086
FXUS63 KGRR 112231
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
631 PM EDT Sun Aug 11 2024

.KEY MESSAGES...

- Still looks dry into Monday night and close to normal for temps
  for Monday

- Mostly dry through midweek, the rain chances increase

&&

.DISCUSSION...
Issued at 231 PM EDT Sun Aug 11 2024

- Still looks dry into Monday night and close to normal for temps
for Monday

While we maintain some cyclonic flow in the mid levels being on the
backside of the departing low in southern Ontario, the flow here in
MI will be confluent.  This will act to limit any updrafts.  An area
of low level convergence over far eastern parts of the CWA is shown
by a few models to develop several showers Monday afternoon that
quickly move east of the CWA, but most models and ensembles keep it
dry.  As a result its likely that the region generally stays dry
through Monday night.  A decaying complex will be tracking south to
southwest of MI Monday with the main impact of that being the
potential for clouds in our CWA.  However despite some cloud cover,
with the coolest air shifting east of the CWA, much of the region is
expected to make a run at 80 degrees, which is close to normal for
this time of the year.

- Mostly dry through midweek, the rain chances increase

The first part to the middle of the week looks pretty typical of
August: partly cloudy, somewhat humid, and highs in the lower 80s.
After that, we`ll see some changes.

As the upper trough begins to slide east, the cooler temperatures
will go with it and be replaced by ridging nosing into the Great
Lakes. That will bring an increase in low level dewpoints and upper
level heights which will be reflected in highs in the 80s.

As we progress toward the end of the week, confidence is increasing
that we`ll see some troughing develop over the Great Lakes. A
phasing of the northern and southern streams may bring in a couple
of short waves that help to carve out the upper trough beginning
Thursday. The resulting surface low will slowly move east across the
state Thursday night through at least Sunday night, and perhaps have
an influence on our weather through the following Tuesday.

Showers and thunderstorms are in the forecast beginning Thursday and
continuing through the weekend. Most members of the ECMWF ensembles
point toward rain...perhaps at least a half inch...during this time.

Temperatures that rise into the 80s Tuesday-Thursday will retreat to
the 70s late week and over the weekend as clouds and precipitation
develop.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 627 PM EDT Sun Aug 11 2024

Diurnal cumulus are diminishing with most terminals going SKC
overnight. The exception is GRR and MKG where nearby stratocu
development supports FEW clouds in the 6kft-8kft range. Daytime Cu
develop late morning tomorrow in the 4kft-7kft range with a
cirrus deck providing high VFR cigs. Isolated showers cannot be
ruled our near LAN/JXN after 18z Monday but given low confidence
and low potential coverage will leave the TAFs dry. Winds from the
west at or below 10 knots are expected through the TAF window.

&&

.MARINE...
Issued at 231 PM EDT Sun Aug 11 2024

Waves were generally in the around 3 feet and trending slowly
downward. Webcams at several sites suggest the waves are a bit
higher near the piers. Thus, some swim risk still exists. No
further increase in the values are predicted this evening as the
pressure gradient and mixing heights decrease. We will let the
marine/coastal headlines expire at 5 pm today.

&&

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

&&

$$

DISCUSSION...MJS/04
AVIATION...Thomas
MARINE...MJS