Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 142221
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
621 PM EDT Sun Apr 14 2024

.KEY MESSAGES...

- Elevated fire weather conditions continue this afternoon
  especially towards the Wisconsin border.
- Dry and mostly clear conditions continue overnight while winds
  turn calmer.
- Dry weather continues through Tuesday. RHs fall to 20-30% in
  the interior west Monday and across much of the UP on Tuesday,
  causing some fire weather concerns.
- A low pressure tracks through the Upper Great Lakes during the
  midweek, causing widespread rain showers and yielding some
  gusty winds.
- Chances of precipitation remain probable (~25-50%) into the
  late- week, though uncertainty exists on timing, intensity,
  and precipitation type.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 242 PM EDT Sun Apr 14 2024

Weakening surface low pressure over the lower Great Lakes will
continue its eastward trek into the evening while surface high
pressure continues to build in from the Northern Plains. Water vapor
imagery reveals plenty of dry midlevel air aloft, while visible
satellite shows mostly sunny skies across much of the UP. Patchy
lower stratus is still apparent across Lake Superior, hugging the
shorelines of the western Keweenaw as well as Alger and Luce
counties amid breezy NW flow. Cloudiness and cool onshore flow will
keep temperatures in the lower/mid 40s - and even upper 30s - right
along the Superior shoreline. Away from Superior, we are still on
track to see highs ranging in the mid 50s (eastern UP and Keweenaw)
to mid 60s (central, western UP).

Meanwhile, our main concern continues to be the elevated fire
weather risk across portions of the UP. NW winds across the eastern
UP have come in stronger than previously expected, perhaps owing to
that longer fetch off of Superior or more efficient mixing than
model soundings would suggest. Gusts around 20 mph are common there,
but confidence in 20-25mph gusts remains higher across the central
and western UP with model soundings continue to indicate mixing to
at least the 850mb level. Dewpoints are responding in kind, already
falling into the lower to mid 30s across the south-central UP and
into the mid/upper 30s away from Superior in the eastern UP. Across
the area with the going SPS (our WI border counties), we are still
on track to see pockets of RH dropping to around 25% this afternoon
while remaining mainly above 40% elsewhere. Don`t burn!

High pressure will continue the dry conditions tonight, but a subtle
shortwave grazing the perimeter of the ridge aloft should drag
additional lower to midlevel cloud cover across Superior. This may
be able to move across the northern half of the UP as well. Expect
mostly clear skies elsewhere, with lows ranging in the mid 30s as
winds turn light.

&&

.LONG TERM /MONDAY THROUGH SUNDAY/...
Issued at 438 PM EDT Sun Apr 14 2024

Next week starts off with a closed low spinning over northern Quebec
and split flow over the west. A closed low in the southern stream
will be located over the Rockies with a trough over British Columbia
in the northern stream. These two features make their way toward the
Great Lakes region Tuesday and Wednesday, phasing Wednesday night
into Thursday and providing the main weather story for the week
ahead. While there is fairly good confidence in the guidance through
Wednesday night, there is a fairly significant spread Thursday
onward. The northern stream trough`s trajectory as it moves east
while becoming a closed low, the associated sfc low, and their
interaction with the southern stream mid to late week is where the
biggest uncertainty lies for precip chances late this coming week
and into the weekend.

Monday and Monday night...

Starting on Monday, the right entrance region of the upper level jet
approaches the CWA from the west during the day. That being said,
mid level ridging moves east into the region yielding no PVA and sfc
high pressure builds southeast over the Upper Great Lakes leaving no
additional forcing for precip. This continued dry weather increases
the fire weather risks as low level lapse rates approach 6-7C/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 than
today as winds are expected to be lighter, with gusts staying below
15 mph (save for the east where min RHs are higher). CAMs do
highlight some lake breezes kicking in off both Lake Superior and
Lake Michigan Monday afternoon, which will help cool temps and raise
RHs. Temps fall back into the 30s (coldest east) Monday night and
skies will stay mostly clear.

Midweek system...

