710
FXUS63 KGRR 141958
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
258 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
&&
.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 /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1235 PM EST Thu Nov 14 2024
This set of forecasts will have impacts to aviation throughout the
entire period. The main impact will be IFR/LIFR through the period
with low clouds expected to hang on through 18z Friday.
The widespread rain has moved east of all of our terminals as of
1730z this afternoon. What is left behind is lower ceilings, and
now some developing drizzle that is reducing the visibilities. We
expect the drizzle to hold on or even develop this afternoon, and
eventually improving some this evening and tonight as the low
moves by.
IFR/LIFR low clouds will likely persist at most of the terminals
until Friday. The exception to this is KMKG where a NNW flow will
bring some locally drier air in. We are expecting the low clouds
to lift up into the lower MVFR range toward the end of this
period, to just after the end of the period.
&&
.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.
&&
$$
DISCUSSION...Ostuno/AMD
AVIATION...NJJ
MARINE...Ostuno
NWS GRR Office Area Forecast Discussion