004
FXUS63 KGRR 251858
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
258 PM EDT Wed Sep 25 2024

.KEY MESSAGES...

- Small rain chances Saturday through Tuesday

- Drier and cooler mid-week next week

&&

.DISCUSSION...
Issued at 258 PM EDT Wed Sep 25 2024

- Small rain chances Saturday through Tuesday

Fair weather with drier air arriving overnight through Thursday.
Confidence is increasing that we will remain dry for Friday, and
see small chances for rain showers beginning Friday night and
lasting into Tuesday.

Many of the various models and ensemble members continue to show
what is left from "Helene" will be absorbed by the Upper Low
centered near AR/TN/MS on Friday. The strength of the upper high
over our area and the upper low will wrap it back to the NW, but
keep most of the system south of the area.

What we will see from this scenario is we will see moisture advect
in from the SE, and weak short waves rotating on the northern flank
of the combined upper low complex. Much of the period from Saturday
through Monday will be dry. There will be periods when short waves
move through, combined with diurnal instability that will fire off a
few showers and even isolated storms at times. The air with this
system will not be that cold with the tropical part of this.

- Drier and cooler mid-week next week

Eventually what will happen by Monday night/Tuesday is we will see a
strong upper jet and associated upper wave dive toward the area.
This is a strong enough system that it will boot the weekend upper
low out. This system will arrive with a strong cold front, and a
chance of showers and storms. The flow ahead of the front will not
be favorable for much rain with the front.

The front is forecast to move through at some point on Tuesday. The
frontal passage looks to end rain chances at that point, and it will
cool the air down markedly as 850 mb temps drop from the low/mid
teens C, to the lower single digits C by Wednesday. This will
support highs in the 60s and lows in the 40s.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 140 PM EDT Wed Sep 25 2024

After widespread IFR low clouds this morning, conditions are
steadily improving from West to East this afternoon. Conditions
have improved to mainly VFR across the west or will within the
first hour of the forecast. Eastern areas will see the MVFR
conditions persist for a couple of hours before the clouds lift
with drier air moving in.

Skies are expected to clear out this evening, and winds will go
light with high pressure moving overhead. Have added some VCFG at
the inland sites. The light winds and clear skies will allow for
the potential with lows expected to be in the 50s, and ground
temps in the 60s with moisture. The fog will then burn
off/dissipate fairly quickly by 13-14z Thursday.

&&

.MARINE...
Issued at 258 PM EDT Wed Sep 25 2024

Winds are expected to remain below 20 knots and waves below 3 feet
into the weekend.

&&

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

&&

$$

DISCUSSION...Ostuno/NJJ
AVIATION...NJJ
MARINE...Ostuno