Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 172330
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
730 PM EDT Tue Apr 17 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 318 PM EDT Tue Apr 17 2018

Low pressure will track just south of Lower Michigan on Wednesday
night bringing rain and snow. Some light accumulations are
possible during the morning commute on Thursday.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 318 PM EDT Tue Apr 17 2018

A brief period of fair weather tonight and Wednesday before sfc
low spreads rain and snow into western zones on Wednesday
afternoon, which spreads east during the evening.

Surface low tracks just south of Lower Michigan with an area of
mid-level frontogenetical forcing passing over the forecast area
for Wednesday evening then moving off to the east Thursday
morning as the closed upper low opens up and is absorbed into a
large upper trough across eastern Canada. Model soundings show
rain or mixed rain and snow change over to all snow by midnight
for most places with accums expected to be an inch or less most
places by the time the precip ends Thursday morning.

Snow accumulations still expected to be an inch or less with sfc
temperatures being marginal and a slushy coating possible on the
roads for the Thursday morning commute. Conditions will improve by
Thursday afternoon as snow ends and temperatures rise above
freezing.

.LONG TERM...(Friday through Tuesday)
Issued at 318 PM EDT Tue Apr 17 2018

We will see a long period of fair weather with temperatures slowly
rebounding from far below normal to near normal under surface and
upper ridging. Height falls begin early next week but any
precipitation should hold off through Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 726 PM EDT Tue Apr 17 2018

The west northwesterly flow of cold air will continue to produce
MVFR/VFR clouds for parts of the region. Satellite loops suggest
far southern Lower Michigan will scatter out...so that is how I
trended the TAFs.

A fast moving storm system arrives Wednesday afternoon. Rain
showers should spread in from the west. There will be some
instability around far Southern Lower Michigan...so I did feature
VCTS for a few sites. During the evening the precipitation is
expected to transition to snow.

&&

.MARINE...
Issued at 318 PM EDT Tue Apr 17 2018

Winds and waves will be decreasing this evening and the Small
Craft Advisory should be coming down at or before 8 PM.


&&

.HYDROLOGY...
Issued at 1122 AM EDT Tue Apr 17 2018

River levels are above normal in Southern Lower Michigan and around
normal in Central Lower Michigan. The significant precipitation over
the weekend has led to rising river levels across the area. With
only a few tenths of precipitation expected Wednesday into Wednesday
night and nothing else until next week, rises are still expected to
continue for the next several days. Minor flooding near river banks
is still possible.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849.

&&

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...Ostuno
AVIATION...MJS
HYDROLOGY...63
MARINE...Ostuno


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