Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 240830
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
430 AM EDT WED AUG 24 2016

.SHORT TERM...(Today and tonight)
Issued at 429 AM EDT Wed Aug 24 2016

High impact weather potential: Chance for thunderstorms into this
evening. Marginal chance for severe weather with the main threat
being damaging winds.

Pattern synopsis and forecast:

Closed off upper low spinning into srn Manitoba with the associated
sfc low in western Ontario. A cold front is draped south of the low
slowly approaching the mid and upper Mississippi valley. The main
warm front extends east of the low, bisecting Ontario. SW flow aloft
is showing a couple of shortwaves, both associated with areas of
showers and thunderstorms. These storms are fed by much higher theta-
e advection due to a 35-40kt LLJ, underneath the advection of
steeper lapse rates aloft and forcing from DPVA and upper
divergence. Additional elevated storms have been developing across
nrn IL and to some extent into srn Lake Michigan, along and north
of a secondary warm front marked by upper 60s sfc dew points.

The two shortwaves dampen out to some degree as they roll on through
today, and the aforementioned forcing does weaken some, along with
the LLJ. Regardless, we will have steeper lapse rates aloft
advecting in with the DPVA from the shortwaves. Seeing showers and
some thunderstorms still seems likely for most of nrn Michigan. We
are in a marginal threat for isolated damaging winds, but wind
fields are not impressive with a 40kt mid level jet and bulk shear
values just below 30kts. Instability looks to be no greater than
several hundred j/kg of either MUCAPE or SBCAPE, so updraft
strengths not to be too impressive. The main upper wave opens up and
works into Ontario late tonight, with the sfc cold front finally
reaching nrn Michigan around daybreak Thursday at minimum heating.
Additional shortwave activity does look to roll up into srn lower
Michigan, which may provide better chances for showers late tonight.
Otherwise, just some isolated showers possible by late tonight.

Lowered high temps a touch today due to incoming thicker clouds and
showers. Readings will be more in the 70s but humid. Lows tonight
quite mild with mid and upper 60s and dreary with most areas
socked in low clouds.

.LONG TERM...(Thursday through Tuesday)
Issued at 429 AM EDT Wed Aug 24 2016

(8/25)Thursday...The cold front stalls out in SE Lower as the 500 mb
shortwave trough dropping into the Upper Great lakes. GFS brings
rain into the SE counties by 18z, with the ECMWF right along the
shore of Saginaw bay in our area. NAM barely gets anything in our
area. So will probably go middle of the road with the ECMWF idea
during the day. The sfc low, to the north, continues to move east,
with the drier air moving into the region. Models suggest that the
area should remain dry overnight as the 850 mb temperatures haven`t
fallen that far to produce LE rain, not to mention some very dry mid
levels (700-500 mb layer RH<20%). However, it does look like it
should begin to get cloud overnight as the 850 mb moisture begin to
push into the region.

(8/26)Friday...models are trying to print out some precipitation, as
the 850 mb temperatures fall to around 8 or 9c which would just put
us into the LE rain delta Ts, and the 500 mb 50 knot RRQ of the jet
streak moves through the area. Moisture on the soundings is pretty
shallow, so would think that the LE rain is possible with help from
the 500 mb jet, but by the evening that things will dry out and we
should get clearing skies.

Extended (Saturday through Tuesday)...The next wave along the fast
500 mb flow expected to come into the Upper Great Lakes is
Saturday/Sunday. There are some disagreements on how the storm will
evolve with the ECMWF very slow solution compared to the GFS. Monday
at this point looks dry as high pressure builds into the region, but
the models keep trying to produce rain near the region. then on
Tuesday, the GFS brings a wave in while the ECMWF keeps the region
dry. So with the uncertainty, will keep the pops low for now.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1145 PM EDT Tue Aug 23 2016

VFR conditions anticipated through tonight with some high cloud
cover drifting through. But, a wave of low pressure in the
midwest will be swinging across the region on Wednesday. This
will bring showers through the region on Wednesday along with
borderline VFR-MVFR cigs, particularly later in the morning and
through the afternoon hours. A little bit better moisture and
instability will push into the region and there may be a few
thunderstorms in northern lower Michigan. But I have not included
any TSTM`s explicitly in the TAF forecast at this juncture.

Lighter surface winds overnight, although with stronger winds aloft
there likely will be a sustained 5 to 10 knot southerly surface
wind through the night. Some marginal LLWS below 1500 feet is not
out of the question. Stronger southerly winds develop again on
Wednesday before diminishing again Wednesday night.


&&

.MARINE...
Issued at 429 AM EDT Wed Aug 24 2016

Advisory level winds will continue over many of the nearshore waters
today, and into this evening for Lake Michigan. These advisory level
winds will be joined by the arrival of showers and thunderstorms.
There is only a small, marginal threat for severe storms for
damaging winds. The gradient weakens while a cold front moves in
later tonight and Thursday which will also result in a lingering
chance for showers and storms. Behind the front, winds turn NW
Thursday night, and there is a small chance for additional advisory
winds.

&&

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

LH...SMALL CRAFT ADVISORY until 6 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 6 PM EDT this evening for LSZ321.

&&

$$

SHORT TERM...Dickson
LONG TERM...JSL
AVIATION...Adam
MARINE...Dickson


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