795
FXUS63 KDLH 162347
AFDDLH

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

.MESOSCALE UPDATE...
Issued at 647 PM CDT Mon Sep 16 2024

Showers and a few thunderstorms over northern St. Louis and Lake
counties continue to percolate along a remnant outflow boundary
from this morning`s convection under a zone of 850-750 mb
isentropic ascent. This nebulous area of convection has
demonstrated a backbuilding tendency and additional convection
has developed farther south toward Hibbing while propagating
northward.

Think this area of precipitation will persist for several more
hours. Southerly low-level flow into this zone of focused ascent
is forecast to increase over the next several hours as a
southerly to southwesterly low-level jet develops. Radar-
estimated precipitation totals have ranged from a trace up to
nearly 3 inches so far today and early this evening. As
precipitation continues, the risk of minor flooding will
gradually increase. If a few stronger cells can develop and
train over the same location, additional flood products may be
needed tonight.

Later tonight the convection over North Dakota and northwest
Minnesota may advance into north-central Minnesota with a risk
of damaging wind gusts and perhaps a few quarter-size (1 inch)
hailstones. Favorable low-level shear is forecast for
supercells as the LLJ develops, though weaker mid-level winds
should limit updraft speed in the hail growth zone. Time will
tell whether much of a severe weather risk develops over
Koochiching County.

&&

.KEY MESSAGES...

- Scattered thunderstorms into this evening mainly north-central
  MN and the Arrowhead.

- A 5-10% chance of a strong to severe thunderstorm and a 5-15%
  chance of heavy rainfall in north-central Minnesota and the
  Arrowhead tonight.

- Warm temperatures continue through mid-week before gradually
  cooling to normal by this weekend.

&&

.DISCUSSION...
Issued at 345 PM CDT Mon Sep 16 2024

Low pressure deepening over the northern high plains is expected
to trigger strong to widely scattered severe thunderstorms over
the northern plains this evening. As the storms move
northeastward, a few stronger thunderstorms could (5-10% chance)
move through just east enough to impact far north-central
Minnesota later this evening as a result. If any stronger
thunderstorms do realize into an isolated severe thunderstorm,
hail around the size of a quarter would be the primary expected
hazard type. The seasonably moist airmass over the Northland
keeps concerns for heavy rainfall in the region too, so any
strong to severe thunderstorm could (5% chance) be accompanied
by heavy rainfall as well into early Tuesday morning.

As the low moves eastward Tuesday, general thunderstorm chances
(30-40% chance) are forecast into tomorrow morning. A stalled
boundary along the Borderlands could (20-30% chance) also
promote further general thunderstorms into Tuesday night. Drier
weather looks likely (90% chance) on Wednesday as a drier air
mass may promote decreased relative humidity from a drop in dew
points into the 50 degree F range behind the passing low
pressure.

A western trough begins to breakdown Wednesday and low pressure
lifts into the northern high plains to deepen into Thursday. A
cold front passes over the region later Thursday. This Thursday
night time period looks to be the best chances for more
widespread rainfall (light to moderate) as the western low
pressure centered in south-central Canada brings in cooler
westerly air behind the front. This late work week into weekend
time period looks to be the first time of returning to normal to
below normal temperatures this fall! Stratiform and widespread
rainfall returns later Saturday and into Sunday.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 647 PM CDT Mon Sep 16 2024

A few storms may move over INL tonight while additional
convection persists north of HIB into the MN Arrowhead. A
somewhat tight pressure gradient will remain over the region
tonight and should keep winds in the 5 to 10 knot range
overnight. If winds go calm for an hour or so, a brief period of
IFR visibility in fog may develop. For now think that chance is
too low to include with this forecast. A strong south to
southwesterly low-level jet will develop tonight and aid storm
development near INL. LLWS will be a concern at BRD, INL, HIB,
and DLH overnight. HYR appears to be east of the strongest winds
aloft, so no LLWS concerns there.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 256 PM CDT Mon Sep 16 2024

Light winds generally less than 15 knots are forecast outside of
scattered thunderstorms where gusty, erratic winds may occur
this evening and again Tuesday on the North Shore. Dry weather
is forecast on Wednesday over the lake.

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.

&&

$$

UPDATE...NLy
DISCUSSION...NLy
AVIATION...Huyck
MARINE...NLy