Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 190159

Area Forecast Discussion
National Weather Service Gaylord MI
959 PM EDT Sun Jun 18 2017

Issued at 959 PM EDT Sun Jun 18 2017

Deep low pressure continues to lift NE away from Lake Superior
toward James Bay late this evening. Upper level trough axis
remains upstream extending thru the Mid and Upper Mississippi
Valley. Deep cyclonic flow...residual low level moisture and cold
air aloft continues to produce widely scattered showers across the
Western Great Lakes region...and will continue to do so into the
overnight hours. Best precip chances across our CWA will remain
across Upper Michigan...with precip chances again expanding
southward into Northern Lower Michigan on Monday as the upper
level trough axis swings into the region. Expect a cool night
across the Northwoods with lows dropping into the low to mid 50s.


.NEAR TERM...(Tonight through Monday)
Issued at 329 PM EDT Sun Jun 18 2017

...Periodic showers and cooler...

High Impact Weather Potential: Chance of scattered thunderstorms
Monday afternoon.

Pattern Synopsis/Forecast: Low pressure currently centered near
Whitefish Point this afternoon will continue its northeastward
progression into Ontario and eventually Quebec tonight. Attendant
cold front will continue to press eastward across Lake Huron aiding
to draw in cooler air across the forecast area with our daytime
highs already in the rear view mirror. Weak mid level forcing aloft
(relatively speaking compared to this morning...coinciding with a
band of showers and thunderstorms) combined with cooling temps aloft
and deeper low to mid level moisture wrapping into the region on the
back side of the departing low pressure will continue to bring low
chances for showers (most numerous across the U.P.) through the
remainder of the day before diminishing this evening.

Broad troughing is expected to continue across the Great Lakes/Upper
Midwest on Monday. Guidance continues to suggest several weak/subtle
shortwaves floating through upper level flow coinciding with diurnal
processes, which should be sufficient to spark another round of
scattered showers (most numerous across northeast Lower) and perhaps
a couple rumbles of thunder, especially midday Monday through the

Tonight`s overnight lows progged to be some 10 degrees cooler than
last night`s...ranging from the low-mid 50s area wide. High
temperatures Monday some 5-10 degrees below normal with low-mid 60s
across eastern Upper and from the mid 60s to low 70s south of the
bridge (warmest across downsloping locations of northeast Lower).


.SHORT TERM...(Monday night through Wednesday)
Issued at 329 PM EDT Sun Jun 18 2017

...Self-destruct Sunshine and Thunder...

High Impact Weather Potential...none.

Pattern Synopsis/Forecast...500 mb upper low will continue to spin
just north of the Upper Great Lakes and with it will rotate spokes
of energy over the forecast area, during the heat of the day. This
will produce showers and thunderstorms during the afternoon which
will probably linger into the evening, before ending. There will
still be a small chance for showers overnight, as another shortwave
trough rotate into the region. However, it looks like it there
will be better chances for the morning on Tuesday as the shortwave
moves into the the forecast area. The trough will still be
influencing our weather into the afternoon during peak heating. GFS
and ECMWF show a few hundred J/kg of SFC and MLCAPE for the
afternoon, so will continue the threat for afternoon thunder.
However, it looks as if the upper level system leaves by the evening
allowing the 500 mb heights to rise the sfc high builds in as well.
It looks like this should remain through the day, however, ECMWF is
suggesting that the warm front kicks off showers in the afternoon
on Wednesday. Will hold off on that for now.

Primary Forecast Concerns...Main concerns will be for thunderstorms.
If there we can get the instability, that it would be possible.
However, it may just be showers Monday evening as the cooler air
will be flooding in, even near the sfc, it may be more of a shower.
Tuesday may even be less of a chance depending on the speed of the
500 mb trough.

.LONG TERM...(Wednesday night through Sunday)
Issued at 329 PM EDT Sun Jun 18 2017

The extended period starts out with zonal flow in the upper levels
through Saturday...then a trough begins to dig in to the Northern
Plains and shift over the great lakes on Sunday (according to the
GFS) or Monday (according to the Euro).

Closer to the surface...a frontal system sweeps through the great
lakes Thursday/Thursday night.  This will be our best chance at any
appreciable rainfall (and possibly some thunder) in the weak/dirty high pressure will try to establish itself
for Friday and Saturday. As the aforementioned troughiness begins to
move over the great lakes...Sunday will bring another chance of
rainfall, depending on which model solution you choose.  But that`s
a long way off yet...and with the differences in guidance, it`s a
bit premature for anything too deterministic.

Temperatures will be generally seasonal through most of the
period...with a trend toward cooler on Sunday.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 700 PM EDT Sun Jun 18 2017

Deep low pressure now centered east of Lake Superior will continue
to push NE tonight...reaching James Bay by early Monday morning.
Upstream upper level trough axis will swing thru Lower Michigan on
Monday...serving to again increase chances of showers and a few
thunderstorms across our area. West winds gusting to 15 to 25 kts
early this evening will diminish to AOB 10 kts after sunset and
will remain so thru Monday.


Issued at 329 PM EDT Sun Jun 18 2017

Low pressure across eastern Upper will continue to trek
northeastward into Ontario and eventually Quebec tonight. Tight
pressure gradient will be enough to continue gusty westerly winds
and small craft advisory conditions right through this evening
before abating overnight. Aside from lingering isolated to scattered
showers, no additional widespread precipitation is expected through
the forecast period.


LH...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LMZ323-341-342-
LS...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LSZ321-322.


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