396
FXUS63 KDLH 030942
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
442 AM CDT Fri May 3 2024

.KEY MESSAGES...

- Areas of Dense Fog expected early this morning around Lake Superior,
  including around the Twin Ports.

- Widespread rain arrives this evening and will persist into Saturday.
  Thunderstorms are unlikely with this system.

- Additional chances for rain arrive early to mid next week,
  with a high potential for widespread soaking rainfall.
  Thunderstorms will be more likely with the system next week.

&&

.DISCUSSION...
Issued at 442 AM CDT Fri May 3 2024

Areas of dense fog have developed this morning in the wake of an
occluded frontal passage. This fog is a result of a combination of
low to near-zero dewpoint depressions, relatively light winds, and
low-level moisture lingering from rain showers last evening.
Visibility of one quarter of a mile or less has been observed early
this morning, mainly in areas adjacent to Lake Superior and
especially around the Twin Ports. A Dense Fog Advisory has been
issued until 8 AM CDT today for this dense fog. Expect fog to
dissipate shortly after sunrise as diurnal heating begins and
southwest winds increase from a tightening pressure gradient.

Once the fog dissipates, much of today will be quiet with mostly
sunny skies. Southwest winds will be breezy today due to a
tightening pressure gradient between low pressure over northern
Ontario and high pressure over Michigan`s Lower Peninsula. A
shortwave will be propagating into the upper Great Plains this
evening, reaching the CWA by Saturday afternoon. Widespread showers
are expected to develop late this afternoon into tonight and
continue into Saturday as southwest winds advect moisture into the
CWA. Dynamic forcing will be favorable within the baroclinic zone of
this shortwave, with strong FGEN expected at 850mb. CAMs are in
solid agreement that a southwest to northeast oriented band of rain
will develop, with highest QPF amounts of 0.3-0.45" very likely (70%
chance) to occur along a line from the Brainerd Lakes to the Twin
Ports  and north to the northern end of the Gunflint Trail. A rumble
of thunder is possible from embedded thunderstorms this evening into
tonight, but the potential is low (<15% chance) due to limited
instability.

Showers will be tapering off Saturday afternoon as the shortwave
trough axis swings through the region. High pressure developing
behind this shortwave will bring mostly sunny skies to the area on
Sunday with comfortable high temps in the 60s. Dry conditions will
linger into Monday before the next chance for rain arrives Monday
night as a negatively-tilted trough enters the upper Midwest. Precip
onset timing is still uncertain with this early week system, as run-
to-run model variations have been trending later in recent runs of
the global deterministic models. Despite timing differences,
confidence is high (80% chance) that large portions of the CWA will
receive a good soaking rain on Tuesday into Wednesday. Global
ensemble total QPF means are around 0.5-1.5", with individual
members showing the potential for locally higher rainfall amounts.
Severe weather and localized flash flooding potential will need to
be monitored as we get closer to early next week. At this time, it`s
still too uncertain for specifics on impacts and exact location.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1244 AM CDT Fri May 3 2024

Low ceilings ranging from VLIFR to MVFR are occurring early this
morning as an occluded front moves through. LIFR fog has also been
observed around the Twin Ports, impacting DLH. Low cigs and reduced
visibility from fog is expected to continue until the occluded front
passes through later this morning. BRD has already seen this frontal
passage, where conditions are VFR. Expect improvement across the
region later this morning, with VFR conditions continuing through
the remainder of the TAF period. Southwest winds will be breezy
today as the region sits between areas of high and low pressure.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 442 AM CDT Fri May 3 2024

A Marine Dense Fog Advisory has been issued this morning for all
nearshore waters of western Lake Superior until 8 AM CDT.
Observations show that visibility of 1 NM or less will be possible
until southwest winds increase and daytime heating begins. Expect
winds to turn southwesterly today and become strong up to 25 knots
through the day, mainly along the North Shore and for South Shore
Waters around and west of the Apostle Islands archipelago. A Small
Craft Advisory has been issued today for most nearshore waters,
excluding Oak Point to Saxon Harbor. Expect breezy southwest winds
to ease this evening as the pressure gradient relaxes.

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 8 AM CDT this morning for MNZ020-021-
     037.
WI...Dense Fog Advisory until 8 AM CDT this morning for WIZ001.
MARINE...Dense Fog Advisory until 8 AM CDT this morning for LSZ121-
     140>148-150.
     Small Craft Advisory from 11 AM this morning to 10 PM CDT this
     evening for LSZ121-140>147-150.

&&

$$

DISCUSSION...Unruh
AVIATION...Unruh
MARINE...Unruh