Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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118
FXUS63 KGRR 222024
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
324 PM EST Sun Jan 22 2017

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 324 PM EST Sun Jan 22 2017

Dense fog is expected to plague the region through tonight, then
visibilities are expected to improve by late Monday morning. Mild
and wet weather will continue through the first half of the week.
Daytime temperatures will be in the 40s Monday and Tuesday, but
we will see good chances of rain Monday afternoon and evening, and
again Tuesday night.

More winter-like conditions should return Wednesday night, and
lasting into next weekend. Temperatures will become more typical
for this time of year, along with chances of snow, especially
Wednesday night through Thursday night.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 324 PM EST Sun Jan 22 2017

Dense fog advisory was extended at the morning update until 10 AM
Monday and this still looks good. Most of the area has seen a
diurnal improvement this afternoon, but the regime has not changed
for tonight. So the fog will become dense once again. We will
begin to realize a better pressure gradient late tonight, when
winds begin to pick up as an intense low pressure moves across
NC. So some improvement may occur as early as daybreak (7 AM)
toward I-94, but it should take until 10 AM for Central Lower MI
to improve.

A surface trough will extend from the NC low to Lower MI. This
should continue to supply enough lift to expect periods of drizzle
and/or light rain tonight. Highest chance over the SE CWA, while
portions of the NW may remain mostly dry. As the low moves NE
toward the mid Atlantic Monday, it will act to throw back
moisture into the Great Lakes. More rain will occur across the
CWA, but lightest toward the lakeshore. Even so, expect all areas
will see less than a quarter inch of rain, tonight through Monday
evening. The rain will diminish late Monday night as the low pulls
away and weak surface ridging moves in.

Tuesday should be a mostly dry day, but by the end of the day
another stacked low will be crossing IA. Good moisture advection
ahead of this low, where some light showers may begin by
nightfall Tuesday. However the bulk of the rain will arrive later
in the evening and overnight. A light rain is expected again with
less than a quarter inch expected. I did remove any mention of
snow on Tuesday night as temps are expected to hold steady in the
mid and upper 30s. Progged dew points remain in the low to mid
30s all night.

.LONG TERM...(Wednesday through Sunday)
Issued at 324 PM EST Sun Jan 22 2017

Made some changes to Superblend in the extended. Bumped up POPs
significantly for Thursday night through Sunday for lake effect snow
and lowered temperatures closer to EC guidance.

Sfc low pulling away on Wednesday with rain transitioning to snow
Wednesday night, followed by a period of west flow lake effect snow
showers into the weekend. Best chances for accumulating snow will be
Thursday night into Friday morning as trough moves through and
inversion heights increase to 8 to 10 kft.

Lake effect should decrease on Friday night then pick up again on
Saturday with the passage of another trough which features a Lake
Superior connection and strong sfc convergence across the SW zones.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1252 PM EST Sun Jan 22 2017

IFR and LIFR conditions will prevail most of the period. There
will be some variations where periods of higher visbys and
ceilings occur this afternoon, but these should be brief and no
significant improvement is expected in the next 24 hours.

&&

.MARINE...
Issued at 324 PM EST Sun Jan 22 2017

Dense fog advisory remains for the nearshore areas through 10 AM
Monday. Periods of fog will be likely at times beyond this, with
dew points remaining in the 30s over the chilly waters, so we`ll
have to monitor trends. Otherwise winds and waves will remain
moderate. We may approach small craft advisory conditions Monday
afternoon and evening over the south end of the lake with a
persistent NNW flow of 15-25 knots.

&&

.HYDROLOGY...
Issued at 329 PM EST Sat Jan 21 2017

While the initial flood wave on the Grand River has moved through
Robinson Township...a second rise in river levels is currently
working through Ionia and Lowell and will cause rises at Comstock
Park...Grand Rapids...and Robinson Township over the next few days.
Current thought is that this next rise will remain below flood stage
at the forecast points.

Rises continue on tributaries to the Grand...such as the Thornapple
at Hastings and Caledonia...Looking Glass at Eagle...and the Maple
River at Maple Rapids.  While some of this additional water will
travel through dams...this will keep levels on the Grand elevated
through at least the middle of next week.

Rainfall from the storm system Sunday night into Monday looks to be
less than one quarter inch for most locations.  While most of that
may end up as runoff...minimal impacts are expected from that event.
Another system will affect the region late Tuesday into Wednesday...
which will bring a colder airmass into the region.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EST Monday for MIZ037>040-043>046-
     050>052-056>059-064>067-071>074.

LM...Dense Fog Advisory until 10 AM EST Monday for LMZ844>849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...Ostuno
AVIATION...Ostuno
HYDROLOGY...MWS
MARINE...JK



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