410
FXUS63 KGRR 110730
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
230 AM EST Tue Feb 11 2025
.KEY MESSAGES...
- Light Snow This Morning
- Widespread 4-7" Snowfall With Areas up to 12" Possible
Wednesday into Thursday
- Snow Expected This Weekend
&&
.DISCUSSION...
Issued at 227 AM EST Tue Feb 11 2025
- Light Snow This Morning
Light radar returns are ongoing across the northwest portion of the
CWA area with light snow continuing through the morning. This all is
driven by a weak 700mb wave and a decaying arctic front crossing the
CWA aided by some lake enhancement. Additional snow of up to 2
inches is expected before ridging arriving this afternoon leads to
snow showers tapering off.
- Widespread 4-7" Snowfall With Areas up to 12" Possible
Wednesday into Thursday
Bottom Line Up Front, have expanded the Winter Storm Watch into
Calhoun and Jackson Counties to account for the southeasterly trend
in the latest guidance.
The synoptic pattern driving this event is the ejection of a mid-
level wave into the region inducing cyclogenesis across the Ohio
Valley. The low then tracks into northwest/north-central Ohio which
synoptically places us in line with the best frontogenetical
forcing. Overall thinking remains the same that widespread 4-7 inch
snowfall is expected with a FGEN driven band of 7-12 inches is
likely to develop, favored south of a Mount Pleasant to Grand Rapids
line. The snow will start during the day Wednesday, peaking the
first part of Wednesday night as the best frontogenetical forcing
takes hold with rates of up to 1"/hr likely. The low then pulls
away late Wednesday night with a transition to light lake effect
snow during the day on Thursday.
One consideration that will need to be watched is mixed
precipitation across the southeastern forecast area. With the
southeastern shift in guidance, the warm nose aloft look to stay out
of the CWA keeping snow as the dominant type across the region
(albeit with only 10-13:1 ratios given a deep sub-DGZ isothermal
layer). The favoring of snow over ice across Jackson and Calhoun
Counties warrants expanding the watch given high QPF of 0.4-0.6" and
our expected SLRs. However, there is a minority of guidance, mainly
the RAP, that does bring in a brief period of warm air and
subsequent mixing with sleet and freezing rain. Further
refinements to the forecast are likely as the exact strength and
path of the low is determined. So some adjustments in snow
amounts, placement, and p-type are possible in subsequent
packages.
- Snow Expected This Weekend
After a brief respite Friday due to surface and upper-level ridging,
snow returns Friday Night into early next week. Similar to the mid-
week system we see a mid-level wave induce cyclogenesis across the
Midwestern US, followed by a period of lake effect as 850mb temps
fall into the -20s C. Long range ensemble forecasts shows QPF values
are likely to exceed 0.25" (60-80%) which brings the potential for
several inches of accumulating snow to the region for the Friday
Night/Saturday system thanks to mid-level FGEN. That is then
followed by additional snowfall Sunday into Monday in the form of
lake effect. Trends will need to be monitored for this timeframe
given the potential for travel impacts.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1250 AM EST Tue Feb 11 2025
VFR conditions prevail early this morning although areas of MVFR
cigs may develop toward/after 12Z. Snow showers producing vsbys
of 3-5 miles are possible for a time this morning at MKG, with
local IFR vsbys north of MKG. VFR is anticipated tonight.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Watch from Wednesday afternoon through Thursday
morning for MIZ037>040-043>046-050>052-056>059-064>067-
071>074.
MARINE...None.
&&
$$
DISCUSSION...Thomas
AVIATION...Meade
NWS GRR Office Area Forecast Discussion
