Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271718
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
118 PM EDT Thu Jul 27 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 321 AM EDT Thu Jul 27 2017

A cold front will move through Lower Michigan today with only
scattered showers and thunderstorms then drier conditions can be
expected into the weekend as high pressure builds in.

&&

.SHORT TERM...(Today through Saturday)
Issued at 321 AM EDT Thu Jul 27 2017

Forecast issues in the near term are for POPs today as cold front
moves through with a few showers and thunderstorms, then the
potential for some diurnally enhanced showers and isolated
thunderstorms on Friday as upper low comes through.

For today, showers across the northern forecast area early this
morning will gradually move south this morning and forecast
soundings show enough instability for thunderstorms across the
central and southern zones through the day. Drying behind the
front begins this evening with showers ending across the southern
zones by midnight.

Heights fall and lapse rates steepen on Friday morning as an upper
low moves across the central Great Lakes with showers and
thunderstorms diurnally enhanced into the afternoon. Superblend
POPs seemed a bit low given the good model agreement on the
strength of this feature and were adjusted up and if trends
continue could be bumped up further in the future.

The upper low departs Friday night with strong sfc ridging and
height rises meaning dry weather Friday night and Saturday.

.LONG TERM...(Saturday night through Wednesday)
Issued at 321 AM EDT Thu Jul 27 2017

A high pressure ridge will continue in control of the wx pattern
Saturday night through Sunday night and bring fair wx with
seasonable temperatures. High temps Sunday will reach 80 to 85
degrees with min temps mainly in the 50`s.

The overall wx pattern continues to look quite dry through next week
as a high pressure ridge will continue to dominate the wx
pattern. A weak cold front moving in from the northwest will
bring a chance for a few showers and storms by late Wednesday or
Thursday but significant rainfall is unlikely as this system will
have very little moisture to work with. Temps will continue
to average near normal through the long range fcst period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 118 PM EDT Thu Jul 27 2017

There is a narrow band of MVFR ceilings assoicated with a slow
moving cold front near I-96 at 17z, this band of clouds will slip
south over time but by the time it reaches the I-94 TAF sites
ceiling should be VFR. I expect skies to clear across the area
this evening then cumulus clouds are expected Friday.

&&

.MARINE...
Issued at 321 AM EDT Thu Jul 27 2017

North winds to 20 knots will build waves to 2 to 4 feet across
the nearshore waters north of Whitehall by late this afternoon.
Some 3 to 5 foot waves are possible near Little Sable and Big
Sable points this afternoon. Winds and waves will decrease
overnight.


&&

.HYDROLOGY...
Issued at 100 PM EDT Thu Jul 27 2017

One to two inches of rain fell across a fair portion of Central
Michigan (along the US-10 and M-20 corridors) Wed and Wed night.
Given the mostly dry conditions over the last two or three weeks,
this rain was effectively captured by the soil and river rises
will be limited. The chance for substantial rainfall over the next
week is very low.

&&

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

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...Laurens
AVIATION...WDM
HYDROLOGY...CAS
MARINE...Ostuno



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