195
FXUS63 KGRR 140734
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
334 AM EDT Sat Jun 14 2025

.KEY MESSAGES...

- Dry weekend

- Increasing humidity and midweek convection

&&

.DISCUSSION...
Issued at 334 AM EDT Sat Jun 14 2025

- Dry weekend

Recent radar imagery shows the last of the light rain south of
I-96 continues to whither away as low pressure over Indiana moves
east. IR loop shows abundant mid clouds across the region due to a
combination of the low to the south and minor short waves to the
north moving quickly in the quasi zonal flow over the UP.

Aloft, zonal flow will overtake much of the western Great Lakes
this weekend bringing a mix of clouds and sun. High pressure over
Ontario will continue to produce an easterly flow and (for the
most part) lower humidity values; dewpoints mainly in the 50s are
expected today and Sunday. Highs today will reach the mid 70s and
tomorrow the lower 80s.

- Increasing humidity and midweek convection

The Ontario high will move east Monday which will enable a
southwest flow to develop. Higher heat and more humidity will be
the result as dewpoints climb into the 60s. Ensembles of both the
GFS and ECMWF sows low pressure developing over the Missouri
Valley Tuesday and moving northeast toward Wisconsin by early
Wednesday. Most of the ECMWF ensemble members produce rainfall;
ensemble mean is closing in on an inch. The GFS mean is about
half the ECMWF. LREF ensemble probabilities of greater than a half
inch of rain Tuesday into Wednesday is just above 50 percent north
of I-96 and closer to 75 percent near I-94. Parts of the central
cwa are fairly parched, according to the Michigan Drought Monitor
and so any rain received would be beneficial.

As the low and associated frontal boundary move through the cwa
Wednesday, instability ramps up with MUCAPE values above 2k
j/kg and moisture transport vector maxima through the heart of the
cwa. Shear values in the 40-50kt range would point toward
convective organization potential so this will be monitored
closely.


&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 133 AM EDT Sat Jun 14 2025

Radar shows light rain diminishing south of I-96 leaving IFR/MVFR
cigs across the I-94 terminals. VFR conditions north of there with
mid level ceilings and no rain.

We`ll see conditions slowly improve along I-94 today as high
pressure to the north tries to nose its way southward. Meanwhile,
VFR conditions will continue along the I-96 terminals.

&&

.MARINE...
Issued at 334 AM EDT Sat Jun 14 2025

A weak pressure gradient and high pressure to the north will
result in an offshore flow today and low wind speeds/wave heights.
Fairly tame marine conditions are expected through the weekend.

&&

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

&&

$$

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