
run at sections of NW lower through 8pm, before we start to lose
diurnal heating. At the same time, a few more showers could pop off
in the cumulus field along and south of M-72, again until loss of
daytime heating. Both of these scenarios would likely fail if not
for help from DPVA from the shortwave. The secondary cold front
continues a very slow southward movement into nrn lower overnight,
before becoming more ill-defined later Monday as winds again try and
turn onshore. Believe patchy fog will be possible tonight ahead of
the front in nrn lower, where the increased sfc based drying does
not occur. This is especially true for the low lying areas where
better radiational cooling occurs from clearing skies, due to that
dry wedge of air sweeping into nrn lower.

The closed off upper low well west gradually opens up and makes in
into the region Monday, with weakening forcing and instability in
the mid levels. Could see a few showers once again, pop off along
the low level ill-defined front, or in areas where lake breezes
result in low level convergence. This looks to be in nrn lower
Michigan. Difficult to say exactly where, but hi-res data suggesting
the better convergence will be across the SE CWA, and also where
daytime heating has a longer chance to develop prior to the weakish
forcing from the shortwave.

Lows tonight ranging from around 30F in eastern upper to the upper
30s around 40F along M-55. Highs in the lower to mid 40s in eastern
upper to the middle to upper 50s south of M-72.


.SHORT TERM...(Monday night through Wednesday)
Issued at 301 PM EDT Sun Apr 16 2017

...Starting Another Set of Wave Trains...

High Impact Weather Potential...Showers and thunderstorms will be
possible for Tuesday night into Wednesday.

Pattern Synopsis/Forecast...Monday night starts off with a flat 500
mb ridge which helps to clear out the region for the night, and
early the next morning. A 500 mb shortwave trough moves into the
Northern Plains and spins up a sfc low that moves into the Upper
Great Lakes by 18z. This will bring showers and thunderstorms Looks
like overnight as the mid-level lapse rates (showalter index) shows
0 to -1C with the front that moves through the region with the sfc
low. By Wednesday morning, the front is through and high pressure
builds back into the region for the morning. However, by 18z/Wed,
The next system to affect the region will begin to move into the
forecast area.

Primary Forecast Concerns...Main concern won`t be for the initial
system moving into the Upper Great Lakes as it travels through the
forecast area on a relatively flat, fast flow. If there is a concern
with it, it would be that little happens as the sfc low moving
through Lake Superior stretches the front out enough that little
happens on the front.

However, if the main concern is the system that arrives on Thursday
as it looks similar to the system that just moved through the
forecast area last night (4/15-16).

.LONG TERM...(Wednesday night through Sunday)
Issued at 301 PM EDT Sun Apr 16 2017

The long term forecast begins with a developing low pressure system
over the Upper Mississippi River Valley that tracks into the Great
Lakes region and begins impacting the forecast area Wednesday night
with WAA precip and then possibly changing to snow Thursday night
into Friday morning as colder air filters in behind the departing
system. High pressure centered over Hudson Bay then ridges into the
Great Lakes region diminishing cloud cover and ending any lingering
showers throughout the day Friday with temperatures moderating a
bit, reaching into the low to mid 50s throughout the remainder of
the week. Long range models are hinting at another storm system
possibly developing on the lee side of the Rockies and impacting the
forecast area at the end of the forecast period.

Low temperatures will be in the 30s.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 728 PM EDT Sun Apr 16 2017

Lower cigs will return to PLN/APN late tonight.

Leftover marine stratus/fog/low clouds have largely (and finally)
eroded as of late this afternoon. A secondary cold front will drop
south into northern lower MI tonight. Enhanced low-level moisture
and associated cloud cover will arrive behind this front. Expect
MVFR to IFR clouds to return to PLN/APN well after midnight, and
gradually lift on Monday. For now will keep cigs just above MVFR
territory at TVC, whereas MBL will see little impact.

Ongoing light nw winds will become north on Monday.


Issued at 301 PM EDT Sun Apr 16 2017

Winds were generally west to north across the region with two cold
fronts in the region. One will cross out of the srn nearshore
waters of Lake Huron over the next few hours, while the other will
slowly sag into nrn lower tonight and linger into Monday. Winds in
most areas will remain below advisory levels due to continued
stable conditions over the cold Lakes, but the gradient does
tighten up into the evening for some potential low end advisory
speeds, especially nrn Lake Huron. Overall higher pressure and
lighter winds will keep winds on the lighter side through Monday
night. Then, the next low pressure system will start to move into
the Great Lakes. Southerly winds do increase ahead of this system,
and again, despite increasingly stable conditions developing, low
end advisory speeds are possible.




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