818
FXUS63 KDLH 101258
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
758 AM CDT Fri May 10 2024

.UPDATE...
Issued at 756 AM CDT Fri May 10 2024

The Frost Advisories and Freeze Warning expire at 8 AM this
morning as temperatures have quickly warmed into the upper 30s
to 40s early this morning.

&&

.KEY MESSAGES...

- Freeze Warnings continue for much of northwest Wisconsin and
  parts of the Arrowhead through 8 AM. Frost Advisories also
  persist through 8 AM for east-central MN into the Twin Ports
  and for northern St. Louis County.

- Scattered showers expected today along and behind a cold
  front, with isolated to scattered thunderstorms also expected
  this afternoon into early evening.

- A few stronger storms this afternoon into early evening could
  produce small hail and gusty winds to 50 mph, with the best
  potential south of a Grand Rapids to Cloquet to Hayward line.

- Several additional chances for showers/thunderstorms this
  weekend and into next week with near to above average
  temperatures. A few stronger thunderstorms could produce small
  hail and gusty again on Sunday afternoon (mainly northwest
  Wisconsin).

&&

.DISCUSSION...
Issued at 449 AM CDT Fri May 10 2024

Early this Morning:

High pressure over the Northland early this morning has led to
the development of a favorable radiational cooling setup tonight
with calm to very light winds and mainly clear skies. As a
result, temperatures have plummeted into the upper 20s to low
30s in parts of the Iron Range, Arrowhead, and large parts of
NW WI. Freeze Warnings are in effect for these areas until 8 AM
this morning due to low temperatures below freezing. Frost
Advisories are also in effect until 8 AM for the MN counties of
Pine, Carlton, Northern St. Louis, and Southern St. Louis due to
low temperatures dropping into the mid-30s. Temperatures begin
to warm quickly within a few hours after sunrise.

Today - This Evening:

A mid-level shortwave trough currently located over southern
Manitoba/northern Ontario as of 4 AM CDT will quickly dive
south-southeast across the Northland today, with an attendant
surface cold front sliding southeast across the area throughout
the day. Expect a mix of clouds and sun with and behind the cold
frontal passage today, with the development of scattered showers
for much of the day into this evening and some isolated to
scattered thunderstorm activity this afternoon into early
evening. High-res model guidance highlights a broad development
of 200-500 J/kg of SBCAPE this afternoon into early evening,
though 0-6km bulk shear will be decreasing to 20-30 knots as the
afternoon progresses. While this isn`t a lot of instability or
shear, dry air and steep low-level lapse rates could drive some
evaporational cooling to enhance downdrafts from any storms that
form, leading to isolated wind gusts up to 50 mph in the
strongest storms along with small hail (pea-sized). The area of
best potential for these stronger storms would be generally
south of a Grand Rapids-Cloquet-Hayward line where the deepest
low-level mixing will be when storms move through. Shower and
storm activity quickly drops off towards and after sunset today.

Precipitation amounts today will scattered and mainly be on the
order of 0.10-0.25" today for locations where showers or storms
move overhead, though isolated pockets to 0.5" are possible in
any stronger storms.

Tonight:

Clearing skies are expected from west to east tonight, which
should allow for a good chance to see the northern lights
tonight. See the Space Center`s webpage for more specific
details about the northern lights potential tonight.

The clear skies and lighter northwest winds tonight will once
again lead to low temperatures falling into the mid/upper-30s
for the MN Arrowhead and parts of NW WI. Frost probabilities in
these areas are 30-40% or less at the moment, but Frost
Advisories may be needed again tonight if forecast low
temperatures drop another couple degrees lower than the current
forecast.

This Weekend:

We see northwest flow with subtle mid-level shortwave ridging
develop for the Upper Midwest on Saturday, leading to sunny
skies to start before some diurnal cumulus develop Saturday
afternoon amid deeper low-level mixing. There is a 30-50% chance
for some scattered showers late Saturday afternoon and evening
and perhaps an embedded thunderstorm during the evening, primarily
in north-central Minnesota. No severe weather is expected and
precipitation amounts are expected to be on the order of one-
tenth of an inch. Expect a warmer day, with highs ranging from
the mid/upper-60s in the eastern CWA to low/mid-70s in the
western CWA.

On Sunday, a shortwave trough and surface low moving across far
northern Ontario will bring an attendant stronger surface cold
front southeast across the Northland, mainly during the morning
in MN and late morning/afternoon in NW WI. The exact timing of
when this front moves across the area will dictate how much of
the warm sector will still be located in parts of our area
during the afternoon when showers and thunderstorm are expected
to develop. Right now this warm sector area is forecast to be
limited to east-central MN into the inland counties of NW WI.
This is the area that could see the development of 500-1200 J/kg
of SBCAPE due to steep mid- and low-level lapse rates. Deep-
layer shear vectors will be weaker (15-25 knots) with this
Sunday system, but the stronger instability and steep lapse
rates could provide enough energy for a few of these storms to
produce small hail and gusty winds. Thunderstorm
coverage/potential drops off quickly by the evening as the cold
front continues moving south.

Next Week:

Look for a drier day on Monday into most of Tuesday as another
shortwave ridge moves through the Upper-Midwest while a more
mature low churns over far northern Ontario. Mostly sunny skies
and high temperatures in the 60s (cooler near Lake Superior) are
forecast.

Ensemble guidance shows general agreement in a stronger
shortwave trough moving through the Upper Midwest sometime in
the Wednesday-Friday timeframe, but varies on when exactly this
trough will move through mid-late week. Nonetheless, expect more
widespread chances (50-70%) for >0.25" of rain with this system,
with a 20-40% chance for greater than 0.5". Temperatures remain
somewhat seasonal most of next week, with highs in the 60s to
around 70 degrees, though cooler near Lake Superior.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 703 AM CDT Fri May 10 2024

Mid-level clouds and scattered showers have begun moving into
north-central MN and will continue to move southeast through the
morning and afternoon. Winds veer to northwesterly in northeast
MN by mid to late morning, while veering to northwesterly in
northwest Wisconsin from midday into the afternoon. As the low-
levels become mixed today, gusts will increase to 20-25 knots
for most terminals, aside from KHYR, from midday through the
afternoon. Some gusts at KBRD could reach up to 28 knots.

Scattered showers move southeast across the Northland today with
and behind the cold front. Isolated to scattered thunderstorms
develop during the afternoon and diminish by mid-evening. Expect
VFR ceilings/visibilities with most showers, though some brief
MVFR is possible with the heavier showers and storms should they
move over a terminal. Gusty and erratic winds up to 40-45
knots and small hail are possible with any of the stronger
storms. Expect winds to quickly weaken mid to late evening and
turn light overnight.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 756 AM CDT Fri May 10 2024

Light southwesterly winds early this morning increase to 7-12
knots by this afternoon out of the west with gusts less than 20
knots as a cold front moves through Lake Superior. Scattered
showers and isolated thunderstorms are possible along and behind
the cold front today, with the thunderstorms mainly during the
afternoon into early evening. Winds turn northwesterly later
this evening and tonight.

South to southwest winds return on Saturday through Sunday
morning, with gusts of less than 15 knots. Winds do turn
northwesterly behind another cold front Sunday afternoon and
evening. A few gusts along the North Shore could approach 20-25
knots Sunday afternoon and evening, so some Small Craft
Advisories may be needed.

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.

&&

$$

UPDATE...Rothstein
DISCUSSION...Rothstein
AVIATION...Rothstein
MARINE...Rothstein