806
FXUS63 KDLH 161759
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1259 PM CDT Mon Sep 16 2024

.KEY MESSAGES...

- The late season warmth continues with highs 10 to around 15
  degrees above normal through at least Thursday.

- Chance for showers and thunderstorms today, mainly over
  northern Minnesota with a better chance tonight, especially in
  far northern Minnesota. Storms late today/tonight could be
  strong and produce localized heavy rain over far north-
  central/northwest Minnesota.

- Periodic chances for more showers/storms through the week.

&&

.DISCUSSION...
Issued at 300 AM CDT Mon Sep 16 2024

The upper pattern featured a West Coast upper low with high
pressure over the Northeast. The Northland remained under
southwest flow aloft with very warm temperatures and plenty of
moisture. Area radars showed isolated to scattered showers and
thunderstorms across far northern Minnesota into the Apostle
Islands as of 0800Z. Chances for showers/storms will continue
this morning, sagging south possibly to the Twin Ports and
northern Wisconsin. Most of the guidance forecasts a lull
occurring by late morning but chances won`t end. However, focus
will shift north this afternoon into tonight into far northern
Minnesota. A shortwave will lift northeast through the Northern
Plains brushing northwest Minnesota. Low level convergence is
forecast around a trough over far north-central Minnesota or
just northwest of there. A very warm airmass will remain in
place with highs in the lower to mid-eighties away from Lake
Superior today with surface dewpoints in the sixties. MUCAPE
values will rise to 1500-2000 J/kg this afternoon. However,
shear will be lacking with effective shear at or less than 20
knots this afternoon and evening. Mid-level lapse rates will be
from 6.5-7 C/km with steep low level lapse rates into early
evening. The CAMS are in general agreement developing strong
thunderstorms late this afternoon or early evening near/over
Koochiching/northern Itasca Counties and the SPC has a Marginal
Risk (level 1/5) for that area. Storm mode is expected to become
messy with clusters of storms and the lack of shear will limit
organization. Severe threats will be hail to one inch in
diameter, especially with more isolated storms earlier in their
formation, and damaging wind to 60 mph. Another threat will be
localized heavy rain due to expected training thunderstorms into
the overnight hours. PWAT values will rise to about 1.3" which
is above the 90th percentile for this time of year. The HREF
supports the heavy rain potential with 24 hour LPMM forecast
showing amounts of 2-3" across Koochiching County. We thought
about a small Flood Watch for Koochiching, northern Itasca, and
perhaps northern St. Louis Counties but the area has been quite
dry and FFG remains rather high. There is also a chance the
storms may occur a bit further north of the current forecast.

Storms will decrease in coverage late tonight into Tuesday
morning and be confined to far northern Minnesota on Tuesday.
Much above normal temperatures will continue with highs again in
the eighties.

There will be periodic chances for more showers/storms through
the week but widespread significant rainfall looks low through
Friday. Much above normal temperatures will continue into
Thursday.

Taking a look well into the future, there is some hope for a
larger system next weekend into early next week as a stronger
shortwave lifts into the region. There is potential for more
widespread rainfall but there remains significant timing and
track differences among the global models and among their
ensemble members so stay tuned for updates as we progress
through the next several days.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1240 PM CDT Mon Sep 16 2024

Weak widely scattered thunderstorms in the Arrowhead and mainly
north of the Iron Range in far northern Minnesota and across
parts of northwest Wisconsin persist into this evening. Another
round of strong thunderstorms are expected to form in the
northern Great Plains late this afternoon and into the evening
hours which could just scrape far north-central Minnesota later
this evening, including INL. Another period of scattered
thunderstorms could start up Tuesday daytime again in the
Borderlands.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 300 AM CDT Mon Sep 16 2024

Winds today into Tuesday will be from 5 to 15 knots. Wind
direction will be variable across the lake this morning,
becoming onshore for most this afternoon into the evening. On
Tuesday, winds will be more southerly along the South Shore, and
more easterly from the Twin Ports up along the North Shore. There
will be a few thunderstorms possible today. Storm chances will
continue tonight but mainly be confined to the North Shore.

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...Melde
AVIATION...NLy
MARINE...Melde