Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 190359

Area Forecast Discussion
National Weather Service Gaylord MI
1159 PM EDT THU AUG 18 2016

Issued at 1052 PM EDT Thu Aug 18 2016

Quiet, mild conditions under mostly clear skies heading through
this evening. Some changes heading through the early morning
hours, with clouds steadily on the increase. Weak wave cutting
across central upper Michigan is managing to kick off a few
showers and thunderstorms. This wave and attendant shower threat should
continue to move east overnight, at least bringing the potential for
scattered showers/storms to eastern upper and parts of northwest
lower Michigan by sunrise. Still expecting patchy/areas of fog to
develop across interior sections of northern lower by morning as
dewpoints remain elevated.


.SHORT TERM...(This evening and overnight)
Issued at 303 PM EDT Thu Aug 18 2016

Somewhat complex weather scenario developing for the end of the week
with northern stream trough evolving into an upper over near Hudson
Bay with a trailing trough/cold front across the upper midwest.
Several embedded shortwave troughs within a developing moist,
southwest flow across the Great Lakes will result in increasingly
unsettled weather.

Scattered diurnal showers/tstms over northeast lower and interior
eastern upper will dissipate quickly by early this evening with loss
of daytime heating.  The overnight period should be mainly dry,
although we may see a few showers/tstms push into far western areas
toward morning in advance of a mid level shortwave and on the
eastern edge of deeper moisture plume pushing into the area out of
Wisconsin.  Light wind regime and increasingly moist low levels
point toward the development of fog once again.  Anticipate areas of
fog to develop over interior northern lower, especially along the M-
55 corridor and possibly northward into the higher terrain along I-
75. Some additional fog also possible in parts of the Au Sable
and Jordan Valley regions. Low temperatures in the sticky
lower/middle 60s.

Mid level shortwave crosses northern Michigan on Friday coincident
with the arrival of higher PWAT air and upstream cold front
pushing closer to the area. Forecast soundings show a fair amount
of skinny cape (1000 j/kg), with still relatively weak shear
limiting any severe potential. Really looks like locally heavy
downpours will be the main threat, with k-indices of 35-40 and
deep moisture through the column. High temperatures a bit tricky
given cloud cover/pcpn, but warm /almost tropical/ airmass
supports widespread 80s with uncomfortably high dewpoints.

.LONG TERM...(Friday through Thursday)
Issued at 303 PM EDT Thu Aug 18 2016

High impact weather potential: wet/stormy weather this weekend,
centering on Saturday.

Weekend wx continues to look rather unsettled. Cold front will
initially be strung out from Hudson Bay to the southern Rockies.
Cyclogenesis will proceed along that front in the upper MS valley
late Fri night, and that low will lift across northern MI late
Saturday. Precip trends are the main concern.

Models...Nam appears too deep and slow with the incoming low.
Gfs/Ecmwf blend is favored with somewhat weaker/more progressive

Fri night...cold front will have made some initial progress into
eastern upper. It will make some inroads into far northern lower
during the night, but will tend to slow overnight as low pressure
develops and deepens in eastern Iowa/nw IL. Leftover diurnal
convection, both generated locally and upstream in WI, will
gradually diminish as we move thru the evening and early overnight.
Might be something of a relative lull in the overnight hours re:
precip, as convection refocuses along the front from WI to MO.
Likely pops will suffice for most areas in the evening, decreasing
to chancy pops overnight. Fog will remain a concern give the very
humid airmass, even with limited breaks in the expected cloud cover.
Sticky min temps mid 60s to lower 70s.

Saturday/Sat initial shortwave digs into upper MI
Saturday, while a trailing wave will head for central/southern Lake
MI by late Sat night. The surface low will steadily deepen as it
moves ne, likely crossing the Straits region Sat evening. Cold front
crosses the rest of the forecast area Sat evening. Heaviest precip
will be along and just left of the surface low track, which still
targets eastern upper MI to some degree. Heavy precip threat fueled
by a large swath of Pwats of 1.75 to 2 inches pushing into lower MI
in the warm sector. Further south, shower/t-storm chances will
increase ahead of and with the cold front. Potential for strong/svr
storms largely dependent on how much we can destabilize. Given how
moist/cloudy/foggy we might be to start the day, realizing
substantial destabilization may prove difficult. SPC has a marginal
risk for much of the area, and would not go any harsher than that
for now. Precip threat will diminish from w to e during the night.

Max temps mid 70s to low 80s. Min temps upper 50s to lower 60s.

Sunday...a breezy and much cooler day, behind the departing (and
deepening) cyclone. Precip chances largely revolve around how
vigorous the secondary shortwave is. Some models allow for a strong
enough wave to allow a wraparound lobe of moisture to work across
the region, with a corresponding chance for showers. Will maintain
small-ish pops in much of the area, though starting to dry out
eastern upper and parts of nw lower MI in the afternoon. Max temps
upper 60s to lower 70s.

A relatively cool and dry start to the beginning of the week with
high temps in the low 70s as a strong sfc high moves into the area.
However the pattern evolves quickly into ridging aloft at 500mb by
Wednesday. Wednesday night into Thursday a potent sfc low will move
through northern Ontario. As a result a cold front will sweep
through the Great Lakes increasing chances for showers and an
isolated thunderstorm on Thursday. Uncertainty with the timing and
strength of the system remain.

Temperatures will be near normal turning above normal after Monday.
highs will be in the upper 70s into the mid 80s. Best chance for
rain will be Wednesday evening and Thursday afternoon.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1149 PM EDT Thu Aug 18 2016

Still looking at some early morning fog development, particularly
impacting KMBL where MVFR vsbys are expected. A storm system over
the Upper Midwest will work toward the western lakes today,
bringing increasing chances of showers and thunderstorms.
Generally prevailing VFR conditions during the day, with MVFR
conditions likely at times around shower/tstm activity. Winds
generally remaining light through the period, although stronger
around storms. Due to lingering uncertainty on exact convective
evolution, will continue to cover shower/storm chances with
vicinity wording only.

Shower and thunderstorm chances continue right through Friday


Issued at 303 PM EDT Thu Aug 18 2016

No small craft headlines expected through the day Saturday,
although increasing southwest flow ahead of a cold front
Friday/Saturday will result in slightly higher waves. A strong
cold front will sweep across the Great Lakes Saturday night,
ushering in much cooler air along with a period of gustier winds.
This will be the timeframe when marine headlines are most likely.
In addition, there will be several potential periods of showers
and thunderstorms through this time.


.APX Watches/Warnings/Advisories...


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