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afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
639 PM EDT Tue Oct 22 2019

Latest update...
aviation

Synopsis...
issued at 328 PM EDT Tue Oct 22 2019

-high wave action with beach and Bluff erosion continues into
early Wednesday

-gusty winds may cause scattered power outages along Lakeshore

-light rain possible late Wednesday into early Thursday

-Saturday night into Sunday morning is looking wetter

&&

Discussion...(this evening through next tuesday)
issued at 328 PM EDT Tue Oct 22 2019

The low centered near Lake Superior will move toward Hudson Bay
over the next 24 hours but Lakeshore flooding impacts will
continue into Wednesday morning unfortunately given an extended
period of gale force wind gusts along the coast. Several reports
of 45 to 55 mph wind gusts have been observed as well as widely
scattered power outages.

What we have observed from our survey team today is some of
the same areas that received beach erosion and Bluff collapse
last week are experiencing additional impacts with 5-10 ft or
more of erosion on top of last week's losses. The hardest hit
areas are expected to be near and north of Port Sheldon where
erosion will continue along with flooding of river mouths and
low lying parking lots, roads, and potentially some homes as
well. The threat winds down early Wednesday morning.

Continued over-lake instability, deep cyclonic flow and
abundant low level moisture will help fuel bands of rain
showers across the region, though any given location will
not be raining continuously. Given the propagation speeds
of these showers, even locations well inland will get
hit-and-miss precipitation through tonight. This activity
winds down quite a bit Wednesday. However, showers are
possible Wednesday night into early Thursday morning as
we get brushed by a 40 kt low level jet centered from in to Ohio and
are impacted by weak surface troughing.

I believe rain chances are looking more likely late Saturday
into early Sunday based on an ensemble analysis. The
deterministic European model (ecmwf) and Gem have already been showing a
Gulf-based low ejecting north toward Michigan for multiple
runs but the GFS has not. The ecm members tell the real story
though with most of the 51 members showing this system impacting
our area. The GFS, in all likelihood, will prove too far east
with the handling of this system (it takes the low up the east
coast). Our current pops are 30% given our blended model solution
for the weekend but we will likely be trending higher with time if
the ensemble guidance continues to suggest impacts.

Additional impactful weather is possible by the middle of next
week as we round out October, but the range of solutions is large.
Temperatures may be cold enough for wintry precipitation as we
get closer to Halloween, but details are unclear at this point.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 639 PM EDT Tue Oct 22 2019

Our storm is slowly lifting out to the north northeast with time.
This slowly is lifting southwest Michigan out of the storms
circulation with time. At 22z the south edge of the MVFR cigs is
near I-94. Clear skies are south of pia to laf. This area if
clearing will continue to lift north with time overnight. I would
think by 14z most if not all of our taf sites will see either
clear skies or at least mostly clear skies. OK, this is Michigan
and winds will be out of the west southwest, which will be off
Lake Michigan, but there is enough subsidence assoicated with the
low level wind flow becoming anticyclonic that I believe the sky
will indeed clear.

There is another system lifting northeast that may bring showers
back to the area Wednesday evening, but that is not a sure thing
so I brought back mid clouds for now and maybe later tafs will
feature showers around 00z Thursday.

With the system lifting out to the north and northeast winds will
slowly decrease. Inland taf sites will see winds under 15 knots
by after 06z.

&&

Marine...
issued at 328 PM EDT Tue Oct 22 2019

The Gale Warning and Lakeshore Flood Warning still look to be in
good shape. Widespread gales have been observed and we are seeing
continued erosion of dunes and the risk for Bluff collapses given
a long duration gale event with waves approaching or exceeding 10
feet in places. The worst has likely either occurred or is
currently occurring as of this writing. But the gradual eating
away of dunes will be a real problem for coastal properties into
early Wednesday. Wave action does subside into the 4 to 6 foot
range Wednesday afternoon, which is still high, but shouldn't
cause too much impact to the dunes and Bluffs.



&&

GRR watches/warnings/advisories...
Michigan...Lakeshore Flood Warning until 8 am EDT Wednesday for miz037-043-
050-056-064-071.

Lm...Gale Warning until 8 am EDT Wednesday for lmz844>849.

&&

$$

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