Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 161355

Area Forecast Discussion
National Weather Service Gaylord MI
955 AM EDT Wed Aug 16 2017

Issued at 955 AM EDT Wed Aug 16 2017

1020mb high spread across srn Ontario down to NW Pennsylvania will
keep the region dry this afternoon and much of tonight. Low clouds
and fog burning off quickly this morning. 12z KAPX sounding showing
a subsidence inversion around 700mb that should keep CU
development in check this afternoon. However, quite a bit of high
and mid level clouds around this morning. Shortwave evident in
visible satellite pix over GRB helping to generate the mid and
high clouds will track over northern Lower this afternoon. So
expect some sunshine across northern Lower but not clear skies.
Eastern Upper will see more sunshine, especially near Whitefish
Bay. Otherwise not much going on today. High temps should be near
normal for this time of year and winds will remain on the light


.NEAR TERM...(Today through Tonight)
Issued at 340 AM EDT Wed Aug 16 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Pretty quiet in the north woods early this morning. Deep upper low
was well away from us, centered out over nrn Quebec, with mid level
ridging working through the Mississippi valley. Sfc high pressure
was settled in over SE Ontario with nrn Michigan seeing sub25%
humidity through a large depth of the atmosphere. There were only
some high clouds drifting across the region, out ahead of weak
vorticity in Wisconsin busting through the mid level ridge axis. All
the action was well west of Michigan, associated with low pressure
in Nebraska, where strong low level jets. deeper moisture and
stronger upper dynamics resided. Temperatures have dipped into the
50s across most of the region, with some of the colder low lying
areas making a run at the upper 40s.

Not much going on today and tonight. The sfc high pressure slides
east with winds more out of the SE/ESE, but light enough for
tendencies in more onshore type lake breezes. The air mass remains
on the drier side of things comparative to surrounding areas, but we
will have more vorticity running by overhead with some slight
increase in low to mid level WAA and some DPVA. This will provide
periods of high level clouds to continue to push through, while
another day of scattered to broken cumulus is expected. Must admit,
was pretty surprised at the coverage of cumulus yesterday afternoon,
but today it ought to be fairly decently spread across the sky. This
is due to fcst soundings suggesting a more pronounced subsidence
inversion just above the low level moisture.

The stronger forcing does not arrive until we head through tonight,
especially late tonight. Stronger WAA and DPVA from a well organized
shortwave, and possibly even a little upper divergence, pushes into
the region by late tonight. This will be associated with deepening
sfc low pressure that works into the upper Mississippi valley, and a
warm front that gets drawn up into srn Lake Michigan. We still might
be battling whether or not we advect enough moisture into nrn
Michigan for any decent rains, but some light rain or sprinkles
might be able to squeeze out of middle level clouds by daybreak.
Lows milder, in the lower half of the 60s most areas.


.SHORT TERM...(Thursday through Friday)
Issued at 340 AM EDT Wed Aug 16 2017

...Still potential for heavy rain Thursday...

Storm system taking shape across the western Plains will track
across Wisconsin Thursday, across eastern upper Michigan Thursday
night then exit across eastern Ontario Friday. Potential for heavy
rainfall and thunderstorm chances are the biggest issues to tackle
in this package.

Thursday into Thursday night...It still looks like the region will
get a decent amount of rainfall with system moving across the region
(with precipitable water values still forecast to push 2 inches).
Exactly where the heavy rainfall will occur remains uncertain.
Models are trying to split bulls eyes of moderate to heavy rainfall
over northern Michigan with one area likely impacting eastern upper
while another area clips north central lower. Have tried to depict
this in the qpf forecast with many spots likely receiving over an
inch and some areas possibly getting upwards of or slightly more
than an inch and a half to two inches. 6 hour flash flood guidance
is fairly high with most spots in the 3 to 4 inch range but a few
eastern counties as low as just over 2 inches (so this is where
rainfall amounts will need to be monitored). Thunderstorms also
remain a possibility but abundant cloud cover should limit
instability (though there is some dynamic forcing evident in div-q
fields). 0-6km bulk shear is in the 40 knot range so any storms that
do form could produce gusty winds.

Friday...Lingering wrap around moisture along with marginal over
lake instability will prolong abundant cloudiness as well as showers
and drizzle...not to mention chilly westerly winds (just a quick
preview of the upcoming fall).

.LONG TERM...(Friday night through Tuesday)
Issued at 340 AM EDT Wed Aug 16 2017

A short wave moving through the flow will bring chances for showers
Saturday across the southern half of the forecast area. Increasing
ridging for Sunday should lead to precipitation free and warmer
conditions. A trough/cold front is then expected to follow at some
point Monday or Tuesday (not much model agreement on the timing).
Pops will increase during this time as a result. Still rather warm
Monday with somewhat of a cool down likely on Tuesday.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 635 AM EDT Wed Aug 16 2017

Still dealing with some fog at PLN this morning, which is likely
to burn off soon. Otherwise, periods of mid and high clouds roll
in with cumulus developing again, more so across the NW lower
airports this time due to a relatively light easterly wind.
Cumulus is likely to be of decent coverage, and maybe even a
sprinkle here and there in NW lower. Clouds will just thicken
overnight, especially NW lower, ahead of low pressure and a warm
front. Expecting some rain by the end of the TAF period.


Issued at 340 AM EDT Wed Aug 16 2017

High pressure slides east today with winds shifting around out of
the SE/ESE, but remaining rather light, with tendencies for the
winds to go more onshore/lake breezes. Winds do increase through
tonight and especially Thursday, out ahead of deepening sfc low
pressure that crosses eastern Lake Superior Friday. Rain chances are
best Thursday, with periods of rain and scattered thunderstorms
expected throughout the day. Thunderstorms will likely be more
common Thursday afternoon and Thursday night, as a warm front first
pushes through, followed by the cold front Thursday night. Winds
will swing more out of the south tonight through Thursday night,
then more westerly Friday after the cold front. Periods of advisory
level winds are expected Thursday through Friday night, maybe even
into Saturday.




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