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000
FXUS63 KMQT 132232
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
632 PM EDT Sat Apr 13 2024

.KEY MESSAGES...

- Scattered showers developing late afternoon into tonight with
  maybe a few thunderstorms possible along WI border and south
  central. Overall rain amounts 0.05 to 0.20 inch, highest
  across the Keweenaw and eastern UP.
- Mostly dry weather through Tuesday morning. RHs fall to around
  30% in the interior west Sunday and Monday, causing some fire
  weather concern.
- A low pressure tracks through the Upper Great Lakes during
  the midweek, causing widespread rain showers.
- Chances of precipitation remain possible (~50%) into the late-
  week, though uncertainty exists on timing, intensity, and
  precipitation type.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 317 PM EDT Sat Apr 13 2024

Afternoon RAP analysis shows the weak ridge axis shifting east of
the area, ahead of a weak shortwave moving along hte Ontario/MN
border. Rather dry midlevel air is apparent on water vapor over the
Great Lakes , but deeper moisture is present with the approaching
shortwave. WAA out ahead of this, with a tight theta-e gradient
draped from the UP northwest through the Arrowhead of MN, has
touched off some weak convection that is finally moving across Lake
Superior and the western and north-central UP UP. That said, with
steep surface dewpoint depressions on the order of 20 degrees, and
very dry afternoon NUCAPS soundings, weak radar returns do not
appear to actually be reaching the ground. Apart from the broken
cloud cover streaming in, would expect no more than some sprinkles
or a stray light rain shower the rest of the afternoon.

Otherwise, temperatures are climbing well into the 50s so far across
the western half of the UP, while northerly flow off of Superior is
keeping the eastern UP comparatively cooler, in the lower to mid
50s. The Keweenaw, Meanwhile, is struggling even to get out of the
40s. Across the western half of the UP, we should see many spots
peaking in the 60s while elsewhere temperatures aren`t expected to
budge much more.

Showers continue to stream into the area this evening ahead of the
approaching shortwave, generally along and north of the theta-e
gradient analyzed over the area. This track would largely keep
showers limited to the northern half of the UP before the shortwave
drops through from 03Z onward. Coverage of showers expands ahead of
the associated cold front, with some dynamical support as the right-
exit region of the upper jet streak becomes directed over the area.
However, showers quickly wrap up from 06Z onward as the front moves
out. Weak, elevated instability apparent in soundings will lead to a
chance for some rumbles of thunder across the south-central UP, with
some heavier embedded rainfall amounts possible in storms.
Otherwise, would expect the highest rainfall totals overnight to be
across the Keweenaw, through the north-central and eastern UP. heavy
rainfall is not expected, with amounts topping out below a quarter-
inch.

Skies clear out behind the passing front, but temperatures stay
fairly mild overnight with most of the area bottoming out in the
mid and upper 30s.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 438 PM EDT Sat Apr 13 2024

The extended forecast starts out dry with good agreement in the
model guidance of a more wet and active period for mid next week. A
mid level closed low over CA on Sunday makes its way eastward over
the Rockies by Monday night, lifting northeast over the Central
Plains through Tuesday. Meanwhile, a trough sets up in the Canadian
Prairie Provinces with a east-southeast track set for the rest of the
week. These features continue their trajectories into the Upper
Midwest/Great Lakes, phasing together Wednesday/Wednesday night. The
resulting closed low/trough will then progress eastward through the
weekend as ridging builds back over the western U.S. This is where
guidance begins to really diverge, but northwest flow over the Upper
Great Lakes with shortwaves riding through the region provide
additional chances for precip this weekend into next week.

Starting Sunday, the shortwave fueling tonght`s precip chances will
be located over the northern end of Lake Superior. While model
soundings show low level moisture in the lowest 5kft in the morning
(also visible in PWATs with values around 0.4" to 0.5"), the
shortwave`s associated PVA remains north of the CWA. Drier northwest
flow also erodes the low level moisture, lowering PWATs by ~0.1"
while q-vector divergence is noted over the UP. Overall, this likely
will delay the low level clouds off Lake Superior from clearing as
the shortwave departs to the southeast, but the area will stay dry.
Despite the lingering cloud cover, dry mid levels will help mix down
lower dew point temps, especially in the southern half of the UP.
This would causing RHs to tank in the afternoon, especially in the
interior west near the WI/MI state line where low level lapse rates
approach 6-7C/km. With highs in the upper 40s to mid 50s near Lake
Superior and mid 50s to possibly upper 60s in the interior, min RHs
will be in the upper 20 to mid 30% range. With wind gusts around 15
to 20 mph, counties bordering WI flirt with elevated fire weather
conditions. Will need to monitor these conditions as we get closer.
With sfc high pressure building in from the northwest Sunday night,
dry weather and light winds continue. Temps fall into the 30s.

