Walhalla, Michigan Weather Forecast Discussion

580
FXUS63 KGRR 071121
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
721 AM EDT Sun Sep 7 2025
.KEY MESSAGES...
- Little to no chance of appreciable rain through next Saturday
- Gradually warming temperatures through Friday
&&
.DISCUSSION...
Issued at 330 AM EDT Sun Sep 7 2025
- Little to no chance of appreciable rain through next Saturday
The short waves that have been driving through the area the last
couple of days have underperformed a bit with regards to rain shower
activity. The short wave coming through tonight is no different,
only producing a couple of isolated showers down toward South Haven.
We will see a fair amount of self-destruct sunshine again today,
building clouds again this afternoon with the heating of the day and
the cold pool aloft remaining over the State. It may not be quite as
extensive as Saturday, and a clearing trend is expected this
afternoon as the cold pool and upper trough move ENE of the area.
Ridging at the sfc and aloft will dominate the weather for Monday in
the wake of the upper trough moving out. The ridge will move east of
the area by Tuesday, setting the area up for an increased flow from
the south ahead of a frontal system leaning in from the west. Rain
chances remain almost zero Tuesday as the low level jet and upper
dynamics all remain far enough away to keep the area dry.
The front will drop in on Wednesday, but rain chances will remain
fairly low for multiple reasons. The moisture flow ahead of the
front will be quite weak as the air will be coming off from the
Appalachians. In addition, the front weakens considerably as the
stronger jet energy lifts north into Canada, and just leaves the sfc
front and weakening upper wave to sink south over the area with
little to no fanfare. This all said, Wednesday looks to have the
best chance of rain in the next seven days, with only a slight
chance.
We will see the Upper Ridge axis over the Plains States nudge toward
the area then by Thursday. The sfc will see Canadian ridging
building in over the area with the cooler and dry flow from the NE
that will become established by Thursday. This will hold stronger
general subsidence over the area into Saturday. Some uncertainty
develops as a upper low over Canada will be trying to drop SE into
the Eastern Great Lakes. Ensemble means keep most of the area fairly
dry through next Saturday, with various tracks showing up next
Sunday.
- Gradually warming temperatures through Friday
It looks like the coldest temperatures of this cooldown were
yesterday with the heart of the cold pool over the area at that time
with 850 mb temps around 2-4C. We will see temperatures gradually
warm through Tuesday ahead of the next incoming front for Wednesday.
It looks like we peak around +12C at 850 mb on Wednesday. These
temps aloft would support highs at the sfc up around 80F.
A slight cooldown can be expected behind the front for late next
week, but nothing as significant as this weekend has seen. We expect
temps to go from around 80F mid week, to come down into the mid 70s
F by next weekend.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 721 AM EDT Sun Sep 7 2025
Most of the terminals have cleared out this morning, with some mid
clouds around 6k ft coming in off of Lake Michigan near Holland
and south. Patchy fog at the I-94 terminals has dissipated. Trend
will be for more mid clouds to develop by late morning, and stick
around a good portion of the day. They will diminish late this
afternoon/early evening, before skies clear out toward sunset. We
have added some fog to KJXN late in this forecast period as
conditions will be similar there, and they see fog a bit easier
than other sites.
&&
.MARINE...
Issued at 330 AM EDT Sun Sep 7 2025
As mentioned with the late evening update last night, thresholds for
meeting SCA and Beach Hazards criteria will be hard to meet today.
We will have a decent gradient lingering into the afternoon hours,
but it looks like it will be a notch below criteria. Moderate beach
hazards are expected with waves a solid 2-4 ft.
Once today`s moderate conditions end, we are looking at an extended
period of sub-headline conditions. Winds may be up around 15 knots
or so through Tuesday, but could be below 15 knots potentially
into next weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...NJJ
MARINE...NJJ

NWS GRR Office Area Forecast Discussion