East Lansing, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

032
FXUS63 KGRR 191844
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
244 PM EDT Sat Jul 19 2025

.KEY MESSAGES...

- Strong storms possible this afternoon

- Heat and humidity builds next week

&&

.DISCUSSION...
Issued at 244 PM EDT Sat Jul 19 2025

- Strong storms possible this afternoon

The MCS that rolled across the midwest last night and the toward
CHI this morning continues to diminish with echos struggling to
reach the cwa. In it`s wake, new convection has developed over the
lake and to a lesser extent across the southwest cwa, but it`s not
doing much either. Despite meager radar echos, the cwa sits on
1k-1.5k SBCAPE and 35kts bulk shear. We have another couple of
hours of peak heating and then instability will likely begin to
wane. Additionally, a weak short wave moving across the cwa should
be east of the cwa by late afternoon and mid level lapse
rates...currently around 7c/km are progd to decrease. Thus if we
don`t see much increase in development within the next couple of
hours, we probably won`t.
u
Low pressure to the west is helping to drive the uptick in
convection over the lake and will pull a weak cold front south
through the cwa around 06z. Once that moves through rain chances
will diminish.

- Heat and humidity builds next week

From late Sunday through mid day Tuesday, dewpoints will be in the
50s resulting in lower humidity. After Tuesday, though, a building
ridge over the Great Lakes and Ohio Valley will result in
dewpoints climbing into the 70s and temperatures climbing into the
lower to mid 90s; a heat advisory may be needed Wednesday and
Thursday as apparent temperatures climb to around 100.

Given the ridge in place, chances of thunderstorms will emanate
from potential ridge rider short waves Wednesday and Thursday
resulting in 30-40 PoPs across the northern cwa.


&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 138 PM EDT Sat Jul 19 2025

Radar is beginning to show echos moving east from the lake as well
as developing across the cwa. Mostly showers at present, but a few
storms over the lake. Moderate instability and shear remain in
place along with increasing low level moisture for storm
development as a weak upper wave moves east. We expect continued
development of convection this afternoon and a few storms that
develop could be strong.

A fairly strong signal is present later tonight once the
precipitation ends for stratus and fog to develop.

&&

.MARINE...
Issued at 244 PM EDT Sat Jul 19 2025

Thunderstorms this afternoon will pose a threat for boaters and
beach goers.

A cold front will move through tonight and high pressure will
build into the region Sunday. Winds will increase but become
northeasterly which will result in some upwelling and also push
higher waves off shore. The upwelling will result in colder lake
temperatures later Sunday.

&&

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

&&

$$

DISCUSSION...04
AVIATION...04
MARINE...04