258
FXUS63 KGRR 061107
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
707 AM EDT Sun Apr 6 2025

.KEY MESSAGES...

- Clearing with mild weather today

- Snow possible Monday morning; Cold through Tuesday

- Chances for Rain through second half of week

&&

.DISCUSSION...
Issued at 349 AM EDT Sun Apr 6 2025

- Clearing with mild weather today

A pattern shift is in store today. Models remain in good agreement
with a strong low slowly moving eastward across northern Canada.
That low will bring a strong gradient over the region which will
fuel cold air advection across Michigan. Dry air along with a mid
level ridge will allow for clearing skies and fair weather today,
albeit slightly cooler than normal. That ridge will be short
lived as a short wave making its way around the previously
mentioned upper level low will couple with mid and low level lows
to drop down through Lower Michigan tonight into Monday.

- Snow possible Monday morning; Cold through Tuesday

Bottom Line up front: Snow is possible for the Monday commute which
could cause some slick spots to the roads, especially bridges and
overpasses. However, given the variability stated above will hold
off on any headlines.

 500 mb PV anomalies will aid a clipper as it treks across Lower
Michigan tonight through Monday morning. Not much has changed
overall in the forecast, though there remains some variation on
snow amounts. Model soundings show a strong low level jet moving
over the area after 06Z Monday. Soundings also show a strong DGZ,
or dendritic growth zone, which will allow for snow generation
between 06Z to 15Z Monday morning.

  QPF is fairly limited, plus given the wet ground and marginal
temperatures, snow will have a tough time accumulating.  Looking at
the latest HRRR, the 10:1 ratio snow total has very little
accumulation, where the Kuchera method shows snow totals potentially
in the 1 to 3 inch range, especially along the US 10 corridor. Using
the Cobb snow tool in conjunction with different models has Big
Rapids northward with a half an inch.   Thus for snow to accumulate
rates would need to be fairly intense and given the ingredients
listed above, there is the possibility for that for a short period.

The snow bands would arrive just before sunrise. Best chance for
snow would be between 10Z to 15Z with light amounts before and
after. Have adjusted the forecast with more widespread snow, up to
half an inch along the I-96 corridor, with slightly lower amounts up
north, with 1 to 2 inches possible.

  Colder air behind the clipper will sink the region into the
doldrums of winter once more. A pause on spring will bring a bitter
beginning to April. Lows Tuesday morning will be in the low 20s
to upper teens. Highs will attempt to get into the upper 30s
Tuesday with lows again in the teens and 20s into Wednesday
morning.

- Chances for Rain through second half of week

 Thankfully the blast of cold air will be short lived. More zonal
flow, along with a mid level level low will bring warm air back
into the region through the latter half of the week.
 However, coupled with this Warm air, will be precipitation. There
remains some variance on timing, location and QPF amounts. Best
QPF should be south of Lower Michigan, with the NAEFS anomalies
being below normal. So while rain is possible late Wednesday into
Thursday it doesn`t seem impactful at this time.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 707 AM EDT Sun Apr 6 2025

High pressure will bring fair weather to the area today with VFR
weather expected. Mid and high clouds are in place across much of
the region and these clouds will be slow to leave the far
southeast towards JXN today. A cold front will drop south into
Lower Michigan tonight, bringing clouds back into the area
overnight. Late tonight MVFR clouds will invade the I-96 TAF sites
with some snow showers possible. Overall fairly benign aviation
weather is expected into at least this evening.

&&

.MARINE...
Issued at 349 AM EDT Sun Apr 6 2025

The strong gradient and low level jet that is discussed above
will bring strong north flow that could bring 35 gales to the near
shore waters south of Manistee. There remains some question on
strength and how sporadic the gales would be. Best chance so far
will be between 15Z Monday to 00Z Tuesday. Thus have issued a gale
watch for that timeframe.

&&

.HYDROLOGY...
Issued at 1043 AM EDT Sat Apr 5 2025

Latest hydro forecasts coming in for the rivers enabled us to
cancel flood warnings for Sycamore Creek at Holt and the Portage
River near Vicksburg. Last night`s rainfall didn`t overperform and
so no additional flooding is expected, other than what`s ongoing,
which is the Red Cedar at East Lansing. That flood warning
remains in effect until early Monday morning. The good news there
is that the current river trace reveals that the crest has arrived
in East Lansing and the Red Cedar will begin to slowly fall this
afternoon.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Gale Watch from Monday morning through Monday evening for
     LMZ844>849.

&&

$$

DISCUSSION...Ceru
AVIATION...Duke
MARINE...Ceru
HYDROLOGY...04