410
FXUS63 KGRR 142317
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
717 PM EDT Wed Oct 14 2026
.KEY MESSAGES...
- Deepening fall system to move through the Great Lakes
- Mainly dry this weekend and into early next week
- Cool temperatures this weekend then moderating some next week
&&
.DISCUSSION...
Issued at 300 PM EDT Wed Oct 14 2026
- Deepening fall system to move through the Great Lakes
Two distinct upper shortwave troughs can be seen this afternoon in
satellite imagery, one over the Central Rockies and the other
moving from the Canadian Rockies into the Canadian Prairies. Both
of these shortwaves will move towards the Great Lakes and phase
with one another as they approach from the west. Rain will spread
in towards daybreak on Thursday. The most widespread rain will
move Thursday afternoon and evening as the right entrance region
of and upper jet moves overhead. A low level jet will impact
southern portions of the state, towards I-94 especially. 850mb
moisture transport is very strong Thursday evening into Thursday
night. All areas will see rain with one half to one inch of rain
likely. Cannot rule out some thunder as the cold front swings
through, but the better instability will remain off to our south.
Lake effect rain showers will combine with diurnal rain showers on
Friday for another wet day. Delta T`s will rise into the upper
teens C which will result in MUCAPE values over the lake on the
order of 600 j/kg. Feel waterspouts are a possibility Friday
morning before the stronger winds move in during the afternoon.
We are looking at gale force winds on Lake Michigan, but on the
land we may not meet advisory criteria with wind gusts expected to
be in the 30-40 mph range as of now.
- Mainly dry this weekend and into early next week
Ridging will take over for the weekend and early next week. We are
looking at a dry forecast from Saturday all the way into
Wednesday. BUFKIT profiles show a very dry atmosphere so there is
fairly high confidence we remain dry Saturday-Wednesday.
- Cool temperatures this weekend then moderating some next week
We will cool into the 50s for highs this weekend as high pressure
moves through the Great Lakes. Lows in the 30s are anticipated for
Saturday morning and Sunday morning. We are likely looking at
frost and freeze headlines at least on Saturday.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 717 PM EDT Wed Oct 14 2026
Chaotic ceilings are expected to start the forecast. Latest
satellite and observational trends suggest a breakout to VFR for
AZO/BTL/JXN near 00z, occuring a few hours later for the other
terminals. Even with this, ceilings are expected to remain
borderline VFR/MVFR, especially overnight once boundary layer
cooling develops with cigs from 2.5-3.5 kft. Beginning late
morning Thursday conditions then become solidly MVFR. Conditions
deteriorate further Thursday afternoon and evening as a low
pressure system brings showers/fog and low clouds to the area.
Conditions are likely to deteriorate to IFR between 18z-21z and
periods of LIFR are possible, though confidence is to low to
include LIFR conditions at this time range (20-30 percent). Once
conditions fall they will remain poor through the rest of the TAF
period.
&&
.MARINE...
Issued at 300 PM EDT Wed Oct 14 2026
A deepening fall system will move through the Great Lakes Thursday
and Friday. North winds will increase behind the low starting
Friday morning. We have a Gale Watch in place beginning at 11am
Friday and lasting into Friday night. Winds are expected to reach
35 to 45 knots on the lake during the peak of the event Friday
afternoon and evening. The winds will be running parallel down the
shoreline, but waves will still be high reaching 10+ feet on
Friday. The largest waves will be at the south end of the lake.
When advisory/warning decisions are made we may need to have a
Small Craft Advisory on the front end of what will likely be a
Gale Warning. Waves will become hazardous to smaller craft in our
area starting as early at 400am Friday. Southwest flow develops
rapidly behind the departing system and we are will likely see
large waves again Saturday evening into Sunday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Gale Watch from Friday morning through late Friday night for
LMZ844>849.
&&
$$
DISCUSSION...Duke
AVIATION...Thomas
MARINE...Duke
NWS GRR Office Area Forecast Discussion
