Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 222051 CCA
AFDMQT

Area Forecast Discussion...CORRECTED
National Weather Service Marquette MI
451 PM EDT Fri Mar 22 2024

.KEY MESSAGES...

- Some light lake-effect snow is possible along the north snow
  belts late tonight into Saturday. Only a dusting is expected.
- Late season winter storm lifting northeast from Colorado early next
  week will bring accumulating snow, several inches possible,
  late Sunday into early Monday before a changeover to rain.
  Hazardous travel expected Sunday night into Monday morning.
- Easterly gales of 35 to 45 knots are possible Monday into Monday
  evening across Lake Superior.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 235 PM EDT Fri Mar 22 2024

As sfc inverted troughing leaves the area the rest of this afternoon
through tonight, we will see the light snowfall across the area end
across the central and east. While we did see a few enhanced bands
of snowfall where possibly moderate snowfall was being seen, given
the transient nature of the bands only an extra fluffy inch or two
was likely seen, mainly over Delta and Schoolcraft counties. That
being said, we are seeing an uptick in reflectivities over the
central early this afternoon via being near the right entrance of a
jet streak. This is highlighting an uptick in snowfall rates due to
the increased synoptic uplift. Therefore, we could see an additional
dusting up to an inch in the central and east before the system snow
gets out of here.

Once the system snowfall gets out of here, expect clearing across
the area this evening. However, with troughing remaining from 850mbs
on up, we could see some light lake-effect snow showers develop over
the north snow belts late tonight. However, with ridging and drier
air in the lowest levels of the atmosphere, thinking accumulations
will be limited to just a dusting. Otherwise, with the clearing
occurring over the area tonight, expect lows to get into the teens
to single digits in the interior west.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 437 PM EDT Fri Mar 22 2024

Significant changes in the flow across N America will occur during
the long term. Fairly deep northern stream troffing is currently
present from eastern Canada to New England, with an embedded
shortwave traversing the area today keeping in widely scattered snow
showers. These start to taper off Saturday with surface ridging and
drier air working in. A longer fetch off of Superior may keep in
some light flurries and snow showers across the NW wind snow belts
in the eastern UP through Saturday, otherwise expect more breaks of
sunshine elsewhere. Temperatures peak in the lower 20s to lower 30s,
warmest in the south-central and where we can see more sunshine.

Meanwhile, a large mid-level low is located off of the West Coast.
In the coming days, that mid-level low will shift into the western
U.S. where flow will become more consolidated into an evolving
deepening trough. The trough will shift out over the central U.S.
during the first half of next week, but the negative height
anomalies will diminish with time as the trough progresses
downstream, suggesting that the initial associated surface low will
also weaken with time. Under the strong WAA regime forced
downstream, snow will spread n into Upper MI late in the weekend,
but with persistent WAA and eventual surface low track over between
northeast MN and the western UP later in the day Tuesday, the snow
will transition to rain Monday into Monday evening. Rain showers
will continue into Tuesday until cold fropa which will bring a
transition to some lighter snow showers into Wednesday.

Northern/southern streams will begin to become more separate again
as the axis of the weakening trough reaches the Great Lakes Wed/Thu
and begins to phase with another clipper-like system that will be
moving into Ontario. During the midweek period, a shortwave will
swing onshore into the western U.S. This wave will progress
downstream, likely passing across the Ohio Valley late week.
Models have been suggesting that the late week wave will pass too
far to the south to bring any precipitation into Upper MI, so we may
be generally dry after Wednesday apart from just some lingering light
LES Thursday. A little farther down the road, another trough will be
amplifying into the western U.S. next weekend. Ensembles are
indicating that this  could go on to produce widespread
precipitation from the Plains eastward, including Upper MI, during
the first days of April. Accumulating snow would be a possibility as
well.

Meanwhile, expect below-normal early in the period to climb above
average for Tuesday. Temperatures will settle back to around or a
little below normal as the mid-level trough passes Wed/Thu.

