Lansing, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

433
FXUS63 KGRR 031144
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
644 AM EST Tue Dec 3 2024

.KEY MESSAGES...

- Lake Effect Snow Diminishes Today

- Clipper Brings Precipitation Tonight into Wednesday

- Arctic Air, Snow, and Wind Arrive Wednesday Night into Thursday

- Unsettled Conditions Into The Weekend

&&

.DISCUSSION...
Issued at 322 AM EST Tue Dec 3 2024

- Lake Effect Snow Diminishes Today

Bottom line up front, have extended the current Winter Storm Warning
until 10am. A meso-low has generated a band of moderate to heavy
snowfall which is feeding into the southern lakeshore counties.
Given the moderate to heavy snowfall will continue through the
morning commute, will extend the warning to cover continued impacts
to travel. Light snow showers north continue through daybreak so
will let the winter weather advisory continue until expiration. Lake
effect snow then diminishes briefly into the afternoon as mid-level
height rises lead to subsidence.

- Clipper Brings Precipitation Tonight into Wednesday

The diminished snowfall will be short-lived as a clipper system
tracks through the region tonight into Wednesday. Widespread
accumulating snow is expected, heaviest near US10. Southwest flow
will lead to lake enhancement, however warm air advection capping
inversion heights around 5kft will limit the effects of this. Near
and south of M20 signals persist for the DGZ to dry out in the late
morning and early afternoon which would bring drizzle and freezing
drizzle potential. With temps right around 32F, the extent to which
freezing drizzle would occur may be limited (chances look to be in
the 10-20 percent range). A solid 1-4 inch snowfall is expected and
we will monitor freezing drizzle potential.

- Arctic Air, Snow, and Wind Arrive Wednesday Night into Thursday

Impactful winter weather continues to look likely Wednesday Night
into Thursday as an arctic front pushes through the CWA and
generates significant lake effect snow behind it. Given mixing to 40
knots very gusty winds are likely, with these winds also bringing
the potential for very significant reductions in visibility with
blowing snow. A favorable environment for snow squalls and lake
effect snow to push well inland looks to be in place as theta-e
lapse rates go negative and surface based instability develops. Lake
effect snow, heavy at times, is likely to continue into the day on
Thursday. Impacts to the thursday morning commute and scattered
power outages are possible. Some guidance like the 06z HRRR trend
the cold air in a bit faster which may lead to flash freeze issues
Wednesday evening though uncertainty is high as to if this can
occur.

In coordination with neighboring offices, we will hold off on any
winter storm watches at this time given impacts are still 2-2.5 days
out and we have ongoing winter headlines through the morning.
However, they may be needed for at least a few counties in future
packages. We will continue to monitor.

- Unsettled Conditions Into The Weekend

Lake effect snow subsides into Friday as surface and upper-level
ridging takes hold before a clipper system brings the potential for
light snow accumulations towards Saturday. Given 850mb temps rise
back above zero this looks to be mainly synoptic in nature with no
lake enhancement. Unsettled conditons remain possible into the rest
of the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 635 AM EST Tue Dec 3 2024

A larger area of stratus/fog continues to impact several of the
TAF sites this morning. This includes KGRR, KMKG, KAZO KBTL and
KJXN. It will gradually dissipate during the mid to late morning
hours. Some clearing near KLAN may slip into that TAF site in the
next hour or so but the low clouds are expected to quickly fill
back into that site. A strengthening southwest wind will develop
over northern IL and southern Lake MI later this morning and into
the afternoon hours. This will push the lake effect snow showers
inland. Thus many of the TAF sites will be seeing some snow today,
but the snow showers are expected to weaken, the further inland
they go. We will need to monitor the low level wind shear risk
later tonight as a low level jet moves in.


&&

.MARINE...
Issued at 322 AM EST Tue Dec 3 2024

2-5 foot waves are expected across the lake today, with winds
increasing tonight and turning southwesterly later today into
tonight. The going small craft advisory looks to be in good shape.

Beginning tonight a period of southwest gales to 35 knots is
expected as a deepening low pressure system enters the region. On
the back side of the low pressure system Wednesday Night winds flip
to northwesterly with high end gales to 45 knots expected and
isolated gusts to 50 knot storms possible (around 20 percent
chance). Given high confidence in gales across the waters will
upgrade the current Gale Watch to a Gale Warning across all
nearshore waters from 06z tonight to 18z Thursday. Freezing spray
becomes a concern as an arctic air mass arrives over the warm
waters, along with snow squalls causing significant reductions in
visibility at times.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 AM EST this morning for MIZ037-
     038-043-050.
     Winter Storm Warning until 10 AM EST this morning for MIZ056-064-
     071.
MARINE...Small Craft Advisory until 1 AM EST Wednesday for LMZ844>849.
     Gale Warning from 1 AM Wednesday to 1 PM EST Thursday for
     LMZ844>849.

&&

$$

DISCUSSION...Thomas
AVIATION...MJS
MARINE...Thomas