Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 301120
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
620 AM CDT Fri Jul 30 2021

.DISCUSSION...(Today through Thursday)
Issued at 345 AM CDT Fri Jul 30 2021

Summary: Chances for scattered showers and thunderstorms today
and Saturday, otherwise mostly quiet and dry conditions. Smoky
conditions will continue to impact the region as winds turn
southwesterly. Temperatures are expected to remain seasonable
through the forecast period.

High pressure over the region this morning will lead to quiet
weather for much of today. Smoke has been reluctant to move
entirely out of our CWA, contrary to what models had previously
suggested it might do. Air Quality Indices remain high,
particularly from Brainerd to the International Border, where
PM2.5 levels range between 100-200 micrograms/cubic meter. As the
high pressure moves eastward, winds will switch to the southwest,
pushing some of the highest concentrations of smoke back into the
Northland over the day, with current smoke models showing near-
surface smoke impacting all of the CWA at some point between now
and Saturday morning.

This evening, a broad jet entrance region moves over northern MN,
pulling a weak surface low over the International Border this
evening and across the upper Great Lakes through the day Saturday.
This will bring a chance for some scattered showers beginning
this evening. Showers are expected to move from north to south
across the CWA overnight into Saturday morning. At this point I am
not expecting these showers to become severe and rainfall is
likely to be nominal. As a cold front sweeps eastward Saturday,
some thunderstorms are possible in NW WI late Saturday afternoon.
With CAPE values around 1000 J/kg and bulk shear around 30 knots,
an isolated severe thunderstorm is possible.

Northerly winds behind the cold front Saturday may allow another
round of smoke from Canadian wildfires to advect into the region,
which could worsen current smoke conditions.

After Saturday, a broad region of high pressure settles over the
upper Midwest and Great Lakes which should keep us mostly dry.
Temperatures through the weekend and into next week are expected
to be in the 70s and low 80s. Smoke may limit daytime heating
today and this weekend, keeping afternoon high temperatures a
couple degrees below their currently forecasted values in areas
where smoke is thick.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 620 AM CDT Fri Jul 30 2021

Areas of smoke and patchy dense fog across the region this morning
have lead to MVFR to LIFR visibilities at HIB, INL, and BRD this
morning. Fog should burn off in the next hour or so, but smoke will
continue to impact all terminals throughout the day today,
eventually reaching DLH and HYR as well. Some gusty southwest winds
are possible this afternoon. Thunderstorms are possible this evening
at INL, and may move south and impact HIB and DLH as well Saturday
morning.

&&

.MARINE...
Issued at 345 AM CDT Fri Jul 30 2021

East-northeast winds continue to persist over much of western Lake
Superior this morning, leading to some 1.5 foot waves at the head of
the Lake and waves up to 3 feet in the Apostle Islands. Winds should
turn southwest today, decreasing waves across the lake, except near
Grand Portage where waves 1 to 3 feet are possible. Some rain
showers are possible Friday evening into Saturday morning. Winds
become gusty at times out of the southwest this evening into
Saturday morning and then turn westerly late Saturday morning. This
may lead to increased waves east of Port Wing and through the
Apostle Islands. West waves may become chaotic around cliff shore on
the South Shore, where they are apt to double in height and produce
conditions difficult to navigate in small craft in cliff rebound
zones. Winds should calm down overnight Saturday, but northerly
winds Sunday may continue to lead to unsettled wave conditions along
the South Shore, through the Apostle Islands, and around the
Bayfield Peninsula.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  80  61  80  55 /   0  30  40   0
INL  84  56  77  50 /  20  40  10   0
BRD  83  60  81  54 /   0  20  10   0
HYR  78  57  80  51 /   0  20  30  10
ASX  79  60  81  54 /   0  40  30  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

DISCUSSION...Levens/GSF
AVIATION...Levens/GSF
MARINE...Levens/GSF


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