769
FXUS63 KAPX 271931
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
331 PM EDT Tue Sep 27 2016

.SHORT TERM...(This evening and overnight)
Issued at 321 PM EDT Tue Sep 27 2016

High impact weather potential: A few thunderstorms remain possible
through Wednesday. No severe weather. Waterspouts possible tonight
into Wednesday.

Pattern synopsis and forecast:

The main feature of note continues to be the swirling upper/sfc low
over Lake Superior that is slowly dropping south this afternoon. The
atmospheric moisture continues to deepen as it approaches,
especially along and ahead of the current shortwave and associated
sfc trough now crossing nrn lower Michigan, and the other pressing
through eastern upper. This is helping expand the steady lake effect
showers that remain locked into the WSW flow regimes. Some pretty
impressive rainfall totals have been seen across far nrn lower and
eastern sections of Chippewa and Mackinac counties of eastern upper.
Several areas have seen 1-2+" of rain in each of the last two 24hr
periods. Stronger shortwave energy was seen wrapping down the
western side of the upper low across the arrowhead of MN, with their
own synoptic rains impacting that area.

Expect the WSW flow regimes to continue getting hit with the best
rains through the remainder of the afternoon and perhaps into a good
chunk of the evening. The shortwave and sfc trough running across
nrn lower will likely continue to produce showers across NE lower
into the evening, while the wave/trough from eastern upper continues
to target the better rains into nrn Lake Michigan into evening.
Meanwhile, the upper/sfc lows will continue dropping southward right
through the spine of Lake Michigan through the night. Winds will be
wildly backing more easterly over this time and also weakening.
Still easily have the low level thermal regime cold enough for lake
effect rains, just doubt there can be any additional significant
rain overnight as it should turn more scattered overnight. Certainly
will not be talking any significant rain totals. In fact, the best
rainfall will likely occur along the max low level convergence track
associated with the sfc low. This also where waterspouts ought to
have the best chance of occurring. Still looking at some relatively
minor instability. Doubt it`s worth even putting into the forecast
(especially since none has occurred the last couple of nights), but
there is a slight chance for thunder.

Wednesday, the low pressure will drop into the Ohio river valley.
The easterly winds become more established, and this will draw in
some slightly warmer air in the low levels which will take delta
t`sinto a more marginal zone. Nevertheless, we are still under
cyclonic flow with still some likely shortwave and sfc troughing
wrapping around the nrn periphery of the system. This will result in
more scattered/pockets of lake/lake enhanced rains. Will just trend
chances for rain down into the scattered categories by later in the
afternoon. Probably still have to continue the mention of possible
waterspouts and chances of thunder for Lakes Michigan and Huron
where instability/waterspouts parameters are best.

Temperatures will still not swing too much. Lows in the mid to upper
40s and highs lower 60s most locales.

.LONG TERM...(Wednesday through Tuesday)
Issued at 321 PM EDT Tue Sep 27 2016

Wednesday night through Friday...

High impact weather potential: Minimal.

Pattern synopsis/Expected evolution: Well-advertised cutoff upper
level low continues to spin across Lake Superior, clearly evident on
water vapor imagery this afternoon. Said area of low pressure will
plague northern Michigan at various times through the weekend as it
gradually sinks toward the Ohio Valley late this work week before
retrograding north this weekend. As a result, much of the same is
expected with mostly cloudy skies, near to slightly cooler than
normal temperatures and occasional showery periods.

Wednesday night: Decent global model agreement that our upper level
low will be centered near Indianapolis on Wednesday night with
lingering wrap around moisture gradually pinwheeling around the
northern periphery. Not expecting widespread precip coverage Wed
night with the highest PoPs (30-40%) focused along and east of M-
65...perhaps aided to a minor extent by an ENE fetch across Lake
Huron and delta Ts hugging the 13 C line helping to kick off lake
induced showers. PoPs taper quickly to the west with the remainder
of the CWA expected to be dry.

Thu - Thu night: Somewhat of a respite in the wet weather is
expected as low pressure stalls out over the Ohio River Valley.
Drier mid-level air is expected to dominate across the northern two-
thirds of the CWA with partly to mostly sunny skies. The exception
will continue to be southeastern zones where enough lingering
moisture is expected to result in more cloud cover and perhaps a few
sprinkles/light showers, although the majority of shower activity
should remain downstate.

Friday: Closed circulation begins to retrograde back north
throughout the day, once again increasing deep layer moisture from
south to north across northern Michigan. PoPs increase with showers
becoming likely across southern/southeastern zones by the afternoon,
continuing to slowly progress northward as the evening wears on into
Friday night.

MG

Extended (Friday night through Tuesday)

All models remain in agreement with the closed upper level low (that
is currently effecting us from the north...but progged to drop south
into the Ohio valley by Friday) retrograding back north over the
southern lakes for Saturday and Sunday.  This will keep periodic
bouts of precip streaming across the CWA through at least the first
half of the extended period. This low finally appears to get it`s
act together and slide east by Monday...which should result in a
drying trend (albeit temporary) into Tuesday. Temperatures will
remain seasonal for Saturday and Sunday will some slight moderation
for Monday and Tuesday...with daytime highs possibly reaching the 70
mark by the end of the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 321 PM EDT Tue Sep 27 2016

...Deteriorating conditions...

Low VFR/temporary MVFR is holding firm today, with all data
suggesting solid MVFR CIGS should be in place. Do believe that MVFR
ought to become the prevailing condition (and some IFR potential
late tonight) across primarily the NW lower airports as deeper low
level moisture arrives with the passing of sfc low pressure down the
spine of Lake Michigan. Lake effect showers will continue to
primarily impact NW lower in weakening WSW flow and with maximum low
level convergence with the low pressure. The solid banding will get
disrupted however, with backing flow to out of a weaker easterly
direction later tonight into Wednesday. Coverage in showers will
also decrease over this time as well. The showers impacting NE
lower/APN is associated with a sfc trough, and these should push of
the coast by evening.

&&

.MARINE...
Issued at 321 PM EDT Tue Sep 27 2016

An upper/sfc low will drop south through Lake Michigan tonight and
then into the Ohio river valley Wednesday into Friday, before trying
to lift back into the region for the weekend. The WSW flow will
trend more weak and out of the east through the night. Lake effect
rains are expected to gradually decrease in coverage and frequency
through the end of the work week (best chances eventually nearer Sag
Bay). Chances increasing again over the weekend.

Advisory level westerly winds may persist into this evening for a
handful of srn nearshore waters, with these same areas possibly
needing renewed SCA`s Wednesday night into Thursday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 6 PM EDT this evening for LHZ345>349.

LM...SMALL CRAFT ADVISORY until 6 PM EDT this evening for LMZ323-341-
     342-344.

     SMALL CRAFT ADVISORY until 8 PM EDT this evening for LMZ345-346.

LS...SMALL CRAFT ADVISORY until 6 PM EDT this evening for LSZ321-322.

&&

$$

SHORT TERM...Dickson
LONG TERM...Gillen/KAB
AVIATION...Dickson
MARINE...Dickson