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000
FXUS63 KGRR 261152
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
752 AM EDT Fri Apr 26 2024

.KEY MESSAGES...

- Occasional showers and storms tonight through Monday

- Briefly Dry Tuesday, then Additional Showers Wednesday/Thursday

&&

.DISCUSSION...
Issued at 353 AM EDT Fri Apr 26 2024

- Occasional showers and storms tonight through Monday

A ridge aloft will slide eastward today and allow a weakening
upper shortwave to move into Minnesota tonight. At the surface a
warm front will move into the area tonight. Surface dew points
tonight will surge into the 50s tonight with MUCAPE values
increasing to around 500 j/kg late. Today will mainly be dry with
a lowering and thickening cloud base ahead of the warm front.
Tonight, showers and a few storms are expected as the instability
increases overnight. Not expecting any strong storms given the
lack of instability associated with the nocturnal minimum.

Saturday we will be in the warm sector of the system as it weakens
and moves into Canada off to our north and west. We are in the day
2 SPC outlook with a slight risk for areas to the north and west
of Grand Rapids. We certainly could see some warm sector
convection on Saturday, but this looks to be scattered and
relatively low chance. What convect we do see in the day 2 period
would likely come Saturday night as upstream storms and the
associated cold front sag in from the northwest. Given bulk shear
Saturday night is near 40 knots over Central Lower and MUCAPE
values will be in excess of 1,000 j/kg cannot disagree with a
threat of some severe weather, but overall feel our chances are
not great. Main factors that would lead away from severe weather
Saturday night are a low level jet that is forecast to weakening
as is the system to the west. We will obviously be monitoring for
severe weather both Saturday afternoon and night, but feeling is
it may not be a slam dunk event.

Chances for showers and storms continue Sunday into Monday as
another plains upper shortwave works northward into Canada. We
will again be downstream of the better activity most likely but
the warm and showery weather will continue. Best chances in this
time frame will likely be Sunday afternoon on the warm front
across Central Lower Michigan. Day 3 only has us in general
thunder from SPC and cannot argue with that.

Highest rainfall totals from this weekend into early next week
will be west of Lake Michigan where the deeper moisture and more
importantly stronger dynamics will be in play. We are still
looking at solid rain in our area though through Monday night
however on the order of 0.50 inches towards Jackson to 1.50 inches
up near Ludington. If we see any hydro issues at all it will
likely be to the north of the Grand River basin up along the
Muskegon and Pere Marquette. Given the totals we are forecasting
though over multiple days we think the rivers will be able to
handle it.

- Briefly Dry Tuesday, then Additional Showers Wednesday/Thursday

A break in precipitation is expected Tuesday as brief weak ridging
moves in place. Conditions turn active with showers Wednesday and
Thursday as a cold front associated with an upper shortwave dives
into the region. An 850mb thermal trough falls into the region late
in the week leading to cooler temperatures starting Thursday. Summer-
like temps in the 70s through the first half of next week will fall
into the low 60s Thursday and Friday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 753 AM EDT Fri Apr 26 2024

A warm front will lift our direction from the Plains states today
and move into the area tonight. As is the case normally with warm
front, ceilings will lower and thicken over the next 24 hours.
Ceilings will remain VFR today, but become MVFR tonight between
02Z and 05Z. At the same time rain showers will spread in. A few
thunderstorms will be embedded as well, especially late in the
night. 3-5SM / MVFR visibilities are likely after 05Z as well.

Winds will be gusty from the southeast both today and tonight.
10-20 knot wind speeds are likely with gusts into the 20-25 knot
range.

&&

.MARINE...
Issued at 353 AM EDT Fri Apr 26 2024

Will hold off on any marine headlines with this morning`s forecast
package. That said, we may need marine headlines as we head into
Saturday in strong southerly flow. Strong warm air advection this
time of year though is always troublesome given the inversion that
develops. Strongest winds will flow over the cold dome near the
surface and never make it down to build waves. Today, winds are
offshore (southeast) and more in the 10-20 knot range. Winds
tonight will begin to ramp up and we could need a headline for
winds alone, but given short fetch (southeast/off shore) and
mixing to the surface concerns will hold off. NAM 3km Bufkit winds
are suggesting solid SCA conditions on Saturday if not Gales. We
will hold off for now and take another look today at any potential
headlines. A prolonged period of stronger south winds will exist
from Saturday right through the day on Monday. Feeling is at least
some of this will struggle to make it to the surface. Areas of
fog may also be an issue Saturday-Monday as higher dew point air
will be advected out over colder water which is usually a set up
for instant fog on the Great Lakes in the spring of the year.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Frost Advisory until 8 AM EDT this morning for MIZ043-050-056-
     064-071-072.
     Freeze Warning until 8 AM EDT this morning for MIZ044>046-051-
     052-057>059-065>067-073-074.
MARINE...None.

&&

$$

DISCUSSION...Duke/Thielke
AVIATION...Duke
MARINE...Duke