Dry weather holds through Monday with mid level ridging building
into the region and sfc high pressure extending over the Upper Great
Lakes. While the right entrance region of the upper level jet
approaches the CWA from the southwest during the day, there is no
significant shortwave providing PVA. Also weak q-vector convergence
looks to remain outside the CWA, yielding little to no forcing for
precip. This continued dry weather increases the fire weather risks
as low level lapse rates approach 7-8C/km and model soundings show a
significantly dry profile. Expect another warmer than normal day
with highs near Lake Superior in the low to mid 50s and mid 50s to
mid 60s for the interior. Lower dew points mix down again during the
afternoon yielding min RHs in the mid 20 to 30% range. Luckily, fire
weather concerns will be lower as winds are expected to be lighter
than Sunday, staying below 15 mph. Regardless, fire weather partners
should continue to monitor this for changes. Temps fall back into the
30s (coldest east) Monday night as clouds increase from the
southwest ahead of the next system.

Moving on to the midweek system, the southern stream deep trough
will be positioned over Plains Tuesday morning while the northern
stream trough will broadly span British Columbia and Alberta. The
southern trough lifts northeast through Tuesday night toward the
Upper Great Lakes while the northern one forms a closed low over
Saskatchewan. Cyclogenesis begins on the lee side of the Rockies on
Tuesday. The sfc low then weakens as it follows the southern trough
into the Great Lakes for Wednesday and Wednesday night. Dry weather
looks to maintain during the day Tuesday, with showers then lifting
north over the UP Tuesday night and Wednesday when the better WAA,
PVA, and q-vector convergence arrives. NBM PoPs then drop off
Wednesday night as dry northwest flow drastically diminishes
available moisture; PWATs around 1" drop to ~0.3. However, with the
current uncertainty in the guidance surrounding the trough/closed
low`s track east through Canada/Great Lakes late next week and into
the weekend, NBM PoPs were left around 20-50% Thursday into the
weekend. Winds will be worth monitoring as NBM shows gusts around 25-
35 mph Tuesday through Wednesday. Another thing to watch with the
late week precipitation relative to the mid-week system will be
precip type. Uncertainty remains high at this time, but GFS and EPS
probabilities of at least 1 inch of snow begin increasing Thursday
night into Friday with around 20-40% by 0Z Saturday.

Additional shortwaves then ride the northwest flow over the Upper
Great Lakes late this weekend into early next week bringing
additional chances for precip. Confidence remains low with the given
spread in the guidance at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 632 PM EDT Sat Apr 13 2024

VFR conditions prevail through the period for IWD and for most of
the period at SAW. SAW will see some fog late tonight which will
bring it down to MVFR for a couple hours. CMX will have rain which
will help to bring in an MVFR deck by late Sun morning off of Lake
Superior which will lower to IFR/LIFR by Sun afternoon.

&&

.MARINE...
Issued at 438 PM EDT Sat Apr 13 2024

Winds late this afternoon into the evening hours will become
northeast as a weak low pressure system tracks east into the Great
Lakes. However, winds are expected to remain below 20 kts through
Monday with high pressure building southeast into the Upper Great
Lakes Monday, holding into Monday night. Our attention then turns to
a stronger low pressure system mid week. This system looks to eject
off the Rockies Monday night, lifting northeast into Wisconsin by
Wednesday afternoon as it weakens slightly. The low then continues
northeast through the Great Lakes Wednesday night with troughing
swinging behind it over Lake Superior Thursday/Friday. East gales
are likely (60-90% chance of gusts exceeding 34 kts) over the west
Tuesday afternoon, expanding eastward over the lake into Wednesday
as the system moves through. Winds remain around 20-30 kts Wednesday
night into the weekend, quickly becoming westerly behind the low
Wednesday night. Winds then veer northwest Thursday night/Friday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 8 PM EDT this evening for LSZ251.

Lake Michigan...
None.

&&

$$

SHORT TERM...LC
LONG TERM...Jablonski
AVIATION...07
MARINE...Jablonski