National Weather Service - Area Forecast Discussion
143
FXUS63 KAPX 161749
AFDAPX
Area Forecast Discussion
National Weather Service Gaylord MI
149 PM EDT Sun Mar 16 2025
.KEY MESSAGES...
- Northern Michigan reality check today...much colder with
accumulating snow.
- Potential wintry weather mid to late week
&&
.UPDATE...
Issued at 1013 AM EDT Sun Mar 16 2025
Couple of observations this morning, it`s taken a little longer
for some of the colder temperatures to advect east and
southeastward, at least by a little. Perhaps it was/is briefly
struggling to get up and over/through the higher terrain this
morning. But since then, the office up on the hill here has
transitioned to snow, with big wet flakes and accumulations
starting. Mackinaw city and vicinity has seen some very heavy
spurts of snow as noted by the webcam, among other obs along and
west of I-75 showing snow as well. Heaviest band of
precipitation believe has shifted every so slightly to the east
compared to yesterday, but despite this, snows still remain
across the Lake Michigan coastal region. Since this shift has
occurred, in conjunction with KGOV & KPQZ becoming snow for
quite a while not, added Crawford and Presque Isle counties to
the advisories. Generally another couple of additional inches
of wetter snows and heavier snowfall rates through this
afternoon and evening. Certainly not a high end advisory but
it`s wintry out there with slick road conditions. Current
thinking is the have western portions of the advisory end at
21Z, extending some of the rest until 00Z.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 321 AM EDT Sun Mar 16 2025
Pattern Synopsis/Forecast:
Complicated regime out there early this morning, with dual cold
fronts working east across the region. Primary cold front with
attendant much more aggressive surge of cold air advection just now
beginning to work into far western and northern sections of the
area, as evident by temperatures dropping into the 30s across
eastern upper Michigan into some of the collar counties of northern
Lake Michigan. Several degrees milder the further east one goes,
with some areas down near Saginaw Bay still in the 50s. Secondary
surge of rain slowly working its way north into lower Michigan,
driving by isentropic ascent/maturing deformation tied to strong
shortwave trough rotating northeast out of the central Plains. Nice
corridor of enhanced pressure falls along the primary cold front to
our south in Indiana, indicative of developing surface low pressure
in response to that approaching wave.
Primary cold front and corridor of rather intense cold air advection
will continue to work slowly east today, all-the-while that upstream
shortwave and maturing surface low work northeast into the Great
Lakes. This sets the stage for an abrupt return to winter-like
weather across the Northwoods, with falling temperatures and a round
of impactful accumulating snow.
Primary Forecast Concerns:
Main focus on snow evolution/attendant amounts and headline
considerations today.
Details:
Complicated forecast today as steady cold air advection undercuts
maturing and what looks to be a relatively moisture rich deformation
axis. Expect precipitation to continue to expand/blossom north in
response to that shortwave and developing surface low, with the
latter expected to cut across southeast lower Michigan this
morning... reaching vicinity Georgian Bay by early this afternoon.
Of course, precipitation type will be ultra sensitive to thermal
trends. Expect precipitation to transition to a snow from west to
east today, with a likely short window for a wintry mix within the
eastward pivoting transition axis. Guidance derived soundings
continue to show a respectable signature for some decent snowfall
rates, with deep vertical moisture and lift within that moisture
rich environment (although corridor of primary lift may fall just
short of an elevated dendritic growth layer). Gradual cooling
profiles through the vertical will also support improving snow to
liquid ratios with time. Still some lingering uncertainty where best
juxtaposition of forcing, moisture, and most aggressive cooling will
occur...as to be expected with such a focused thermal gradient. With
that said, there does appear to a bit further and quicker
displacement with all the above in the latest hi-res guidance
suite...a trend at least partially supported by real-time satellite
and upstream radar observations. Evening forecaster used these
trends to expand inherited winter weather advisory a row of counties
further south. Will leave headlines as they are for now, with an
expected 2 to 6 inches within the headline areas of northwest lower
and eastern sections of eastern upper Michigan....with most of that
likely occurring this morning into early this afternoon. If east
trends continue, could easily see the need to expand these headlines
another row of counties east. Increasingly gusty northwest winds
will of course usher in much colder temperatures, with readings
falling into the 20s and 30s through the day. Those gusty winds will
also likely produce some blowing snow, although loss of snowcover in
recent days will limit this potential some.
