839
FXUS63 KMQT 010748
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
348 AM EDT Wed May 1 2024

.KEY MESSAGES...

- Breezy west winds gusting up to 40 mph, mainly this afternoon.
- Active pattern continues through next week as a series of low
pressure systems track across the U.S. and affect Upper MI. Above
precipitation expected, including chance of thunderstorms at times.
- Temperatures won`t stray too far from normal, but they
will probably be above normal more often than below normal.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 347 AM EDT Wed May 1 2024

The well-advertised band of rain showers is lifting northeast across
the UP along a warm front extending east from a 1002 mb surface low
west of Duluth. Lightning is mostly absent from ongoing activity,
but there is a cluster of lightning/thunderstorms near Green Bay, WI
where SPC Mesoanalysis analyzed around 250 J/kg MUCAPE. Surface
observations across the UP show temperatures mainly around 40F
though there are mid-40s near the WI state line. Light east-
southeast winds advected moisture off Lake MI allowing low stratus
and fog to develop across east-central portions of the area where
clear skies occurred last evening. Increasing upper level clouds
make it difficult to see fog/stratus on RGB satellite imagery, but
several eastern UP surface observations indicate vsby at or below 1
mile.

Looking ahead through today, any lingering fog should diminish as
rain moves through this morning. Rain ends early this morning across
most of the west-central UP, but the Keweenaw and eastern UP will be
slower to dry out. The track of the low pressure remains low
confidence and has important implications for today`s wind
forecast. The most likely scenario is a surface low over
eastern Lake Superior by early afternoon with the associated
cold front passage already across most of the area. Despite very
dry mid-levels, model soundings indicate sufficient boundary
layer moisture for nearly continuous stratus or broken cumulus
that limits surface heating and mixing depth. This lowers
confidence in afternoon wind forecast, but EFI values of 0.7-0.9
and SoT >0 indicates unseasonably strong winds. EPS output and
sounding analysis suggests potential for westerly gusts to
around 40 mph especially across the south-central UP where mid-
level winds are stronger and downsloping west winds allow for
deeper mixing. Downsloping also boosts high temps into the low
60s across the south-central with 50s elsewhere except for 40s
on the Keweenaw. Across the eastern UP, west winds back Nwerly
this afternoon as the low pressure tracks over Ontario resulting
in a pseudo lake breeze/cool front that may force a shower or
two across the far east.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 352 PM EDT Tue Apr 30 2024

Active weather continues for the extended period with on and off
waves of showers and thunderstorms, some showing the potential for
heavier rainfall amounts. Repeated rain chances, with above-normal
precipitation expected for the coming week and beyond, will have the
benefit of easing drought conditions as well as the associated
wildfire concerns. Otherwise, expect temperatures to hover around
normal for the start of the forecast period before climbing above
average for next week.

A brief dry period is expected behind our exiting low pressure
system Wednesday night, with clearing skies and gradually decreasing
winds. Attention then shifts to the next shortwave ejecting out of
the Plains Thursday ahead of a broad parent low centered over the
Canadian Prairies. An associated surface low closes off and heads
into northern MN by the evening. In response, a sfc warm front will
lift northward towards Upper MI with a waa/isentropic ascent regime
advancing across the Upper Mississippi Valley into Upper MI. Expect
shra to spread into west and central Upper MI during the aftn, then
continue Thu night. With precipitable water increasing to 200-250pct
of normal, decent rainfall should occur. Ensemble probability
guidance suggests a 30-60pct chc of rainfall of at least 0.5 inches
and a 10-20pct chc of exceeding 1 inch. Probabilities are highest
over south-central Upper MI. Some thunder is possible with several
models hinting at a few hundred j/kg of elevated CAPE later Thursday
into Thursday night. WPC has us under a Marginal risk for excessive
rainfall during this period, but with flash flood guidance still
running rather high, significant hydro issues are not expected.

