045
FXUS63 KGRR 301911
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
311 PM EDT Mon Mar 30 2026
.KEY MESSAGES...
- Strong possibly severe storms overnight into Tuesday morning
- Potential Severe storms Tuesday afternoon and evening
- Wintry Mix,rain midweek with rain this weekend
&&
.DISCUSSION...
Issued at 252 PM EDT Mon Mar 30 2026
- Strong possibly severe storms overnight into Tuesday morning
High level clouds continue to steam through the northern Great
Lakes today with warm air pouring into Lower Michigan. That warm
air and westerly flow will set the stage for overnight convection.
Latest guidance continues to have zonal flow through the upper
levels and a negatively tilted mid levels There has been an uptick
in potential overnight into Tuesday morning. This corresponds to
the strength of the jet and the warm air advection out ahead of
it. Temperatures today are into the 70s across much of southern
Lower Michigan. While dewpoints are only in the mid 40s, those
will increase as the evening continues. So warm daytime temps,
along with warm air advection this evening will bring a better air
mass for convection overnight. Given those above features, that
should allow for more CAPE which, with strong mid level shear,
should allow for any storms to filter down winds. There remains
some question on timing. Some of the CAMS want to bring
convection in later, some sooner and there is some variance in
where the boundary sets up. Several runs of the NAM have it north
of I 96 and some versions of the HREF has the boundary further
south. Best chances for overnight storms will be between 2 AM and
7 AM. The main threat is damaging winds and large hail. While
there is some cap in place given the time of day, the surface
temps and strong winds aloft should be able to overcome any
capping inversion.
- Potential Severe storms Tuesday afternoon and evening
Much of the forecast for tomorrow remains the same. There are
questions of whether or not the atmosphere will be able to
recharge in the wake of the overnight convection. If skies clear
out and temps get back into the mid to upper 60s, then there
should be enough CAPE to go along with the short wave that arrives
early to mid afternoon. Best shear, 40 to 50 kts, and helicity
should be after 19Z as the front drapes across the region from the
northeast to the southwest. That favors the potential for super
cell development tomorrow afternoon and evening. Damaging winds
and large hail are the primary concern. However given the shear
and the shape of the hodographs, there is the potential for
tornadoes, especially along the frontal boundary. Depending on the
speed of the front, storm threat could linger through the first
half of the evening.
- Wintry Mix,rain midweek with rain this weekend
Wednesday remains dry though there could be some lingering rain
showers early Wednesday in far southern Michigan. Otherwise, cold
northwesterly flow will filter in behind the front with otherwise
dry conditions with highs in the 40s. Colder temperatures
Wednesday night will set the stage for rain and freezing rain. The
0C line at 850 mb has shifted southward . here will be a
significant warm nose at 850mb that would melt any snow/ice, but
surface temperatures continue to trend around 32 along I-96 with
temperatures below 32 north. Areas along the lakeshore may remain
warm enough limit ice accumulations. The warm front then moves
north Thursday with areas transitioning to rain during the morning
and afternoon. There is still some uncertainty with the exact
amounts, but ice amounts are trending upward and would be highest
on elevated surfaces. Keep up to date with the forecast as any ice
accumulations could be impactful.
Rain continues into Thursday with decent rainfall, upwards of an
additional inch on Thursday. After a break on Friday there
remains good agreement on a deep trough moving through the regions
Saturday into Sunday. Some differences in timing, but overall
rain and maybe a few thunderstorms move in Saturday with a cold
front moving through Saturday night into Sunday. Cold air will
advect in on the backside of the low with the potential for snow
to mix in as Sunday morning as temperatures fall. Cold, blustery
northwesterly flow will greet Southern lower Michigan Easter
morning.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 120 PM EDT Mon Mar 30 2026
Skies are mainly clear across the region this afternoon. However,
things will change this evening as a warm front moves north and
lower clouds develop. Chances for showers and thunderstorms will
increase after midnight as low pressure draws closer. LLWS is also
expected after midnight as strong southern flow increases aloft.
Finally, IFR cigs are possible toward 12z.
&&
.MARINE...
Issued at 252 PM EDT Mon Mar 30 2026
Southerly winds continue today with waves around 1 to 2 feet.
Southwest winds increase tonight into Tuesday as the low
approaches with lighter winds in the northern zones. Small Craft
Advisory conditions are expected from Whitehall to the south
before extending north as the cold front moves through Tuesday
evening. Thunderstorms are also expected tonight into Tuesday with
the potential for strong to severe storms.
Small Craft Advisory conditions likely linger into Friday with
another system tracking through the region.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 8 AM Tuesday to 8 AM EDT Wednesday for
LMZ844>847.
&&
$$
DISCUSSION...Ceru
AVIATION...04
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