The southern stream closed low will be positioned over the Central
Plains Tuesday morning while the northern stream trough will extend
from British Columbia into Alberta. The closed low lifts northeast
into Wisconsin by Wednesday morning while the northern trough moves
east and forms a closed low somewhere over Saskatchewan; this
northern trough is where uncertainly stems from the rest of the
forecast. Cyclogenesis begins on the lee side of the Rockies Monday
night into Tuesday. The sfc low then weakens as it follows a similar
track to the closed low, moving northeast into the Upper Mississippi
Valley by Wednesday morning.

With guidance trending toward a slower southern sfc low approach,
dry weather looks to maintain during the day Tuesday. Widespread
showers then lift north over the UP Tuesday night, continuing on
Wednesday when the better WAA, PVA, and q-vector convergence
arrives. With the slower onset of the low, skies will remain clearer
longer in the day Tuesday. That alongside impressive dry low to mid
layers noted in the model soundings elevate fire weather concerns.
Highs are expected mainly in the 50s, but some biased corrected
guidance hinting at low to mid 60s in the interior; the keweenaw
will be the coolest in the upper 40s. With lower dew points mixing
down, min RHs will be in the 20% range. Lowest end of guidance does
show potential for RHs to bottom out in the teens, and with gusts
hanging around the 15 to 20 mph range, wildfire potential will be
elevated. Will need to monitor this closely in future forecast
packages, but it is suggested you avoid burning if possible on
Tuesday despite precipitation on the way.

PoPs increase Tuesday night ahead of the low, continuing into
Wednesday as the low moves into Wisconsin. Confidence is high in a
soaking rain with this system as PWATs highlight a stream of
moisture off the Gulf of Mexico moisture surging into the Upper
Great Lakes by Wednesday with values around 0.9" to 1.1". This is
above the 90th percentile of Green Bay`s climatology. This
translates into good coverage of QPF, with a storm total forecast
ranging around 0.5" to 2". This should help alleviate fire weather
concerns moving through the rest of the week.

Meanwhile, another sfc low is developing in Saskatchewan associated
with the northern stream trough becoming a closed low. This weaker
sfc low, like the mid level features, will move east and phase with
the southern sfc low late next week as it moves northeast through
the Great Lakes. Dry northwest flow behind the sfc low drastically
diminishes available moisture; PWATs drop to ~0.3. Thus PoPs drop
back down to around 30% or lower. With the current uncertainty in
the guidance surrounding the closed low`s track east through
Canada/Great Lakes late next week, NBM PoPs were left around 15% to
40% Thursday into the weekend. Winds will be worth monitoring
Tuesday night into Wednesday as the NBM has probabilities exceeding
50% for gusts above 40mph in the east and Keweenaw. Forecast gusts
are around 30 to 40mph for now.

The weekend onward...

The closed low lifts northeast into Quebec late next weekend.
Confidence remains low with the given spread in the guidance at this
time, but some snow showers may try to mix in late Friday into
Saturday as the closed low departs. The GEPS and EPS probabilities
of at least 1 inch of snow begin increasing Friday night with around
10-20% by 0Z Sunday. Additional shortwaves then ride the northwest
flow over the Upper Great Lakes into early next week, but dry
weather looks to persist into Tuesday with dominating sfc high
pressure moving southeast through the CONUS.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 620 PM EDT Sun Apr 14 2024

VFR prevails for the forecast period.

&&

.MARINE...
Issued at 438 PM EDT Sun Apr 14 2024

High pressure is expected to build southeast over the Upper Great
Lakes tonight through Monday morning, then extend further over the
entire Great Lakes Basin Monday night. This will keep winds below 20
kts through Tuesday morning. 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 into Thursday. 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. Internal guidance shows the probability
of high end gales (exceeding 40 kts) are around 30-50%. Winds fall
below gales Wednesday afternoon and remain mainly between 20-25 kts
Wednesday night into the weekend. Winds quickly becoming westerly
behind the low Wednesday night, then veer northwest Friday night.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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


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