Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

000
FXUS63 KDLH 171732
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1232 PM CDT Sun Mar 17 2024

.KEY MESSAGES...

- Scattered snow showers and flurries continue tonight into
  Sunday for mainly the Arrowhead and northwest Wisconsin. A
  localized quick dusting is expected this morning with any snow
  shower.

- Lake effect snow continues along the South Shore through
  Sunday night, ending late Monday morning. A Winter Weather
  Advisory continues for Iron County through Monday morning.
  Total accumulations of 4 to 8 inches, and locally to around 10
  inches are expected for northern Iron County.

- Near-critical fire weather conditions are possible on a daily
  basis into the middle of this week due to low humidities and
  breezy winds.

&&

.DISCUSSION...
Issued at 442 AM CDT Sun Mar 17 2024

Lingering Snow Showers and Flurries Today:

Radar imagery early this morning continues to show scattered horizontal
convective snow showers across northeast MN and NW WI. These
showers are the result of continued synoptic cyclonic flow and
cold air advection, combined with steep low-level lapse rates. Amounts
with these snow showers will remain localized light dustings as
seen on area webcams early this morning, though some brief
reductions in visibility down to 1-3 miles remain possible in
the showers. The snow showers should wane as we head into mid to
late morning, but some flurries should hang around across the
Northland into midday and possibly the afternoon over the North
Shore.

In addition to the lingering snow, today will also be brisk.
Morning lows in the teens only warm into the 20s to around 30
degrees this afternoon, which will be accompanied by northwest
winds gusting up to 25 to 30 mph and closer to 35 mph along the
North Shore. This temperature and wind combination will keep
daytime wind chill values between 10-20 degrees, with wind
chills around zero degrees tonight as lows drop back down into
the single digits to mid teens.

South Shore Lake Effect Snow through Monday Morning:

The lake-effect snow machine has already begun along the South
Shore snowbelt as colder 850 mb temperatures of -13C to -17C
have moved over the Northland, and, in tandem with warm Lake
Superior surface temperatures, are generating up to 300-400 J/kg
of lake-induced instability. A prolonged period of moderate
snow, locally heavy at times in northern Iron County, should
persist throughout the day today and into Monday morning. The
highest snowfall rates (6-hourly rates up to 2-3 inches in
northern Iron County) should persist through the morning hours
today before intensities drop off slightly for this afternoon
into tonight/Monday morning. Lack of antecedent snow cover,
warm ground temperatures and higher sun angles should look to
cut into totals a bit during the daytime hours today. With that
said, the prolonged period of moderate snowfall should still
lead to total event accumulations ranging from 4 to 8 inches in
northern Iron County with locally higher amounts to around 10-11
inches possible by the time snow comes to an end midday on
Monday. Southern Iron County will range from 1-4 inches, with
these amounts decreasing from north to south. Similarly, Ashland
County should see its highest amounts of 2 to 4 inches near the
northern Iron County border, with amounts dropping off to 0.5
to 2 inches for the remainder of the county. Northern Bayfield
County should expect around 1-2 inches of snow from this event,
with the remainder of the South Shore and NW WI expected to see
an inch of snow or less. The Winter Weather Advisory remains in
effect for Iron County until Noon on Monday when drier air
moving into the region and winds backing to westerly will shut
off the lake-effect snow.

Near-Critical Fire Weather Conditions into Mid-Week:

The cooler temperatures today should help to limit the concern
for near-critical fire weather conditions today, despite minimum
afternoon humidity values of 30-40% and breezy northwest winds.
While we see winds decrease on Monday and quick-hitting light
snow (30-50% chance) Monday afternoon into Monday night in the
Arrowhead into NW WI, snow amounts look to be less than an inch
and not aid in alleviating dry conditions across most of the
area. Minimum RH values dipping to 25 to 35 percent over most of
the Northland, lowest in central MN into the Pine Barrens of NW
WI, will again lead to the potential for near-critical fire
weather conditions. The same story of dry conditions, low
humidities, and windy conditions sets up the potential for near-
critical fire weather conditions again for Tuesday and
Wednesday. Wednesday looks to be the lowest humidity day of the
week, with minimum humidity values dipping into the 20s for most
of the Northland, and possibly mid to upper teens for the St.
Croix River Valley and Pine Barrens of NW WI.

Lake Week Precipitation Chances:

There is a signal, though inconsistent at times, for some
shortwave energy to cut across Minnesota as a larger low churns
across far northern Saskatchewan and Manitoba. This shortwave
energy could bring us quick-hitting snow chances (30-50%) on
Thursday, thought the trend in global guidance pushes most of
the snow with this system south of the Northland and mainly
across the southern half of Minnesota. Model guidance diverges a
bit further heading into next weekend and early the following
week with regards to more potent, Colorado Low-esque low
pressure system/cutoff low bringing higher snow potential to
the Midwest. However, confidence in precipitation
amounts/placement is low as spread in low tracks with this
system are still all over the place across the Midwest.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1231 PM CDT Sun Mar 17 2024

A broad area of MVFR/VFR stratocumulus over the area this
afternoon will continue into the afternoon with scattered
flurries/snow showers, producing MVFR visibilities. Late this
afternoon and evening these clouds will slowly lift and diminish
in coverage, allowing all of the MN terminals to return to VFR
by 00z this evening. Lake Effect stratus should push MVFR
ceilings across KHYR tonight before sliding during the early
morning hours Monday. Northwest winds around 15 knots with gusts
of 25 to 30 knots this afternoon will slowly diminish this
evening as a ridge of high pressure slides towards the area
overnight, then across the Northland on Monday, with winds
dropping off to less than 10kts overnight through the remainder
of the TAF period.

&&

.MARINE...
Issued at 442 AM CDT Sun Mar 17 2024

Winds turn more north-northwesterly today with gusts generally
to 25 to 30 knots. The exception to this is wind gusts to
around 35 knots along the North Shore from Silver Bay to Grand
Portage this morning due to better mixing and stronger winds
coming off of the higher terrain. A Gale Warning remains in
effect through Noon for Silver Bay to Grand Portage where the
strongest gusts are expected. Meanwhile, Small Craft Advisories
remain in effect for the remainder of the nearshore waters into
tonight, with waves of 3 to 7 feet also persisting along the
South Shore. Additional Small Craft Advisories will likely be
needed for the North Shore after the Gale Warning ends.

Winds weaken for early Monday and back to westerly and then
southwesterly. Gusts could increase to 20 to 25 knots Monday
afternoon and evening in western Lake Superior, so additional
small craft advisories may be needed at that time. Looking
farther ahead, winds become gusty again out of the northwest on
Tuesday, with some Gale Warnings possible (40-70%) along the
North Shore and winds and waves likely being hazardous to small
craft elsewhere.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...Winter Weather Advisory until noon CDT Monday for WIZ004.
MARINE...Small Craft Advisory until 5 AM CDT Monday for LSZ121-140>148-
     150.

&&

$$

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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.