Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 250145
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
945 PM EDT WED AUG 24 2016

.UPDATE...
Issued at 945 PM EDT Wed Aug 24 2016

Surface low pressure sits across Ontario this evening with a cold
front stretching southward through northern Lake Michigan/SE
Wisconsin and into the midwest. Subtle mid level trough and
associated low-mid QG-forcing (primarily responsible for todays
showers/storms) is exiting into the eastern lakes region. There
is still a tongue of waning instability ahead of the front from
the midwest up into northern Michigan. Better instability is of
course off to our south. But we have had a few thin lines of
showers develop and move across the CWA this afternoon and into
the evening.

Rest of tonight, with waning instability and loss of QG-forcing,
shower activity should continue to dwindle through rest of the
evening. We don`t completely lose the instability overnight however,
and I suppose a stray shower or two is not completely out of the
question. But for the most part we should be dry and have removed
all pops from the forecast after midnight or so. Patchy to areas
of fog will become more prevalent given todays rain and as we
cool off overnight.

&&

.SHORT TERM...(This evening and overnight)
Issued at 247 PM EDT Wed Aug 24 2016

Slow-moving surface low remains centered over Western Ontario this
afternoon...with the associated cold front trailing southward thru
the Upper Mississippi Valley into the Southern Plains. Thick low
cloud cover has greatly hindered instability potential throughout
the day. So far...we have only managed a few hundred joules of
MUCAPE across our CWA this afternoon. Thus...resulting convection
has been relatively weak despite lift/support from an approaching
cold front...modest wind shear and descent 850 mb theta E ridging.
Initial area of widespread showers with embedded thunderstorms has
exited NE out of our CWA...leaving mainly scattered showers with
possibly an isolated hit of lightning across our area. Temps have
been slow to warm into the low to mid 70s under thick cloud cover.

A look at upstream satellite and surface obs shows plenty of low
clouds and only a few showers lingering over Wisconsin and Western
Upper Michigan along and ahead of the cold front. The hope for any
clearing (and thus destabilization) is rapidly dwindling...as is the
potential for any thunder...much less marginally strong/severe
storms. Also...wind fields will gradually weaken as we head toward
sunset. Have therefore decreased POPs for the remainder of the
afternoon and thru the evening...anticipating mainly scattered
showers and only a slight chance for thunder. Slight chance for
showers and storms will be confined to the SE half of our CWA
overnight and Thursday as the cold front moves thru the NW half
tonight.

Expect another mild and muggy night ahead of the cold front...with
overnight lows only cooling into the low to mid 60s. CAA will be
slow to kick in behind the front...so Thursday will be another warm
day as afternoon highs warm back into the upper 70s and lower 80s.

.LONG TERM...(Thursday through Wednesday)
Issued at 247 PM EDT Wed Aug 24 2016

High impact weather potential: Small chance for a few scattered
thunderstorms late Saturday afternoon. A better chance for storms
arrives Saturday night.

Pattern synopsis/Expected evolution: Quite the active weather
pattern across the Great Lakes as we begin the forecast period this
afternoon with two well-defined shortwaves aiding in kicking off
showers and thunderstorms across northern Michigan today. The
initial and more robust wave lies just north of the International
Bridge this afternoon while the weaker secondary wave is sliding
across central Lower MI. A cold front is draped across far western
WI, ever so slowly washing out as it pushes eastward, crossing our
area on Thursday. Beyond Thursday, surface high pressure settled
overhead while heights aloft begin to rise, ultimately bringing a
return to dry conditions and near-normal temperatures for the end of
the work week into the first half of Saturday before precip chances
increase once again.

Thursday night - Friday night: By Thursday evening, the system
bringing us rain today is progged to be over western Quebec with
high pressure gradually nosing into the Great Lakes from the west.
CAA continues in earnest behind Thursday`s cold front with H8 temps
expected to fall from ~15 C to ~10 C and dew points progged to drop
into the mid-50s overnight. Overall, precip-free conditions and much
cooler/less humid conditions are expected when compared to Wednesday
night`s mugginess. Lows expected to bottom out in the mid-50s inland
to around 60 degrees along the lakeshores.

A nice day looks to be on tap for Friday as heights rise aloft and
aforementioned high pressure settles overhead. Partly to mostly
sunny skies, precip-free conditions, and near normal temperatures
are expected. Highs are expected to range from near 70 north of the
bridge to the mid-upper 70s near Saginaw Bay.

Saturday: By Saturday morning, high pressure is slowly shifting off
to the east with its progression aided by an approaching, well-
defined, trough axis moving through the northern Plains. Global
model guidance continues to differ wildly in the evolution of the
system at the mid-upper level with nearly a 24 hour difference in
terms of the trough axis arrival over northern Michigan. As one
would expect, the result leaves little confidence in terms of the
associated surface features at this point. At this juncture, would
hedge my bets toward the ECMWF/GEM as at the very least has had run-
to-run consistency over the last couple of runs. Will introduce low
PoPs late Saturday afternoon to account for any scattered
development well ahead of the wave; however, the best precip
coverage/intensity is expected to arrive Saturday night associated
with the arrival of better forcing for ascent and deep layer
moisture (PWs ~1.50+ inches for a period Sat. night).

Gillen

High pressure begins to exit to the east while a trough fills in
behind it. The timing of this trough is uncertain as the ECMWF has
it passing through the northern Great Lakes much slower than the
GFS. Surface low pressure associated with this trough will move
through the state Sunday into Monday bringing shower and
thunderstorm chances for the beginning of the week. Multiple
shortwaves pass over the region as the trough exits east and the
persistent ridge in the southeast stays parked. However chances for
showers will stay low for the middle of the week as high pressure
will take over at the surface Tuesday and inhibit any development.
Temperatures will stay above average through the extended period,
hovering around 80 degrees.

SML

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 733 PM EDT Wed Aug 24 2016

A few showers will roll through northern lower Michigan through
the course of the evening, ahead and along a cold front that will
slip through tonight. Isolated thunder not out of the question,
but chances are to low to include in any terminal forecast at this
point. Largely VFR cigs/vsbys through the evening. But lower cigs
and some stratus is anticipated later this evening and overnight
bringing periodic MVFR conditions to the terminal sites.

On Thursday, VFR conditions return. Another round of showers/storms
will roll across southern and central lower Michigan, but expected
to remain away from the terminal sites.

Gustier SW winds will diminish quickly in the next one to two
hours. Winds veer more westerly heading into Thursday but with
sustained winds mainly 10 knots or less.


&&

.MARINE...
Issued at 247 PM EDT Wed Aug 24 2016

SCA criteria winds and waves will continue thru this evening for
most of our nearshore areas as SW winds continue to gust to 25 kts
ahead of an approaching cold front. Hazardous swimming conditions
will also persist thru this evening along our Lake Michigan beaches.
Conditions will fall below SCA criteria late tonight and will remain
so thru Friday as high pressure slowly builds into the area.


&&

.APX Watches/Warnings/Advisories...
MI...BEACH HAZARDS STATEMENT until 11 PM EDT this evening for MIZ015-
     016-019-020-025-031.

LH...SMALL CRAFT ADVISORY until 11 PM EDT this evening for LHZ348-349.

LM...SMALL CRAFT ADVISORY until 11 PM EDT this evening for LMZ341-342-
     344>346.

LS...SMALL CRAFT ADVISORY until 11 PM EDT this evening for LSZ321.

&&

$$

UPDATE...Adam
SHORT TERM...MLR
LONG TERM...Gillen/SML
AVIATION...Adam
MARINE...MLR


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