808
FXUS63 KDLH 040827
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
327 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

- Off and on rain and thunderstorm chances through this week.
  Wednesday and Wednesday night bring the best chance for
  widespread showers and storms.

- The potential for heat-realted illness will increase Thursday  and
  Friday.

&&

.DISCUSSION...
Issued at 318 AM CDT Mon Aug 4 2025

Current Conditions/Today:

Radar this morning shows light returns from scattered showers. A
slow moving MCV over the Red River Valley is the culprit for this
activity and will be the focal point of weather as we start the work
week. An anticyclone aloft over Manitoba has set up a Rex Block for
the Northland leading to this MCV to slowly churn as it treks into
the Northland. Fortunately, this set up has no strong moisture
feed otherwise we would be looking at some flooding concerns.
Instead we will be getting scattered light rain showers through
the day. Can`t fully rule out some rumbles of thunder at times
in the afternoon as diurnal processes aide with spreading the
coverage. But overall, the environment is weakly forced and does
not support the development of any strong or severe storms.

Tuesday - Tuesday Night:

Tuesday the anticyclone locking everything in place begins to
migrate east into Ontario which should allow the low spinning
over the Northland to move north. However, models are not great
when it comes to the progression of blocking patterns so
confidence is on the low side. Regardless, southerly flow
increases on Tuesday with temperatures warming up. Depending on
the progression of the low we could see additional showers and
isolated storms. However, the influx of warm air will lead to
some capping issues with model soundings showing an inversion
between 700-800mb.

Late Tuesday the blocking pattern should be completely broken
down as new surface low moves across the Canadian Prairies. An
increased low level jet will also help to pivot the baroclinic
zone out of the Red River Valley and into the Northland. A
corridor of strong to severe storms will likely develop over the
Northern Plains Tuesday evening and migrate east overnight.
Instability parameters look to drop off a cliff as the storms
encroach our region so severity will follow suit. For now,
expect some showers and rumbles of thunder entering from the
west early Wednesday morning.

Midweek:

After the initial wave of showers and storms on Wednesday
morning we will have to wait and see how well the atmosphere can
recover. With the parent low pressure up in southern Manitoba
we will firmly be in the warm sector and should be able to
generate some moderate to strong instability by the afternoon.
We should also start to see some noticeable contributions from
evapotranspiration as the southwesterly flow increases our
dewpoints. One limiting factor looks to be bulk shear. The 00Z
suite of guidance shows it to be on the low side around 30 kts
with a small area of stronger shear near the Brainerd Lakes
region. Additionally, the increased warm air advection will lead
to strong capping inversions that will have to be overcome for
convection to start firing off. For now, SPC has a marginal risk
(threat level 1 out of 5) clipping into Cass and Crow Wing.

End of the Work Week:

The pattern remains quite active with multiple shortwaves passing
through the region. We will also be maintaining our higher dewpoints
thanks to our low level flow out of the south and southwest. While
it is too soon to get into the specifics, both instability and shear
parameters will be favorable for strong to severe storm chances.
Another area of concern aside from storms will be the increase in
heat. The continuance of warm moist air pouring into the region will
raise heat risk up into the major category (level 3 out of 4) for NW
WI and Moderate (level 2 out of 4) for many others. The heat begins
on Thursday with the hottest day likely being Friday. Heat headlines
may be needed.
&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1221 AM CDT Mon Aug 4 2025

A slow but persistent MCV is located over the Red River Valley this
evening and is helping to generate scattered light rain showers
across the region. This feature is expected to persist through
the forecast period. Coverage may increase in the afternoon as
diurnal processes take hold. Thunderstorm threat remains low
(10%) so have left it out of the TAFs for the time being.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 318 AM CDT Mon Aug 4 2025

East to Northeasterly winds expected today with speeds around 5 to
10 knots. Some funneling may lead to a few gusts at the head of the
lake to 15-20 kts. A few isolated showers will be possible today.
Later this week the weather pattern becomes even more active with
increased chances of strong to severe storms.

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.

&&

$$

DISCUSSION...Britt
AVIATION...Britt
MARINE...Britt