641
FXUS63 KGRR 041500
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1100 AM EDT Fri Apr 4 2025

.KEY MESSAGES...

- Showers return this evening into Saturday

- Cold air returns Sunday through the first half of next week

&&

.UPDATE...
Issued at 1100 AM EDT Fri Apr 4 2025

Forecast is on track with sunny skies eventually giving way to
thickening cloud cover approaching from the southwest. Main issue
continues to be how much rain to expect tonight as guidance has
been showing considerable spread in QPF guidance. Hopefully new
12Z HREF guidance will help nail things down a little better.

&&

.DISCUSSION...
Issued at 249 AM EDT Fri Apr 4 2025

- Showers return this evening into Saturday

Fairly consistent forecast, though partly due to the stationary
high situated over the southeast. That will keep the ribbon of
moisture through the central US.

 There is some model differentiation how far north the best QPF
reaches. While most of the region should receive some rainfall,
the best moisture will be south of Michigan. that said, NAEFS mean
Pwats are one inch to 1.25 inches along and south of the I-94
corridor. So expect the heaviest rainfall to be there. Currently
half around a half on inch of QPF, though locally heavier amounts
are possible.

While rainfall could begin late this afternoon, early this evening,
the heaviest showers will be tonight into early Saturday morning.
The deep upper level low moving through the southeast and through
Texas will keep moisture advection through Saturday into Sunday.
However, as the low moves eastward, so will the moisture, which
will keep the rainfall to the southeast.

- Cold air returns Sunday through the first half of next week

 Cold dry air will begin to move in Saturday night into Sunday.
due to a strong upper level low moving through southern Canada.
That upper level wave will dominate the pattern over Michigan
through the first half of the upcoming week.
 850mb temps drop to -8C Sunday to -12C Monday night. This will
drop temps 12 degrees below normal.
 The cold air advection will couple with the trough, though there
is some timing differences. If the trough comes early enough,
there could be a decent potential for snow across the Lower
peninsula Monday, especially along and north of US 10.

That clipper will keep cold air over the region through Tuesday.
Warm air advection will then be on the horizon though the latter
half of the week with another round of showers possible. However,
there is low confidence on timing.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 727 AM EDT Fri Apr 4 2025

VFR conditions continue before rain moves in tonight between 0-6Z
Saturday with ceilings lowering to IFR/LIFR values between 9-12Z
Saturday. Visibilities could drop down to 2 to 5 SM with the rain.
Easterly winds are expected into Saturday morning.

&&

.MARINE...
Issued at 420 AM EDT Fri Apr 4 2025

Easterly flow will keep winds and waves fairly calm today into
tomorrow. However, strong flow from the northwest tomorrow
afternoon could create conditions that could be hazardous to small
craft. Winds could gust into the the 20 to 25 kt range Saturday
afternoon. There remains some questions on strength and timing
so will wait on any headlines for now.

&&

.HYDROLOGY...
Issued at 356 PM EDT Thu Apr 3 2025

A widespread 1 to 2 inches of rain yesterday, with some areas closer
to 3 inch rain totals are all getting the rivers moving today. In
general, there`s going to be just barely enough room in the big
rivers to avoid any significant flooding, but some of the smaller
rivers and midsize tributaries have seen - or will soon experience -
some minor flooding. This includes the Portage River near Vicksburg,
Sycamore Creek near Holt, and the Red Cedar River in East Lansing.
It`s possible that the lowest/most vulnerable streets along the
Grand River in Comstock Park could also see some very minor flooding
by this weekend, but it`s a bit too early to say for sure.

Our next chance of rain comes in Friday evening, but thankfully will
be much more of a glancing blow for our watersheds, and the main
impact will be to simply prolong the current high water levels
rather than create any new or worse flooding.

&&

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

&&

$$

UPDATE...Meade
DISCUSSION...Ceru
AVIATION...RAH
MARINE...Ceru
HYDROLOGY...AMD