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000
FXUS63 KMQT 131715
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
115 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
  central and east.
- 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 likely (~50%) into the late-
  week, though uncertainty exists on timing, intensity, and
  precipitation type.

&&

.UPDATE...
Issued at 848 AM EDT Sat Apr 13 2024

Temperatures early this morning bottomed out in the lower to mid 30s
across most of the area, but some spots particularly in the western
half of the UP dropped further into the 20s. Still, as of sunrise,
we are already recovering nicely in the the lower to mid 30s in the
west, and the upper 30s in the east. Temperatures have been adjusted
downward slightly over the next couple of hours to account for those
slightly lower values.

Otherwise, spotty shower activity is evident on DLH radar closer to
the international border. Whether any of this is actually reaching
the ground is the real question - but will still keep in that slight
chance for showers to move into the UP this afternoon ahead of the
main round of rain showers overnight.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 406 AM EDT Sat Apr 13 2024

This morning will start off dry and sunny as weak ridging aloft
and at the surface moves west to east across the area. However,
associated lift/forcing from upstream shortwave energy noted
early this morning over British Columbia and the lee of the
Canadian Rockies will likely bring an increase in clouds and
scattered rain showers later today into tonight as the
shortwaves track along the MN/Canadian border and northern Lake
Superior. Increased elevated instability may even produce a few
thunderstorms along the WI border and south central sections of
the U.P tonight.

As the shortwaves now over western Canada track across the
MN/Canadian border and northern Lake Superior later this afternoon
into tonight, associated waa/isentropic ascent along with an
advancing sharp 850 mb theta-e gradient and vigorous upper
diffluence from the right entrance region of a 100 kt upper jet
streak extending from northern Lake Superior into the Lower Great
Lakes by this evening, should in concert help generate thickening
clouds and scattered showers across Upper Mi spreading from the
western U.P. this afternoon into central and eastern Upper Mi this
evening. Latest CAMs simulated reflectivity suggest convection
initially will develop over the Canadian Prairies this morning
before tracking across Lake Superior and northwest/north central
Upper Mi this afternoon and then spreading across the rest of Upper
Mi later this evening/overnight tonight. Best shower coverage looks
to be across northwest/north central and eastern U.P. with lesser
coverage southwest and south central. However, better elevated
instability (up to 500 j/kg) for possible t-storms appears to be
focused along the WI border and south central late this evening and
overnight. Convection should mostly clear east of the cwa by sunrise
Sunday.

Highs today over the interior west half will reach into the lower
60s while most of the rest of the cwa will be in the 50s. Mixing
through dry air mass initially will drop dew points into the mid 20s
with afternoon min RHs along the WI border/interior west dropping
near 25 pct. Fortunately, winds over this area will be light w/gusts
less than 15 mph which should ease any fire weather concerns. Low
tonight will be in the mid 30s north to near 40F south central.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 416 AM EDT Sat Apr 13 2024

With the departure of troughing aloft, Sunday looks to be fairly dry
under northwesterly flow. In spite of the 00Z HREF showing lingering
low cloud cover especially near Lake Superior, extremely dry
midlevels could cause dew points (and thus RHs) to tank, especially
in the interior west. HREF minimum RH values in the afternoon fall
into the 30% range, and with northwest wind gusts up to 15-20 mph,
fire weather partners should monitor the forecast, especially along
the MI/WI state line. Otherwise, bias-corrected model guidance shows
highs near 70 in the south-central UP, with 60s across much of the
rest of the southern half of the UP with 50s near the Lake Superior
lakeshores as flow off of the ~38 degree lake will moderate the
temperatures there. If breaks in the low level cloud cover occur
sooner than later, the 70 degree isotherm may come as far north as
Gwinn and Amasa.

