462
FXUS63 KDLH 040538
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1238 AM CDT Tue Jun 4 2024

.KEY MESSAGES...

- Dense fog will form over Lake Superior tonight and may impact
  areas along it`s shores.

- A line of showers and thunderstorms will develop and move
  eastward across the Northland Tuesday afternoon and evening. A
  few storms may be strong to severe. Locally heavy rainfall is
  possible and could lead to localized minor flooding.

- Rain and storm chances will continue each afternoon and
  evening Wednesday through the end of the week.

&&

.DISCUSSION...
Issued at 452 PM CDT Mon Jun 3 2024

A stationary front loitered over northwest Wisconsin and
portions of the Minnesota Arrowhead late this afternoon.
Meanwhile a weak cool front stretched from near International
Falls to near Brainerd to southwest Minnesota. In the warm
sector between these two fronts, isolated to scattered showers
and a few thunderstorms developed over the past several hours.
Weak deep layer shear and limited instability means most of the
storms have been short lived. The exception is a cell over west-
central Wisconsin, northeast of Eau Claire. We expect a few
additional storms to develop through early evening.

Areas of fog may develop tonight, particularly over portions of
the I-35 corridor and northwest Wisconsin where heavy rain fell
earlier this morning.

Another cold front will propagate eastward across northern
Minnesota and northwest Wisconsin Tuesday and Tuesday night.
Southerly flow aloft and mainly clear skies ahead of the front
are forecast to provide MLCAPE values of 1000-2500 J/kg by late
afternoon. Deep layer shear of around 30 knots is forecast
ahead of the front with straight to cyclonically curved
hodographs below 3 km becoming shorter above 3 km. The limited
shear and hodograph presentation raises questions about storm
modes. We expect widespread convection along the front as it
progresses eastward through the afternoon. At the moment, shear
parameters and limited moisture aloft seem to limit the hail
potential with storms. It seems penny to half-dollar size hail
is probably the top end of the hail potential, with most storms
producing smaller hail. The low-level wind shear seems favorable
for rotating storms, although dry air entrainment and
shortening hodographs with height would suggest difficulty
maintaining updraft strength. It would seem the tornado risk is
somewhat mitigated by these factors. Think the SPC Marginal and
Slight Risk areas are appropriate based on the 12Z guidance.

Storm motions and orientation to the front raise concerns about
training storms and locally heavy rainfall. With recent heavy
rain and localized minor flooding today, and more rain coming
tomorrow, think the risk of additional minor flooding is high
enough to support a Flood Watch from the Brainerd Lakes east
including northwest Wisconsin.

For Wednesday and Thursday an upper level low will be in place
across the western Great Lakes. This will continue the potential
for numerous rain showers and thunderstorms, especially during
peak daytime heating through sunset each day. Severe threats
like hail, tornadoes, and strong winds appear to be minimal, as
CAPE values are expected to not exceed more than 1000 J/kg with
weak shear. While these rain showers and thunderstorms do not
have the flood concerns of Tuesday and Tuesday night, areas in
NW Wisconsin already wet from the rain on Sunday night and
Monday morning, especially the Knife, St. Croix, Namekagon, and
Bois Brule River basins should expect continued higher water
levels.

For Friday into the weekend, an upper level ridge will attempt
to build in the western CONUS, but does not appear to be very
strong. Thus the Upper Midwest is expected to remain in
northwest flow, with winds exceeding 100 kts at the 300 mb.
However, the moisture from the Gulf might not be as strong as it
will be for Tuesday-Wednesday. While daily rain shower and
thunderstorm chances are inevitable, uncertainties remain into
the weekend due to the timing of possible shortwaves embedded
within the fast flow.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1238 AM CDT Tue Jun 4 2024

Conditions varied widely across the Northland. Fog was
developing and stratus was expanding. IFR conditions will
expand over northwest Wisconsin and around Lake Superior with
some fog further inland as well. IFR or lower visibility and
ceilings will occur at KHYR/KDLH/KHIB and could occur at KBRD
but higher clouds moving in there should lower the chances
some. The fog and stratus will lift for most through the day but
take longest around Lake Superior which will see off lake winds
through most of the day which won`t help matters. A cold front
will push through the Northland Tuesday afternoon and evening
bringing with it showers and thunderstorms. Some of the storms
during the afternoon and evening could be severe with large hail
and damaging wind both threats. Showers and some isolated
thunderstorms will continue after the main line of storms push
through but will eventually end from west to east.

Gusty southerly winds will occur prior to the front with decent
mixing leading to gusts of 20 to 25 knots. Winds will switch to
west or southwest behind the front and be quite a bit lighter
through Tuesday night.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 452 PM CDT Mon Jun 3 2024

Light winds this evening will turn northeasterly and increase
slightly overnight to around 10 to 15 knots. With heavy rainfall
over the waters early Monday, dense fog may redevelop over the
lake. Fog lingered near Grand Marais as of 3 PM and thus we
extended the Marine Dense Fog Advisory until late Tuesday
morning. The advisory may need to be expanded should the dense
fog redevelop elsewhere. A cold front will move across the
region from west to east Tuesday. Showers and thunderstorms are
forecast late Tuesday afternoon through early Wednesday morning.
A few storms may be strong to severe with large hail and wind
gusts of 30 to 45 knots possible. Fog may redevelop once again
Tuesday night.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch from this afternoon through Wednesday afternoon
     for MNZ034-036-038.
WI...Flood Watch from this afternoon through Wednesday afternoon
     for WIZ001>004-006>009.
MARINE...Dense Fog Advisory until 10 AM CDT this morning for LSZ140>143.

&&

$$

DISCUSSION...Huyck
AVIATION...Melde
MARINE...Huyck