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000
FXUS63 KMQT 270730
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
330 AM EDT Sat Apr 27 2024

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms today. A severe
  storm possible south central and eastern forecast area.
- Breezy today with strongest winds this afternoon south
  central where gusts to 35-40mph expected.
- Active pattern continues as 3-4 low pressure systems track
  across the region over the next week. Above normal
  temps/precip are expected including thunderstorm chances.
- Given the persistently dry pattern between May 2023 and March
  2024, think most rainfall will be beneficial though
  thunderstorms may result in ponding for poor drainage areas.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 329 AM EDT Sat Apr 27 2024

Water vapor imagery and RAP analysis show mid-level troffing over
the western U.S. One vigorous shortwave is evident over the southern
Rockies with a second well-defined wave lifting ne into the Upper
Mississippi Valley. At the sfc, weakening low pres associated with
the latter wave is over sw MN. Ahead of these features, clusters of
shra are occurring across the Upper Mississippi Valley into the
western Great Lakes early this morning. Thunder is mostly confined
to western WI, closer to the well-defined shortwave. Current temps
across Upper MI range thru the 40s F.

Low pres will continue to weaken slowly as it tracks ne, crossing
western Lake Superior late morning thru the aftn and exiting
northern Lake Superior by evening. Expect sct shra to continue today
as this low tracks across the area. Greatest coverage of shra and
some tsra will occur in association with the well-defined wave now
over southern MN. This wave will reach western Lake Superior/western
Upper MI this morning. The tail end of this wave could support
stronger thunderstorm development early aftn into central and
eastern Upper MI. Consensus of 00z CAMs, including HRRR runs since
00z, is for mlcape to reach as high as 500-1000j/kg with s central
Upper MI, Menominee County in particular, at the higher end of the
instability. Deep layer shear up to 50-55kt will support organized
storms and a svr risk (large hail/damaging wind). However, CAMs are
very muted on new storm development early this aftn, so confidence
is low that any new storms will develop let alone development of any
svr storms. Time period to monitor will begin around noon and end by
5pm as much of the instability will be shunted s and e of the area
by that time. Breezy winds will increase this aftn, especially s
central. Per mixing depth on fcst soundings, expect gusts up to 35-
40mph this aftn s central with 25-30mph fairly common elsewhere.
Will need to monitor for potential wind advy (gusts 45mph or higher)
as the day progress. If clouds break more to allow more insolation
to further raise mixing height, stronger winds aloft will be tapped.
Expect high temps today mostly in the 60s F. However, s central
Upper MI will reach the lwr 70s F. Also, temps over the w will begin
to fall in the aftn as low pres lifting n of the area causes winds
to shift wnw.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 407 PM EDT Fri Apr 26 2024

The active weather pattern of late shows no signs of stopping
through the next week. By Saturday night, a handful of 500mb troughs
of various lengths are expected over the CONUS, which of most note
to interests in Upper Michigan are a departing trough over Lake
Superior and the next upstream trough, an anomalously deep (-13 dam
per 12Z GEFS) trough over the Four Corners region. Lagging showers
from the departing system will keep low PoPs in the forecast
Saturday night before the western trough negatively tilts and races
northeast to the Upper Great Lakes basin for the end of the weekend
and the beginning of next week. Attention then turns westward again
as an anomalous trough races along the USA/Canada border through the
early week and has ramifications on the precipitation pattern for
the middle of next week and beyond.

Saturday night, the trough affecting the weather earlier in the day
will be lifting into northern Ontario, leading to height rises over
the Upper Peninsula. This will act against any ongoing lingering
showers, but enough remaining shortwave energy and orographic uplift
from the northerly flow will keep some slight chance PoPs (15-30%)
in the forecast. GEFS mean precip in that time period is only a
couple of hundredths, so any showers that linger will be light in
nature.

