181
FXUS63 KDLH 272012
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
312 PM CDT Thu Mar 27 2025

.KEY MESSAGES...

- Two winter storms will impact the Upper Midwest Friday through
  the weekend.

- The first storm will impact most of northeast Minnesota and
  northwest Wisconsin Friday and Friday night. The most
  significant hazard will be freezing rain and icing potential.

- There is a 30-50 percent chances of thunderstorms on Friday. A
  few storms may have hail to one inch in diameter.

- A second storm will move into the Upper Midwest Saturday night
  into Sunday. The track of this storm is still uncertain,
  however, this storm could (40-60 percent chance) bring another
  round of accumulating snow and freezing rain to portions of
  the Northland, especially northwest Wisconsin.

- Gale Warning for all of western Lake Superior Friday morning
  through at least Saturday night.

&&

.DISCUSSION...
Issued at 252 PM CDT Thu Mar 27 2025

Tonight through 7am Friday Morning...

The main concern for tonight will be with a band of precipitation
along the International Border associated with mid level
frontogenesis and warm air advection north of the strong warm front.
The most likely precipitation type will be snow through 09Z Friday
as the melting layer aloft will not have established itself yet.
Thereafter, the melting layer aloft increases near the International
Border, leading to a potential to begin mixing in some sleet via
partially melted snow. Given this is a narrow banded precipitation
setup from frontogenesis, there is still some uncertainty to
navigate on how much of the band will fall north or south of the
border. This obviously has big implications for snowfall totals
along the border. For locations south of a line from
approximately Big Falls through Lutsen, dry mid level air will
be in place to largely limit the precipitation potential.
However, saturating low levels through the night may lead to
pockets of drizzle or freezing drizzle.

Friday Morning through Friday night...

An impressive warm front will propagate north through the day on
Friday, and will be located from near Fergus Falls MN to just north
of the Twin Cites to just south of Green Bay by 21Z. An impressive
melting layer/warm nose aloft will establish itself across northeast
Minnesota and northwest Wisconsin in warm air advection. The
strength of this warm nose will range from very close to 0C near
the International Border, to near +10C from the Brainerd Lakes
through Hayward. Elevated buoyancy on the order of 500-800 j/kg
above the warm nose in steep mid level lapse rates will also
spread north through the day supporting a 30-50 percent chance
of elevated thunderstorms embedded in the wintry mix. Given a
highly sheared environment and cold temperatures, severe hail is
not out of the question, especially from the Brainerd Lakes
through the I-35 corridor and into northwest Wisconsin. In fact,
some soundings are quite impressive and show a scenario of
elevated thunderstorms with both a hail and freezing rain threat
at the same time.

In regards to winter impacts, the biggest question is the strength
of the low level cold layer below the impressive melting layer
aloft. The most likely area for sub-freezing temperatures Friday
afternoon as precipitation coverage increases is across Lake
and Cook counties with a 70-90 percent chance of temperatures
remaining below freezing. This rapidly decreases to around a 50
percent chance for the Twin Ports and only a 5-10 percent chance
for the Brainerd Lakes. Given the late March strength of
insolation even through the clouds, ice accumulations will be
highly dependent on surface temperatures. The greatest ice
accumulations are expected across Lake and Cook counties where
there is 60-80 percent chance of at least 0.10 inches of ice
accumulation, and a 30-50 percent chance of greater than 0.25
inches of ice. This is largely tied to the best co- location of
the warm layer aloft and re- freeze layer near the surface and
some lake moisture enhancement as well. Elsewhere, the most
likely scenario is for between a light glaze to around 0.05
inches of ice accumulation from the Borderlands through the Iron
Range, Twin Ports and across the South Shore as surface
temperatures fall late Friday afternoon and into the evening.
Upgraded the Winter Storm Watch to a Winter Weather Advisory for
the Arrowhead, Twin Ports and Iron Range, and expanded it west
to include Itasca county for late Friday morning through Friday
evening. Also added the South Shore to a Winter Weather Advisory
for Friday evening and night as colder air arrives in at the
surface and the freezing rain threat increases. An expansion of
the Advisories are not out of the question depending on surface
temperatures and icing potential, and there is still a 20-30
percent chance of needing an Ice Storm Warning for portions of
the North Shore, again dependent on where surface temperatures
are through the day tomorrow.

Saturday Evening through Sunday...

The next storm system quickly arrives into the Upper Midwest and
Great Lakes Saturday evening through Sunday. There are two distinct
scenarios for how this will impact the Northland. This first is
represented by the CMC and ECE families with a more northerly track
of the surface low. This places the overall precipitation shield
further north with a 50 percent or greater potential for 4 plus
inches of snow from the Brainerd Lakes through the North and
South Shores and a similar chance for greater than 0.10 inches
of ice accumulation for Hayward through Philips in northwest
Wisconsin beneath a melting layer aloft. The GEFS and NAM have a
more southerly track and with more limited winter impacts.
Given the uncertainty, and the complexity of the first storm
Friday and Friday night, will hold on a watch for now.


&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1227 PM CDT Thu Mar 27 2025

VFR conditions across northeast Minnesota and northwest
Wisconsin this afternoon and into the evening. The one exception
will be near the International Border where a band of snow is
expected to spread over by 23-02Z tonight, and remain into
Friday morning. Some freezing rain and sleet will mix in Friday
morning. Elsewhere across northeast Minnesota and northwest
Wisconsin, low level stratus, fog and drizzle will expand from
south to north through the night north of a strong warm front.
IFR conditions are expected. Precipitation will increase across
the area through the day on Friday falling as a mix of all
precipitation types of rain, freezing rain, sleet and snow. A
few thunderstorms are also expected Friday afternoon and
evening. IFR conditions expected.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 1227 PM CDT Thu Mar 27 2025

Easterly wind gusts may to reach up to 30 knots later tonight.
A Small Craft Advisory is in effect tonight and into early
tomorrow. Friday afternoon and throughout the day on Saturday,
east to north east gusts of up to 40 knots are expected. Wave
heights may reach up to 12 feet during this time. A Gale Warning
is in effect Friday morning and all day on Saturday.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory from 3 AM Friday to 1 AM CDT Saturday
     for MNZ010-011.
     Winter Weather Advisory from 10 AM Friday to 1 AM CDT Saturday
     for MNZ012-018>021-026-037.
WI...Winter Weather Advisory from 7 PM Friday to 7 AM CDT Saturday
     for WIZ001>004.
MARINE...Small Craft Advisory from 10 PM this evening to 10 AM CDT
     Friday for LSZ121-140>148-150.
     Gale Warning from 10 AM Friday to 1 AM CDT Sunday for LSZ121-
     140>148-150.

&&

$$

DISCUSSION...PA
AVIATION...PA
MARINE...IGS/PA