With a cold or occluded front passing through sometime early in the
day Friday, with drier air working in behind it, would expect a
trend toward dry weather. Dry weather continues at least through
Saturday morning ahead of another shortwave that will bring our next
chances for showers into the afternoon. Chances for rain showers
continue into the night.

High pres ridge arriving on Sunday will support a dry day.
Uncertainty in timing shortwaves grows significantly early next
week, but that`s not a surprise given the time range. The next wave
should arrive sometime in the Mon/Tues timeframe, as well as our
next round of associated rain showers.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 138 AM EDT Wed May 1 2024

VFR conditions will not last much longer as a low pressure system
lifts across Lake Superior late tonight into Wednesday. This brings
showers across the area late tonight into Wednesday morning. MVFR
vsby should accompany these showers but upstream obs indicate cigs
only dip to low VFR/MVFR. There was a broken IFR deck at SAW and it
may return before rain showers scour it out, but confidence was too
low to include in TAFs. After the rain ends, IFR cigs spread across
IWD/SAW with LIFR expected at CMX. Expect cigs to slowly lift
Wednesday afternoon and may even scatter out to VFR at the end of
this TAF period.

&&

.MARINE...
Issued at 352 PM EDT Tue Apr 30 2024

Weakening low pressure centered just east of Lake Superior will
continue to slide eastward this evening, with weak height rises
expected over Superior as ridging briefly builds in from our south.
Winds mainly out of the W/SW will fall below 20 knots heading into
the early evening, but will pick up again out of the E/SE as another
surface low heads towards the area tonight. Expect gusts to increase
to around 20-30 knots across western Lake Superior by midnight, then
to around 20-25 kts over the eastern half of the lake into Wednesday
morning while the surface low begins to move over the lake. The
surface low finally exits eastern Lake Superior near Michipicoten
Island mid to late afternoon on Wed. There is a potential for a
short period of NE gales to 35kt over western Lake Superior late
tonight/early Wed, followed by the westerly winds that strengthen on
the south side of the low as it moves eastward. There is higher
confidence in reaching gales to 35 knots across eastern Lake
Superior during the afternoon/evening (around 50% chance), but there
is still a 3-6hr window during this period of higher gales to 35-
40kts east o the Keweenaw (around 20% chance).

After this period of stronger winds, high pressure arrives Wed
night, resulting in a quick drop of winds to under 20kts across the
lake. These lighter winds will linger across eastern Lake Superior
on Thu. Over western Lake Superior, NE winds will be on the increase
again on Thu as the next low pres moves out over the central Plains.
Expect NE winds to 30kt by late Thu aftn over western Lake Superior.
E to SE winds will increase to 30kt over eastern Lake Superior Thu
night. There is a 25-40pct chc that low end gale gusts could occur.
As low pres lifts into northern Ontario and Fri, winds will shift s
to sw. While gusts up to 30kt will continue over western Lake
Superior, winds will fall off to under 20kt over the eastern lake.
Over the weekend, expect winds mostly under 20kt across the lake.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory from 7 AM EDT /6 AM CDT/ this morning to
     3 PM EDT /2 PM CDT/ this afternoon for LSZ240.

  Small Craft Advisory from 7 AM EDT /6 AM CDT/ this morning to
     8 PM EDT /7 PM CDT/ this evening for LSZ241-242.

  Small Craft Advisory until 11 PM EDT this evening for LSZ243-
     244.

  Small Craft Advisory until 8 PM EDT this evening for LSZ245-
     246.

  Small Craft Advisory from noon today to 8 PM EDT this evening
     for LSZ247-248.

  Small Craft Advisory from 5 PM this afternoon to 11 PM EDT
     this evening for LSZ249.

  Small Craft Advisory from 3 PM this afternoon to 5 AM EDT
     Thursday for LSZ250-251.

Lake Michigan...
  Small Craft Advisory from 10 AM this morning to 8 PM EDT this
     evening for LMZ250.

&&

$$

SHORT TERM...EK
LONG TERM...LC
AVIATION...07/EK
MARINE...LC