408
FXUS63 KDLH 201220
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
720 AM CDT Mon Jul 20 2026

.KEY MESSAGES...

- Hot today with strong west winds today in the wake of a cold
  front this morning leading to near-critical fire weather
  conditions as west winds gust to 20 to 30 mph.

- There is a risk for isolated strong to severe storms to
  rapidly develop in northwest Wisconsin along the exiting the
  cold front this afternoon in the 4 PM to 7 PM timeframe. While
  the probability for any storms developing is very low (10 to
  30 percent), if storms develop there is a high likelihood
  they would quickly become severe and capable of producing very
  large hail, damaging winds, and possible a tornado.

- Drier with more seasonable temperatures on Wednesday,
  gradually warming up again towards next weekend.

&&

.UPDATE...
Issued at 203 AM CDT Mon Jul 20 2026

Low pressure was located just north of Lake Winnipeg early this
morning with an occluded front extending to near Winnipeg. A
warm front then extended southward across the eastern Dakotas
with a cold front extending to the southwest to south-central
North Dakota and northwest South Dakota. An area of
thunderstorms was moving into far western Minnesota south of
I-94 with other isolated showers and thunderstorms just north of
the International Border. Additionally, a few isolated showers
were seen across northwest Wisconsin. Models continue to develop
showers and storms across northern Minnesota over the next few
hours and move that activity through mid-morning. Questions
remain as to when and where these showers and thunderstorms
develop, if at all. While the airmass ahead of the cold front is
favorable for severe elevated storms, forcing with the front is
weak. If any storms do develop, elevated CAPE of 2000-3000 J/kg
along with shear around 40 knots will allow for storms capable
of producing damaging winds and large hail.

Further convective evolution for later this morning and
afternoon will depend on what happens with this possible first
round of activity and the speed of the cold front across the
region. There are indications that the bulk of the strong
convection this afternoon will be east and south of our CWA, but
there are a few CAMs that do develop this activity across
northwest Wisconsin. This remains a conditional threat, but all
modes of severe weather will be possible should storms develop
ahead of the cold front. Additional showers and thunderstorms
will be possible this afternoon and evening behind the cold
front, but will likely not be strong or severe. The main change
for the forecast today is the issuance of a Heat Advisory across
the southern half of the forecast area. WBGTs will be above 79F
this afternoon in these areas along with a Moderate Heat Risk in
place, prompting the advisory. Some areas may need to be
cancelled early depending on the timing of the front.

&&

.DISCUSSION...
Issued at 257 PM CDT Sun Jul 19 2026

Early this Morning:

A strong shortwave dives southeast overnight with an occluded front
pressing in from the west. Temperatures aloft are expected to rapidly
cool as an upper level low churns across Manitoba into Ontario.
This will lead to steep mid level lapse rate to further aide in
storm growth. Timing and placement of storms remain contested
among the high res guidance but they are beginning to hone in
the main activity being after midnight. The convective parameter
space will boast MUCAPE over 800 J/kg and a strong upper level
jet will be nudging in across the Northern Plains to increase
bulk shear values of 40-50 kts. This would promote the growth of
elevated storms capable of large hail and some damaging winds.
SPC has this largely outlined as a marginal threat (1/5) with a
small sliver along our western counties of slight risk (2/5).

Monday:

Lingering storms from the overnight hours are expected to exit by
late morning. The key to Monday`s forecast will be the placement of
the frontal boundary. This remains a highly contested feature among
all available guidance with the CAMS suggesting it will be out of
CWA by the afternoon. Not confident enough to buy into this solution
given how poor these suite of models have been performing as of
late. It seems reasonable to stick with what SPC has outlined which
is an Enhanced risk (3/5) through Price county and a Slight risk
(2/5) trailing behind it through NW WI and into NE MN. With the
morning activity expected to clear out fairly quickly we should have
ample time to refill the ingredients for severe storms in the
afternoon. MLCAPE will be high with values over 2500 J/kg paired
with bulk shear of 40-50 kts. This combo of ingredients would support
supercell growth and low level helicity could also induce a few
tornadoes. Again, all of this is predicated on the placement of the
frontal boundary for the afternoon and evening hours.

