Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 230741

Area Forecast Discussion
National Weather Service Gaylord MI
341 AM EDT TUE AUG 23 2016

.SHORT TERM...(Today and tonight)
Issued at 339 AM EDT Tue Aug 23 2016

High impact weather potential: A minimal chance at a thunderstorm
through daybreak.

Pattern synopsis and forecast:

High pressure was over the east coast early this morning while low
pressure was in the Dakotas. Nrn Michigan in between these two
features with a tightening pressure gradient resulting in periodic
gusty SW warming winds. A weak shortwave aloft was crossing nrn
Michigan on the leading edge of steeper lapse rates aloft (6 c/km)
within an area of enhanced 925mb-700mb theta-e advection. Forcing
from the wave is supported by a region of upper divergence and has
resulted in an area of showers over nrn Lake Michigan and NW lower.
This rainfall was falling apart overhead, as it is running into our
drier air, and by out-running the stronger support being supplied by
an LLJ laid out in central upper.

The wave and theta-e advection pass by around daybreak with the LLJ
weakening and veering with time. This will result in the demise of
all rain showers and any minimal thunder threat. Mid level heights
then rise through the day with increased overall subsidence ahead of
a strong eastward-moving closed low spinning across srn Canada. Any
forcing from additional weak waves in the flow aloft, shift north
into Ontario, while PWATS/atmospheric moisture drop through this
evening. A relatively sunny day heading through this morning, and a
mostly clear evening.

Late tonight, the flow turns more SW aloft ahead of the spinning
closed low, with more defined/stronger shortwave energy punching up
through the mid/upper Mississippi valley and western Great Lakes.
Renewed 925-700mb theta-e advection tries to sneak into the Manistee
area at daybreak with no other forcing than DPVA in the picture.
Doubt there will be any possible rain to make it in by daybreak.

Most areas will see highs today in the low to mid 80s with lows
tonight in the lower half of the 60s.

.LONG TERM...(Wednesday through Monday)
Issued at 339 AM EDT Tue Aug 23 2016

(8/24)Wednesday...Models continue to slow the runs down
progressively over the last several days and are beginning to show
holes in the QPF. This has caused me to slow down the onset of the
rain and lower the pops a bit, so that we are in low likelys, and
not high likely/categorical. The ECMWF and NAM due has different
amounts for likely rain, so will keep the high chance to likely as
it seems that when the thunderstorms roll in most everyone will see
rain. 500 mb winds are pretty anemic (25 knots) so am not expecting
much in the way of a severe threat, there is some decent MUCAPE, but
it looks skinny, so again thunderstorms, but not likely severe.
after 00z, the rain should begin to leave the region, wouldn`t be
surprised if my timing is a little slow based on the HiRes models,
but the ECMWF/GFS shows the rain continuing through 06z, before
things begin to dry out.

(8/25)Thursday...The cold front stalls a bit, downstate, and allows
a wave or two to move up the front and produce some rain in NE
Lower, but the front begins to move out of the region overnight, as
the sfc high begins to build into the region. The 500 mb flow goes
zonal again, pushing the waves out of the region.

Extended (Friday through Monday)...As I have been saying the last
few days, the pattern is for a decent frontal passage every couple
of days and looks like it will continue on into the following week.
the models are in agreement that after Wednesday/Thursday passage,
that the next is Saturday/Sunday. The GFS suggests that there could
be more rain as the cold front stalls, kind of like the forecast on
Thursday. ECMWF dries things out on Monday. So we will see, keeping
the chance pops in the forecast for now.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1156 PM EDT Mon Aug 22 2016

...VFR conditions...

Band of elevated showers/embedded thunder expected the next few
hours across KTVC and KPLN. May see a brief reduction in vis in
any heavier showers. Otherwise, just a mid cloud deck. Wind shear
now expected to develop across the area as surface winds remain
light and low level jet overspreads the region. Showers will
quickly come to and end during the early morning hours, leaving
behind just a few high cloud on Tuesday. Gusty southwest winds
expected across the taf sites during the daylight hours.


Issued at 339 AM EDT Tue Aug 23 2016

A tighter SW flow pressure gradient continues to set up over the
nearshore waters. There are already several locales with advisory
level winds over Lake Michigan, and periodic advisory level winds
will become more common across Whitefish Bay and parts of the Lake
Huron nearshores through today. Lake Michigan will continue to see
these winds through at least tonight, and likely Wednesday. Will
keep current headlines only through tonight however. The gradient
loosens up later Wednesday and Wednesday night as a cold front
approaches with good chances for showers and possible storms.


.APX Watches/Warnings/Advisories...
MI...BEACH HAZARDS STATEMENT through this afternoon for MIZ015-016-

LH...SMALL CRAFT ADVISORY until 6 PM EDT this evening for LHZ345-346-

LM...SMALL CRAFT ADVISORY until 5 AM EDT Wednesday for LMZ323-341-342-

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



SHORT TERM...Dickson
MARINE...Dickson is the U.S. government's official web portal to all federal, state and local government web resources and services.