000
FXUS63 KDLH 221132
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
632 AM CDT Mon Apr 22 2024

.KEY MESSAGES...

- Near critical fire weather conditions are expected this
  morning into the mid-afternoon for portions of the MN
  Arrowhead and northwest WI.

- A Clipper System will bring scattered to widespread rain
  showers today into tomorrow with isolated non-severe
  thunderstorms possible. Snow is likely to mix in with the rain
  on Tuesday for portions of the area as cold air filters in.

- A Colorado Low is likely to bring widespread rain to the Upper
  Midwest later this week into this upcoming weekend.

&&

.DISCUSSION...
Issued at 440 AM CDT Mon Apr 22 2024

Cloud cover will be increasing through the morning today as an
Alberta Clipper propagates towards the area. Ahead of this clipper,
conditions will be dry this morning into the early afternoon. Model
soundings from the CAMs show a deep mixing layer developing despite
the increasing mid to high-level cloud cover. This deep mixing layer
extending in excess of 7,000ft AGL is expected to drop min RH as low
as 25% today, especially in the northern portion of the Arrowhead
and in north-central WI. When combining this dry air with breezy
southwest winds, near-critical fire weather conditions are expected
today in northern St. Louis, Lake, and Cook Counties and portions of
northwest WI. One unusual difference with today is that peak drying
will not be following typical diurnal patterns. Instead of peak
drying occurring in the late afternoon, minimum RH is anticipated to
occur around midday due to the arrival of rain this afternoon.

As low pressure continues eastward towards the CWA, a line of
scattered to widespread showers are expected to arrive this
afternoon as a band of enhanced negative omega and FGEN move in
ahead of a weak cold front. Expect some virga to initially occur due
to the abundant amount of low-level dry air. Showers will progress
eastward across the CWA through the afternoon and evening. While a
rumble or two of thunder is possible today, thunderstorms are
unlikely due to weak MUCAPE of 100 J/kg or less. Expect a brief
break from rain showers this evening into tonight as a dry slot
moves through ahead of the low pressure center.

An additional round of showers is forecast to occur on Tuesday as
the Clipper propagates through the CWA. While much of this second
round of precip will fall as rain, snow will likely mix in over the
Arrowhead and much of northwest WI due to CAA on Tuesday. Snow
accumulations are expected to range from nothing up to 0.2" at most
in far northeastern MN and in northern Iron County by Tuesday
evening. Also of note on Tuesday will be the potential for isolated
non-severe thunderstorms. These isolated thunderstorms will be most
likely in east-central MN and northwest WI where instability will be
highest (MUCAPE up to 100-200 J/kg).

Quiet weather is expected on Tuesday night through Thursday after
the clipper moves downstream of the CWA. Dry conditions are likely
on Wednesday as high pressure builds over northern Ontario. This may
lead to another day of near-critical fire weather conditions.

Looking ahead, a deep trough is likely to bring a strong Colorado
Low to the Upper Midwest during the latter half of the workweek into
Saturday. This late week system will have the potential to bring
decent amounts of rainfall as it taps into strong moisture advection
from the Gulf of Mexico. Early indications from the NBM show that
QPF amounts in excess of 1" will be possible (40-60% chance) across
a large portion of the CWA between Friday and Saturday evening.
Global deterministic models are also showing that thunderstorms will
be likely as a tongue of elevated CAPE extends into the CWA. This
late week system will be one to monitor over the next few days as
models continue to converge on a solution and confidence in specific
impacts increases.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 632 AM CDT Mon Apr 22 2024

VFR conditions will start the period. An area of low pressure will
be moving towards the region today from Canada, arriving into far
north-central Minnesota by this evening. Southwest winds preceding
this low pressure are expected to be breezy this morning into the
afternoon. Scattered showers will begin this afternoon, likely
falling initially as virga. Timing for rain today has trended later,
with precip onset likely around mid-afternoon. As the low pressure
center moves into the region, MVFR and IFR cigs are likely over INL
early Tuesday morning.

&&

.MARINE...
Issued at 440 AM CDT Mon Apr 22 2024

Southwest winds are expected to increase this morning to speeds of
10 to 15 knots with gusts up to 25 knots along the South Shore and
from Duluth to Two Harbors. A Small Craft Advisory was issued for
today, covering the entire South Shore and the zone from Duluth to
Two Harbors due to these elevated winds. A clipper moving through
this afternoon into Tuesday will bring light rain showers then a
rain/snow mix as cold air is advected over the lake.

On the back side of the system, winds will shift to the northeast
and increase starting Tuesday morning. Winds above 20 knots with
gusts up to 30 knots will very likely necessitate another round
of Small Craft Advisories on Tuesday into Tuesday evening. A
Gale Warning may also be needed in the outer Apostle Islands and
from Grand Marais to Grand Portage on Tuesday as gusts approach
35 knots. Confidence in gale-force wind gusts on Tuesday is
around a 40% chance in the aforementioned waters on Tuesday.

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 from 10 AM this morning to 6 PM CDT this
     evening for LSZ121-144>148-150.

&&

$$

DISCUSSION...Unruh
AVIATION...Unruh
MARINE...Unruh