035
FXUS63 KDLH 221744
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1244 PM CDT Tue Apr 22 2025

.KEY MESSAGES...

- Isolated showers linger in portions of the Arrowhead and
  northwest Wisconsin tonight into Wednesday.

- Potential for Dense Fog off of Lake Superior at the head of
  the Lake and for the North Shore tonight into early Wednesday
  morning.

- Additional rounds of rain Thursday into Friday and Sunday into
  early next week.

&&

.DISCUSSION...
Issued at 337 AM CDT Tue Apr 22 2025

Today-Wednesday:

Low pressure located in east-central North Dakota as of 3AM CDT
will continue shifting northeast throughout today and tonight
into far southern Manitoba and northwestern Ontario. As it does
so, frontogenesis extending southeast from the low will continue
to push a band of light, scattered showers currently moving into
the Brainerd Lakes northeastward through the Northland today and
this evening. With some weak instability also present aloft
through an hour or two after sunrise, have also introduced a
slight chance (15%) for an embedded thunderstorm or two in the
Brainerd Lakes. While hi-res model guidance does show additional
weak instability developing this afternoon into evening, it
appears to be in locations behind the band of showers, so don`t
expect additional thunderstorm development into the remainder of
today. The low pressure then slowly churns east across northern
Ontario tonight into Wednesday, leaving lingering isolated rain
shower potential (10-30%) in the Arrowhead and northwest
Wisconsin, though most locations in the Northland should remain
dry for tonight into Wednesday. Can`t rule out a brief mix of
wet snow with the rain in the tip of the Arrowhead tonight as
temperatures drop to around or just above freezing there, but
don`t expect any accumulating snow. As for rainfall amounts,
most will come with the frontal rain band, ranging from around
one-quarter to one-third inch in north-central MN to around or
less than one-tenth of an inch for the Twin Ports, Arrowhead,
and northwest WI.

Another weather note for today into early Wednesday will be
easterly to northeasterly winds off of Lake Superior. This will
keep the North Shore, Twin Ports, and east-facing portions of
the South Shore cooler today. It will also introduce a potential
for dense fog/very low clouds to push into the head of Lake
Superior and the North Shore tonight into early Wednesday. We
will need to monitor this fog signal in subsequent forecasts and
model trends to determine if a Dense Fog Advisory will be
needed.

Thursday-Friday:

This period will be highlighted by cooler temperatures near Lake
Superior due to onshore winds and otherwise widespread high
temperatures in the 50s to near 60 degrees for the remainder of
the Northland. There will also be a time from Thursday into
the first half of Friday where additional light rain showers
are possible (30-60% chance) mainly south of the Iron Range as a
weaker low pressure system tracks south of the Northland, from
the central Plains east into the southern Great Lakes. The low-
end thunderstorm potential for Thursday has disappeared with
this update as mid-range model guidance keeps instability south
of the Northland.

Next Weekend-Early Next Week:

Areas away from Lake Superior will once again see a warming
trend for Saturday into early next week with highs in the upper
50s to widespread 60s for locations away from Lake Superior.
This will be due to high pressure on Saturday shifting east of
the region and surface winds turning southeasterly ahead of
what global model ensembles generally agree on being a
developing Colorado Low later Sunday that is then forecast to
eject northeast to somewhere across the Upper Midwest through
the first half of next week. There is still a fairly large
amount of spread and uncertainty regarding the track and timing
of the low pressure, so confidence in rainfall amounts and
thunderstorm/severe weather at this time range are currently
low. With that said, NAEFS and ECMWF Ensemble Situational
Awareness Tables point to a surge of 90+ percentile PWATs for
this time of year at around or just over 1" with trajectories
of western Gulf moisture surging northward ahead of the Colorado
Low. Therefore, there should be plenty of moisture present for
a better soaking rain potential to hopefully alleviate some of
the Moderate to Severe drought conditions that have developed
across parts of northwest WI and north-central/northeast MN.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1244 PM CDT Tue Apr 22 2025

A band of light rain in far northern Minnesota early this
afternoon enters Ontario through the next few hours, leaving
behind lingering rain showers into the overnight hours. MVFR
ceilings trail behind the rain band and are expected to clear
out of most terminals 22-02Z. Fog is likely to form tonight
along and west of the Bayfield Peninsula into the Twin Ports and
along the North Shore. There is 50-60% chance of dense fog
affecting some terminals in the Twin Ports and along the North
Shore. At this point, LIFR conditions are expected and are in
the DLH TAF. Skies clear and visibilities improve within a
couple hours either side of 12Z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 337 AM CDT Tue Apr 22 2025

Northeast winds develop today, gusting into the low-20 knots
range briefly this afternoon into early evening in the
southwestern arm of the Lake. A Small Craft Advisory may (30-50%
chance) be needed at the head of the Lake this afternoon and
evening, but the potential was too low at this time to issue
one. There is potential for dense fog to develop, mainly at the
head of the Lake tonight into early Wednesday morning due to
moisture in the marine boundary layer due to rainfall moving
through today.

A wind shift to southwesterly occurs Wednesday, but winds
remain below 20 knots under a stable lake warm air advection
regime, with winds then lightening and veering northerly
Wednesday night. Winds veer back to northeasterly for Thursday,
with gusts generally remaining around 15 knots, though some
funneling of winds into the head of the Lake could push gusts to
around 20 knots.

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...None.

&&

$$

DISCUSSION...Rothstein
AVIATION...NLy
MARINE...Rothstein