Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 221725

Area Forecast Discussion
National Weather Service Gaylord MI
125 PM EDT Mon May 22 2017

Issued at 1017 AM EDT Mon May 22 2017

Vertically-stacked low pressure remains centered over Southern
Ontario late this morning...with deep cyclonic flow across the
entire Upper Midwest and Great Lakes region. Potent short wave
riding thru the fast 500 mb flow is approaching our CWA attm...
producing a batch of enhanced showers now moving into far Northern
Lake Michigan toward northern sections of our CWA. This wave will
slide across our area thru early afternoon...pushing NE into SE
Ontario by late afternoon. Enhanced lift and moisture with this
feature will result in an uptick in shower activity thru early
afternoon...before the wave begins to pull away by mid to late
afternoon. POPs should be limited to Eastern Upper Michigan by
late in the day once the wave exits our CWA. Ample cloud cover and
lack of sufficient instability should keep any chances of thunder
at bay.


.NEAR TERM...(Today through Tonight)
Issued at 311 AM EDT Mon May 22 2017

...Cool-ish and damp-ish...

High impact weather potential...none.

Mature surface low continues to spiral away nw of Thunder Bay
Canada. Occluded front is now well downstream, and post-frontal sw
low-level flow is well established. We had been beneath the mid-
level dry slot, but that is also departing eastward, with expanding
clouds and cooling cloud tops here and upstream. Very light radar
returns, evidence of sprinkles but nothing more, are seen over far
northern Lake MI and surroundings. More vigorous showers are seen
upstream. Precip trends are the main concern. prominent shortwave rotating around the closed low will
pivot ne-ward across northern MI this morning. Areas of showers
presently in northern WI are associated with this wave. Forcing will
be sharpest across eastern upper MI, which is also where the deepest
moisture lies (closest to the upper low). Morning pops will range
from likely in far nw lower and eastern upper MI, to negligible in
the se. For the afternoon, sct showers will continue to cycle
eastward in close proximity to the 500mb low. Northern lower will
see enough post-wave subsidence to see those showers end and partial
clearing result, especially south of M-32. Temps are still on the
cool side aloft, though, and some meager instability may result.
SbCape values are progged up to 200j/kg down in the TVC/CAD area. No
obvious triggers around (too much synoptic sw wind for lake
breezes), but a bit of a vort max is crossing central lower MI, and
our low-level is backing ahead of a better shortwave digging toward
Iowa/southern MN. Will hold off on any pops thru 00z (though will
break out some precip immediately thereafter).

Healthy max temp range, thanks to plenty of clouds north and
eventually some partial sunshine south. Highs from the low/mid 50s
eastern upper, to the mid 60s in the far se.

Tonight...weak surface low will spin up in Iowa, ahead of digging
shortwave from the larger upper low to our north. Backing low-level
flow ahead of the low result in some 850mb theta-e advection into
central lower MI. This is in an environment with MuCape values of
100-200j/kg. This all will result in sct showers transiting southern
sections of the forecast area, primarily near and south of M-72.
There will also still be sct showers hanging around eastern upper MI
in the 1st half of the night, due to the nearby upper low. The upper
low will more bodily lift out to the ne overnight, and pops will end
in eastern upper with partial clearing north of M-32. This will be
conducive to some patchy fog overnight in northern sections.

Min temps near 40f in eastern upper MI to mid/upper 40s in the south.


.SHORT TERM...(Tuesday through Wednesday)
Issued at 311 AM EDT Mon May 22 2017

...Cool and showery conditions continue...

High impact weather potential: Slight chance of thunder Tuesday
afternoon, mainly south of M-72.

Pattern forecast: Longwave troughing is expected to encompass the
eastern half of the CONUS by midweek as ridging builds across the
West Coast into southwestern Canada. Main feature controlling our
weather will continue to be stationary closed low pressure aloft,
bringing occasional showery periods as several waves of energy dive
out of Canada and pinwheel around the parent low. At least a brief
reprieve from wet weather arrives toward the end of the work week as
high pressure settles in before additional rain chances arrive over
the Memorial Day weekend.

Primary forecast challenges/concerns: Shower chances throughout the
forecast period and slightly below normal temperatures.

A rather cool and damp pattern is expected throughout the forecast
period with several waves of showers expected to make their way from
south to north across northern Michigan. Neither Tuesday or
Wednesday are expected to be complete washouts as the timing of
shower chances revolves around several shortwaves rotating around
aforementioned cutoff low pressure aloft. Perhaps a rumble of
thunder two Tuesday afternoon, mainly south of M-72, as a paltry
instability axis briefly folds into the area, but as it stands right
now, the best chance for more frequent showers will be Tuesday
night; however, the pattern as a whole isn`t one where you`d expect
widespread precip over the entire area for an extended period of it`s likely that some will do "better" with respect to
rainfall amounts than others. Shower chances continue Wednesday, but
again is expected to be more so of a hit or miss type scenario
rather than widespread appreciable rainfall.

High temperatures a couple of degrees below normal on Tuesday
ranging from near 60s north of the bridge and through the 60s south.
Cooler temps Wednesday with widespread readings between the upper
50s to low 60s.

.LONG TERM...(Wednesday night through Sunday)
Issued at 311 AM EDT Mon May 22 2017

High impact weather potential: Minimal.

Showers remain possible Wednesday night through at least the first
half of Thursday before high pressure settles atop the Great Lakes,
at least briefly. Uncertainty increases over the upcoming Memorial
Day weekend as ensemble guidance spreads significantly in terms of
rain potential. Worth monitoring as we get closer for periods of wet
weather to impact any kick off to summer outdoor activities, but at
the very least a return to normal temperatures looks to prevail.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 125 PM EDT Mon May 22 2017

Deep cyclonic flow and residual low level moisture will keep
Northern Lower Michigan under low clouds and periodic chances of
showers tonight. Another wave will push toward southern sections
of our CWA on Tuesday...producing additional showers for Tuesday.
Overall conditions will remain MVFR/low VFR...with a diminish to
IFR late tonight into early Tuesday as some fog develops. W/SW
winds gusting to 10 to 20 kts this afternoon will become
light/variable tonight.


Issued at 311 AM EDT Mon May 22 2017

Somewhat gusty sw winds will continue today, as low pressure
remains just north of Superior. Advisory-level conditions are
expected on Lake MI and in the Straits. Lighter and more variable
winds are expected to develop tonight and persist into Tuesday


LH...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LHZ345.
LM...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LMZ323-341-


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