-- Discussion containing changed information from previous version are highlighted. --
909
FXUS63 KGRR 011804
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
204 PM EDT Wed May 1 2024

.KEY MESSAGES...

-- Changed Discussion --
- Showers exit this morning, another low chance Thursday

- Breezy Winds continue

- Best Rain Chances are Friday and Next Tuesday

- Warm Pattern Persists through Middle of Next Week
-- End Changed Discussion --

&&

.DISCUSSION...
Issued at 337 AM EDT Wed May 1 2024

- Lingering showers this morning, then again Thursday

There is a broken line of light showers over Lake Michigan as of 07z
this morning that is trying to make its way over the area. This rain
activity is out ahead of a low level jet that is pushing 50 knots,
and bringing a temporary surge of some moisture and warmth aloft.
Drier air at the sfc is eating away at the leading edge of the rain.
Over the next 2 to 4 hours, the moisture aloft will be low enough
and some low level moisture arrives to bring our best chance of
rain, which is still not great.

After the next 2 to 4 hours, the nose of the low level jet
translates east quickly, and we lose moisture aloft quickly. Other
than the early morning light showers and clouds, we will see
clearing take place by mid-late morning from West to East.
Temperatures will not really be affected as the air is not really
different behind the system than ahead of it. Highs will be in the
70s.

Dry weather will hold on then from this morning through Thursday
morning with upper ridging building in and amplifying a bit. Our
next threat of rain will be Thursday afternoon. This will be
somewhat of a similar setup as this morning as a low level jet to
our west noses in here late Thursday. The majority of the rain
should stay off to our west through Thursday afternoon as the best
convergence at the nose of the low level jet is located out there.
We do see a portion of the warm and moist nose clip the area, which
will bring a low chance of the rain showers at that time.

- Best Rain Chances are Friday and Next Tuesday

A shortwave pivoting northeast on the ern periphery of the nrn
Plains trough on Thursday night and Friday helps send a warm front
then cold front through the region. Pops ramp up late Thursday night
in mainly wrn sections as the warm front lifts northward and brings
in PWATs around 1.25 and mid 50 dew points although at this time the
low level jet looks unfavorable for more widespread convection.

On Friday as the sfc cold front drags eastward across the area we
see likely pops for showers and storms. The severe wx threat looks
low since the best deep layer shear stays to our west and degree of
instability is questionable as well.

Only small pops are warranted on Saturday and Saturday night as
another weakening sfc frontal boundary slips through then it looks
like we end up mainly dry for Sunday/Monday as the main baroclinic
zone slips south of MI thanks to sfc ridging building in.

Our next good chance of showers and storms after Friday comes next
Tuesday when the sfc high slips away and the frontal zone comes back
north as a warm front. Deep layer shear is progged to be better on
Tuesday since the Plains upper trough is positioned a bit farther
east by that time, so there could perhaps be some stronger storms.

- Warm Pattern Persists through Middle of Next Week

Persistent troughing aloft from the northern Rockies to the northern
Plains/south-central Canada through the middle of next week keeps
positive height anomalies over the Great Lakes Region. The upshot is
for several days in a row with highs temperatures in the 70s which
is about 10 degrees above normal for early May.  Frequently cooler
near Lake Michigan however as is always the case this time of year.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
-- Changed Discussion --
Issued at 138 PM EDT Wed May 1 2024

- Breezy Winds continue

Gusty winds continue through the rest of the day as a low level
jet has mixed to the surface. Winds have shifted to the west and
will remain in the 30 to 35KT gust range. Winds will weaken near
and shortly after sunset, around 01 to 02Z.
 Winds will be light overnight and most of the day tomorrow with
clouds overspreading the region tomorrow. Expect VFR through the
period with a chance for showers and storms, especially the
western TAF sites tomorrow afternoon.
-- End Changed Discussion --

&&

.MARINE...
Issued at 337 AM EDT Wed May 1 2024

We will be able to let the Small Craft Advisory continue as is this
morning, and allowing it to expire this afternoon. The core of best
winds is moving through right now. Winds will diminish as conditions
over the more stable cool waters improve.

The next wind event that might necessitate another Small Craft
Advisory looks to begin Thursday afternoon and continues through
Thursday night ahead of the next system that will approach the area.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for
     LMZ845>849.

&&

$$

DISCUSSION...Meade/NJJ
AVIATION...Ceru
MARINE...NJJ