Saginaw, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

178
FXUS63 KDTX 031021
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
521 AM EST Tue Dec 3 2024

.KEY MESSAGES...

- Snow showers and minor snow accumulations of an inch or two are
possible Wednesday afternoon and Wednesday night.

- 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...

For this morning, there remains a low-end chance that any prolonged
clearing can lead to visibility reductions of 3SM or less and
possibly IFR cig development, but this has held off so far across SE
MI, while staying confined to western Michigan. KMBS to KFNT would
be the most susceptible to clearing trends based on current satellite
observations. Otherwise, winds back from west to southwest today,
releasing lake moisture inland. This will increase cloud coverage
through the day, possibly bringing a brief window for MVFR between
the 00Z-04Z window as some of the lower based clouds that are
projected to pool around the southern Lake Michigan basin release
northeast. Improving cig heights quickly follow this last release of
lake moisture overnight. Wind speeds and gust quickly ramp overnight
where gusts of 20-25 knots will be likely.

 DTW THRESHOLD PROBABILITIES...

*  High for ceilings 5000 ft or less this morning, moderate
   for this afternoon.

&&

.PREV DISCUSSION...
Issued at 312 AM EST Tue Dec 3 2024

DISCUSSION...

The forecast concerns through the short term involve the forecast
amplification of a mid level wave now over NW Canada, forecast to
evolve into a deep upper low as it crosses the Great Lakes region
Wednesday into Thursday. The last couple runs of model deterministic
solutions have trended a little farther south into the Great Lakes
with the track of the mid level low. Overall, the forecast concerns
the last couple days with respect to snow chances, gusty winds and
cold temperatures with this system remain valid.

For today, there will be subtle mid level height rises across the
western Great Lakes while sfc high pressure expands across the Ohio
Valley. The low level wind fields will in turn back to the southwest
by late this afternoon. The backing wind fields will push ongoing
morning lake effect activity over the thumb offshore. Model
soundings and RH plan views do suggest that there will be some
influx of lower clouds and perhaps a few flurries as the flow
drives remnant Lake Michigan activity inland. Overall, ample cloud
variability will offer enough solar insolation to drive afternoon
highs back into the 30s. Mid level clouds will then increase across
the forecast area tonight as broad mid level isentropic ascent
overspread the Great Lakes in advance of the aforementioned mid
level wave approaching from Canada. Per model soundings, the low
levels will remain quite dry. Toward Wednesday morning, mid level
lapse rates are forecast to steepen, which may support some
flurries. Model soundings across the thumb region in particular
indicate enough low level moistening by morning to support high
chances for light snow, with minimal accumulations.

The region of mid level ascent is then forecast to slide east by mid-
late Wed morning, opening the door to some drier mid level air to
overspread Se Mi. Meanwhile, model soundings indicate the low levels
moistening under increasing southerly flow preceding the deepening
upper low, although not quite to the degree of some earlier model
runs. Large scale dynamics will then come into play Wed
afternoon/evening as the compact mid level low plunges southward
into the Great Lakes. Mid level positive PV advection and good
divergence within a cyclonically curved jet max on the 1.5 PV
surface will result in a period of good ascent late day Wednesday.
Steep mid level lapse rates will also contribute to a brief period
of respectable lift. Model soundings suggest enough saturation to
support a burst of snow with the ascent. Rapid post frontal cold air
advection will then support a period of decent snow shower activity
Wed night. Given the brevity of the better large scale forcing,
total QPF will likely just be a couple tenths of an inch or less.
Snow-liquid ratios will also increase from 10:1 at the start of the
event to 16:1 by late Wed evening. Based on this and available prob
guidance an inch or two of accumulation seems reasonable, with
locally higher amounts possible in higher intensity snow showers Wed
night.

There will be a rapid steepening of the low level lapse rates Wed
night as this upper low drives arctic air (850mb temps to -20C over
Wisconsin) across the region. Model soundings actually suggest near
dry adiabatic lapse rates to 700mb Wed night with a solid region of
35-40 knots within the mixed layer. Good downward momentum
transport will ensue late WEd night into Thurs morning as the upper
low exits the region to the east and even takes on a negative tilt.
This will result in strong winds Wed night-Thurs. Model soundings
and probabilistic wind guidance suggest a marginal wind advisory
event possible, with wind gusts in the 35 to 45 MPH range. Combined
with the arctic air, wind chill readings will be in the single
digits. The prevailing northwest flow will keep the more intense
lake effect activity west and northwest of Se Mi. Sfc high pressure
is then forecast to quickly expand into the area Friday while a
moderating trend then gets underway during the weekend.

MARINE...

Active stretch of marine weather will occur through the mid week
period as a strong clipper tracks across the northern Great Lakes
Wednesday and Thursday. Today will start off without much fan fair
as northerly winds decrease a bit early in the day while backing to
the southwest by this evening. A quick ramp up of winds will then
occur tonight which could lead to a round of southwesterly gales
funneling through Saginaw Bay and out into Central Lake Huron. The
clipper then pulls a cold front across the region Wednesday evening
which will bring about stronger northwesterly flow due to intrusion
of cold air and will necessitate a Gale Watch across all of Lake
Huron and Lake St Clair through Thursday evening. Snow squalls will
also be likely on Thursday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Watch from Wednesday evening through Thursday evening for
     LHZ361-362-441>443-462>464.

     Gale Watch from this evening through Thursday evening for LHZ363-
     421-422.

Lake St Clair...Gale Watch from Wednesday evening through Thursday evening for
     LCZ460.

Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....AM
DISCUSSION...SC
MARINE.......DRK


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