425
FXUS63 KGRR 130704
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
304 AM EDT Wed May 13 2026
.KEY MESSAGES...
- Cool today, then warmer
- Unsettled late weekend into next week
&&
.DISCUSSION...
Issued at 304 AM EDT Wed May 13 2026
- Cool today, then warmer
Today might be the last day in the 50s that we see for a while. A
cold front passed through a few hours ago and temperatures
continue to slowly drop. While the precipitation has moved east,
cloudy skies are moving in as the upper trough moves overhead. H8
temperatures started out last night around 10c and will fall
to -2c by 18z. Combined with a brisk northwest wind, today will
feel rather chilly with highs in the upper 40s near US-10 to mid
50s near I-94. After today we`ll see a warm up that will feature
highs in the 60s Thursday and 80s Saturday through Monday.
- Unsettled late weekend into next week
Broad zonal flow aloft will transition to southwest flow Sunday.
H8 temps will climb into the mid teens during this period and
moisture return will slowly increase too.
On the surface, a weak low over Indiana may generate over the
southern cwa Saturday, otherwise a mainly dry day is expected.
By Sunday, a developing low over the Plains will begin to
strengthen in response to an approaching upper trough and a strong
flow of moisture off the Gulf will surge northward. An approaching
warm front will be a focus of showers/storms Sunday, some of which
could be strong. NCAR medium range AI progs point toward Sunday
and Monday as days we could see strong to severe storms ahead of
an approaching cold front. The highest chances will be west of the
cwa closer to the cold front. Much uncertainty remains. However,
synoptically some ingredients are beginning to be shown that could
result in thunderstorm activity.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 139 AM EDT Wed May 13 2026
Showers and thunderstorms have cleared the terminals and the rest
of the period will be dry, but cloudy. Latest IR loop shows some
breaks in the clouds ahead of a larger area of cloudiness that
will move over the terminals within the next few hours associated
with cold air advection. We`ll see cigs fall to MVFR prior to 12z
and remain there much of the day before clearing and a return to
VFR by 00z.
&&
.MARINE...
Issued at 304 AM EDT Wed May 13 2026
Cold air advection is ongoing and waves will build to 6-8 ft today
before decreasing tonight as high pressure builds in. The small
craft advisory continues until Thursday morning.
South winds will develop ahead of the next system Thursday night
and waves will build again with highest waves north of Holland.
Another headline will likely be needed then.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 2 AM EDT Thursday for LMZ844>849.
&&
$$
DISCUSSION...04
AVIATION...04
MARINE...04
NWS GRR Office Area Forecast Discussion
