Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 272340
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
740 PM EDT Mon Mar 27 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 320 PM EDT Mon Mar 27 2017

A busy spring pattern will persist through the next week. Several
upper level waves will track west to east across the country. Each
system will bring precipitation chances of some degree to parts
of Lower Michigan. Dry times are almost evenly distributed in the
forecast with fair weather from the later half of Tuesday into
Wednesday and again next weekend. High and low temperatures are
expected to be near seasonal normals.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 320 PM EDT Mon Mar 27 2017

An upper level shortwave and weakening surface low will pass well
to our south this evening and overnight. Initially, rain chances
extended as far as central Lower Michigan. Trends have continued
to keep rain further south, especially with high res models.
Regional radar and surrounding observations point in the same
direction. Rain chances will largely remain south of I-96, but
probabilities have been lowered. What falls will likely be
scattered an light, primarily along and south of I-94 this
evening.

Aside from any leftover sprinkles, the overnight hours continue to
trend drier. Low level moisture hangs around a bit, raising the
question whether patchy fog will develop overnight. Winds may be
the mitigating factor here, as they switch out of the north and
wind speed minimums are short lived. The highest likelihood would
be across the south (AZO to JXN) where ground moisture is high,
as well as the far north within cooler valleys. Even what develops
shouldn`t result in real impact, but deserves a mention.

The remainder of the period looks rather nice. Dry air increases
in depth, which should break clouds Tuesday afternoon from north
to south. We should see a sunny end to Tuesday with sunshine
extending Wednesday. High clouds will begin to stream in Wednesday
afternoon well ahead of another closed upper level system over the
plains. High temperatures may be underdone a bit, depending on how
fast clouds move in. Rain is likely to hold off through much of
Wednesday before developing late Wednesday night.

.LONG TERM...(Thursday through Monday)
Issued at 320 PM EDT Mon Mar 27 2017

Little change in previous thinking. There is remarkably good
agreement among the mid range models with respect to a slow moving
southern stream upper trough that is expected to bring the next
chance of precipitation to the area beginning late Wednesday night
as it lifts northeast. As noted already, slow movement of this
system will draw a lot of Gulf moisture northward ahead of it. We
still expect an initial brief period of mixed precipitation type
early Thursday morning related to wet bulb effects with expected
cold dry northeasterly winds in the lowest levels.

Thursday afternoon and evening could see a period of heavy rain
south of I-96 as several medium range solutions point towards low
level fgen coupled with upper deformation ahead of the approaching
low. Predictability with such details at this time range is limited,
so will keep watching, especially since this same area experienced
the greatest rain totals over the last couple of days.

Very low predictability on next round of precipitation advertised
Sunday into early Monday. Overall pattern shows this system to be
much drier, so little or no impacts expected.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 740 PM EDT Mon Mar 27 2017

MVFR ceilings covered the region early this evening, although a
few breaks with VFR weather was around too. Expect the MVFR will
linger through the night before finally breaking up Tuesday
morning. Some patchy IFR ceilings will possibly develop after
04Z, but this was left out of the TAFs as the areal coverage
should not be that great. Conditions will finally improve by late
morning/early afternoon on Tuesday as ceilings lift, and then
eventually scattered out from the north by late afternoon.

&&

.MARINE...
Issued at 320 PM EDT Mon Mar 27 2017

Dense fog will continue to gradually lighten up through the
evening with drier air working in from the north.

Northerly winds will keep most of the wave action offshore for the
most part. Big Sable and Little Sable Points may see waves briefly
reach near 3 feet Tuesday afternoon/evening. However, winds then
turn out of the east and push waves out over open waters again.


&&

.HYDROLOGY...
Issued at 320 PM EDT Mon Mar 27 2017

Most rivers have demonstrated within bank rises after rainfall over
the last 4 days. However, more elevated river levels at Ionia,
Hastings, Eagle, and Holt may be susceptible to additional rainfall
expected Thursday and Friday, possibly another 0.50"-1.00". This may
act to provide secondary river crests heading into the end of the
week and weekend, potentially higher than the current crests.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...JAM
SHORT TERM...JAM
LONG TERM...TJT
AVIATION...JK
HYDROLOGY...Hoving
MARINE...JAM



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