Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 281947
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
347 PM EDT Thu Mar 28 2024

.KEY MESSAGES...

- Lake effect snow diminishes this evening and tonight.
- Next chance of widespread precipitation occurs Friday night and
Saturday. A quick round of around 2 inches of wet snow is expected,
with a 15-30% chance of light freezing rain in the interior west.
- Another system arrives in the Great Lakes Mon/Tue, bringing
chances for rain/snow.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 123 PM EDT Thu Mar 28 2024

GOES 16 visible imagery on loop show the continued cloud cover
stretching downwind of Lake Superior into Upper Michigan thanks to
continued cyclonic flow tied to an exiting mid-upper level low and
lake induced instability. Within this flow, snow showers have
persisted into the Keweenaw, as have light snow or flurries across
the Michigamme Highlands and Gogebic Range per webcams and surface
obs. The overall trend though has been decreasing activity, thanks
to mid-level ridging inching across the Northern Plains and surface
high sliding into Wisconsin. This is supporting increasing dry air
into the column. Daytime highs have so far climbed into the 20s
across the west and low 30s south and east.

For the remainder of today and tonight, snow shower activity should
continue to diminish in the Keweenaw and west half, but increase
some across the east near Lake Superior thanks to increasing surface
convergence associated with a weak surface trough. Additional snow
accumulations should be less then an inch. Elsewhere, conditions
should be dry. Light winds set in across the region with lows
dipping into the teens interior west and near 20 or low 20s
elsewhere.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 346 PM EDT Thu Mar 28 2024

An active weather pattern will remain in the mid latitudes for the
long term forecast period. A 500mb ridge will build in to provide
dry weather Friday ahead of an approaching shortwave riding the
US/Canada border. This will bring a quick round of mainly light
precipitation before conditions aloft go zonal to slightly ridging,
which should usher in seasonal, if quiet, weather into next week. A
deeper trough then ejects out of the Rockies, which may bring
impactful weather to the UP, but will be highly sensitive to minor
variations in the track of the resulting surface low pressure. The
end of next week looks dry as ridging builds back over the Upper
Great Lakes.

Friday, approaching surface ridging will end snow showers at or
before 12Z. The 12Z HREF shows a brief period of scattered to clear
skies before high clouds build in from the west. The HREF also shows
a lake breeze off of both Lakes Michigan and Superior, which will
help moderate lakeshore temperatures somewhat, but not before
temperatures in the southern UP climb into the mid 40s.

The calm will be interrupted by a shortwave that will be
traveling along the USA/Canada border through Saturday. This
will support a weak 1005 mb (12Z GEFS mean) surface low pressure
passing through the Upper Great Lakes and precipitation chances
begin over the UP around midnight Friday into Saturday. With
surface temperatures in the low 30s and upper 20s overnight, wet
10:1 - 15:1 snow should be the dominant precip type, but the
LREF shows about a 15-30% chance of FZRA in the interior west
and ~15% chances of rain or sleet elsewhere. Even on that chance
that FZRA forms, not much glaze should form given the previous
warmer temperatures heating up the ground. LREF QPF accumulation
probabilities show a 40% chance that the western UP could
exceed 0.25 inches, dropping to 10-20% in the central UP. This
works out to roughly 2 inches of wet snow accumulation Saturday,
which could locally cause some sloppy travel conditions, but
widespread winter impacts should be minimal.

-Flow goes zonal Sun despite shortwave passing to the north due to
amplifying southeast CONUS ridging and surface high dropping south
along the western shores of Hudson Bay
-This high may depress approaching Colorado Low too far south, but
model spread is high
-Keeping PoPs despite historically these setups aren`t favorable
plus trend lately given persistent chances for impactful weather
-Dry wx to follow

Following the passage of the shortwave, the flow aloft goes
zonal even in spite of a stronger shortwave passing to the north
on Sunday. This is due to a ridge over the southeastern US
amplifying, and as a result, Sunday into Monday should be mostly
quiet with near- seasonal temperatures. Upstream, a deeper
trough will be exiting the Rockies, supporting a deep Colorado
Low which will arrive in the Upper Great Lakes Tuesday. The GEFS
shows some of these low centers falling into the 970s mb,
though the mean is closer to 990mb. It will bear some monitoring
how this low interacts with a surface high following the
western shores of Hudson Bay from north to south ahead of the
low`s arrival. NBM PoPs have trended south the last couple of
runs, signaling that the high may be depressing the low too far
south. Given how storms lately have generally trended south with
consecutive model runs and how positively-tilted troughs
without a supporting northern stream shortwave have not
supported significant systems, forecaster confidence is
pessimistic about the potential for impactful weather next week.
However, with almost half of the LREF showing 6 inches of more
of accumulated snowfall by the end of next week, the potential
of higher winter impacts is too high to ignore. Ridging should
build in behind the passage of the low, providing dry weather to
end the week, though a brief period of LES following the low
cannot be ruled out.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 123 PM EDT Thu Mar 28 2024

Lake effect snow showers and cloud cover will continue this
afternoon and overnight. Most, if not all, snow shower activity
should be limited to KCMX with the trend being diminishing activity
this evening. Gusty westerly winds upwards of 25-30 kts and blowing
snow will also continue into the evening hours at KCMX. Ceilings
will gradually lift to VFR this evening and overnight at all sites.

&&

.MARINE...
Issued at 346 PM EDT Thu Mar 28 2024

With low pressure departing to the north and high pressure building
in, westerly winds 25-30 kt over Lake Superior will veer
northwesterly and fall below 20 kt by Friday morning. A weak low
pressure passing in the vicinity of Lake Superior overnight Friday
into Saturday will briefly cause northeasterly winds to funnel in
the west half of the lake, resulting in gusts to 25 kt. Otherwise,
under weak surface pressure gradients, Lake Superior will remain
below 20 kt winds until the middle of next week when a stronger low
pressure passing through the Great Lakes basin will increase wind
gusts, but uncertainty is high about track, timing, and intensity of
the low pressure.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 8 PM EDT /7 PM CDT/ this evening
     for LSZ240.

  Small Craft Advisory until 2 AM EDT /1 AM CDT/ Friday for
     LSZ241>243.

  Small Craft Advisory until 6 AM EDT Friday for LSZ244.

  Small Craft Advisory until 2 PM EDT Friday for LSZ250-251.

Lake Michigan...
None.

&&

$$

SHORT TERM...JTP
LONG TERM...GS
AVIATION...JTP
MARINE...GS


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