000
FXUS63 KGRR 130151
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
951 PM EDT Fri Apr 12 2024

.KEY MESSAGES...

- A few showers/storms mainly North Saturday night

- Mild Next Week With Strong Storms Possible Tuesday/Wednesday

- Cooler Weather With Showers Late Next Week

&&

.UPDATE...
Issued at 949 PM EDT Fri Apr 12 2024

The winds have steadily decreased this evening and no sites have
reached criteria in past 2 hours. With the pressure gradient
expected to slowly weaken overnight, we cancelled the wind
advisory early.

&&

.DISCUSSION...
Issued at 304 PM EDT Fri Apr 12 2024

- A few showers/storms mainly North Saturday night

Before we get into the details about the next system, we just need
to address this afternoon`s wind situation briefly. The winds had
been gusty today, but not too bad until just recently as expected.
Winds had been gusting 25 to 30 mph with a recent uptick along the
land areas of the lakeshore. KMKG had a recent gust to 48 knots as
the clouds are starting to clear out, and better mixing of the winds
aloft down to the sfc are taking place. We expect this trend to
continue inland as clearing takes over the next 2 to 4 hours before
winds then diminish.

Skies are expected to clear out nicely then through this evening
from West to East. Some high clouds are likely to move overhead
Saturday afternoon in advance of the next system that will move
through Saturday night.

The trend of the potential for showers and storms has shifted north
a bit over the past couple of days. That is because the track of the
short wave of interest is now staying north of the state, vs. moving
across Northern Lower as indicated a couple of days ago. This wave
will not have a lot of moisture to work with being so far north.
What it will have is a good deal of warm air well SW of the area
being tapped by a strong low level jet of 40+ knots to focus the
warm air advection.

The nose of the low level jet will be focused on Central and
Northern Lower, keeping most of, it not all of the rain north of I-
96. Thunder remains possible with any rain showers as elevated LI`s
are below zero a little. Sfc based instability is pretty much non-
existent, so worst case scenario with any storms might be some small
hail and lightning. This will move through quickly Saturday night,
and should be mostly gone by 12z Sunday.

- Mild Next Week With Strong Storms Possible Tuesday/Wednesday

A consensus of latest medium range guidance continues to indicate
that temperatures will average much above normal for this time of
year from Sunday through the middle of next week with high temps
mainly in the upper 60`s to lower 70`s. This will occur as upper
level ridging builds in from the west and amplifies significantly
out ahead of a strong Plains states system.

Isentropic upglide/elevated instability north of a warm front will
bring the first chance of showers and storms early Tuesday. A better
chance for rain and convection will come Tuesday night aided by
forcing from a vigorous llj on the order of 45-55 kts aimed squarely
at southern lower Michigan. Another chance for showers and
convection will come Wednesday along and ahead of the cold front.

- Cooler Weather With Showers Late Next Week

A significant wx pattern change will come late next week as an upper
level low/trough gradually moves in from the wnw. Therefore much
cooler wx is expected late next week along with potential for some
showers and perhaps a few storms as the upper trof axis moves in.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 711 PM EDT Fri Apr 12 2024

Winds are the primary aviation concern with this TAF package as
widespread gusts of 30-40 knots occuring for the next few hours
from the northwest before becoming 20-25 knot gusts overnight and
into the day on Saturday as winds become more westerly to
southwesterly. Conditions will approach LLWS criteria at all TAF
sites except MKG from 03z to around 09z as surface winds begin to
decrease with winds near 40 kts around 2000 ft. Looks to remain
just below the criteria for inclusion so did not include in the
TAFs with this package but if winds calm faster than forecasted
that impacts are possible. High confidence in VFR conditions
through the TAF period as any lingering VFR cigs present erode
into SKC to FEW cirrus tonight continuing into Saturday.

&&

.MARINE...
Issued at 304 PM EDT Fri Apr 12 2024

We will be holding on the Gale Warning for just a bit longer for the
time being. We will eventually need to transition to a Small Craft
Advisory this evening. Winds at the coastal observing sites are a
bit marginal with less mixing over the cooler waters, as compared
the inland areas starting to warm up and gust a bit higher.

After a brief break in the wind on Saturday with high pressure
moving through, winds will pick up again Saturday night into Sunday
in association with the next wave moving through.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until noon EDT Saturday for LMZ844>849.

&&

$$

UPDATE...MJS
DISCUSSION...Laurens/NJJ
AVIATION...Thomas
MARINE...NJJ