-- Discussion containing changed information from previous version are highlighted. --
947
FXUS63 KGRR 051636
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1236 PM EDT Sun May 5 2024

.KEY MESSAGES...

- Dry and mild through early Tuesday

- Frequent chances for Rain Tuesday through next weekend

&&

.UPDATE...
Issued at 953 AM EDT Sun May 5 2024

Latest visible imagery shows cloud cover decreasing in NNW flow,
but it`s going to take several more hours before we see much
sunshine, especially in the southeast cwa. NamNest has a better
handle on cloud cover than the GFS and shows more in the way of
diurnal cu and so we`ll follow that guidance. We`ll also trim our
highs by a degree or so too.

Any drizzle occuring over Mid Michigan will be short lived should
be done by noon as that`s when lift in the cloud layer decreases.

&&

.DISCUSSION...
Issued at 327 AM EDT Sun May 5 2024

- Dry and mild through early Tuesday

We continue to see the line of showers and storms from earlier
steadily lose their steam as they progress to the east early this
morning. They have lost just about any kind of diurnal instability
they had earlier, and the outflow from the line raced out ahead of
the actual showers and storms. In addition, the already weak support
aloft with the weak short wave is gradually diminishing with the
short wave weakening.

The sfc front as of 07z/3 am EDT has made it roughly to the U.S.-131
corridor. Even with the widespread rain diminishing and moving east,
there remains a small chance of a pop up shower until this front
moves through. The front should be east of our area over the next 2-
3 hours, which will then end the rain chances.

High pressure will build in over the area through early tonight, and
will slip east of the area on Monday. We will see the atmosphere dry
out and winds diminish as it moves overhead. Winds will then pick up
from the East on Monday on the SW flank of the ridge. Temperatures
will be a bit cooler today by around 10 degrees behind the front,
but will still be around or just barely above average in the mid to
upper 60s. We will then see some recovery on Monday as temps aloft
warm a bit with return flow taking place.

- Frequent chances for Rain Tuesday through next weekend

AN upper low across the northern Rockies on Tuesday will merge with
a northern stream longwave trough across the Great Lakes by the end
of the week. The persistent troughing will result in chances for
showers much of the week into next weekend.

The best chance for rain will be on Tuesday afternoon as an occluded
front moves through and again on Wednesday night and Thursday in an
area of frontogenesis north of a low pressure center tracking across
southern Lower Michigan,

A cool Canadian airmass moves in for the end of the week and we will
have to watch for frost potential if skies clear out Friday night.
The upper troughing could result in lapse rates steep enough to
bring some diurnally driven showers Friday and Saturday afternoons.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
-- Changed Discussion --
Issued at 1227 PM EDT Sun May 5 2024

Dry air advection will be on the increase this afternoon as an
area of high pressure builds in from the west. Satellite trends
show the the area of clouds over Southern Lower MI, shifting south
with time. Thus the TAF sites will feature mainly clear skies
through the period. There is a small chance that an area of lower
clouds/fog may redevelop late tonight as decent radiational
cooling is expected, however confidence on it occurring was too
low to add it to the forecast at this time. An onshore flow will
likely develop at KMKG this afternoon as temperatures warm up
inland.
-- End Changed Discussion --

&&

.MARINE...
Issued at 327 AM EDT Sun May 5 2024

We will see somewhat gusty winds this morning and again this
afternoon. Right now, it seems that conditions will remain just shy
of Small Craft Advisory criteria.

The winds this morning are in the immediate wake of the cold front
with cooler air filtering in. The winds this afternoon will be the
scenario where the ridge builds in, and combines with the daytime
land/lake pressure difference to increase the winds a bit. Winds
will get up to about 20 knots and waves will likely be 2 to 3 feet.
We will continue to monitor for the possibility of needing to issue
a SCA.

It looks like we should generally see relatively quiet conditions
out on the lake, with most of the next few days staying under SCA
criteria. The only exception to this is Monday night into Tuesday
ahead of the next system moving through the area.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

UPDATE...04
DISCUSSION...Ostuno/NJJ
AVIATION...MJS
MARINE...NJJ