996
FXUS63 KDLH 020516
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1216 AM CDT Tue Jul 2 2024

.KEY MESSAGES...

- Areas of heavy rain possible overnight into Tuesday. Flood Watch
remains in effect over northern Minnesota. The potential for rain
to linger into early Wednesday morning have increased.

- Gusty southerly winds 30 to 40 mph possible overnight into Tuesday
morning.

- Another system with more heavy rain chances late Thursday
  through Friday.

&&

.DISCUSSION...
Issued at 302 PM CDT Mon Jul 1 2024

Through the day , a broad upper level shortwave has pushed in over
the Upper Plains, along with a plume of Gulf of Mexico moisture
surging northward. SPC Mesoscale Analysis shows PW values up to 1.9"
along the MN/Dakotas border, expected to move eastward tonight. This
saturation is present through the column, with dewpoint depressions
of 1-2 degrees or less up through 500mb. Model soundings continue
show a classic warm rain environment setup with freezing levels near
13kft pushing into the area overnight. This is a concerning
potential heavy rain set up, on top of areas that saw 2-3x their
normal June monthly rainfall. There has been some training of storms
north of Grand Forks today which dropped over an inch of rain in 6
hours for some places. This convection was largely not handled well
by CAMs, so have have opted to stay on the bullish side with PoPs
and QPF overnight across the International Border, despite latest
guidance trending the heaviest rainfall northward. A Flood Watch
remains in effect across the northern third of the CWA or so, an
area where soils are saturated, streamflows remain above normal, and
an inch or two in a couple hours could lead to flash flooding.

Some moderate to heavy rain is possible in the rest of the CWA as
well overnight, with a half to one inch possible. Some over
achievement of rainfall totals is possible here as well, but there
is a little more room in lakes, rivers, and soils for rain to fall
here, and there is less signal for possible training of storms.

Overnight tonight, a screaming low level jet pushes east across the
region, with 850mb wind speeds of 40-50 knots. With ongoing rain,
and a weak to isothermal low level temperature modeled temperature
profile, it seems reasonable that some of these winds could mix down
to the surface leading to very gusty southerly winds into Tuesday
morning. Some gusts of 30-40 mph could make it to the surface before
this LLJ moves off and winds calm through Tuesday midday.

Through the day Tuesday, a secondary shortwave embedded within a
larger trough moves through, which keeps rain chances going through
the day across the Northland. Scattered showers with light to
moderate rain may continue into Wednesday morning. Tuesday will be a
warm and very moist day with temperatures near 80 and dewpoints in
the low to mid 60s.

Late Thursday and into Friday, a deeper shortwave trough with a cut
off low is progged to push over the International Border and sweep
over the Upper Great Lakes. With good synoptic forcing and another
round of attending deep moisture, this will be another one to watch
for heavy rain potential. Timing has trended slightly later for the
onset of this possible precipitation, now more overnight into Friday
morning.

Temperatures rise through the week, with high temps nearing 80 by
July 4th, which is right around to slightly above normal for the
time of year.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1216 AM CDT Tue Jul 2 2024

Deteriorating conditions are expected tonight with ceilings
lowering through MVFR to IFR. Showers and thunderstorms will
move through the region as well...with chances lowering from
southwest to northeast later tonight into Tuesday morning. A
strong low level jet will create low level wind shear overnight
but it is forecast to shift east Tuesday morning.

A frontal boundary will still be west of the Northland at 12Z
Tuesday and it will move through the Northland with more chances
for isolated to scattered showers and thunderstorms. Conditions
will improve through the day to VFR but dips lower will occur
with any showers/storms.

Winds tonight into Tuesday morning will be challenge with
occasional strong gusts with the low level jet overhead.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 302 PM CDT Mon Jul 1 2024

The main concern is increasing southerly winds tonight into Tuesday
ahead of an approaching low pressure system. A Small Craft Advisory
is in effect for Chequamegon Bay to Saxon Harbor for late tonight
into early Tuesday afternoon for gusts of 25-30 kts. Across the
remainder of the South Shore to the Twin Ports, while the
forecast for tonight into Tuesday favors southerly gusts just below
20 to 25 kts, strong winds aloft will be screaming at 35 to 50
knots. There is high uncertainty if these much stronger winds
be able to reach the water surface and prompt an expansion of
the Small Craft Advisory. There is a similar concern for
Chequamegon Bay to Saxon Harbor where gale force gusts could
(20-40% chance) occur. This will be closely monitored through
the evening and updates will be given as needed. Should these
strong winds actually manifest at the water surfaces, it will be
most likely along the immediate shoreline, decreasing the
further away from the mainland one gets. Some large ships may
observe very strong winds at the pilot house while the surface
of the lake remains largely untouched.

Southerly winds should be weaker on the North Shore as those
strong winds aloft are not expected to be able to make it down
through the stronger stable layer there. That said, waves along
the North Shore from Taconite Harbor to Grand Portage will
build tonight into Tuesday to around 3-4 feet from moderate
south winds in the open waters. This will be another area to
watch for a Small Craft Advisory. Otherwise, widespread rain
showers with embedded thunderstorms will occur overnight,
decreasing through the day into Tuesday.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch through this evening for MNZ010>012-018>021.
WI...None.
MARINE...Small Craft Advisory from 4 AM early this morning to 3 PM CDT
     this afternoon for LSZ121-148.

&&

$$

DISCUSSION...Levens
AVIATION...Melde
MARINE...PA/Levens/AP