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000
FXUS63 KGRR 150716
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
316 AM EDT Mon Apr 15 2024

.KEY MESSAGES...

- Sunny and mild today, Increasing clouds Tuesday

- Risk for Thunderstorms Tuesday Night into Wednesday

- Steady cool down for the end of the week

&&

.DISCUSSION...
Issued at 316 AM EDT Mon Apr 15 2024

- Sunny and mild today, Increasing clouds Tuesday

Latest satellite imagery shows mostly clear skies across the upper
Great Lakes thanks to high pressure building into the region.
North winds aloft will result in cooler temperatures today
compared to yesterday; mid 60s to around 70.

Clear skies tonight will send temperatures down to near freezing
near US-10 and to the mid 40s near I-94.

A developing Plains low will move in this direction Tuesday. We`ll
see increasing clouds during the afternoon. Strong warm front
activity will see showers and storms develop over the MS Valley
and move east toward Lower MI. Most likely, precipitation will
hold here off until Tuesday evening.

We`ll see east winds strengthen Tuesday, so highs in the lower to
mid 60s will feel a bit cooler than that.

- Risk for Thunderstorms Tuesday Night into Wednesday

The arrival of a low level jet, weak elevated instability and a low
level Theta-E ridge will support an increased risk for a few
thunderstorms Tuesday night.  An approaching upper level wave from
the southwest will also generated diffluence aloft so deeper lift
lift is looking likely.  As a result, we will maintain the risk for
showers and thunderstorms then.

On Wednesday, the mid to upper wave tracks through.  Models are
generating some surface based instability with the highest values in
southern parts of the CWA. The ECMWF and GFS generally keep the
instability limited with values under 750 J/kg but the CMC is much
higher with values topping 1000 J/kg in the afternoon. Afternoon
deep layer shear values are generally shown to be in the 30 to 40
knot range so some organized convection is possible.


- Steady cool down for the end of the week

The wave that tracks through the region on Wednesday lifts up into
Southern Hudson Bay on Friday.  Cold air advection on the backside
of this system strengthens over the Great Lakes Region resulting in
steadily falling 850 mb temperatures. The 850 mb thermal trough
arrives on Saturday, with values around -8 deg C, so a cooler than
normal temperature pattern is expected.  Ridging moves in by Sunday
so that will help to scatter the clouds out.  With some potential
for clearing and a ridge moving in, we will potentially see
overnight lows dipping down to around the freezing mark both
Saturday night and Sunday night.


&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 730 PM EDT Sun Apr 14 2024

Very high confidence in VFR conditions throughout the TAF period
as SKC is expected at all TAF sites for the next 24 hours, except
for a few passing mid-level clouds that may briefly clip
terminals overnight. West- northwest winds of 10-15 knots become
north winds at or below 5 knots overnight before becoming westerly
around 8-13 knots Monday afternoon.

&&

.MARINE...
Issued at 316 AM EDT Mon Apr 15 2024

High pressure overhead today will result in relatively light
wind/waves. As low pressure approaches Tuesday, the pressure
gradient and corresponding southeast winds will increase; a Small
Craft Advisory will likely be needed Tuesday afternoon. There`s
also a weak signal for potential gales Tuesday night north of
Grand Haven that we`ll keep an eye on.

&&

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

&&

$$

DISCUSSION...MJS/04
AVIATION...MJS
MARINE...04