Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 250740
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
340 AM EDT Mon Mar 25 2024

.KEY MESSAGES...

- Warm, Windy with showers and possible storms to start the week

- Cooling back down for Wednesday

- Risk for some showers mainly over the weekend

&&

.DISCUSSION...
Issued at 336 AM EDT Mon Mar 25 2024

- Showers and Storms through the first half of the week

Bottom line up front: Warm air advection willl bring warmer
temperatures through mid week with gusty winds Today and tomorrow
with upwards of 40 mph winds possible Tuesday afternoon. Showers
are expected Monday night through Tuesday with storms possible
Tuesday afternoon with a marginal risk of severe Tuesday afternoon
and evening.


- Cooling back down for Wednesday

Stronger cold air advection persists Tuesday night into Wednesday,
sending the temperatures back down to colder than normal levels. The
low level thermal trough arrives Wednesday afternoon and lingers
into Thursday.   Ensemble max temperature suggest the CWA will stay
in the 30s for Wednesday and upper 30s to mid 40s for Thursday,
which is at least several degrees below normal.


- Risk for some showers mainly over the weekend

A southwesterly low level jet forms upstream Friday and reaches into
the OH Valley on Saturday. Meanwhile aloft over the Great Lakes
Region we will see a west northwest flow persisting. This pattern
supports a strengthening baroclinic zone over the area Friday night
into Saturday. Gulf moisture will be advecting northward and into
the Lower Great Lakes Region with PWATs once again approaching an
inch then. As this moisture interacts with strengthening frontal
zone, scattered showers could form. The frontal zone is forecast to
slip slowly south into Sunday, and that may focus the highest rain
chances south of the CWA.


&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 134 AM EDT Mon Mar 25 2024

The main impact to aviators will be the low level wind shear. The
duration of the impact is unusual. The TAF sites maintain a
general east to southeast flow as a low level jet moves in. Even
as the direction of the low level jet shifts from southeast to
south southwest, the surface winds generally maintain the east to
southeast direction through the period. Thus there will be an
unusually large vector difference with the winds in the surface to
2k ft level, leading to the wind shear risk.

Aside from the wind impacts, conditions are likely to remain VFR.
We may see a few showers later in the day or at night, but the
current thinking is that they will be too scattered to include
them in the forecast. After 06z Tue, the showers will fill in and
clouds bases will be lowering toward the MVFR category.

&&

.MARINE...
Issued at 336 AM EDT Mon Mar 25 2024

Small craft advisory will continue through today and tonight.
Strong offshore flow will continue through this timeframe keeping
conditions hazardous to small craft present.
 Models remain consistent on the increased gradient strenthening
late Monday night throught Tuesday. Storm low level jet will only
aid is these winds which could bring gales and waves upwards of 6
to 8 feet, especially as winds shift behind the front.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 3 AM EDT Tuesday for LMZ844>849.
     Gale Watch from late tonight through Tuesday evening for
     LMZ844>849.

&&

$$

DISCUSSION...MJS/Ceru
AVIATION...MJS
MARINE...Ceru


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