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FXUS63 KGRR 271845 CCA
AFDGRR

Area Forecast Discussion...CORRECTED
National Weather Service Grand Rapids MI
245 PM EDT Thu Mar 27 2025

.KEY MESSAGES...

- Mostly Warmer, But Looming Cold Air North, And Chances For
Showers/Storms Friday to Sunday

- Rain Changing To Snow Before Ending Sunday Night to Monday

- Precip Likely on Wednesday, Chance for Snow or Storms

&&

.DISCUSSION...
Issued at 223 PM EDT Thu Mar 27 2025

- Mostly Warmer, But Looming Cold Air North, And Chances For
Showers/Storms Friday to Sunday

Friday, elevated showers and thunderstorms are possible to the north
of a warm front that will be advancing into Lower Michigan. HREF
average MUCAPE is about 500 J/kg or less. Chances are likely during
early morning in Southwest Michigan then coverage may become
spottier as the zone of convective development shifts north
throughout the day. HREF LPMM QPF indicates narrow swaths of 0.25 to
0.50 inch possible.

Saturday, the front draped over Lower Michigan during the weekend
will have a significant difference in temperatures on the south vs
north side. While Northern Michigan is set up for substantial wintry
mix, Southern Michigan is favored for spring warmth in the 60s, and
Central Michigan`s temperature forecast is lowest in confidence (has
the broadest range in possibilities). The front may sag southward
during the day Saturday, behind the departing H8 weak low, as the
southerly wind component in Southern Michigan weakens and northerly
wind component in Northern Michigan strengthens. Showers may
continue to develop in the vicinity of the front, and it may be
drizzly to the south. Temperatures Saturday are favored to start off
mild (in the 50s) in Central Michigan before an increasing
membership of the ensembles drop the temperatures into the 30s.
Highs near I-94 are still favored to be in the 60s or around 70. The
front may settle near I-96 by Saturday evening, separating
temperatures around 60 south and around 40 north.

Sunday, restrengthening south flow ahead of the next Midwest low
pressure wave may advance the front northward again. 60s are favored
again in Southern Michigan, while Central Michigan will either be
stuck in the 30s or surge back into the 50s. The GEFS is colder than
the other ensemble systems (the ENS and the GEPS) with the midwest
low tracking farther south, but if the colder solution wins out,
we`ll be talking icy mix in Central Michigan reaching near and south
of US-10. The ENS and GEPS bring relatively higher CAPE values into
Lower Michigan, making thunderstorms a continuing possibility.


- Rain Changing To Snow Before Ending Sunday Night to Monday

The GEFS generally has an earlier departure of the low and its
associated precipitation on Sunday, keeping any chance of wintry
precip contained to that day. The ENS and GEPS bring a sharper upper-
level shortwave trough and its associated low through a little later
Sunday night or Monday. Cold air on the northwest side of the low
may change rain to snow before the precip ends. The chance of an
impactful snow (greater than 2 inches) for Monday appears low, and
any accumulations would be more favored north and northwest of Grand
Rapids toward Ludington. Ensemble systems are in more uniform
agreement that daytime temperatures Monday will be below normal.


- Precip Likely on Wednesday, Chance for Snow or Storms

Ensemble systems are in good agreement of the next synoptic wave and
its associated spring-like low pressure system providing
precipitation on Wednesday. However, what is more unsettled is the
extent to which warm air will get drawn toward Michigan ahead of the
low. Within each ensemble system is a wide range of possibilities
for daytime temperatures, but overall, high temperatures between the
lower 40s and 60s are all possible. Colder solutions bring some
snow, mostly an inch or two, while warmer solutions bring in more
instability along with thunderstorm chances and some potential for
rain amounts over 1 inch.


&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 223 PM EDT Thu Mar 27 2025

VFR conditions continuing today into the evening. Clouds will
increase and lower from the west today with a few light showers
possible this afternoon. Most of the showers have faded in the drier
lower atmosphere.

 Cigs will drop as a warm front moves into from the south overnight.
Cigs will drop to MVFR after 08Z with periods of showers after 09Z.
Periods of IFR cigs and vsby will begin from the southwest then
envelop all TAF sites between 10Z to 14Z. IFR cigs and vsbys will
continue through tomorrow morning with conditions improving to MVFR
at the southern TAF sites of JXN, BTL and AZO after 17Z. IFR
conditions will be possible at KGRR, LAN and MKG past 18Z but as the
front lifts northward into Friday afternoon, conditions will
improve.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 5 PM Friday to 11 AM EDT Saturday for
     LMZ844>849.

&&

$$

DISCUSSION...CAS
AVIATION...Ceru