000
FXUS63 KGRR 301223
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
723 AM EST Thu Nov 30 2023

LATEST UPDATE...
Aviation

.SHORT TERM...(Today through Friday)
Issued at 344 AM EST Thu Nov 30 2023

Few icy spots may be possible this morning as patchy fog moves
through areas mainly along and north of I-96. Road temps are
currently in the upper 20s with air temps right around freezing. An
SPS may be warranted to highlight potential hazardous driving
conditions for the morning commute due to black ice.

Zonal flow dominates the regime over the eastern CONUS today
supporting decent warm air advection with 850mb temps climbing
towards +3C to +4C. This will bring high temperatures back into the
40s today. In addition to warmer temps, winds will be breezy as a 45-
50 knot LLJ sets up overhead. Inversion heights up towards 1-2kft
will support gusts to 25-35mph mixing down to the surface this
afternoon.

Bigger area of focus for the forecast will be on a system that will
move through the area late tonight through Friday. In this event, a
shortwave will track northeasterly from the Southern Plains into the
Ohio Valley/southern Michigan. This system still looks likely to
produce a mix of rain and snow with the rain/snow mix arriving
near I-94 after midnight, then towards the I-96 corridor after 7am
Friday producing mainly snow. Model guidance continues to
highlight the higher swath of 1-3 inches of snow occuring within
the I-96 to M-46 corridor, but with many varying thermodynamic
parts in play it`s possible this band of snow could be much more
narrow. Possible mesoscale banding will support higher snow rates
at times Friday morning which may allow some accumulation on area
roads. Hazardous travel will be possible for the Friday morning
commute.

.LONG TERM...(Friday night through Wednesday)
Issued at 344 AM EST Thu Nov 30 2023

The front remains nearly stationary over the MI/IN/OH state line
area for Friday night with a second upper shortwave sliding through
aloft. Weak persistent isentropic upglide will continue much of
Friday night, so we expect precipitation to continue Friday night
with a rain/snow mix north of I-96 and rain off to the south. There
is potential for a wet 1-2 inch snow fall over portions of the
central and northern CWA. Location of the front and exactly what the
low level thermal profile are like will dictate location and
amounts. At this point though it looks like north of I-96 and on the
order of around an inch potentially.

Precipitation tapers off on Saturday, but does not completely end as
we move through the weekend given an upper trough and shortwaves
moving through the region. We have higher pops into Sunday as our
model blend is likely leaning a bit on the GFS which has a surface
low moving directly through the CWA. The ECMWF is further east with
the low development. Rain and snow are in the forecast over the
weekend with critical temperatures near thresholds for both ptypes.

As we head through the early to middle portion of next week,
conditions become a bit quieter as northwest flow trends towards
ridging. One final low may move through the region in the Tuesday
time frame though and we have 20-40 pct pops in the forecast for
both rain and snow.

Temperatures through the period will be near normals and also
conducive for a mixture of precipitation types (Rain/Snow).

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 724 AM EST Thu Nov 30 2023

VFR conditions are in place at most TAF sites at 12z, the
exception being MKG where some fog is occurring. Any fog should
lift quickly this morning with VFR prevailing by 15z at the
latest. Clouds will lower and thicken this evening into the
overnight hours with low ceilings developing. MVFR ceilings will
develop around 00z this evening and lower to IFR and LIFR
beginning around 05z. Some precipitation will spread into southern
TAF sites (AZO, BTL and JXN) after 09z. A mix of rain and snow is
possible.

&&

.MARINE...
Issued at 344 AM EST Thu Nov 30 2023

Small Craft Advisory will continue. Waves will increase today
with strong southwesterly winds building towards 20-25 knots,
gusting to 30 knots this afternoon. Into this evening winds will
shift northerly and waves will quickly fall to 1 to 2 feet late
tonight into Friday morning.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 11 PM EST this evening for LMZ844>849.

&&

$$

SHORT TERM...Thielke
LONG TERM...Duke
AVIATION...Duke
MARINE...Thielke

NWS GRR Office Area Forecast Discussion