Monday, as upper 1010s mb surface high pressure remains over much of
the Great Lakes, the day will begin dry. However, PoPs creep up
throughout the day in the west as the UP becomes underneath the
right entrance region of a 100kt 250mb jet along with slight
850mb WAA and subtle shortwave energy embedded in northwesterly
flow at 500mb. The LREF only shows a couple of hundredths of
precipitation throughout the day Monday, so impacts should be
minimal of whatever showers do form on Monday. If showers end up
not materializing, fire weather could yet again be another
concern as RHs could fall into the 30s in the interior west once
again with wind gusts of 10-20 mph. It will be worth watching
as this time frame enters the domain of higher resolution model
guidance in the next 12-24 hours.

Upstream, a deep cutoff low at 500mb over the Desert Southwest will
be kicked east as a trough transiting through British Columbia
compresses the ridging over the West Coast. As the Desert Southwest
trough kicks east, it will initiate a lee cyclone, peaking in
strength in the 980s mb range Tuesday in the Central Plains. The low
will then lift into the Upper Great Lakes region by late Wednesday,
weakening slightly into the 990s mb of central surface pressure.
Widespread showers are near-certain, with the transport of Gulf of
Mexico moisture above in the 97.5th percentile of the NAEFS
climatology resulting in PWATs climbing to near an inch. Despite
this, there is still considerable spread in the ensembles regarding
precipitation totals, as the 90th percentile of guidance shows
around 2 inches of QPF possible by the end of the week, but the 10th
percentile is around a half inch. Wind gusts will also be worth
watching as the NBM shows wind gusts in the 25-35 mph range by
Tuesday night. NBM PoPs show that widespread showers will taper off
somewhat Thursday, but as the GFS 500mb plots show multiple 500mb
shortwaves following the passage of the low, precipitation may
linger into the weekend, especially as LREF mean accumulated precip
climbs steadily (a pattern common in wet patterns with
significant ensemble spread). One thing to watch with the late
week precipitation relative to the mid-week system will be
precip type, as the LREF shows some members with snow as soon as
Thursday morning. Uncertainty is high at this time, but given
the assortment of ensemble accumulated snowfall solutions,
winter lovers may be getting one more shot at some accumulation
by the end of next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 115 PM EDT Sat Apr 13 2024

VFR conditions prevail the rest of today while midlevel clouds begin
to fill in ahead of our next disturbance. This may bring some low-
impact showers to CMX by late afternoon, then to IWD and SAW later
tonight. Showers end by 06Z, but with lower-level moisture behind
rain showers and onshore flow, patchy fog and low stratus will lead
to MVFR and possibly IFR ceilings at CMX later tonight. Ceilings may
also lower to MVFR at SAW, but confidence is low. Expect
restrictions to linger at CMX the rest of the forecast period.

&&

.MARINE...
Issued at 416 AM EDT Sat Apr 13 2024

Gales have now ended across Lake Superior this morning, with wind
gusts falling below 25 kt by the mid-afternoon hours. A few gusts of
20-25 kt are possible as a weaker low pressure passes south of Lake
Superior today, primarily during the period of northeasterlies
funneling into Duluth. Through Monday evening, ridging will
keep wind gusts below 20 kt. As a strong low begins to eject out
of the Rockies Monday night, the enhanced pressure gradient
will cause northeasterly and easterly wind gusts up to 30 kt
through Tuesday morning. As the low approaches Lake Superior
Wednesday, gales are likely (50+%), though the direction will
rapidly shift as the most likely path of the low brings it
directly across Lake Superior. Northwesterly winds remain high
behind the low as between the departing low, high pressure over
the Plains, and any trailing low pressures into the weekend,
gradient flow will be strong, though uncertainty is high in
timing the strongest winds. Once wave heights fall below 4 feet
tonight, expect waves below 4 feet until Monday night, when 4-8
foot waves begin to overspread the lake by late Tuesday, with
the highest being 8-10 ft waves north of the Keweenaw
Peninsula Tuesday night.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 2 PM EDT this afternoon for LSZ249-
     250.

  Small Craft Advisory until 8 PM EDT this evening for LSZ251.

Lake Michigan...
None.

&&

$$

UPDATE...
SHORT TERM...Voss
LONG TERM...GS
AVIATION...LC
MARINE...GS