204
FXUS63 KGRR 310519
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
119 AM EDT Sun Aug 31 2025

.KEY MESSAGES...

- Quiet and Mild through Tuesday night

- Widespread rain likely Wednesday

- Much cooler and unsettled Thursday and beyond

&&

.DISCUSSION...
Issued at 249 PM EDT Sat Aug 30 2495

- Quiet and Mild through Tuesday night

The dry and mild conditions we have seen over the past couple of
days will only continue for the early portion of the week. Upper
troughing over the region is keeping the temperatures a bit cool,
along with a flow around the Canadian Sfc Ridge overhead. The dry
weather is the result of the area being downstream of the upper
ridge, and confluent flow aloft overhead.

The only change expected over the next few days will be a slow and
gradual increase in temperatures. We are looking at highs mainly in
the 70s through Monday, then some 80s are more likely by Tuesday and
Wednesday. We will see little to no increase in moisture through
Tuesday night, so plenty of sunshine during the daylight hours, and
clearing skies at night.

- Widespread rain likely Wednesday

We are looking at a fairly strong wave that will approach the area
on Wednesday, bringing a fairly good chance of a widespread rain
late Wednesday and Wednesday night.

This strong wave will be coming in from the far Northern sections of
Alaska and Canada. It will be dislodged by a building upper ridge
over the Western portion of North America, and send it down to be
right over the area by Thursday.

This wave will initially not have any Gulf moisture associated with
it. However as the wave and front move in, it will connect with
another low over the SE U.S. and in an indirect way bring Gulf
moisture up. We should see the precipitation shield with this
system expand over the area as a result. Thunder looks possible at
this juncture with sfc based and elevated LI`s just a little below
0C. The limited instability, night time timing are definitely
factors against any meaningful organization for now.

- Much cooler and unsettled Thursday and beyond

Thursday through Saturday looks like it is going to be much cooler,
with periodic shower chances from Thursday through next Saturday.
The strong wave coming down from NW Canada will be combining with
the residual upper low over the SE U.S. to form a much larger upper
low that will sit in place for a few days.

We will see embedded short waves round the periphery of the low, and
drop right through our forecast area. This means we will have
unsettled conditions from Thursday through Saturday with highs lucky
to be in the 60s. It will not be a widespread or all day rain. It
will be scattered to numerous showers at times, with plenty of dry
periods also.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 118 AM EDT Sun Aug 31 2025

VFR conditions will continue through Sunday evening with light
and variable winds. JXN will see some shallow ground fog again
tonight, with the fog dissipating after daybreak.

&&

.MARINE...
Issued at 118 AM EDT Sun Aug 31 2025

High pressure will bring light winds and waves a foot or less
through mid-week. A Small Craft Advisory may be needed by
Wednesday and Thursday as low pressure moves through.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...NJJ
AVIATION...Ostuno
MARINE...Ostuno