Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 290149

Area Forecast Discussion
National Weather Service Gaylord MI
949 PM EDT Wed Sep 28 2016

Issued at 948 PM EDT Wed Sep 28 2016

Pronounced deep cutoff low spinning over the lower Great Lakes
region this evening, centered over Indiana. Deep moisture/cold air
aloft and ongoing larger scale QG-forcing continues to produce
"spiral bands" of showers rotating around this system with the
best coverage through lower Michigan and into the Ohio Valley. We
did have one band of showers/thunder rotate westward through parts
of northern lower Michigan south of M-72 earlier. Last remnants of
that activity is now working through parts of Grand Traverse and
Wexford counties. Otherwise, cloud cover is thinning overall
across the CWA.

Rest of tonight: Deeper moisture/QG-forcing associated with
cutoff low to the south expected to remain out of our area. But,
high resolution guidance runs over the last few hours continue to
suggest to possibilities of shower redevelopment off Lake Huron
and pushing through the far SE counties during the overnight. SPC
mesoanalysis does reveal upward of 500 J/KG MUCAPE over the lakes
currently, thanks to the warmer/moist boundary layer and cool air
aloft. So it`s not inconceivable and I will leave inherited lower
end shower chances intact across that area.

Otherwise, with persistent moist easterly low level flow off the
lake, forecast RH profiles and soundings also suggest stratus
possibilities overnight, particularly over NE lower Michigan.
Tough call here, but I will keep overall partly cloudy skies going
for NE lower Michigan overnight with that in mind.


.SHORT TERM...(This evening and overnight)
Issued at 348 PM EDT Wed Sep 28 2016

High impact weather potential: None.

Pattern synopsis and forecast:

The upper level and sfc lows that plagued nrn Michigan over the last
few days has continued to sink south into the Ohio River valley
today. A nice wedge of low to mid level drier air has swept in
across nrn lower with ample sunshine out there, while remnant sfc
troughing arced from the sfc low back around through Wisconsin and
then across eastern upper. Here, there were still some lower level
clouds and isolated showers. Denser clouds and isolated-scattered
showers (with an embedded rumble of thunder or two) were wrapping up
through the SE CWA, associated with stronger shortwave energy
lifting into Detroit. Low to mid level WAA (resulting in decaying
overlake instability) and upper divergence was working with the
leading edge of steeper lapse rates, resulting in those showers.
Gusts were also increasing out of the east/ENE as the pressure
gradient was tightening.

Despite the upper/sfc lows continuing to sag further south through
tonight, the stronger shortwave energy and aforementioned forcing
will linger around the srn CWA, generally south of M-72. This will
result in small chances for showers a a few storms with some
easterly wind gustiness to continue into this evening. The low
pressure system continues to drop further south into Thursday, but
deeper Atlantic moisture gets tapped and advected through the srn
and eastern Great Lakes, and the gradient tightens further. So,
while the least chance of showers south of M-72 appears to be the
overnight hours, but chances return later Thursday, focused more
so near Saginaw Bay with the return of some better WAA and upper
divergence with those steeper lapse rates. Overlake instability
will be marginal at best (plus a relatively short fetch in that
area) for any sort of lake assistance. All-in- all, most folks,
especially in the NW CWA will have a pretty nice day Thursday.

Lows tonight in the lower half of the 50s for most with highs
Thursday middle 60s SE (in thicker cloud and possible showers) to
the lower 70s in eastern upper.

.LONG TERM...(Thursday through Wednesday)
Issued at 348 PM EDT Wed Sep 28 2016

Thursday night through Saturday...

High impact weather potential: None.

Pattern synopsis/Expected evolution: Periods of unsettled weather
right through the upcoming weekend will be the main story through
the forecast period thanks to a well-advertised cutoff upper level
low continuing to spin across the midsection of the country. By
Thursday evening, said upper level low is progged to be centered
over central KY with little eastward progression thanks to strong
ridging off the eastern seaboard before retrograding north toward
the Great Lakes on Friday into the upcoming weekend. As a result,
the week should end similarly to how it started with showery
conditions expected Friday through Sunday.

Thursday night - Friday: Closed circulation begins to slowly
retrograde north late Thursday night into Friday with deep layer
moisture gradually increasing from south to north throughout the
day. As a result, a fairly wide spread in sensible weather across
the CWA is expected. Partly to mostly sunny skies and mild
temperatures are expected across eastern Upper (highs in the upper
60s) while locales south of the bridge should feature extensive
cloudiness, slightly cooler temperatures and increasing chances for
rain showers as the day progresses. It certainly looks like the best
threat for showers (south of the bridge) arrives late in the
afternoon/evening as stronger forcing for ascent and better moisture
arrive in association with the low progressing toward Indianapolis.
Will continue the inherited feel of the forecast with increasing
PoPs from south to north (highest across the far south/southeast,
gradually tapering as you head north) throughout the day.

Friday night - Saturday: By Friday night, there is fairly decent
global model guidance agreement that the center of aforementioned
low pressure lies near the MI/IN/OH border with lobes of moisture
pinwheeling around the northern periphery, resulting in continuing
scattered precip chances locally. Neither Friday night or Saturday
is expected to be a complete washout with showers remaining
occasional and rather light in nature. Little to no E/ESE flow lake
effect/enhancement is expected with diminishing inversion heights and
minimal over lake instability thanks to a shrinking delta T as H8
temps surge to roughly +11 C by Saturday morning.


(Saturday night through Wednesday)

...Nothing of real significance expected...

Some lingering showers to end the weekend as pesky upper low slowly
exits to the northeast. Pattern remains amplified thereafter, with
strong hints that rather robust upper level ridge builds overhead to
start next work week, bringing a much deserved dry and seasonably
mild few days of weather. Possible Atlantic tropical activity may
help further amplify/slow the overall pattern, raising concerns that
current model consensus blend of introducing additional rain chances
Tuesday night and Wednesday may be a touch too quick.



.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 804 PM EDT Wed Sep 28 2016

VFR conditions anticipated tonight through Thursday although some
lower clouds may materialize across northern lower Michigan late
overnight through early Thursday morning. There is a possibility
of LLWS across northern lower Michigan tonight, as low level flow
increases tonight. However, chances appear to low to include in
the terminal forecasts at this point.


Issued at 351 PM EDT Wed Sep 28 2016

Low pressure will continue to sink south into the Ohio river
valley tonight, while the pressure gradient tightens up further
over Lakes Michigan and Huron. Another long period of advisory
level winds will impact most nearshores of nrn lower Michigan,
with new advisories already issued through Friday. Additional
nearshore waters may also need headlines. The low pressure is
still expected to return over the weekend, which will weaken the
gradient and bring back better chances for showers.


LH...SMALL CRAFT ADVISORY until 5 PM EDT Friday for LHZ348-349.

LM...SMALL CRAFT ADVISORY until 5 PM EDT Friday for LMZ323-342-



SHORT TERM...Dickson
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