047
FXUS63 KGRR 051914
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
314 PM EDT Fri Jun 5 2026
.KEY MESSAGES...
- Periods of showers and thunderstorms through Saturday
- Chances for showers and storms Monday night into mid week
- Warm and humid next week
&&
.DISCUSSION...
Issued at 313 PM EDT Fri Jun 5 2026
- Periods of showers and thunderstorms through Saturday
Several rounds of showers and storms are expected across Southwest
Lower Michigan between this afternoon and Saturday evening. The
first threat comes this afternoon and evening as a mesoscale
convective vort (MCV) moves northeast through the forecast area.
The leading edge of this vort max has become diffuse with time,
but is situated near mid lake over the southern bowl of Lake
Michigan. Little in the way of convection is ongoing at this time
associated with it. Most unstable CAPE values are only around 500
j/kg at this time, which is probably the main reason we are not
seeing more activity develop. This is due to fairly widespread
showers today along with lingering cloud cover. There are a few
breaks in the overcast for additional heating, but there are not
many. Overall feeling the threat this afternoon and evening is
fairly low given the lack of building instability. Not out of the
realm of possibilities though that we could see a few strong winds
gusts if storms can organize. We will be watching.
Tonight, instability actually builds in a southwest flow as
unstable air is advected in southwest flow ahead of a cold front.
We are expecting MUCAPE values to reach the 1000-2000 j/kg range
despite the time of day. This is owed to the deep moisture that
moves in. Tonight`s convection actually has more going for it with
better dynamics in play. A shortwave moves in from the northwest
which will be driving a cold front into the unstable airmass over
our area. Deep layer shear is roughly 30-40 knots so severe
weather is very much possible. Actually all hazards are in play
tonight.
The severe weather threat may continue towards daybreak in
Southern Lower Michigan towards I-94 as the deep moisture remains
in place ahead of the cold front. There may be just enough time to
rekindle a few storms near I-94 again into the midday hours before
the cold front sweeps south. The main threat may actually be the
overnight convection though after midnight.
- Chances for showers and storms Monday night into mid week
The upper pattern for several days in a row now has shown
shortwave troughing trying to move into the mean ridge position
across our area. Hard to ignore this continuity. We have chances
for showers and storms from Monday night at least into mid week.
- Warm and humid next week
Warm and humid conditions are expected all next week. 80s for
highs will be common and we will push into the 90s late in the
week. The ECWMF is not as warm as it was a few days ago at 850mb
on Thu/Fri as 24-25C has come down to 21-22C. Bottom line it is
going to feel like summer, but maybe not quite as warm as we were
thinking.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 212 PM EDT Fri Jun 5 2026
Multiple threats exist in the next 24 hours for aviation purposes.
We have a few rounds of showers/storms possible one occurring this
afternoon and evening, another overnight after midnight and
another possible Saturday midday. The other threat is lower
ceilings that dip overnight to IFR and LIFR.
Regarding the chances for showers and storms we have the chance
for a wave of activity to move through this afternoon and early
evening. The best time frame looks to be from around 300pm through
900pm. Another surge of showers/storms may move in from the
northwest after 100am in the morning. Finally, more storms are
possible during the late morning and midday hours before a cold
front drops south of the area.
As for ceilings, they will steadily lower through the evening and
overnight hours, bottoming out in the IFR/LIFR range.
&&
.MARINE...
Issued at 313 PM EDT Fri Jun 5 2026
Have opted to drop the Small Craft Advisory and the Beach Hazards
Statement as conditions are below criteria at this point and not
expected to make a significant increase this evening. There may be
some 3 footers for a time this evening near Muskegon, but all the
nearshore buoys to the north right now are indicating 1-2 foot
waves. The gradient gets more slack as we head into tomorrow, so
we should remain below advisory thresholds heading into the
weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Duke
AVIATION...Duke
MARINE...Duke
NWS GRR Office Area Forecast Discussion