Farther north, an upper level low will be transitioning into an open
wave with cyclonic flow aloft coupled with plenty of PVA. Wrap
around moisture around this cyclone will spawn scattered showers
across northern MN with some isolated storms possible. Weaker
instability across this area should keep development of stronger
storms at bay. Additionally, strong westerly winds will be filtering
in across the region tomorrow with gusts over 30 mph expected
through the day.

Tuesday:

Another wind shift from out of the north is in store for the
Northland on Tuesday. A weak cold front will also drop from out of
the north with low chances (15-20%) of precipitation, may end up
with numerous areas seeing sprinkles given the dry air aloft. Wind
gusts in excess of 30 mph will be possible and could reintroduce
another round of smoke engulfing the region. High res smoke guidance
is not properly displaying this outcome at the moment due to how the
models initialize with hotspot information. But Air Quality
will be something to keep an eye on for the Tuesday timeframe.

Midweek:

Fairly mild forecast midweek through the end of the work week.
Temperatures will be trending back up into the upper 70s and low
80s. The northerly winds taper off on Wednesday as high pressure
moves across the Upper Midwest. Our next batch of precipitation
chances (20-30%) arrive Thursday afternoon as some weak surface
convergence floats through the region.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 720 AM CDT Mon Jul 20 2026

Increasing west winds today with generally VFR conditions today,
then MVFR stratus clouds late tonight. A few isolated showers
and storms may impact INL and HYR this afternoon but any storms
are expected to be brief in duration. West to west-northwest
winds gusting to 20 to 30 knots through today, peaking with a
few gusts to 35 knots late this afternoon. Winds turn more
northwesterly as cold front moves north to south across
northeast Minnesota tonight bringing the low-level stratus
clouds and MVFR ceilings, with northwest winds remaining
sustained at 10 to 15 knots through the overnight hours.

&&

.MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 203 AM CDT Mon Jul 20 2026

Southwesterly winds of 10 to 20 knots with gusts to 25 knots
will be in place through through the day before becoming
northwesterly as a cold front moves through late this afternoon
and evening. Winds will diminish a bit overnight before
increasing again on Tuesday. Small Craft Advisories are
currently in effect for today with additional advisories
possible for Tuesday with gusts to 20 to 30 knots, highest along
the North Shore. Winds will then quickly diminish Tuesday
evening to 5 to 10 knots from the northwest for Tuesday night.
These northwesterly winds tonight and tomorrow may bring smoke
back into the area.

Strong to severe thunderstorms remain possible early this
morning with wind gusts in excess of 40 knots and large hail
being the primary threats. After a break for the late morning
and early afternoon hours, additional thunderstorms will be
possible that may be strong to severe, but confidence on the
timing and location of this activity remains lower than normal.

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

&&

.FIRE WEATHER...
Issued at 203 AM CDT Mon Jul 20 2026

Showers and thunderstorms remain possible early this morning,
but coverage and timing remains in question. Should any storms
develop, they may be strong to severe with damaging wind gusts
and large hail as the main threats. Winds will increase out of
the west today with gusts to 20 to 30 mph. Gusts in excess of 30
mph will be possible as well. A Fire Weather Watch remains for
the Arrowhead due to the ongoing wildfires and the uncertainty
as to how much precipitation may impact the fuels today.
Additional showers and thunderstorms will be possible across
northeastern Minnesota this afternoon and evening with strong to
severe storms possible ahead of the cold front across northwest
Wisconsin. This activity may develop to the east, however.
Rainfall amounts of a tenth of an inch to 0.35 inches will be
possible with heavier amounts under any storms. Winds will be
more northerly for Tuesday with gusts again of 20 to 30 mph
plus. Highs will be in the 70s with afternoon RH values likely
remaining above 40%.

See the Fire Weather Forecast product for a more thorough
breakdown of fire weather conditions.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Heat Advisory from 11 AM this morning to 7 PM CDT this evening
     for MNZ020-034>038.
WI...Heat Advisory from 11 AM this morning to 7 PM CDT this evening
     for WIZ001>004-006>009.
MARINE...Small Craft Advisory until 1 AM CDT Tuesday for LSZ121-140>148-
     150.
     Heat Advisory from 11 AM this morning to 7 PM CDT this evening
     for LSZ142.

&&

$$

UPDATE...BJH
DISCUSSION...Britt
AVIATION...JJM
MARINE...BJH
FIRE WEATHER...BJH