Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 140700
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
300 AM EDT Thu Mar 14 2024

.KEY MESSAGES...

- Showers and Scattered Thunderstorms Today

- Chance of rain Saturday, then colder with snow showers

&&

.DISCUSSION...
Issued at 300 AM EDT Thu Mar 14 2024

- Showers and Scattered Thunderstorms Today

A warm front extending from west to east near the MI/IN border
will focus development of showers and scattered thunderstorms
today. The overall svr wx risk which was low has decreased further
as an overall short range guidance consensus and 00Z HREF all
suggest the warm front will not make it much further north than
the MI/IN border. This keeps instability of any significance
focused south of our area across IN/OH. The 00Z HREF shows only
100-250 j/kg of SB/MU CAPE near to south of I-94.

So the svr wx risk looks very low today and mainly confined to
near/south of I-94. Weak elevated instability north of the warm
front will result in scattered non severe convection. Rainfall
amounts with this system should generally fall into the one
quarter to three quarters inch range with locally higher amounts
in excess of an inch as suggested by the 00Z HREF LPMM product.
These type of rainfall amounts are not sufficient enough to cause
any significant hydro issues.

Lingering evening showers and isolated convection early will come
to an end rather quickly by mid to late evening on the back side
of this system. Skies will become partly sunny Friday and it will
be cooler with weak northerly flow cool air advection.

- Chance of rain Saturday, then colder with snow showers

No significant changes planned for this forecast. As noted
previously, late Saturday is trending slightly drier south of M-46.
We will get a shot of light lake effect snow Sunday morning in the
wake of the cold front associated with Saturday`s precipitation.
Accumulations should be nearly non-existent given relatively warm
surface temperatures.

No changes in expectations for Sunday night into Monday with the
secondary surge of colder air. Light accumulations by the lakeshore
seem like a reasonably good bet, with an emphasis on "light". A
slight chance for light snow remains possible early Tuesday due to
the possibility of a clipper type of feature dropping down the back
side of the broader scale exiting upper trough.

After reasonable confidence for a dry Wednesday, predictability
breaks down again from Thursday onward. This is due to possible
development of a southern stream trough over the southern plains. At
this time thunderstorms are not expected, however.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 152 AM EDT Thu Mar 14 2024

In the very short term, we are warily monitoring radar for a
thunder threat at LAN. This is associated with the same activity
that rather surprisingly brought recent thunder to GRR. At this
writing, there does remain some electrical activity with a cell
south of GRR and that is moving slowly eastward.

We could be looking a rapid transition to IFR conditions after 14Z,
starting with visibility restrictions, then accompanied by ceilings
below 1000 ft. These low ceilings are likely to predominate
through at least through 00Z this evening.

Thunderstorms become increasingly probable after 16Z for our
southern terminals (AZO-BTL-LAN), but for the sake of brevity only
including VCTS wording at this time. The main threats will be
lightning and possibly small hail. Because the storms will be
largely elevated north of a warm front, we do not expect a
significant surface wind gust threat.

&&

.MARINE...
Issued at 300 AM EDT Thu Mar 14 2024

Northeast winds will be light this morning before increasing a bit
this afternoon. Winds will back to the north tonight but will be
rather light. Winds will back to the southwest and increase
considerably Friday night and Saturday. Small craft advisories will
likely be needed Saturday as southwest winds increase to over 20
knots.

&&

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

&&

$$

DISCUSSION...Laurens/TJT
AVIATION...TJT
MARINE...Laurens


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