High pressure builds rapidly into the area tonight, bringing with it
dry conditions and gradually clearing skies. Those clearing skies
and some fresh snow cover will allow temperatures to drop into the
teens across most of the interior. Sometimes Mother Nature can be
downright rude...lol.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 321 AM EDT Sun Mar 16 2025
PATTERN SYNOPSIS/FORECAST:
Longwave troughing encompasses the central US/Canada...with various
perturbations amid the broader flow, including our dear departing
upper low...now spinning up into Ontario as of 3z. Sharp baroclinic
zone stretches across the area from this system down into eastern
TX...with 140+kt upper jet over Michigan. Bulk of the deepest
moisture trapped across the Gulf Coast states with a system tracking
through the TN Valley on the nose of 120+kt upper jet...though some
better pwats still trying to eke northward into the OH Valley. 700mb
trough axis over IA into northern MO where cloud tops are beginning
to cool along a deformation axis. Excellent cold advection across
the central US and Canada in the wake of all of this activity...with
a much more potent system over Manitoba, where 850mb temps fall into
the -16C range.
Another wave spinning up along the lingering boundary will move
northeastward across the area today. Broader trough will track
through the region into tonight...with ridging trying to build into
the Upper Midwest by Monday. However...northern stream activity
zipping across southern Canada looks to keep ridge tamped down a
bit...potentially bringing a bit of activity to our area for
Monday/Monday night. Baroclinic zone then stalls SW-NE across the
country...waiting with bated breath as troughing digs across
California...into the central US by midweek. Yet another strong
surface low expected to develop over the central US as a
result...with current expectation for this to try to track into the
Upper Great Lakes during the Wednesday/Thursday timeframe...bringing
an excellent shot at precipitation to the region. Think we will
remain active going into late week behind the primary system...as
additional PV digs into the back of the trough and reinforces the
cold, northwest-flow idea over the Great Lakes for a time. Pattern
appears rather progressive, though...with signals for yet another
system trying to form across the central US by next weekend...but
still quite a bit of time...and quite a bit of forecast
concerns to contend with...between now and then.
Primary Forecast Concerns:
Rain/snow/wintry precip midweek...Stalled boundary combined with
some marginal theta-e advection should lead to development of a
swath of synoptic precip largely along and north of said boundary
starting as early as Tuesday night for us. Question will be where
the boundary ends up...as this will play a large role in a) position
of heaviest precip, and b) how much of the precip will fall as rain
vs snow (not out of the question there could be a corridor of
mix/ice...but less certainty in this idea attm). Further north/west
solution with the boundary would leave much more, if not all, of the
CWA in the warm sector, keeping precipitation largely rain through
the bulk of Wednesday...possibly even focusing the best lift and
moisture convergence north/west of us, which could keep us quieter
than current expectations. Do have concerns this could end up a bit
like the system from a couple weeks ago when MQT ended up with a
bunch of wet snow and we got mainly rain.
However...one of the windows of concern for impacts is Wednesday
night/Thursday as the deformation axis (and potentially efficient
precip) looks to cross the region. Not impossible the SW-NE oriented
deformation axis may hang out over some area for an extended period
of time as it slowly exits ENE...which could further enhance
precip/snow totals if this idea verifies. Additionally...expectation
for N/NW flow to take over ahead of another PV axis trying to dip
into the area Thursday, combined with potential for 850mb temps to
fall below -12C, suggests the Lakes should come into play before
this system is all said and done. Not sure that it will be "pure"
lake effect, particularly if we are still under the axis of better
synoptic moisture as the lake machine kicks on...which could lead to
some enhanced snowfall totals as well. Combined with signals for
better winds again with this system...could certainly be looking at
a rather dreary/wintry mid-late week...a stark contrast to what
we`ve gotten used to in the last week or so. Definitely worth
keeping an eye on, as current signals point toward some kind of
higher QPF/snow event over some portion of the Upper Midwest/Great
Lakes for Wednesday/Thursday.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 144 PM EDT Sun Mar 16 2025
SN/SHSN will continue through 00Z, diminishing from west to east
across northern MI. Much of the terminals will see SHSN subside AOB
20-22Z, exception being KAPN which will be a few hours later, with
dry conditions expected through the rest of the period. Thus,
MVFR/IFR CIGs/VIS through the early afternoon become VFR for many
tonight, especially after 00Z. There will be periods of LIFR at
times through about 21Z, due to VSBYs within SN/+SN. Winds through
the rest of this afternoon remain from the northwest and average 15-
20G25-30KT, decreasing tonight.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 5 PM EDT this afternoon for
MIZ016>018-020>022-025>028-031>033-087-088-096-097-099.
MARINE...Gale Warning until 10 PM EDT this evening for LHZ346>348.
Small Craft Advisory until midnight EDT tonight for LHZ349.
Small Craft Advisory until 10 PM EDT this evening for LMZ323-
344>346.
Small Craft Advisory until midnight EDT tonight for LSZ322.
Gale Warning until 8 PM EDT this evening for LSZ321.
&&
$$
UPDATE...JLD
SHORT TERM...MSB
LONG TERM...FEF
AVIATION...JLD
NWS APX Office Area Forecast Discussion
Lake Huron Weather
