134
FXUS63 KGRR 251142
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
742 AM EDT Wed Sep 25 2024

.KEY MESSAGES...

- Rain Ends this Morning, Then Dry

- Small chances for rain showers over the weekend

- Above normal temperatures much of the forecast period

&&

.DISCUSSION...
Issued at 350 AM EDT Wed Sep 25 2024

- Rain Ends this Morning, Then Dry

The surface low that brought active weather yesterday will continue
to pass to the northeast early this morning, then surface ridging
will fill into Lower Michigan. Upper level subsidence will build
into the day and clouds will push out to the east throughout the
afternoon. Temperatures peak in the low 70s.

- Small chances for rain showers over the weekend

The main chance for precipitation will come this weekend in the form
of scattered rain showers. An existing upper low in the mid
Mississippi Valley will combine with the remnant low of what will
become Hurricane Helene. This two features will become one dominant
low over the weekend centered in Kentucky and Tennessee. Lower
Michigan will be well north of this feature, but moisture will
increase across the area in the Friday night through Sunday time
frame. There is a distinct difference in moisture depth from north
to south, with profiles across Central Lower almost cloud free and
fairly deep moisture near I94. So, we expecting showers to mainly
affect areas near and south of I96, especially down towards I94.
That said, this will certainly not be a washout with only isolated
to scattered activity, Friday night through Sunday.

Ridging builds in for Monday bringing dry weather again, followed by
a cold front that will move through the area on Tuesday. Small
chances for rain showers will be possible Tuesday morning as the
front quickly moves through.

- Above normal temperatures much of the forecast period

850mb temperatures will be in the lower to middle teens C much of
the forecast period which will provide above normal temperatures.
Highs look to be in the 70s most days. The Tuesday cold front will
change the game with 850mb temperatures plunging towards zero C.
Highs will quickly move back to normal or even below normal next
Tuesday and Wednesday with highs in the lower to middle 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 742 AM EDT Wed Sep 25 2024

A mix of conditions exist across the area at 12z. A clearing area
has developed over Southwest Lower Michigan, including AZO and
BTL. This area will likely fill in by 15z. Otherwise, widespread
IFR and MVFR ceilings exist. A fairly rapid lift/clearing to VFR
conditions should occur across the entire area between 15z and
19z. The switch to VFR will move from west to east during that
time frame. VFR will then prevail this afternoon and into tonight.
There is the potential for some fog development towards 12z
Thursday, but left that out of the TAFs for now. Winds will be
light from the west today at 5 to 10 knots.

&&

.MARINE...
Issued at 350 AM EDT Wed Sep 25 2024

Waves will remain low through the end of the week, but conditons
may turn choppy this afternoon as northerly winds build waves to
2 feet across the southern half of Lake Michigan. Easterly winds
will build into Friday resulting in high wave heights for the
Indiana, Illinois, and Wisconsin shorelines with wave heights
along the West Michigan lakeshore staying generally around 1 to 2
feet through Saturday. An SCA may be needed late in the week
across the southern marine zones mainly for hazardous wind gusts.

&&

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

&&

$$

DISCUSSION...Duke/Thielke
AVIATION...Duke
MARINE...Thielke