Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 121955

Area Forecast Discussion
National Weather Service Gaylord MI
255 PM EST Sun Nov 12 2017

.NEAR TERM...(Tonight through Monday)
Issued at 254 PM EST Sun Nov 12 2017

High impact weather potential: Areas of freezing drizzle again
tonight into early Monday morning.

Pattern synopsis and forecast:

A shallow mid level trough and it`s associated sfc reflection
remained situated from eastern upper down through eastern Lake
Michigan. Periods of drizzle and light fog continued in these areas
within moist low level environment. This was probably aided to some
degrees, by weak 1000-850mb westerly flow and overlake instability
(marginal across the srn CWA) resulting in some moisture flux off
the Lakes. Not much change since this morning. Upstream across the
central and nrn plains, broad high pressure was seen, with sunnier
skies and little to no weather.

The shortwave trough departs this evening into the overnight hours,
while the weakish westerly flow results in maybe a degree cooling
over the Lakes. While the sfc troughing will likely be washed out or
shoved east, we will still have some minimal moisture flux helping
to keep the low levels moist, but not deep enough to eclipse -10C.
Areas of drizzle and a return to some freezing drizzle is expected
again, but it might just be a little less frequent and patchy. This
same scenario continues into Monday morning, before the next
shortwave starts pushing into the western Great Lakes. WAA out ahead
of this feature will gradually break down the overlake instability
through the day. Will have to at least keep a mention of patchy
drizzle until then.

Lows tonight in the upper 20s to lower 30s with light fog across the
region. Highs Monday in the upper 30s to lower 40s.


.SHORT TERM...(Monday night through Wednesday)
Issued at 254 PM EST Sun Nov 12 2017

...Widespread rain likely Tuesday night into early Wednesday...

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast...High pressure ridge axis will cross
northern Michigan Monday night, with warm air advection developing
on the back side of this departing system. Strengthening return flow
draws increasing moisture into the region on Tuesday, with upstream
isentropic lift progressively spreading more mid/high clouds into
the region and eventually precipitation. Two shortwaves will merge
over the Upper Great Lakes on Wednesday, with a developing surface
low tracking across southern Ontario, dragging a cold front through
northern Michigan.

Primary Forecast Concerns...Increasing precipitation chances and
ptypes Tuesday night into Wednesday.

Forecast soundings showing a shallow layer of moisture trapped near
the surface Monday night as the surface ridge crosses northern
Michigan. With light boundary layer winds, this will mean continued
low stratus and perhaps some fog. Looks like the low levels will
start to dry out a little towards midday Tuesday as daytime mixing
gets going, but as mentioned above, strengthening isentropic lift by
that time will be spreading additional mid/high clouds into the
area. There may be some breaks of sunshine, but the general rule
will be more clouds than sun.

PWATs will steadily increase through the day to over 0.75" Tuesday
night. As the better isentropic lift is shunted off to the east,
decent mid level forcing will come into play overnight as a potent
shortwave slides into the region. Looking like fairly widespread
precipitation as a result, though not particularly heavy with QPF
less than a half inch across the entire forecast area. Bulk of the
steadier precip will exit by mid to late morning, with scattered
showers accompanying the cold front. Drier air and subsidence
overhead for Wednesday afternoon, but falling H8 temperatures
over Lake Superior will lead to some lake enhanced showers for
eastern Upper by late afternoon.

Most precip associated with this system will fall as liquid, but
temperatures in portions of interior northeast Lower may flirt
with freezing Tuesday evening, perhaps allowing some wet snowflakes
to mix with the rain early.


.LONG TERM...(Wednesday night through Sunday)
Issued at 254 PM EST Sun Nov 12 2017

The extended period starts out with a system finishing up over the
the lakes..and moving off to the east.  However, with a pretty
progressive pattern across the CONUS, the respite from the active
weather will be short...maybe 24-36 hours.  The next system will
move in earnest as a surface low advances quickly from the plains on overhead by Saturday.  Models agree that this low
deepens as it heads over the Great Lakes and lifts up toward Hudson
Bay.  This will help draw down some cold Canadian air and set up
northwest flow across the lakes for Sunday...which could get the LES
machine cranked back up.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1243 PM EST Sun Nov 12 2017

A weak sfc trough has moved into NW lower and eastern upper and
was producing periods of drizzle and light fog at mainly the NW
lower airports, aided by thick low level moisture. This trough
departs east and winds go light NW through tonight, but shallow
overlake instability may be able to still squeeze out some periods
of drizzle into Monday morning. Primarily MVFR CIGS through the
period, with MVFR VSBYS at times in drizzle and light fog.


Issued at 254 PM EST Sun Nov 12 2017

No marine concerns as high pressure gradually works in over the
Great Lakes through Tuesday, before the next low pressure system
intensifies in Ontario Tuesday night into Wednesday. This will
tighten up the gradient for a pretty solid chance for advisory level
winds, with a small chance attm, for low end gales.




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