983
FXUS63 KGRR 220830
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EST Wed Jan 22 2020

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 330 AM EST Wed Jan 22 2020

- A few rounds of snow or mix Thursday to Saturday

- Benign weather early next week

&&

.DISCUSSION...(Today through next Tuesday)
Issued at 330 AM EST Wed Jan 22 2020

-- A few rounds of snow or mix Thursday to Saturday --

Whatever filtered sunshine we see today will likely be the last for
this week. A pair of troughs/vorticity maxima over the Canadian
Rockies will dig into the central US, forming a closed low on
Thursday which will lumber toward the eastern US by Sunday.

Snow will develop amid isentropic lift on Thursday. It will start
off as virga but will eventually reach the ground as low level dry
air moistens and gradually advects away. The areas most favored to
see about 1.5 inches during the day would be near/west of US-131
while 0.5 would be possible toward US-127. Impacts to travel will
likely be minor due to temperatures near freezing, though initially
cold roads may allow snow to stick.

The greatest and most likely time frame for precipitation will be
Friday into Friday night as the low hooks northward from the lower
Ohio river valley. The NAM, GFS, ECMWF, and ensembles are in general
agreement of 0.25 to 0.50 inch precip occurring in central to
southern Michigan, though amounts don`t look like they will be
neatly distributed. To further complicate the forecast for snow
amounts, warm air advection around 900 mb Friday morning may cause a
changeover to a mix or rain for part of the day, but the degree of
which is very much in question as the low level temperatures would
be just marginally warm enough to melt falling snow. Areas which
change over to snow sooner and receive relatively heavier
precipitation could be dealing with 1 to 2 inches of wet snow by
Friday night, but this detail is low confidence. Lingering snow
showers are expected to last into Saturday.

-- Benign weather early next week --

Even after the departure of the low on Sunday, there may be enough
low level moisture and lift to consider drizzle or freezing drizzle.
Ridging and high pressure will likely become established by Tuesday.
Temperatures will likely be a little warmer than January norms.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1200 AM EST Wed Jan 22 2020

MVFR lake-effect clouds are spread across MKG-FFX-RQB and north,
and should persist for much of the morning. Otherwise, prevailing
VFR with south-southwest winds are expected over the next 24
hours. Gusts 15 to 20 KT are possible during the afternoon.


&&

.MARINE...
Issued at 330 AM EST Wed Jan 22 2020

Hazardous winds and waves on Lake Michigan will be maximized this
morning before gradually diminishing through Thursday morning. Could
be a few gusts near gale force around Big and Little Sable Points,
which is where waves and potential shoreline erosion will be
greatest.

&&

.HYDROLOGY...
Issued at 315 PM EST Tue Jan 21 2020

The river flood warning at Robinson Township has been cancelled.
This leaves the Grand River basin free of any flood alerts.
Further south, an ice jam formed on the Kalamazoo River near
Comstock on Monday and this continued into today. Flows were
backed up to near flood stage at times but as of this afternoon a
substantial drop was noted. However, the river may fluctuate again
over the next 24 hours given the erratic nature of ice jams and
changing river flows. We are not expecting much, if any,
additional ice formation in the river given our mean daily
temperatures will not be below 20 degrees this week. Residents and
businesses should continue monitoring the river while the jam is
present.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Advisory until 5 PM EST this afternoon for
     MIZ037-043-050-056.

LM...Small Craft Advisory until 10 AM EST Thursday for LMZ846>849.

     Small Craft Advisory until 4 AM EST Thursday for LMZ844-845.

&&

$$

SYNOPSIS...CAS
DISCUSSION...CAS
AVIATION...CAS
HYDROLOGY...Hoving
MARINE...CAS

NWS GRR Office Area Forecast Discussion