Lansing, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

314
FXUS63 KGRR 251800
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
200 PM EDT Fri Jul 25 2025

.KEY MESSAGES...

- Showers and Storms this Afternoon and Evening

- Additional Round of Storms Saturday

- Hot and Humid Monday with Slight Chances for Storms Next Week

&&

.DISCUSSION...
Issued at 200 PM EDT Fri Jul 25 2025

- Showers and Storms this Afternoon and Evening

The lake boundary, front shifting south through the area, and the
disturbance to the south are sparking off showers and storms this
afternoon mainly along and south of I-96. Surface based
instability is currently in the 1000 to 2000 J/kg range from north
to south. Low level lapse rates are not ideal, but if storms are
able to grow tall enough, gusty winds are possible. Otherwise
lightning and heavy downpours will be the main hazards with any
thunderstorm. Drier conditions move in after sunset, but isolated
showers and storms may linger mainly along and south of I-94
overnight.

- Additional Round of Storms Saturday

Late tonight into Saturday morning an 850-700mb jet along with
500mb positive vorticity advection will provide a source of lift
bring scattered showers and storms through the morning hours. A
lull is possible during the afternoon with isolated showers and
storms redeveloping during the late afternoon and evening as
another round of positive vorticity advection swings through with
the shortwave trough. Soundings are rather saturated especially
with the 2 inch precipitable water values, as with the pattern
we`ve been in heavy rainfall rates are possible with these storms.
However they should not linger over any one location limiting
rainfall amounts. Known trouble spots will be susceptible to minor
flooding. As for the potential for severe storms it is
borderline. Mean MUCAPE values are expected to be around 1000
J/kg, shear around 30 knots will be present and could help storms
organize and produce gusty winds but due to the timing confidence
is not high that we will reach severe levels. Best chances are
along and south of a Holland to Alma line.

- Hot and Humid Monday with Slight Chances for Storms Next Week

Heat indices may once again approach 100 on Monday with highs in
the upper 80s to low 90s and dew points in the 70s across much of
the area. However an MCV expected to move through sometime during
Monday morning may lower these values if it hold together. Cooler
temperatures are expected for the remainder of the week with a
couple shortwave troughs potentially sparking off showers and
storms Tuesday night into Wednesday (20 to 30 percent).

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 200 PM EDT Fri Jul 25 2025

Scattered heavy rain showers have developed vicinity of GRR, AZO,
BTL, and should eventually affect JXN and LAN as well this
afternoon. A few cells could intensify enough to produce
lightning. Weak to moderately strong microbursts are possible
underneath some showers/thunderstorms along with with
intermittent IFR heavy rain downpours. A few showers may linger
overnight, then become more common on Saturday along with ceilings
possibly dropping below 2,000 feet.

&&

.MARINE...
Issued at 200 PM EDT Fri Jul 25 2025

Other than a few showers and storms south of South Haven, dry
conditions are expected until Saturday morning when isolated to
scattered showers and storms move in from the southwest. The best
chances will be south of Muskegon throughout the day. Isolated
gusty winds and higher waves will be possible in any thunderstorm.

Additional chances for storms (20 percent) exist for Monday, and
Tuesday night into Wednesday, otherwise dry conditions are
expected through most of the upcoming week. Additionally waves are
expected to remain 2 feet or less with winds remaining below
Small Craft Advisory criteria through the upcoming week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ037>040-
     043>046-051-052.
MARINE...None.

&&

$$

DISCUSSION...RAH
AVIATION...CAS
MARINE...RAH