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819
FXUS63 KDLH 032153
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
453 PM CDT Mon Jun 3 2024

.KEY MESSAGES...

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- 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.
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&&

.DISCUSSION...
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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.
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&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1250 PM CDT Mon Jun 3 2024

A mix of VFR and MVFR conditions are in place across the region
early this afternoon as cloud cover lingers across the region.
As a cold front moves through later this afternoon and evening,
VFR conditions are expected to spread across the region. Winds
off Lake Superior overnight are expected to lead to the
development of fog and low stratus and impact mainly KDLH with
conditions dropping to IFR. MVFR ceilings are expected to
develop elsewhere across the Northland. MVFR or lower conditions
will then prevail through the remainder of the period. There is
the chance for some fog to develop at HYR during the early
morning hours, but confidence was too low to include at this
time. Winds will remain under 10 knots into Tuesday morning with
gusts to 15 to 20 knots developing by mid to late Tuesday
morning.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
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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.
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&&

.DLH WATCHES/WARNINGS/ADVISORIES...
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MN...Flood Watch from Tuesday afternoon through Wednesday afternoon
     for MNZ034-036-038.
WI...Flood Watch from Tuesday afternoon through Wednesday afternoon
     for WIZ001>004-006>009.
MARINE...Dense Fog Advisory until 10 AM CDT Tuesday for LSZ140-141.
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&&

$$

DISCUSSION...Huyck/AP/PA
AVIATION...BJH
MARINE...Huyck