717
FXUS63 KDLH 251118
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
618 AM CDT Wed Sep 25 2024

.UPDATE...
Issued at 412 AM CDT Wed Sep 25 2024

Satellite imagery shows slowly expanding coverage of dense fog
that surface stations are showing produces visibility around 1/4
mile. Went ahead and issued a limited coverage Dense Fog
Advisory mainly for central St. Louis and Douglas Counties, but
also included Bayfield County too since that fog bank pushes
eastward into the Bayfield Peninsula. High res guidance points
to some of the fog spreading eastward from Aitkin County into
Pine County so will monitor for any expansions of the Advisory
over the next few hours.

&&

.KEY MESSAGES...

- Dense fog will be observed in parts of the Northland through early
  this morning before tapering in coverage by mid-morning.

- Warm temperatures well-above normal persist mid-week through
  Sunday.

- A cold front is expected to cross over the region sometime
  early next week and will bring cooler temperatures back to
  near to slightly below normal and may (20-30% chance) bring
  rain showers back into the forecast.

&&

.DISCUSSION...
Issued at 208 AM CDT Wed Sep 25 2024

A weak cool front ahead a Canadian shortwave trough departs the
Western Great Lakes and leaves the Upper Midwest between that
feature and a high amplitude ridge over the Northern High
Plains. As that larger-scale ridge axis shifts eastward, the
ongoing fog in the Northland is forecast to expand in coverage
into early Wednesday morning. Surface observations show locally
dense fog producing visibility around 1/4 mile. Into the pre-
sunrise early morning hours today, expect more widespread
coverage of reduced visibilities for the morning commute. It is
yet to be seen if the spatial coverage of dense fog will warrant
an Advisory or not, but satellite imagery, surface observations
and webcams will be monitored over the next few hours.

Fog lifts this morning from 8-9 AM today back to mostly sunny
skies. Southerly return flow associated with that ridge axis
shift eastward allows temperatures to warm to well-above normal
starting today. Maximum temperatures are forecast for the mid to
upper-70s. A few locations in north-central Minnesota are
expected to reach that 80 F mark even this afternoon.

The temperatures increase a few more degrees into the end of
this work week and linger into the weekend. Deterministic model
guidance shows a fair signal for a potent, but fairly dry, cold
front dropping southward next Monday PM and Monday night. There
is a return of 10-30% chance of rain showers in the forecast
with that cold front right now, but the dry profiles do not
favor much more than scattered light rain showers right now for
Monday into Tuesday. A drop in temperatures to slightly below
normal for the first day of October is much more likely though
for next Monday night into Tuesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 617 AM CDT Wed Sep 25 2024

Fog creates MVFR to IFR visibility through 14Z this morning.
West winds 5-10 knots today become calm again overnight. Another
night of fog may create MVFR to IFR visibility again after 06Z
Thursday.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 152 AM CDT Wed Sep 25 2024

Southwest winds 5 to 15 knots today gust locally near Grand
Portage to 20 knots. Wave heights up to 3 feet are also forecast
for those far North Shore waters today before southwest winds
taper overnight tonight and to easterly Thursday 5-10 knots.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ019.
WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ001-002.
MARINE...None.

&&

$$

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