Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KGRR 271921

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

Synopsis/Short Term/Long Term/Hydro/Marine

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

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 18Z TAFS through 18Z Tuesday afternoon)
Issued at 201 PM EDT Mon Mar 27 2017

The AZO-BTL-JXN terminals along the I-94 corridor will be the most
likely to see IFR and even LIFR ceilings centered around 06Z
tonight. Some improvement to IFR/MVFR is expected by 09Z when
winds turn northeast and get a little stronger. This is a little
less climatologically favorable for IFR/LIFR at some sites like
JXN but slightly more favorable at AZO/BTL/GRR. So, most sites
stand a good chance of experiencing IFR ceilings well past 12Z
Tuesday. Fog will be a secondary issue with visibilities expected
to stay above 1 mile even along I-94 corridor sites.


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.


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.


LM...Dense Fog Advisory until 4 PM EDT this afternoon for LMZ844>849.



MARINE...JAM is the U.S. government's official web portal to all federal, state and local government web resources and services.