As far as particulars for the upcoming winter storm:

Though light snow may begin to spread into the area early in the
day, the main surge of strengthening waa/isentropic ascent will
advance into the area late Sunday into Sunday night, reflected
in our highest PoPs and QPF arriving 00Z Monday. Guidance
continues to indicate that ascent will be strongest across the
western UP Sunday night, with the left exit region of the LLJ
directed over the area. Ascent diminishes to the east, so snow
will be lightest there. Ensembles indicate a widespread quarter
to half inches of QPF by Monday morning, and with SLRs starting
off around 20:1 Sunday and slowly falling into Monday morning,
we could be looking at a widespread 3-6in by across the western
UP, with locally higher amounts possible. Lighter amounts
generally around 2-4in are expected to the east. Would expect
hazardous travel conditions to develop across Upper MI Sun night
into Monday morning.

A surge of drier air will likely cut off snow across the central and
eastern UP, and the western UP may even see a brief dry period early
Monday. However, with WAA continuing and the left exit region of the
upper jet moving over the area lending some divergence aloft, expect
steadier precip to develop again by Monday afternoon. Ptype issues
will come into play with snow likely mixing with rain and changing
over to rain entirely from south to north later in the day Monday.
Uncertainty in how quickly snow changes to rain persists, but the
changeover will occur last over nw Upper MI. There is also more
uncertainty in whether this next push of isentropic ascent on Monday
will result in steady, light precipitation, or moderate to heavy
precip rates. At the very least, would not be surprised by some
locally higher QPF across the eastern UP where southeast flow is off
of Lake Michigan, and elsewhere across the UP where upsloping occurs.

Rain lingers Monday night at least through Tuesday morning as the
surface low slowly moves northward between the western UP or
northeast MN, followed by cold fropa into Tuesday evening. Light
snow showers will follow Tue night, lingering through Wednesday
before tapering off into Thursday. Any snow accumulations would be
light. Dry weather will follow on Fri.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 138 PM EDT Fri Mar 22 2024

Conditions will gradually improve this afternoon as the inverted
trough leaves the area and sfc ridging moves overhead. However, with
troughing remaining higher up in the atmosphere, some lake-effect
snow showers could develop across the TAF sites late tonight, mainly
over KSAW and KCMX. These showers could (50% chance) drop conditions
back down to IFR/MVFR late tonight into Saturday.

&&

.MARINE...
Issued at 437 PM EDT Fri Mar 22 2024

Winds generally out of the NW continue to gust to around 20 knots
this afternoon, increasing to around 20-25 knots for tonight with
colder air flowing into the area. Winds will then diminish to mostly
under 15kt on Saturday as high pressure builds over the lake. As the
high then shifts east and deep low pressure develops over eastern CO
on Sunday, SE to E winds will begin to ramp up, reaching 20-30kt
over far western Lake Superior and around 20kt across the east by
late afternoon. Winds increase further Sun night/Mon as the low
lifts northeastward. Winds up to 30kt are expected across much of
Lake Superior Sun night with gale potential increasing to 60-75pct
by Mon morning - especially across western Lake Superior. Easterly
gales of 35-40kt are expected for Mon/Mon night, with a potential
(around 40%) for higher-end gales. As low pressure lifts to western
Lake Superior on Tue, winds will begin to diminish, but gale-force
gusts will still be possible across the eastern half of the lake.
Winds remain elevated at around 20-30 knots into the midweek period.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from Monday morning through late Monday night for
     LSZ162-243>245-251-263-264-266-267.

  Small Craft Advisory from midnight EDT /11 PM CDT/ tonight to
     8 AM EDT /7 AM CDT/ Saturday for LSZ240.

  Small Craft Advisory from midnight EDT /11 PM CDT/ tonight to
     10 AM EDT /9 AM CDT/ Saturday for LSZ241>243.

  Small Craft Advisory from midnight tonight to noon EDT
     Saturday for LSZ244.

  Small Craft Advisory from 2 AM to 2 PM EDT Saturday for LSZ248-
     251.

  Small Craft Advisory from 2 AM to 4 PM EDT Saturday for LSZ249-
     250.

Lake Michigan...
None.

&&

$$

SHORT TERM...TAP
LONG TERM...LC
AVIATION...TAP
MARINE...LC


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