159
FXUS63 KGRR 121513
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1113 AM EDT Wed Mar 12 2025

.KEY MESSAGES...

- Warmer than normal rest of the week

- Showers and Storms Late Friday into Saturday

- Cold and Wet Sunday, a return to warmth next week

&&

.UPDATE...
Issued at 1113 AM EDT Wed Mar 12 2025

Main fcst adjustment this morning was to lower the dew pts and
RHs this afternoon. Fire weather section updated below. Otherwise
decreasing clouds occuring as expected with fcst highs ranging
from the mid 40s around Clare to the mid 50s around Kalamazoo.

&&

.DISCUSSION...
Issued at 330 AM EDT Wed Mar 12 2025

- Warmer than normal rest of the week

 The only change to the forecast is the addition of some gusty
winds this morning. Though there is zonal upper level flow a
negatively tilted ridge through the mid levels is building over
the Mid Atlantic and the Eastern Great Lakes. As noted in
previous discussions, easterly winds will be emanating from this
ridge. There is also a negatively tilted mid level trough that is
tilted across southern Michigan this morning through Mid day.
That trough, and subsequent gradient should allow for 925mb winds
to mix to the surface this morning into early afternoon. That will
mean some wind gusts in the 20 to 30 mph range this morning.

Have also leaned on some of the short range guidance due to this
and have adjusted daytime highs today. Highs will be back into the
50s today and will continue to climb every day into Saturday.
Friday and Saturday Max temperatures are still trending in the low
70s and upper 60s respectively. This would put those days at 20
to 30 degrees above normal.


- Showers and Storms Late Friday into Saturday

Forecast trend continues for the system that will move through
the region to begin the weekend. Models remain in agreement
 The large upper level system will be accompanied by a strong low
level jet, currently around 50kts. Though the system is arriving
into lower Michigan at night, that shear shouldn`t need much CAPE.

 Previous discussions noted the strong isentropic ascent that the
low level jet will create when combined with the PV advection.
Given those ingredients, along with PWATS upwards 0.75 of
according to the NAEFS. That anomalous moisture should be more
than enough for thunderstorm development early Saturday morning.

 Though the showers and storms will move through early Saturday, The
gusty wind trend for Saturday continues with the low level jet
persisting through the daytime Saturday. That will mean winds of
30 to 40 mph through the daytime and into the early evening.

- Cold and Wet Sunday, a return to warmth next week

 A deepening upper level trough will be setting up over the high
plains and the upper mid west late Saturday into Sunday. That
potentially could bring some more showers and storms Saturday
night into early Sunday morning.

There is some question on position of highest QPF and many put it
just east of the region, however there remains some potential for
another half an inch rainfall into Sunday morning. Latest Plumes
show some variance and a large bulk of the members trending on
the low side, but the model mean remains a chance of showers
Saturday night. Cold northwesterly flow will follow the trough as
it exits to the east. That will bring temperatures back down to
normal with a cooler and wetter Sunday. While those temperatures
will linger through Monday the warmth should return as we move
through the upcoming week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 645 AM EDT Wed Mar 12 2025

VFR conditions will continue to dominate the pattern over the next
24 hours. Some gusty winds through the south will be possible this
morning. Otherwise, calmer winds with mid to high clouds will
continue this afternoon into tomorrow.

&&

.FIRE WEATHER...
Issued at 1113 AM EDT Wed Mar 12 2025

Fuels continue to dry out and an elevated fire danger will exist
the next few days. Early season warmth and no more snow cover in
pre green up mode has been resulting in much lower dew points and
relative humidities than model guidance indicates, and will
maintain that lower bias in the fcst through Friday.

Winds should be fairly light on Thursday but conditions on Friday
may approach Red Flag Warning criteria when temps reach near 70
with a southeast wind gusting up to 30 mph. Dew points are shown
to rise to near 50 for Friday but that seems too high given
southeasterly sfc flow plus potential for mixing down drier air.

Rain on Friday night should alleviate fire weather concerns at
least to some extent, as well as the colder air which arrives
on Sunday. However if rainfall amounts Friday night and early
Saturday end up being scant, the expected gusty winds of up to
40-50 mph on Saturday afternoon/evening could be a big concern
since highs near 70 are expected then as well.

&&

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

&&

$$

UPDATE...Meade
DISCUSSION...Ceru
AVIATION...Ceru
FIRE WEATHER...Meade