Area Forecast Discussion
Issued by NWS Gaylord, MI

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769
FXUS63 KAPX 271727
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
127 PM EDT WED JUL 27 2016

.UPDATE...
Issued at 1013 AM EDT Wed Jul 27 2016

Quiet out there this morning, waiting on diurnally driving
instability and enhanced low level convergence axes to kick off
afternoon showers and thunderstorms. Diffuse and slow moving
front dropping slowly south into northern lower should only help
the cause. Not much deep layer support, however, with main
shortwave looking to remain upstream today. 12Z local sounding
shows the convective potential, with respectable mid level lapse
rates and plenty of positive area. Same sounding also displays the
negatives, with plenty of lower level cinh and only marginal
amounts of moisture through the sounding. With that said, really
think these negatives will be at least partially overcome through
surface based moisture pooling along convergence axes and further
boundary layer warming. Simple pattern recognition supports a
decent Lake Michigan shadow in background light northwest flow
regime. Feel "best" coverage will be across northeast lower
Michigan, with even some help from Lake Huron induced wind fields.
Given limited deep layer dynamics and marginal moisture profiles,
do believe coverage will remain isolated to scattered. Limited
vertical wind shear should largely limit storm organization and
keep most below severe limits. Although, with mean layer cape
profiles likely to exceed 1K joules/kg and hints of good cape
through the favored hail growth zone, cannot completely rule out
an isolated severe wind gust or large hail report. Will continue
to monitor.

&&

.SHORT TERM...(Today and tonight)
Issued at 330 AM EDT Wed Jul 27 2016

...A somewhat unsettled day and night ahead...

High impact weather potential: a few strong pulse storms possible
this afternoon/evening south of M-32. Isolated showers are found
near Bois Blanc Isl down to CVX. A larger cluster of shra/tsra is
seen between ESC and MNM...extending w into n central WI.
The front will slowly move south today, reaching the M-72/M-55
corridors late in the afternoon. Convection should see something
of a lull this morning, but building instability looks to get
things going again as we move thru the afternoon. Precip and
temperature trends are the main concern.

Today...will have to keep an isolated shra/tsra in the morning
forecast. Mlcapes of 300- 500j/kg still linger here, which may
allow a few shra/tsra to kick off along the front and/or outflow
boundaries, or move in from upstream. But generally expect the
northern WI activity to weaken as it tries to move east. So think
most places will be dry for the first half of the day, with more
sun south of M-72 than north.

Temperatures will zoom upwards thanks to diurnal heating. Noting
that TVC/APN both managed to (unexpectedly) crack 90f yesterday,
will generally beef up guidance max temps a smidge, especially in
northern lower MI. Dew points will also be heading higher,
especially near/south of M-32, thanks to moisture pooling along the
incoming front. Dew points there should rise into the mid 60s. That
will result in mlcapes rising to 1-1.5k j/kg, with less than 10j/kg
of cinh (located at 850mb). That`s not much of an obstacle, and with
the incoming front, lake breezes, and potential outflow boundaries,
we should have the trigger mechanisms needed. So will have sct pops
breaking out this afternoon. Question is where things will get
started, along the boundary (per the Rap), or slightly into the
cooler/drier air (per the Nam)? The answer is probably both; most
models take ongoing convection in northern MN steadily eastward
today, eventually threatening the Straits region with some precip.
There is an actual shortwave (the main forcing mechanism aloft) on
that latitude.

So will have sct convection across most of the forecast area this
afternoon. Parts of Chippewa Co will be the primary exception. Shear
is weak today (0-6km bulk shear circa 20kt), so nothing terribly
organized will get going. Still might be enough instability/local
forcing to support a few strong storms of a pulse nature. This will
be especially the case south of M-32.

Max temps lower 80s to around 90f.

Tonight...afternoon pops will carry over into the evening,
particularly in northern lower MI. Front eventually heads south of
MI, which when combined with loss of heating will severely
diminish instability. A shortwave diving into the central plains
will help spin up a low along the front in northern IL. There
will be some fgen processes supporting precip north of this low
overnight, mainly in WI. This is close enough to warrant keeping
chance pops overnight, mainly in nw lower MI. Leftover evening
precip will contribute to reasonably abundant low clouds in the
post-frontal airmass, so anticipate a mostly cloudy night (except
fewer clouds in eastern upper MI). Some fog may also be warranted,
especially in southern sections where surface dew points will
remain quite elevated.

Min temps upper 50s to lower 60s.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 AM EDT Wed Jul 27 2016

...Perhaps a few showers and storms Thursday...

Models are in general agreement over a low grade long wave trough
across the Great Lakes region through Saturday. This will be
followed by rising heights as a stronger ridge builds toward the
region through the middle of next week. This pattern should generate
seasonable temperatures through Saturday then warmer and
progressively more humid conditions after that. There will be
chances for showers and thunderstorms across the southern half of
the forecast area Thursday into Thursday night but little to no
appreciable rainfall is expected after that (at least not during
this forecast cycle anyways). The main forecast concerns revolve
around pops early on then how much/fast it will warm up after that.

Thursday into Thursday night...A short wave currently evident on
water vapor imagery over Montana moves through the flow and across
central Michigan. This feature may lead to the development of
showers and possible thunderstorms, mainly south of M-32 and perhaps
even south of M-72. Models vary on just how far north precipitation
chances should be with only a few hundred j/kg of mixing layer cape
across far southern zones. Have kind of taken the middle ground here
with slight chance pops up to M-32 and low chance pops along and
south of M-72. Highs in the pleasant middle 70s to around 80. Lows
in the mostly comfortable middle 50s to near 60.

Friday into Saturday...High pressure pressing down from the north
looks to suppress showers and storms to along and south of M-55.
Therefore will continue to trend pops in this direction as well.
Highs in the middle 70s to lower 80s with lows mainly in the 50s.

Sunday through Tuesday...Ridging aloft will continue to build in
from the center portion of the country. This should lead to rain
free, warmer and progressively more humid conditions through the
period. Highs generally in the lower and middle 80s but some spots
may push into the upper 80s by Tuesday. Lows only falling off into
the upper 50s to middle 60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 124 PM EDT Wed Jul 27 2016

...Primarily VFR conditions expected...

Isolated showers and thunderstorms will continue to develop this
afternoon, with the most probable locations for impact being KTVC
and KAPN. Large area of mid to high clouds will spread across the
region tonight, perhaps bringing a few more widely scattered
showers. Skies should begin to mix out some later Thursday morning
from north to south. Light wind regime through this taf period.

&&

.MARINE...
Issued at 330 AM EDT Wed Jul 27 2016

Weak cold front will cross northern MI from north to south thru
the evening. Light w to sw winds ahead of the front, will give
way to nw to n winds behind it. Those winds will be light tonight,
but pick up a smidge on Thursday. Still, winds and waves should
remain below advisory criteria.


&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...MSB
SHORT TERM...JZ
LONG TERM...Sullivan
AVIATION...MSB
MARINE...JZ



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