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fxus63 kgrr 182312 
afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
612 PM EST Mon Nov 18 2019

Latest update...
aviation

Synopsis...
issued at 306 PM EST Mon Nov 18 2019

* cloudy with areas of drizzle tonight into Wednesday

* need to watch potential for fog and freezing drizzle tonight

* wet, windy, warmer for Thursday

&&

Discussion...(this evening through next monday)
issued at 306 PM EST Mon Nov 18 2019

Looking at dreary conditions developing this evening and tonight, as
all of the area becomes overspread by low clouds, areas of drizzle,
and fog/haze. The two main concerns for tonight will be how thick
fog can become and potential for freezing drizzle. Low-level flow
will turn light from the southwest over southwest portions of the
state late this afternoon and tonight, advecting additional low-
level moisture into the area while mid-levels (and the dgz) remain
dry. Hi-res guidance and forecast soundings are supportive of
visibility restrictions through the night and into Tuesday, but do
not show strong signals for visibilities falling to 1/2 mile or
less. With regard to freezing drizzle potential, temperatures
overnight look to only fall into the low and mid 30s after about
5am, limiting potential for impacts on roads. Still, could see some
slick spots develop, especially on bridges and overpasses. Will need
to monitor the potential for dense fog and freezing drizzle
overnight into Tuesday morning. Conditions on Tuesday and Tuesday
night will remain dreary, with high confidence that the area will
remain socked in under low clouds and see areas of drizzle, possibly
even freezing drizzle again, as temperatures drop overnight into
Wednesday morning. Temperatures Tuesday night/Wednesday morning look
to range from the upper 20s (mid-michigan) to low/mid 30s, and will
need to watch potential for slick spots where drizzle redevelops.

Surface and upper ridging will expand into the area Wednesday, but
strengthening subsidence inversion at mid/low levels will just lock
low-level moisture (low clouds and possibly patches of drizzle) into
place. Warm air advection ahead of approaching low pressure may stir
things up enough for some brief clearing, but latest model timing is
starting to favor Wednesday evening/overnight after the sun has gone
down.

Low pressure will lift through northern Michigan Thursday. Rain will
spread into the area during the morning and afternoon as a warm
front lifts northeast. Temperatures during the afternoon and evening
will become more comfortable, with increasing confidence to see
temperatures near to just over 50 degrees along/south of the I-96
corridor. Winds will also become gusty within the warm sector during
the day and as cold air advection ramps up during the evening behind
a cold front. It's a little preliminary, but most models (including
most Euro ensemble members) are supportive of gusts in the 30-40 mph
range for areas away from the Lakeshore (35-45 mph along lake
michigan), but will have to watch potential for deeper solutions to
pan out (such as the 12z operational gfs) which could yield stronger
gusts.

Colder and drier air will surge into the area behind the front
Thursday evening. This will allow precipitation to change to a
rain/snow mix or all snow before it ends. Ridge will quickly build
into the western Great Lakes by Friday/Friday evening, limiting
window for lake-effect snow even if dgz remains saturated after the
cold frontal passage. Little to no accumulation is expected Thursday
night-Friday at this point. After one day of above normal
temperatures for areas south of US-10, we will fall back into the
30s for highs on Friday and Saturday.

&&

Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 604 PM EST Mon Nov 18 2019

IFR or LIFR will be observed especially west of the lan and jxn
terminals. Worst conditions will likely be from mkg to GRR and
azo/btl where a period of LIFR is expected (in fact already
observed for much of the day at mkg). High resolution model
guidance is not pessimistic enough with observed cigs/vis and so
lowered values for both parameters in the tafs. West of lan/jxn we
are expecting IFR/LIFR with drizzle to be the most significant in
the 00z- 06z timeframe. Not out of the question that cigs may dip
to 300 ft at times. Visibility down to 1/2 mile also is possible
but we're not expecting that to be dominant enough to put in a
prevailing group at this time.

&&

Marine...
issued at 306 PM EST Mon Nov 18 2019

Relatively light winds and low wave heights are expected through
Wednesday. We will see drizzle and haze/fog which will reduce
visibility at times, however. Winds will increase from the
south/southeast Wednesday night, then shift to the west/northwest
late Thursday as low pressure lifts through northern Michigan. The
passage of this system will likely lead to a period of strong winds
and large waves along the Lake Michigan shoreline late Thursday into
Friday, with dune/beach erosion a concern. We are also watching
potential for a brief period of gale-force gusts Thursday. Another
round of strong onshore winds is possible Saturday and Saturday
night.



&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

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