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000
FXUS63 KAPX 241903
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
303 PM EDT Sat Jun 24 2017

.NEAR TERM...(Tonight through Sunday)
Issued at 302 PM EDT Sat Jun 24 2017

High impact weather potential: Scattered, mainly afternoon and early
evening thunderstorms. Severe storms not expected, but small hail
certainly possible in peak heating.

Pattern synopsis and forecast:

Broad upper troughing engulfs the Great Lakes this afternoon, with
several vorticity centers rotating through nrn Michigan, but one
main shortwave trough seen quite easily on satellite imagery. This
wave was crossing into Wisconsin and was spreading it`s DPVA into a
corridor of higher lower level theta-e air stretched out from SE
lower Michigan up through nrn lower. This was also occurring while
co-located with steeper lapse rates aloft of 6.5-7.0 c/km and low
level cyclonic flow. As a result, we have quickly sparked numerous
showers and scattered thunderstorms in nrn lower. MLCAPES have been
a little better than earlier though, up to 800j/kg. Low freezing
levels likely leading to some small hail, but severe weather is
still not expected attm. Maybe an isolated strong storm can generate
bigger hail. Latest visible satellite imagery and sfc obs also
showing lake breezes trying to get going across mackinac county of
eastern upper. The air mass was a bit drier up that way and thus far
not a whole lot going on there.

The Wisconsin shortwave will cross into nrn Michigan tonight, with
the axis of higher moisture/theta-e wrapping northward into far nrn
lower and eastern upper through the night. This will also result in
a weak sfc low and trough axis to slide down into the area, which
will increase low level convergence. Thus, current main batch of
showers and scattered storms in the srn CWA will translate northward
tonight. Coverage will likely wane to the south with loss of daytime
heating, while potential instability heading into the nrn CWA also
waning with nightfall. This shortwave crosses nrn Michigan by Sunday
morning, with some minor mid level ridging arriving for the
afternoon. Will still have cooler air aloft and some general low
level convergence and/or lake breezes. This ought to provide for
continued scattered rain showers, and due to what appears to be less
instability than this afternoon, only isolated non-severe storms.

Highs in the middle to upper 60s Sunday with lows tonight in the
upper 40s to lower 50s most areas.

&&

.SHORT TERM...(Sunday night through Tuesday)
Issued at 302 PM EDT Sat Jun 24 2017

...Below normal temperatures with showers and a few storms...

High Impact Weather Potential...A few (largely) non-severe
thunderstorms through the first half of the week.

Pattern Synopsis/Forecast...Long wave troughing remains intact
across central and eastern Canada down into the Great Lakes/New
England region...with strong long wave ridging up along the west
coast. Long wave trough will be reinforced through Monday by passage
of a couple short waves and attending cold cores (first one early
tomorrow and second on Monday)...which will keep the shower/
thunderstorm threat going. Troughing may finally start to progress
out of the region Tuesday onward...as upstream blocking ridge along
the west coast flattens and progressed eastward through the
CONUS...and open the door for warmer air to work back into the
region.

Primary Forecast Concerns...Minimal. Second piece of short wave
energy will slide down through the region late Sunday night into
Monday with another core of -22C or colder air at 500 MB passing
overhead Monday. This will bring another round of showers through
the region starting later Sunday night as associated QG-forcing for
ascent increases ahead of the wave...further augmented during the
day Monday with daytime heating. Severe threat will remain minimal
although with wet-bulb zero heights dipping to around 5500
feet...pulse hail producers with the strongest updrafts will
continue to be the main concern.

As mentioned above...upper trough and cold air aloft may start to
exit the region Tuesday. It`s a matter of timing...but right now
Tuesday still appears dry for the most part...although I wouldn`t be
surprised that we see a few lingering afternoon showers.

&&

.LONG TERM...(Tuesday night through Saturday)
Issued at 302 PM EDT Sat Jun 24 2017

High impact weather potential: Chance of thunderstorms at various
times Wednesday afternoon through Friday.

Upper level ridging and attendant surface high pressure progressing
across the western Great Lakes is expected to lead to a pleasant
start to the long term forecast period both Tuesday night through
the first half of Wednesday. However, a much more active pattern is
expected to return for the second half of next week as several
developing waves are expected to track from the central and northern
plains into the Great Lakes. Details are far from certain at this
juncture, but the greatest threat for widespread precip is expected
Wednesday evening-night with at least chance PoPs littering the
remainder of the forecast from Thursday through Friday night across
portions of northern Michigan.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 128 PM EDT Sat Jun 24 2017

Troughing and cool air aloft with disturbances passing through
over the TAF period will result in scattered showers and isolated
thunderstorms. These will mainly be tied to afternoon diurnal
heating. Deeper lower level moisture rolls in here later this
afternoon and mainly tonight, and MVFR CIGS are becoming more
likely to develop. Winds rather light through the period with a
tendency to go onshore in the afternoons.


&&

.MARINE...
Issued at 302 PM EDT Sat Jun 24 2017

Gradient winds and waves not expected to be of any issue into the
coming work week. An overall west/NW direction to the winds Sunday,
with lake breeze tendencies and scattered to numerous showers, and
isolated storms mainly during the afternoons and early evening. More
variable winds for Monday with a weak low overhead. Again, more
showers and isolated storms.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...SMD
SHORT TERM...TBA
LONG TERM...MJG
AVIATION...SMD
MARINE...SMD