Saginaw, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

407
FXUS63 KDTX 040502
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1202 AM EST Wed Dec 4 2024

.KEY MESSAGES...

- Snow showers are possible over the Thumb Wednesday morning with
these chances expanding over the rest of the area by the latter half
of the day.

- An arctic cold front crosses the area during the evening which is
expected to support convective snow showers. Snow squalls are likely
within this activity with gusts up to around 40-45mph producing near
whiteout conditions. With arctic air quickly following overnight,
any melting that occurs on untreated roadways will quickly freeze.

- West to northwest wind gusts of 35 to 45 MPH are expected
Wednesday night and Thursday.

- Wind chill readings will plunge into the teens and single digits
Wednesday night and Thursday as arctic air advances across the
region.

- A slight warming trend is forecast this weekend.

&&

.AVIATION...

Extended period of warm air advection overnight and early Wednesday
ahead of an intense low pressure system tracking across the northern
great lakes will lead to some variability in low level moisture
quality early in the period. Lower stratus tied to the advective
process now lifting north across portions of Indiana. Potential
remains for some degree of this cloud to enter southeast Michigan
late tonight and particularly Wednesday morning, bringing a return
of MVFR restrictions. Greater low level saturation will commence
throughout Wednesday, supporting a more widespread expansion of MVFR
stratus with some prospective flurries or brief snow showers
plausible into the afternoon. A more focused window for intense snow
showers/squalls centered on Wednesday evening, offering a rapid
reduction in visibility and a quick accumulation of snow. Gusty
southwest winds in excess of 25 knots through the afternoon,
shifting to west-northwest and turning even gustier with the passage
of an arctic front Wednesday night.

For DTW...Potential for a period of intense snow showers/squalls
Wednesday evening /00z-03z/. Gusty west-northwest will develop with
the passage of a strong arctic front Wednesday, reaching in excess
of 35 knots at times.

 DTW THRESHOLD PROBABILITIES...

*  Low for ceilings 5000 ft or less tonight. Medium Wednesday
   morning. High Wednesday afternoon and evening.

*  High precipitation type as snow Wednesday afternoon and evening.

*  High to reach crosswinds thresholds Wednesday night.

&&

.PREV DISCUSSION...
Issued at 324 PM EST Tue Dec 3 2024

DISCUSSION...

Southwest flow is developing this afternoon in advance of a clipper
system dropping out of northern Canada towards the upper Great
Lakes. WAA that accompanies this flow lags by a couple hours
offering a brief window where remnant lake effect snow showers from
SW lower MI could creep into the Shiawassee/Tri-Cities/western Thumb
area this early this evening. Activity will be decaying by this
point as lake effect is being cut off by warming lower levels so
expectation is only for some flurries or spotty light snow showers.
Lead vorticity/height falls reach the area by Wednesday morning
coinciding with steepening mid-level lapse rates, particularly the
Thumb. Soundings show deeper saturation compared to yesterday`s runs
supporting better ice nuclei to support spotty flurries within this
steepening lapse rate environment (rather than spotty freezing
drizzle that was looking favored from prior model cycles). Soundings
over the Thumb show the greatest moisture depth which given its
better placement to lead height falls, likely supports light snow
showers and minor accumulations through the morning.

Maturing low reaches the northern Lake Huron shore latter half of
the day Wednesday as its parent mid-level trough drives directly
over southern lower MI. Strong jet streak along the base of the
trough sinks south into northern IN/OH providing additional upper
divergence as its left exit region sets up over SE MI. Following a
midday lull, lead cold front is set to cross the region during the
afternoon bringing the next chances for snow showers. Models are
varying to what degree activity is able to develop along it owing to
it preceding the main mid-level trough and subsequent strongest
lift. Moisture quality within this system isn`t anything remarkable
with the strength of ascent being the driving factor for both
coverage and intensities. Given the better saturation depths over
the northern CWA from the morning, thinking is these areas would
have the best chance to see light snow showers develop along this
front- only minor accumulations possible.

Focus is on Wednesday evening into the early overnight period with
the arrival of the arctic cold front and mid-upper trough. Clipper
reaches peak strength during this timeframe as it matures into a
closed low near the Georgian Bay shoreline. Local gradient tightens
in response with 35-45kt flow likely within the lowest 10kft. Due to
the passage of the prior cold front, strengthening CAA results in
the development of convective instability (>30 J/kg) and increasing
convective depths which are further magnified along/immediately
behind the arctic front- convective depths spike to at or above
10kft feet. Given the strength of frontal forcing and upper synoptic
support, numerous convective snow showers are likely with the
passage of the arctic front. Additionally, snow squalls are
extremely favorable in this environment with snow squall parameters
well in excess of 1 due to the potential for brief but intense snow
rates and strong wind field as gusts reach the 40-45mph range. Rates
under these convective snow showers could easily be over 0.5"/hr
especially if a mesovortex develops which some of the hi-res
solutions show signal for. The speed of the frontal progression is
the limiting factor for accumulations as snow showers/squalls only
linger over locales for an hour or two. Prior forecast of 1-2" still
looks most reasonable at this time, however locally higher totals
not out of the realm of possibility for the reasons above.

Core of the arctic airmass settles across the Great Lakes Wednesday
night as the mid-upper trough shifts over the eastern Great Lakes.
Northwest wind gusts strengthen through the night as low level lapse
rates steepen and mixing depths still hold around 4-5kft. Forecast
soundings still are marginal for gusts reaching wind advisory
criteria (45mph) with the 45-50kt flow residing just above forecast
mixing heights. Running forecast will still hold sub-advisory with
Thursday morning gusts up around 40mph. Regardless, wind chills
crater, falling into the single digits. Breezy conditions linger
through the day Thursday keeping feels like temps only in the teens.
High pressure gradually builds into the region late this week with
warming trends possible by this weekend.

MARINE...

The deepening mid week low is now over Manitoba and still
strengthening. The strong high to our south is now centered over
TN/KY and the combination of the two system will act to strengthen
the pressure gradient through this evening and overnight. This will
result in the first round of Gales over Saginaw Bay and Central Lake
Huron. The clipper then tracks across the northern Great Lakes
Wednesday and Wednesday night, while pulling a cold front across the
region Wednesday evening. This will flip the winds around to the
northwest with quick intrusion of cold unstable air. We`ll hold onto
the Gale Watch Wednesday night and Thursday across all of Lake Huron
and Lake St Clair through Thursday evening. Already issued Gale
Warning for Lake Erie after coordinating with our neighboring
office. Snow squalls will also be likely on Thursday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 10 PM this evening to 10 PM EST Thursday for
     LHZ361-362-441>443-462>464.

     Gale Warning until 10 PM EST Thursday for LHZ363-421-422.

     Small Craft Advisory until 10 PM EST this evening for LHZ441>443.

Lake St Clair...Small Craft Advisory until 10 PM EST this evening for LCZ460.

     Gale Warning from 10 PM this evening to 1 PM EST Thursday for
     LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 7 PM EST this evening for LEZ444.

     Low Water Advisory until 1 AM EST Thursday for LEZ444.

     Gale Warning from 7 PM this evening to 1 PM EST Thursday for LEZ444.

&&

$$

AVIATION.....MR
DISCUSSION...KDK
MARINE.......DRK


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