Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kgrr 221929 

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

Latest update...

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 18z tafs through 18z Wednesday afternoon)
issued at 135 PM EDT Tue Oct 22 2019

Radar showing bands of showers moving through west Michigan this
afternoon. Ceilings have varied between MVFR and VFR today but
visibilities have remained VFR even in areas of rain. Lightning
has not been detected across west Michigan with the rain today.
Southwest winds at 15 to 25 mph with gusts around 40 mph will
continue through the evening before diminishing late.

The showers will continue through this evening before tapering
off overnight. Have maintained previous forecast of MVFR ceilings
through midnight with VFR ceilings expected by sunrise Wednesday.
Kazo/kbtl/kjxn should see improvement in cloud coverage/category
before kmkg/kgrr/klan as storm system moves north overnight. Fog
threat too low to mention at this time.


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-

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



National Weather Service Glossary of Abbreviations