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379
FXUS63 KGRR 300157
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
957 PM EDT Wed May 29 2024

.KEY MESSAGES...

- Clearing and chilly tonight

- Low Chance of Weekend Showers, Mainly on Saturday

- Periodic Shower/Storm Chances Early Next Week

&&

.UPDATE...
-- Changed Discussion --
Issued at 956 PM EDT Wed May 29 2024

High pressure settled over Lake Superior continues to sink over
lower Michigan this evening and tonight. Winds become calm
overnight with skies staying clear. Clear skies with minimal wind
will support decent radiational cooling tonight, with lows
dropping into the mid to upper 30s near and north of M-20 (few
degrees warmer near the lakeshore) and into the low 40s further
south. Patchy frost looks possible in low-lying areas north of
M-20 where temps could fall into the low 30s.
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&&

.DISCUSSION...
Issued at 240 PM EDT Wed May 29 2024

- Clearing and chilly tonight

Cu continues to develop and move south across the cwa this
afternoon. A few showers have also developed south of GRR along
the US-131 corridor...in line with earlier CAMs. The diurnal loss
of heating coupled with subsidence associated with the high that`s
building in will help to dissipate the cu field toward evening.
That`ll leave some high clouds overnight that are advecting
southwestward around the departing upper low.

The only concerns tonight really deal with the frost potential
over the northern cwa. Lows in the mid to upper 30s are expected
over the northern two rows of counties which would support some
patchy frost development. Low lying areas may see temperatures
fall into the lower 30s too which may support a bit more frost
development. It doesn`t appear that frost will be widespread
enough to support a headline. However, if you live in a low lying
area within the northern two rows of counties and have tender
vegetation outside, it may be best to cover it to mitigate any
frost damage.

High pressure will produce sunny skies and highs in the lower 70s
Thursday and clear skies Thursday night. Temperatures won`t be as
cold Thursday night due to the high drifting east and warmer south
winds developing.

- Low Chance of Weekend Showers, Mainly Saturday

We continue to have confidence that Friday will be a dry and mild
day. Maybe one of the nicest days over the next week. High pressure
at the surface will be slipping east late in the day, while the
upper ridge axis arrives Friday evening.

The models remain in good agreement in bringing the first chance of
rain in for this weekend for the day on Saturday. This event does
not look to be a big problem, except for being a wet afternoon on
the weekend. Forecast instability indicates little to no support for
thunder, except maybe across the far south. Also, the supporting
upper wave is in the process of weakening as it approaches.

The good thing is that the Saturday system is expected to sweep any
appreciable moisture out of the area, and allow for short wave
ridging aloft and at the sfc to keep Sunday mainly dry. This will be
the other nicest day of the bunch, as mild air remains in place
along with the mainly dry conditions.

- Periodic Shower/Storm Chances Early Next Week

The zonal flow will remain entrenched in place over the area,
bringing multiple waves and chances of rain to the area. The next
one in the series is expected to come in during the Monday time
frame. This wave looks to be a little more potent as the zonal flow
buckles a little bit more with stronger energy moving in across the
NW portion of the country. That will amplify the pattern a little
downstream, and increase the strength of the systems a little. In
addition, it looks like a bit more instability will be available to
provide for convection chances. It might be something to watch with
the decent mid level flow in place.

After a break on Tuesday, and even stronger system looks to be
possible centered around the Wednesday time frame. This is the
stronger wave over the Pacific NW states, and amplifies the flow.
This has a stronger jet associated with it, and will tend to draw
more moisture and instability up out ahead of it. Still a long ways
off, but it does look to become more active next week with the upper
flow amplifying a bit, and warmer temperatures.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 720 PM EDT Wed May 29 2024

A field of cumulus around 3-4k feet persists across southern
lower Michigan this evening with otherwise clear skies elsewhere.
This field will dissipate over the next few hours with VFR
persisting through the forecast period. Wind drops down to 5
knots or less overnight with continued clear skies. Expect
continued light winds to 5 knots or less tomorrow afternoon with
slightly stronger winds to 5 to 10 knots possible near the
lakeshore.

&&

.MARINE...
Issued at 240 PM EDT Wed May 29 2024

Web cams along the lake shore indicate waves are 3-4 on the north
sides of piers. Winds and waves will decrease tonight as high
pressure settles over the Great Lakes. However, several hours will
pass before waves decrease below advisory criteria. As such, the
Small Craft Advisory and Beach Hazards Statement will continue
into the evening.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
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MI...Beach Hazards Statement until 10 PM EDT this evening for MIZ043-
     050-056-064-071.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ844>848.
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&&

$$

UPDATE...Thielke
DISCUSSION...NJJ/04
AVIATION...Thielke
MARINE...04