316
FXUS63 KGRR 151749
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
149 PM EDT Sat Aug 15 2026
.KEY MESSAGES...
- Chance of showers and isolated thunderstorms through Sunday
- Drier and less humid through early part of week
- Another frontal system could bring showers and storms midweek
&&
.DISCUSSION...
Issued at 144 PM EDT Sat Aug 15 2026
- Chance of showers and isolated thunderstorms through Sunday
Light showers are all that is currently moving through the region as
quasi stationary front continues to keep a weakening MCV south of
Michigan. The stable air over southern Michigan should continue
to stifle convection. As a SFC low moves eastward this afternoon
and evening it could move north enough to allow for scattered
showers and isolated storms along the I -94 corridor. The shear
and CAPE remain through IN and Ohio so the threat of severe from
any storms to forms continues to diminish. Any showers and storms
that form will be aided by the humid air mass and heavy rainfall
will be possible.
A short upper level wave and a deepening mid level trough will swing a
frontal system through the area tomorrow. This could allow for another chance
for showers tomorrow morning into early afternoon.
While lapse rates aren`t great and the front is coming at the wrong
time of day for convection, there should be sufficient CAPE and
PWATS are upwards of 2 inches from latest CAMS. So any showers or
storms that do form could have periods of heavy rain.
- Drier and less humid through early part of week
The front will move through tomorrow with cooler and drier air in
its wake which will drop Temps and dewpoints down to normal making the
are more comfortable.
Max temperatures will be near normal, in the low 80s, through
Tuesday.
- Another frontal system could bring showers and storms midweek
The quasi stationary high that was sitting over the south and allowed for
all the weather to move through Illinois and Indiana this past week will
shift to the west.
This upcoming week will be dominated by a large upper level low that will build over
the Hudson Bay. A it treks to the east will should move
south over northern Ontario and a cold front extending from it should move
from the northwest, across Michigan and sweep into the mid Atlantic
by Thursday.
There is some question on timing but currently, there is the
potential for showers and storms Tuesday night into Wednesday.
This should also clear temperatures off for the latter half of
this upcoming week.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 130 PM EDT Sat Aug 15 2026
Generally a cloudy day across the terminals and that will
continue through the period. The northern terminals are mostly VFR
while lower categories are noted near the I-94 corridor. Ceilings
and visibilities will fall tonight as fog develops with LIFR
conditions likely. Low pressure moving toward the state will keep
the threat for showers over the southern terminals.
&&
.MARINE...
Issued at 149 PM EDT Sat Aug 15 2026
Offshore flow will continue through today and into tomorrow which
will keep winds and waves low in the nearshore. Larger waves will
build as they move westward in the open waters.
Showers are storms are possible early Sunday and a cold front
will shift winds to the north tomorrow night, with building waves
in the open waters while waves should remain between 1 to 3 feet
in the nearshore.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Ceru
AVIATION...04
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
