685
FXUS63 KAPX 212339
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
739 PM EDT Fri Mar 21 2025

.KEY MESSAGES...

- Strong cold front set to bring a chilly start to the weekend

- Accumulating snow Sunday afternoon/evening into Monday along with
  breezy conditions at times.

- Lake effect snow transition/chances Monday/Monday night.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 309 PM EDT Fri Mar 21 2025

Pattern Synopsis/Forecast:

Gusty southwest winds developing across the Northwoods early this
afternoon...driven by increasing pressure gradient between departing
high and shortwave trough digging southeast across Ontario into the
upper Mississippi Valley. Rather sharp and intensifying cold front
running just a bit ahead of that shortwave...currently stretching
northwest to southeast across central Lake Superior into central
Wisconsin. Despite appreciable forcing, lack of a more coherent and
and focused axis of moisture advection resulting in only light and
disorganized showers along and ahead of this front. Those gusty
southwest winds have ushered in a bit milder airmass across northern
Michigan, with temperatures across much of northern lower punching
up into the 40s this afternoon.

Upstream wave and its attendant cold front will continue to dig
southeast, cutting across our area tonight into early Saturday.
Impressive shot of modified polar air set to follow the passage of
these, resulting in much colder weather for the start of the
weekend.

Primary Forecast Concerns:

Impacts from passing intense front, to include temperature trends
and rain/snow concerns.

Details:

Expect at least a broken band of showers to accompany the frontal
passage this evening, with a transition to snow as cold air advection
intensifies immediately behind frontal passage. Again, deep layer
moisture component is significantly lacking, suggesting only minimal
snow accumulations. Still, rapidly falling temperatures will result
in a quick freeze of initial wet roadways, likely resulting in some
slick driving conditions on those secondary and untreated road
surfaces. North-northwest flow lake component set to develop quickly
behind the front. Despite a developing impressive over-water thermal
gradient as H8 temperatures drop into the negative teens, quick loss
of any synoptic moisture contribution should throttle back on lake
snow intensity. Probably looking at an additional inch or so of wind
driven snow by morning, greatest centered southeast of Grand
Traverse Bay.

Shot of some true winter-like temperatures arrive for Saturday, with
top-down thermal analysis supporting highs only reaching the 20s
across a vast majority of the area...with downslope areas down near
Saginaw Bay perhaps tacking on a few more degrees. Gusty northwest
winds will of course make it feel several degrees colder. Boundary
layer moisture will continue to erode and convective cloud depths
decrease with time on Saturday, again throttling back on lake snow
organization...despite the maintenance of an excellent over-water
thermal gradient. Expect mostly light and disorganized north-
northwest flow lake-induced snow showers to continue...especially
during the morning. Looking at another inch or so of new
snow...again "heaviest" centered southeast of Grand Traverse Bay.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 309 PM EDT Fri Mar 21 2025

Pattern Synopsis and Forecast:

Brief shortwave ridging moves overhead Saturday night into early
Sunday, displaced through the day by an incoming upper low and
subsequent sfc low. Upper low and sfc feature will track through or
in the vicinity of the Straits region, with a band of precipitation
spreading through N MI Sunday afternoon and evening. Winds will be
breezy to windy at times, but not always as the low tracks overhead
leading to lulls in certain areas. Thermal environment suggests
marginal temperatures, at least initially across northern lower the
farther south you go, and thus not a whole lot of efficient
accumulation. There will be a better region of lift and sustained
snow across the E UP (perhaps leaking down into the Straits) due to
the track of the aforementioned features. Thus, best potential for
modest snowfall accumulations will be across eastern upper, but
accumulating snow will be possible most locations. Most guidance
shows a modest to moderate potential (30 to 60%) for 4 inches of
snow across Eastern Upper, and lower probs (generally <30%) most
other areas across northern lower, which makes sense conceptually.
As this system departs to the east, colder northwest flow,
reinforced by a shortwave moving through after the system moves out
on Tuesday, will result in a transition to lake effect snow/snow
showers at times early next week. Quick look at progged soundings
during the transition to lake effect suggests a marginal environment
in regards to low level temps and inversion heights, and so a couple
of inches for northwest snowbelts looks possible but this will be
fine tuned for sure in the coming days.

Almost synchronized with the short wave later Tuesday will be another
feature diving south across in the vicinity of the OH Valley.
Current indications are this energy will be too far south for
impacts, with another quick moving frontal feature later Wed-Thurs.
Looks minimal in regards to QPF with this feature. Later in the
period Friday into the weekend has the potential to be active, but
plenty of uncertainty remains looking at ENS pressure centers.
Temperatures through next week will be within a couple degrees of
normal as far as high temperatures are concerned (mid 30s to low 40s
most areas).

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 739 PM EDT Fri Mar 21 2025

A quick-hitting band of rain and snow showers will cross
northern MI early tonight, with light lake effect snow lingering
later tonight in nw lower MI. MVFR cigs will develop across the
area, and brief IFR vsbys are possible.

Current somewhat gusty sw winds will veer nw-nnw tonight and
remain blustery.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 5 PM EDT Saturday for LHZ345>349.
     Small Craft Advisory until 5 PM EDT Saturday for LMZ323-341-
     342-344>346.
     Small Craft Advisory until 5 PM EDT Saturday for LSZ321-322.

&&

$$

SHORT TERM...MSB
LONG TERM...JLD
AVIATION...JZ