Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 141147
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
747 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 /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 747 AM EDT Thu Mar 14 2024

Main change for this update was to slightly delay onset of IFR
conditions, which should first manifest as reduced visibility in
rain and fog and then be accompanied by ceilings below 1000 feet
towards afternoon. Thunder has been delayed slightly with this
update and its northward extent is somewhat in question. VCTS
seems prudent this afternoon at AZO-BTL-JXN. Probabilities are
non-zero for sure at GRR and LAN farther north, but too low to
mention explicitly at those terminals. As noted previously, main
thunderstorm hazard would be hail given the elevated nature of any
storms making it into our forecast area.

&&

.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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