National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDLH 201725
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1225 PM CDT Sat Apr 20 2024

.KEY MESSAGES...

- Lingering light snow showers/flurries today. Very little to no
  additional accumulations expected.

- Near-critical fire weather concerns are expected today and
  Sunday due to low minimum relative humidity and breezy
  northwest winds.

- A clipper system will bring light rain late Monday through
  Tuesday. Some light snow could mix in Monday night into
  Tuesday.

- Additional precipitation chances late next week into weekend.

&&

.DISCUSSION...
Issued at 407 AM CDT Sat Apr 20 2024

Today:

Light snow showers/flurries that are ongoing early this morning
due to steep low-level lapse rates and some saturation in the
lower portion of the dendritic growth zone. This snow will
gradually end over NE MN by late this morning, but linger for
parts of NW/north-central WI until around midday as drier air
works southeast across the area and erodes what little low-
level moisture is left in the atmosphere. Very light dusting at
best is expected from these snow showers, but many locations
will not see any additional accumulations with little to no
reductions in visibility.

Decreasing cloud cover occurs from northwest to southeast today,
becoming mostly sunny this afternoon, with some scattered
cumulus during the afternoon in NW WI. Winds out of the NW
remain breezy today, gusting up to 20 to 25 mph for most through
the afternoon. These winds combined with minimum afternoon RH
values as low as 20-30% will likely lead to near-critical fire
weather conditions for the afternoon into early evening. The
lowest RH values will generally be from the Brainerd Lakes east into
the Twin Ports and St. Croix River Valley. High temperatures
will be a few degrees below average for this time of year,
topping out in the mid to upper 40s.

Sunday:

Shortwave ridging will keep skies sunny to partly cloudy for
most of the Northland with even drier air than today. Breezy
northwest winds with gusts up to around 20 to 25 mph again
combine with afternoon RH values of 20-30% to create near-
critical fire weather conditions again. The lowest RH values on
Sunday are expected to extend from central to the Twin Ports and
east into the Pine Barrens of NW WI. Mixing heights in the
atmosphere could reach as high as 750-800 mb, so the afternoon
RH values may need to be refined even lower if newer model runs
trend towards these higher mixing heights. Look for a warmer
day, as well, with highs reaching the 50s for all but the tip of
the MN Arrowhead and areas immediately near Lake Superior.

Monday - Tuesday:

A trough currently located just off the West Coast will close
off and track east into southern Saskatchewan by 12Z Monday and
then dive through the International Border/northern MN Monday
night and through Lake Superior on Tuesday. Still some slight
spread in the low tracks, the consensus is to track very close
to or directly through the Northland.

Strong northerly winds will be ushering in increasing moisture
and much warmer temperatures ahead of this system on Monday,
leading to high temperatures in the low to mid 60s for most.
Precipitation will start in the form of rain Monday
afternoon/evening given the warmer temperatures. However, some
colder air aloft and at the surface gets pulled in with the
backside of this system, so some light snow could mix in as well
across northern MN, the MN Arrowhead, and possibly parts of the
South Shore Monday night into Tuesday. While the predominate
form of precipitation should be in the form of rain, the
aforementioned locations have a 25-50% probability of seeing
measurable snow accumulations (light dusting), though
probabilities of 1" of snow are less than 10-20%. Rain and
liquid water equivalent melt from the snow of around 1/4 to 1/3
inch of liquid aren`t out of the realm of possibilities with
this system, though these higher amounts look to be relegated to
the Arrowhead and NW WI for the most part.

Wednesday - Next Weekend:

Another ridge is poised to bring drier weather to the central
CONUS for Wednesday through much of Thursday before another
trough swings through late week into next weekend and brings the
Northland its next shot at precipitation. Still a lot of spread
in the timing/location of this trough and resulting transport of
moisture from the Gulf of Mexico late next week, so precip
chances and amounts will still need some refining. The
temperature signal mid to late next week looks to be around to
slightly above average for late April, which would generally
equate to seeing highs in the 50s to low 60s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
-- Changed Discussion --
Issued at 1224 PM CDT Sat Apr 20 2024

MVFR Stratus with a few flurries are lingering over northwest
Wisconsin. This should continue to slide to the southeast. KDLH
is right on the edge of it and should break out to VFR no later
than 19z, and KHYR around 20z. Once these sites return to VFR
conditions should remain that way through the remainder of the
TAF period. Northwest winds sustaining in the 10-15 knots with
gusts around 20 knots should diminish to 10 knots or less, then
increase once again after 14z.
-- End Changed Discussion --

&&

.MARINE...
Issued at 407 AM CDT Sat Apr 20 2024

Wind forecasts have continued their downward trend for today and
Sunday. Northwest winds with gusts to around 20-25 knots fall
below Small Craft Advisory criteria later this morning and
afternoon, remaining elevated longest for the Apostle Islands.
However, there appears to be a period of time from this evening
into tonight where winds turn westerly and gusts drop below 20
knots, so Small Craft Advisories were removed for this evening
and tonight. A short-fuse Small Craft Advisory may be needed
for wind gusts to 20-25 knots later tonight into early Sunday
morning. Winds become light and variable Sunday night, becoming
southerly by Monday morning. Winds are expected to turn lighter
as Sunday progresses given warmer air aloft creating a more
stable marine layer that would inhibit stronger gusts from
reaching the water surface. Winds then turn light and variable
Sunday night before turning breezier out of the south on Monday.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MN...None.
WI...None.
MARINE...Small Craft Advisory until 4 PM CDT this afternoon for
     LSZ140>143-146-148.
     Small Craft Advisory until 6 PM CDT this evening for LSZ147-
     150.
-- End Changed Discussion --

&&

$$

DISCUSSION...Rothstein
AVIATION...LE
MARINE...Rothstein