Sunday morning, ahead of a 500mb trough exiting the Rockies, a near-
1000mb low pressure will be over the Central Plains. Isentropic
upglide ahead of the lifting warm front will bring gradually
increasing PoPs throughout the day. The warm front of the low should
arrive around Sunday evening with the cold front passing Monday
evening as the low transits through the Upper Great Lakes at around
1005 mb. Following strong 850mb CAA in the morning, Sunday will be
the coldest day of the week, with gridded MOS guidance showing highs
only in the 40s and lower 50s. ECMWF EFI SoT between 0 and 1 by
Monday indicates the potential for an unusually high
precipitation total potential. The NAEFS climatology percentiles
for vapor transport, PWAT, and humidity are all in the
90-99.5th percentile range through late Monday, leaving the
ingredients for some higher QPF forecasts. Ensemble forecasts do
have a somewhat high spread, but the range of plausible
forecasts (80% probability) is between a half inch of rain and 2
inches of rain by Monday night, leading to the WPC issuing a
Marginal Risk of Excessive Rainfall. A few rumbles of thunder
are also possible, with the GEFS and Canadian ensemble showing
generally up to 700 J/kg of SBCAPE especially on Monday.

Ensemble spread increases significantly following the passage of the
system by Tuesday, but the general idea is that a trough passing
along the USA/Canada border will support a low pressure tracking
just north of Lake Superior which should support rain showers
roughly in the late Tuesday/early Wednesday timeframe. Another
system could pass in the Thursday timeframe, but NBM PoPs of only 15-
30% highlight the uncertainty in the timing and location of such a
system. Confidence is increasing that ridging will build over the
region for next weekend, giving at least some period of time for the
UP to dry out. Soils could be particularly soggy by then, as the
GEFS accumulated QPF by the end of next week ranges from 1 to 4
inches.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 136 AM EDT Sat Apr 27 2024

Shra will be overspreading the area overnight as low pres
approaches. Might be thunder as well, but confidence is low on
whether IWD/CMX/SAW will be affected, so mention was not
included in fcst. Expect a transition to MVFR in the 06-09Z
time frame with higher confidence now in further deterioration
to IFR after 12Z. A period of LIFR also cannot be ruled out
from late morning through the afternoon, but that is lower
confidence. Slight improvement to MVFR will be possible by this
evening, but that will be best case scenario. Meanwhile, LLWS
will be a threat at all TAF sites in the 06-18Z time frame due
to an associated low-level jet. And, strong southeasterly
surface winds (becoming west-southwesterly) this afternoon will
gust to 28 kts. Eventual wind direction will be northwesterly
by this evening.

&&

.MARINE...
Issued at 530 AM EDT Fri Apr 26 2024

Southeast winds gusting up to 25 mph are occurring early this
morning with the strongest winds across the east half of the lake.
Southeast winds increase up to 30 knots across the eastern lake
Friday afternoon. A few gale force gusts up to 35 knots are possible
near the tip of the Keweenaw and the international border through
Saturday morning. A low pressure tracks across Lake Superior on
Saturday resulting in a period of light and variable winds. Cold air
advection increases Saturday night resulting in northerly winds
gusting up to 30 kts across north-central portions of the lake.
Another low pressure approaches Lake Superior on Sunday causing
winds to back northeasterly and increase to gales across the far
western lake. Winds back easterly Sunday night as gales spread
across all but far eastern Lake Superior. A local office tool
indicates 60-90% chances for 40-45 kt gales across the far
western lake Sunday afternoon and evening with lower 25-50%
chances across the north-central lake. Gales are forecast to
subside on Monday as the low`s center lifts across Lake
Superior. Winds become west- southwesterly Monday night while
decreasing to 20 to 25 knots. Light winds less than 20 knots
prevail Tuesday then another system moving through Tuesday night
and Wednesday increases west winds to around 25 kts.

Thunderstorms are possible over portions of Lake Superior tonight
through Saturday evening then again Sunday evening through Monday
evening.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from Sunday morning through Monday morning for
     LSZ162.

  Gale Watch from Sunday evening through Monday afternoon for
     LSZ242>246-264>266.

  Small Craft Advisory until 6 PM EDT this evening for LSZ244-
     245-249-250.

  Small Craft Advisory until 2 PM EDT this afternoon for LSZ246.

  Small Craft Advisory until 8 AM EDT this morning for LSZ248.

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

  Gale Watch from Sunday afternoon through Monday afternoon for
     LSZ263.

Lake Michigan...
  Small Craft Advisory until 8 PM EDT this evening for LMZ221.

  Small Craft Advisory from 7 AM this morning to 5 AM EDT Sunday
     for LMZ248.

  Small Craft Advisory until 5 AM EDT Sunday for LMZ250.

&&

$$

SHORT TERM...Rolfson
LONG TERM...GS
AVIATION...TDUD
MARINE...GS