Scientific Forecaster Discussion
fxus63 kgrr 130257
Area forecast discussion
National Weather Service Grand Rapids Michigan
957 PM EST Tue Nov 12 2019
issued at 315 PM EST Tue Nov 12 2019
- record cold through Wednesday
- more snow late Wednesday into Thursday morning
- not as cold but still colder than normal after that
issued at 953 PM EST Tue Nov 12 2019
We issued a Lakeshore flood advisory for several of the northern
zones. It looks like the southerly winds will increase enough to
generate waves over 6 feet mainly north of Holland with 10 foot
waves possible especially toward little and big Sable points.
While the impacts tend to be limited for southerly wind
events...enough onshore component north of Holland exists for some
impacts. Thus we issued the headline for that reason.
Update issued at 501 PM EST Tue Nov 12 2019
The winter weather headlines were allowed to expire at 5 PM.
Overall the weakening trend to the snow showers continues. Any
additional impacts are expected to remain very localized and
Discussion...(this evening through next tuesday)
issued at 315 PM EST Tue Nov 12 2019
Lake effect snow event is slowly winding down as inversion heights
lower with shortwave ridging building in overnight. This was a
significant early season event notable for record cold air mass
allowing high snow to liquid ratios more typical of much later in
the season. Powdery snow really piled up with more than 2 feet in
the Allegan County snow belt.
For tonight...skies should partially clear after a day of record
cold maximum temperatures...allowing temperatures to plummet
towards record low minimums. Some mid to high clouds come in from
the west after midnight but this should not be thick enough to
prevent temperatures from falling to the 5 to 15 degree range with
sub zero readings in the cold hollows.
Southwest flow lake snow bands expected to form by Wednesday
afternoon. Inversion height is around 5 kft, which will limit
lake snow band intensity, but there is deeper moisture and
isentropic ascent above that. The combination of these two
contributing factors should lead to a general 3 to 5 inch
snowfall from northern Muskegon County to Oceana and Mason
counties from Wednesday evening to Thursday morning.
We will probably be issuing a Winter Weather Advisory for this
event later tonight after the current snow is over.
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 623 PM EST Tue Nov 12 2019
The lake effect snow showers will continue to diminish this
evening. The risk for impacts is much lower now than earlier in
the day. Still...there could be local brief MVFR or lower
conditions close to the Lakeshore but confidence of that occurring
at any of the taf sites was too low to include it in the forecast
into Wednesday morning.
Another storm system will move in from the west Wednesday
afternoon and into the night. This will cause the snow to increase
once again. At this time through 00z Thursday it looks like only
kmkg will see impacts developing by that time. The wind will also
be on the increase with gusts around kmkg up over 25 knots
issued at 926 PM EST Tue Nov 12 2019
We cancelled the Small Craft Advisory for this evening but issued
a Gale Warning for Wednesday. The wind will shift and become
southerly ahead of the next storm for Wednesday. A stronger low
level jet arrives and that combined with some mixing over Lake Michigan
should allow for gale force wind gusts. Given the wind
direction...the waves will be highest across the northern zones.
This flow direction will partially limit the impacts of the
waves along the shoreline.
Michigan...Lakeshore flood advisory from 9 am to 4 PM EST Wednesday for
Lm...Gale Warning from 9 am to 4 PM EST Wednesday for lmz844>849.