171
FXUS63 KGRR 061825
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
225 PM EDT Tue Oct 6 2026
.KEY MESSAGES...
- Small chances of rain mainly North each night through Fri night
- Warming temperatures this weekend
- Rain chances return Sunday for southern areas
&&
.DISCUSSION...
Issued at 225 PM EDT Tue Oct 6 2026
- Small chances of rain mainly North each night through Fri night
Not much change expected in the upper air pattern for the region as
compared to previous forecasts. Rain chances have increased just
slightly for each night through Friday night.
The northern branch of the upper jet core is expected to remain just
north of the area through Thursday night. It is far enough north to
keep the forecast area out of diurnal chances of rain and more
widespread cloud cover. However, it is just close enough that we
continue to get barely clipped by short wave troughs embedded in the
flow.
For tonight, Wednesday night, and Thursday night, the timing of the
short waves are such that they are bringing the very limited rain
chances each night. This limits the amount of instability helped by
the diurnal boost. In addition, these waves have no access to any
low level moisture below 7-8k ft. This will limit any rain to mainly
sprinkles, to just isolated coverage of any showers that would
produce measurable rain.
The upper jet nearby will finally lift northward after Thursday
night as the long wave trough is able to move out. The building
ridge will help a sfc warm front lift NNE toward the area Friday
night. This is likely to be another round of sprinkles and a few
light showers with limited low level moisture once again.
- Warming temperatures this weekend
The warm front will move away from the area by Saturday morning,
allowing the warm sector to move up and over the area for Saturday.
The models have been fairly consistent in bringing +20C air over the
area at 850 mb. This would translate to max temperatures at the sfc
approaching 80F. Plenty of subsidence over the area on Saturday will
protect the area from any rain through Saturday night.
- Rain chances return Sunday for southern areas
We have been mentioning a system that will be over the Gulf late in
the week that will try to approach the area later Sunday. This
system has some potential tropical moisture as it will be over the
Gulf to start with. The long wave flow will be arranging itself on
the backside of the ridge to be oriented from SW to NE. This flow,
and a short wave that is embedded with the upper flow will will be
oriented from SW to NE, and will try to absorb the tropical system
and drive it toward the region. The trend for this system has been
for it to inch toward the area as it rotates out of the Western Gulf.
Upper lows are notorious for wobbling and not following the forecast
track very well. This one would be becoming extra-tropical as it
leaves the Gulf coast region. We will need to monitor the movement
of this system as if it can rotate a bit further north, it will
bring more rain chances on Sunday than we have been advertising.
Once this low rotates away from the area later Sunday, we will fall
under back under upper ridging, dry out, and warm back up.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 120 PM EDT Tue Oct 6 2026
Scattered mid clouds are moving across the region in conjunction
with a weak lobe of vorticity aloft. A cold front will move
across the terminals late tonight. A 45kt LLJ will precede the
front after 00z and LLWS is possible. Otherwise VFR conditions are
expected through the period.
&&
.MARINE...
Issued at 225 PM EDT Tue Oct 6 2026
No changes needed at this time to the marine headlines. The
strongest of the winds are just beginning to move in at this time
behind the warm front that moved through earlier. The strongest of
the winds will be north of Whitehall, where we have the Gale Warning
out. Winds and waves will taper off, with the far southern marine
zone likely staying just below Small Craft Advisory criteria. This
will last until Wednesday when everything will settle down for a bit.
Much of the period through the weekend will see elevated winds and
waves with a decent gradient remaining in place. The only time winds
look to stay below 15-20 knots will be Thursday night under a ridge.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 4 PM EDT Wednesday for LMZ845>847.
Small Craft Advisory until 2 PM EDT this afternoon for LMZ848-
849.
Gale Warning until 11 PM EDT this evening for LMZ848-849.
&&
$$
DISCUSSION...NJJ
AVIATION...04
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
