875
FXUS63 KGRR 140747
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
347 AM EDT Fri Jun 14 2024

.KEY MESSAGES...

- Much quieter weather through Saturday

- Hot and Humid Sunday and into Next Week

- A Few Chances for Showers/Thunderstorms Sunday and into Next Week

&&

.DISCUSSION...
Issued at 347 AM EDT Fri Jun 14 2024

- Much quieter weather through Saturday

High pressure is building in the wake of the cold frontal passage
yesterday. There is even a secondary dew point boundary that has
been settling south through the area this morning. Ahead of this dew
point boundary, some fog has formed with some moisture pooling ahead
of it, and with a moist boundary layer from the rain down south last
evening. This looks to be temporary early this morning, and then
burn off/lift into a fair weather cumulus deck.

We can not rule out a brief sprinkle/shower over the eastern portion
of the area this afternoon. This would be the result of some diurnal
troughing over the warmer land mass between the cooler lakes, along
with some residual low level moisture. It seems like it is a
legitimate "silent 10 percent". The moisture will eventually mix
out, and then dissipate completely after sunset tonight. Saturday
will see much less in the way of cloud cover with drier air
expected.

- Hot and Humid Sunday and into Next Week

No big changes in thinking tonight when it comes to the heat that is
expected to arrive this weekend and persist into next week. There
are differences though between the operation GFS and ECWMF. The
ECMWF is much more bullish on the ridging with 500mb heights
climbing into the upper 590s. Correspondingly. the ECMWF has warmer
850mb temperatures, reaching +21C to +22C. The GFS is more on the
order of +18C to +20C. Bottom line though is it will be hot with
highs in the upper 80s to lower 90s most days between Sunday and
Thursday of next week. If the ECWMF is what verifies we could be
more mid 90s most days. Surface dew points look to easily be in the
upper 60s to lower 70s which will push heat indices towards 100 at
times. Heat Advisory criteria is 100 degrees, so we will make a run
at this level on a couple of days. Again, if the ECWMF verifies it
could be multiple days at or above heat indices of 100. Summer
weather is on the way.

- A Few Chances for Showers/Thunderstorms Sunday and into Next Week

We cannot rule out a couple of chances for showers and thunderstorms
through the period. Once again, this very much comes down to
differences in the GFS and ECWMF. In the GFS being not as bullish on
the ridge, it allows a front to be closer to us versus well off to
the north and west.

The first opportunity for precipitation will come Sunday into Sunday
night as a wave moves through the Great Lakes aloft. Not a slam
dunk, but chances for showers and storms it appears. Confidence in
precipitation is not high Sunday through Thursday given the model
disparity. The next chance for showers and storms will come out on
Wednesday into Thursday as the boundary off to our north sags into
the area in the GFS. As mentioned above, model differences make this
a low confidence forecast. Bottom line, hot and humid with a few
chances for storms meaning it will feel very summer like.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 212 AM EDT Fri Jun 14 2024

The main concern with this set of aviation forecasts is the
potential for some light fog along the I-94 TAF sites this
morning. A cold front stretches from near FNT to GRR to MKG at
06z. South of this front abundant low level moisture is in place.
Light winds combined with the low level moisture will result in
light for. At this point only included at JXN, but can see AZO and
BTL needed to be updated if the fog becomes pervasive.

VFR ceilings are expected throughout the forecast. High clouds
(bases at or above 15,000 feet) are expected the remainder of the
night with some broken cumulus today (bases around 4,000 feet).
Winds will become northerly (350-030) at all TAF sites tonight.
Wind speeds will be on the light side at 5 to 10 knots for the
most part.

&&

.MARINE...
Issued at 347 AM EDT Fri Jun 14 2024

We are watching for the potential of one of the more subtle elevated
wave events for the nearshore late this afternoon, especially for
the southern half. The scenario is where high pressure is building
in, and combines with the lower pressure over the warmer land mass.
The winds will initially be offshore for the first half of the day,
and will then turn onshore mid-late afternoon. That will bring some
of the better wave action over the open waters toward the shoreline.
Right now, the best bet is that we will see winds and waves stay
just shy of Small Craft Advisory and Beach Hazards criteria. If the
potential increases a little more, headlines may be needed to be
issued by the day shift.

We will see good beach and boating weather then for Saturday with
high pressure overhead and lighter winds and smaller waves. Winds
and waves will then increase on Sunday as the high moves east of the
area, and a solid southerly gradient moves overhead. This looks
likely to need some advisories and statements for the increasing
hazardous conditions.

&&

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

&&

$$

DISCUSSION...NJJ/Duke
AVIATION...Duke
MARINE...NJJ