759
FXUS63 KDLH 261848
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
148 PM CDT Fri Jul 26 2024

.KEY MESSAGES...

- Increasing temperatures and humidity through the weekend. Above
normal high temperatures and near record warm overnight low
temperatures expected.

- Chances for afternoon/evening showers and storms Saturday and
Sunday. An isolated severe storm possible where the best instability
is present.

- Some heavy rain possible under training storms through the
  weekend. Best chance for widespread excessive rain Sunday-
  Monday.

&&

.DISCUSSION...
Issued at 147 PM CDT Fri Jul 26 2024

High pressure over the Great Lakes continues to very slowly push
eastward through this weekend as a stout low sweeps over central
Canada, bringing an extended frontal zone over the Northern Plains
and Upper Midwest over the next 3-4 days. We`re just beginning to
see the effects of this setup, with a line of clouds and
precipitation over North Dakota, and the first day of robust WAA
into the Northland along with good moisture return. Temperatures are
rising into the upper 70s and low 80s today with dewpoints soaring
into the 60s. To our west this afternoon is a taste of what`s to
come tomorrow - temperatures in the high 80s to near 90 and
dewpoints in the upper 60s to low 70s (resulting in heat indices in
the 90s across the board). Generally temperatures in the 80s should
continue, not just this weekend but through much of next week as
well. There wont be much recovery overnight, with overnight lows
largely in the 60s through that same time period. Widespread
HeatRisk values of 3 on Saturday, and a couple isolated areas of 4
mean that folks without access to adequate cooling and hydration
will likely be affected. CPC graphics outline our region in good
chances for above normal temperatures through at least early August.

The other impact of our frontal system will be chances for showers
and thunderstorms. Overnight tonight, the first couple areas of
showers and storms could brush portions of Koochiching County, but
latest trends have this overnight convection backing off in space
and time so we may not see any precipitation in the CWA until closer
to midnight at which point an isolated storm could intensify to
severe levels along a CAPE gradient with up to 30 knots of bulk
shear. As instability dissipates overnight so too should any storm
coverage. With a lot of warm moist air coming in Saturday,
redevelopment is expected over north-central MN in the afternoon and
evening hours. Robust MLCAPE and bulk shear of 30-45 knots could
lead to some isolated severe storms once again with all hazards
possible (severe threat for Itasca, Kooch, Cass, Crow Wing, and
central/northern St. Louis Counties). Additionally, training storms
are possible which could lead to some heavy rain. We are working
with a very moist atmosphere with forecast PW values of 1.5-2", deep
saturation and freezing levels in excess of 10kft. Some of these
storms on Saturday may be outrunning the best synoptic support and
could be somewhat scattered or discontinuous leading to more
splotchy coverage of the heaviest rain. However, some bullseyes of
2"+ could be possible, best chance in Koochiching County.

Sunday, we get the "best" of all worlds with widespread heat,
moisture, and synoptic support for much of NE MN. Still some model
discrepancies to work through for the Sunday-Monday timeframe, but
generally some isolated severe storms could be possible in the areas
of best instability and shear (currently around the Brainerd Lakes
area). With good synoptic support as the frontal area moves over the
area, training storms could be prevalent with PW near 2", deep warm
cloud layers (over 10kft), areas of slow Corfidi vectors, and deep
layer parallel flow. Sunday-Monday will be a time period to monitor
for heavy rain and flash flooding potential for portions of north-
central and northeast Minnesota, especially areas along and north of
the Iron Range which may receive some areas of heavy rain before
this round. Additionally, areas from Int. Falls to Ely are some of
the few that are still running around to above normal for
precipitation over the last 30 days and have normal to above normal
streamflows persisting. Should the trend for heavy rain continue and
confidence in placement increases, a Flood Watch may be needed.

Through the rest of next week, heat persists with passing shortwaves
and 500mb vort maxes bringing chances for showers and
thunderstorms.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1241 PM CDT Fri Jul 26 2024

A fairly broad area of MVFR stratocumulus clouds is affecting
HYR/BRD/DLH/HIB this afternoon associated with warm air
advection. Most models suggest these will scatter out in the
next 2 to 3 hours, but models have also been handling their
presence poorly so it is not out of the question that they could
linger a bit longer into the afternoon. Breezy southerly winds
are expected through the period. There is a 40 percent chance
for showers and storms at INL tonight in the vicinity of a cold
front to the west, but latest models suggest most of these
showers and storms will remain west. A broad area of MVFR
ceilings and perhaps some fog is expected to develop at most
terminals late tonight into early Saturday morning. These clouds
are expected to scatter out in the morning, leading to VFR
conditions.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 147 PM CDT Fri Jul 26 2024

Winds out of the south to southwest will persist through the
weekend, with gusts up to 20 to 25 knots in the afternoon and early
evenings, and gusts of 10 to 15 knots during the overnight and
morning hours. This persistent south wind will lead to increased
wave heights, especially for portions of the North Shore, but even
just off shore on the South Shore waves of 1 to 3 feet are possible.
From Taconite Harbor to Grand Portage, waves up to 5 feet could be
possible Saturday into Sunday, and a small craft advisory may be
needed. With current warm lake water temperatures, it is unlikely
that these stronger winds would stay aloft. Showers and
thunderstorms possible Sunday afternoon into Monday. Some upwelling
could be possible along the North Shore by Sunday afternoon and
evening, but there is a robust warm water layer to move offshore
before that can occur. Monday, winds should begin to quiet as the
pressure gradient weakens.

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...Levens
AVIATION...JDS
MARINE...Levens