Portage, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

155
FXUS63 KGRR 150151
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
851 PM EST Thu Nov 14 2024

.KEY MESSAGES...

- Drizzle and showers ending tonight

- A few showers and unseasonably mild through early next week

- Cool and rainy middle next week, snow showers late week

&&

.UPDATE...
Issued at 851 PM EST Thu Nov 14 2024

We have added patchy fog to the forecast for the rest of the
evening into the overnight period for areas east of US-131. Sfc
obs attm indicate patchy fog is developing across this area. A
consensus of latest higher res model guidance such as latest runs
of the HRRR suggest that fog will continue to develop east of
US-131 through the rest of the evening and overnight. The fog is
not widespread or dense enough to warrant a fog headline. However
localized dense fog is possible. Otherwise the going forecast
looks excellent and no other changes are necessary.

&&

.DISCUSSION...
Issued at 258 PM EST Thu Nov 14 2024

- Drizzle and showers ending tonight

Low pressure transferring to the Atlantic coast this evening with
showers moving east and drizzle slowly decreasing. High pressure
builds in by Friday with some lingering lake effect rain showers
in northerly flow but these will be light and largely remain
offshore.

- A few showers and unseasonably mild through early next week

An amplified large-scale weather pattern continues this weekend,
with a ridge of high pressure over much of the eastern CONUS and a
sharp trough in the western CONUS. Michigan falls into broad
southwesterly flow starting this weekend as the ridge axis slides to
our east. A fast-moving and fairly weak system moves through the
upper Great Lakes Saturday night, bringing a few showers and gusty
southwest winds to West Michigan, but overall having a pretty minor
impact on us. The more consequential movements in the atmosphere
during this time will be a developing cutoff low near the desert
southwest, sitting in the base of the amplifying longwave trough.

- Cool and rainy middle next week, turning to snow showers late week

Guidance is in good agreement that by Monday morning the cutoff low
near the four corners will eject rapidly to the northeast and head
toward the Great Lakes. The main impact for us will primarily be
another round of widespread beneficial rain for the day Tuesday.
This low pressure will be filling/weakening as it moves our
direction, and the remnant low stalls over Wisconsin through
Wednesday. At the same time, a vigorous upper trough approaches
quickly from the west during this timeframe and will capture the
leftover storm system in Wisconsin. This combined system turns into
a large and slow-moving low pressure system that will begin
anchoring a longwave trough over the Great Lakes for the 2nd half of
next week... possibly continuing through next weekend.

While this will keep showers in our area for several consecutive
days, the bigger impact will be the ushering in of the first winter-
like temperatures of the season on the backside of the low. There is
still pretty significant spread among the global models on exactly
where the upper low migrates, which will determine how quickly the
cold air rushes into Michigan, but at this point it looks like late
Friday into Saturday is the best bet - kicking off lake effect snow
bands and likely bringing the first snowflakes of the year to most
areas. It`s too early to spend much time thinking about any lake
effect snow accumulations, but it`s definitely in the realm of
possibility and will be a main focus of the forecast as we get
closer in time.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 600 PM EST Thu Nov 14 2024

Primarily IFR/LIFR conditions are forecast tonight through midday
Friday due to low cigs and patchy fog. Conditions will only slowly
improve to primarily MVFR late Friday morning and early afternoon
as fog dissipates and cigs slowly improve. Winds will be light at
below 10 kts at all the terminals through the next 24 hrs.

&&

.MARINE...
Issued at 258 PM EST Thu Nov 14 2024

Conditions will continue to the relatively placid on Lake Michigan
until Sunday when southwest winds will quickly ramp up to abo0ut
30 knots as low pressure approaches.

&&

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

&&

$$

UPDATE...Laurens
DISCUSSION...Ostuno/AMD
AVIATION...Laurens
MARINE...Ostuno