365
FXUS63 KDLH 091702
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1202 PM CDT Thu May 9 2024

.KEY MESSAGES...

- The potential for frost in the interior Arrowhead persists
  through 7-8 AM this morning as temperatures remain at or a few
  degrees above freezing.

- Another period of sub-freezing temperatures (northwest
  Wisconsin and the Arrowhead) sets up again Thursday night,
  with frost also possible for east-central Minnesota and
  northward throughout Carlton and St. Louis Counties.

- Scattered thunderstorms are expected to form Friday afternoon,
  with isolated strong thunderstorms possible in the late
  afternoon to mid-evening hours Friday. Severe storms are not
  currently expected.

- Temperatures around sunrise on Saturday are forecast in the
  low-40s and increasing to low to mid-60s F by early afternoon
  under mostly sunny skies. Precip chances build in Saturday
  evening, with thunderstorms on Sunday.

&&

.DISCUSSION...
Issued at 356 AM CDT Thu May 9 2024

Surface temperatures right around to a few degrees above
freezing are being observed early this morning in the interior
parts of the Arrowhead where winds are generally calm to only a
few mph from the northeast. Where winds are 4-5 mph or more the
surface temperatures have remained around 40 to mid-40s helping
inhibiting frost potential within about ten miles of Lake
Superior. Temperatures remain within the frost-tolerance
threshold through 7-8 AM this morning so the Frost Advisory
remains in effect. A couple of locations where dewpoints have
been observed into the upper-20s even dropped to 29 F so far in
far eastern interior Cook County.

Quiet weather is expected today outside of some breezy morning
northeasterly winds near Lake Superior. A very dry airmass aloft
is forecast to help to drop surface RH down to 25-30% in
north-central MN, but light winds limit any general fire weather
concerns and no less the gradual green-up and recent rainfall.

Surface high pressure allowing for calm winds under a mid-level
ridge aloft creating a very dry and cool airmass creates an
80-90% chance of sub-freezing surface temperatures for nearly
all of northwest Wisconsin beginning late this evening through
Friday morning. A Freeze Watch has been issued for all but
Burnett County from 10 PM to 9 AM as a result. At to slightly
above freezing temperatures remain very likely (70% chance) from
Aitkin to eastern Itasca to eastern Koochiching Counties and
eastward into the Arrowhead tonight, including nearly of the
Twin Ports. Frost Advisories very easily could be again needed
in future forecast updates to cover these low to mid-30 F low
temperatures expected by early Friday morning. A building
pressure gradient allowing for light southwesterly winds to
persist overnight in the Brainerd Lakes and northward into
western Koochiching County highly limits any frost/near-freeze
potential for this part of the Northland. Today during the
daytime is the time to prep those early uncovered gardens,
flower beds, outdoor plants for these freezing temperatures
expected tonight.

A shortwave trough digs southeastward early Friday morning over
southern Manitoba to create the next round of rainfall for
Friday morning over north-central Minnesota and later northeast
MN. One to two tenths of an inch of rainfall is the most likely
rain amounts expected currently. As the trough moves into the
Borderlands Friday late morning though, increased mid-level
lapse rates, greater saturation and CAPE up to 800-1000 J/kg are
very likely to create scattered thunderstorms Friday afternoon
through Friday evening. Wind shear around 25 knots could support
stronger thunderstorms in the late afternoon to early evening
time period Friday across the region. Small hail and wind gusts
of 40-50 mph are the primary hazard threats at this time. While
CAPE decreases in the late evening hours, lingering isolated
thunderstorms and rain showers exit the Arrowhead and northwest
Wisconsin last Friday night.

Temperatures around sunrise on Saturday are forecast in the
low-40s with west to northwest winds around 5 mph. By early
afternoon, temperatures increase to to low to mid-60s F under
mostly sunny skies with westerly winds around 7-10 mph. There
is a 40% chance of temperatures in north-central Minnesota
reaching 70 F. Not a bad day for the boat eh? Speaking of
boating though, keep in mind wearing life jackets even with
these pleasant air temperatures, the water temperatures remain
fairly cold compared to the air temperature. Cold water safety!

By Saturday evening, there is a 20% chance of rain showers
building into the Northland though, which further builds to
30-40% chance by Sunday (best chances in the Arrowhead and
northwest Wisconsin). Keep in mind rain gear for the second half
of the weekend and having an alternative plan if out on the
water and thunderstorms begin to approach those inland lakes
Sunday.

A dry start to the next work week with temperatures about 5 to
10 degrees above normal may (20% chance) lead to rainfall by
next Tuesday PM.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1202 PM CDT Thu May 9 2024

VFR conditions will persist through the TAF period at all sites,
with a low probability (10-20%) for a brief (<1 hour) period of MVFR
conditions at HIB/INL on Friday afternoon as showers and
thunderstorms associated with a cold front move across northeast
Minnesota, with the most likely timeframe for any MVFR conditions in
the afternoon beyond the current TAF issuance period. North to north-
northeast winds today around 5 to 10 knots (strongest at DLH and
HYR), becoming light/southerly overnight then west/northwesterly at
10 to 15 knots Friday as the cold front moves from west to east
across the region.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 1202 PM CDT Thu May 9 2024

Today will be another day of gusty northeast winds creating
elevated wave heights from 3 to 5 feet in the southwestern arm
and along the South Shore through this afternoon. Small Craft
Advisories are in effect. Winds decrease in the early to mid-
afternoon hours today though and shift southwesterly tonight.
Southwesterly winds 10-15 knots, locally gusting to 20 knots
north of Grand Marais on Friday build wave heights again of 2-4
feet along the North Shore. An approaching shortwave trough from
the north creates thunderstorm chances Friday afternoon and
evening. Local outflow driven erratic wind gusts to 35 knots
are possible from any stronger thunderstorms.


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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...Freeze Watch from 10 PM CDT this evening through Friday
     morning for WIZ001>004-007>009.
MARINE...Small Craft Advisory until 1 PM CDT this afternoon for
     LSZ142>148-150.

&&

$$

DISCUSSION...NLy
AVIATION...JJM
MARINE...NLy