Lymantown, Wisconsin Weather Forecast Discussion

561
FXUS63 KDLH 061741
AFDDLH
Area Forecast Discussion
National Weather Service Duluth MN
1241 PM CDT Sat Sep 6 2025
.KEY MESSAGES...
- Small Craft Advisories are in effect for portions of the
  North Shore this morning and for portions of the South Shore
  through this evening. Conditions will be hazardous to
  recreational users.
- Frost Advisory this morning for portions of northeast
  Minnesota, including the Arrowhead, Iron Range and Borderlands
  areas.
- Continued cool today with scattered rain showers and a few
  embedded thunderstorms.
- Frost will be a concern tonight and Sunday night before
  temperatures warm later next week. Additional Frost Advisories
  will likely be needed.
- There is a small chance (around 20%) of isolated thunderstorms
  Monday afternoon and evening. A few storms may be strong.
&&
.DISCUSSION...
Issued at 331 AM CDT Sat Sep 6 2025
Today and tonight...
Skies cleared over most of northern Minnesota early this
morning. Cold air advection continued and air temperatures
dropped into the middle 30s to middle 40s as of 2 AM. Expect
additional cooling north of the Iron Range including Bigfork,
International Falls, Cook, Orr, and Ely. Frost Advisory remains
in place. While winds aren`t quite calm at observation sites,
they are likely light enough to allow patchy frost to develop in
sheltered locations where skies are clear.
GOES-East water vapor imagery revealed a lobe of vorticity near
the Ontario/Manitoba border east of Lake Winnipeg. That feature
was located on the western periphery of a broader cutoff low
and associated trough centered over far northeast Ontario.
Models seems to have a decent handle on the lobe of vorticity
and associated shortwave trough. The consensus brings that
feature southward into northern Minnesota by 15Z with a band of
stronger vorticity accompanying it to the west where the
interface between a northerly upper-level jet streak and weaker
flow associated with the cutoff low and trough is located. Cold
air advection, cyclonic flow aloft, and height falls with the
shortwave trough are expected to support the development of
showers and perhaps a thunderstorm or two today. In fact the
Canadian radar network already shows returns over central and
southern Manitoba and a sliver of northwest Ontario as of 0230Z.
That activity will propagate southward into central Minnesota
by late this morning and into northwest Wisconsin during the
afternoon. Enough diurnal heating is forecast to support a few
hundred joules of MLCAPE from north-central and central
Minnesota east into northwest Wisconsin. A few rumbles of
thunder are likely, although widespread and persistent storms
are unlikely.
The shortwave trough rotates out of the Northland this evening
with clearing skies expected. The main upper-low and trough will
shift farther east overnight. Surface high pressure will build
eastward into central and north-central Minnesota which will
relax the pressure gradient and allow for light to calm winds
overnight. Another Frost Advisory will likely be needed for
tonight for portions of northern Minnesota at least. Overnight
lows will dip into the lower to upper 30s.
Sunday through Monday night...
The upper-level trough will advance farther east Sunday.
Northwest flow will continue aloft while an 850 mb ridge builds
eastward through Sunday night. High pressure at the surface will
result in lighter winds. Modest warm air advection will boost
temperatures into the upper 50s to middle 60s.
Warm air advection continues into Monday with temperatures
climbing to near normal, in the low 60s to low 70s. A shortwave
trough is forecast to propagate across the region Monday and
Monday night. The warm air advection will allow modest
instability to develop over western Minnesota nosing into
central and north-central Minnesota during the afternoon. MLCAPE
of 500-1000 J/kg is forecast during that time.
Large-scale ascent with the passing trough and isentropic
ascent should be sufficient for showers to develop during the
afternoon and evening. A strong storm or two can`t entirely be
ruled out, although limited effective shear on the order of 25
knots would support pulse-type storms. Hail from dime to quarter
size and wind gusts of 40 to 60 mph would be the greatest
threats should storms develop.
Tuesday through the end of the week...
Isentropic ascent will continue over northwest Wisconsin and
the I-35 corridor Tuesday. A cool front is forecast to make its
way southward across the Northland. Light rain is forecast to
continue. Temperatures will be near normal once again with highs
in the middle 60s to middle 70s. Light rain pushes farther east
by Tuesday night. Wednesday will be slightly cooler and there
may be diurnal showers under modest cold air advection. Thursday
and Friday should also see near normal temps. Another round of
showers may arrive for Friday. Several shortwave troughs may
propagate through the southwest flow over the Plains. Southerly
flow over the Upper Midwest will result in modest isentropic
ascent which may be enough for scattered rain showers to end the
work week.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1241 PM CDT Sat Sep 6 2025
The main concern for this afternoon is scattered showers and the
stray possibility for a brief thunderstorm. Confidence is low
enough not to include a thunder mention in the TAFs. The
showers are ongoing, and despite a little gap between INL/HIB,
their coverage is scattered to numerous such that the best way
to handle them is with PROB30 in the TAFs through this
afternoon. Right around sunset, the showers are expected to
decrease in coverage and intensity before coming to an end this
evening. Occasional wind gusts to 15-20 kt can be expected in
and around any of these showers.
Tonight, largely VFR conditions, though some fog is possible in
the usual low-lying areas (mainly HIB/BRD/HYR) with clearing
skies and light winds. A period of MVFR/IFR visibility is
possible in the early morning hours.
Northwesterly winds this afternoon become light tonight, then
westerly Saturday morning.
&&
.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 331 AM CDT Sat Sep 6 2025
Gusty northwest winds are likely over portions of the North
Shore early this morning. Thus the Small Craft Advisory for
Taconite Harbor to Grand Portage was extended until 10 AM.
Strong northwest winds will persist today across the lake. Wind
speeds and gusts will drop below 22 knots although wave energy
stored in the waters should continue to create waves of 2 to 5
feet along portions of the South Shore. Rebounding waves near
cliff faces may be locally higher. Thus the Gale Warning was
taken down and replaced with a Small Craft Advisory until 10 PM
tonight from Port Wing to Bayfield and the Outer Apostle
Islands. Recreational boaters will experience challenging
conditions in those areas. Winds are forecast to back westerly
for a time today before veering northwest and northerly
overnight tonight. Additional Small Craft Advisories may be
needed.
High pressure builds into the region on Sunday and winds are
forecast to back southwesterly and weaken with time. Winds of 5
to 15 knots are forecast Sunday and Monday. The strongest winds
and highest waves are forecast off Grand Portage during that
time due to funneling between Isle Royale and the mainland.
A few thunderstorms are possible Monday afternoon and Monday
night. Winds will be gusty and erratic near storms. A few wind
gusts up to 40 knots are possible with the storms.
For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...Small Craft Advisory until 10 PM CDT this evening for LSZ146-
     147-150.
&&
$$
DISCUSSION...JDS
AVIATION...JDS
MARINE...JDS

NWS DLH Office Area Forecast Discussion