384
FXUS63 KDLH 031110
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
610 AM CDT Wed Jul 3 2024

.KEY MESSAGES...

- Scattered showers and a few isolated storms this afternoon and
  early evening.

- Slow-moving system will bring a chance of moderate to heavy
  rainfall to northwest Wisconsin and portions of central and
  east-central Minnesota July 4 afternoon and evening through
  Friday morning.

- Several chances of showers and storms forecast during the next
  7 days.

- Near-normal temperatures throughout the forecast period.

&&

.DISCUSSION...
Issued at 426 AM CDT Wed Jul 3 2024

A few isolated showers were located along the International
Border early this morning. A cool front stretched from an area
of low pressure over far northern Ontario across the Arrowhead
to near Aitkin and then west into southeast North Dakota. A few
surface pressure troughs were found both ahead and behind the
front. Look for those showers to move eastward and gradually
dissipate over the next several hours.

GOES-East Bands 8, 9, and 10 water vapor imagery reveals a
broad area of cyclonic flow over the Canadian Prairies into the
Upper Midwest early this morning. Of particular note are several
small-scale vorticity maxima from southeast North Dakota west
into north-central Montana. Cold air advection is forecast over
the Northland today, strongest over northern Minnesota. Look for
scattered showers and a few thunderstorms to develop late this
morning into the afternoon and persist through this evening.
Forecast MLCAPE of 250-750 J/kg will be found with 0-6 km deep
layer shear of 25 to 35 knots. The weak instability will limit
the potential for strong to severe storms. One or two storms may
produce pea-size hail. Severe weather is not anticipated and
locally heavy rainfall is unlikely. The train of smaller
vorticity maxima should propagate eastward into central MN and
northwest WI this afternoon and may provide enough lift to
generate isolated showers over those areas. Have added small
PoPs with this update to account for that potential.

Temperatures today are forecast to reach the middle 70s north
to the low 80s in the St. Croix River Valley and adjacent areas
of the I-35 corridor and northwest Wisconsin. Partial clearing
is expected tonight which should allow for areas of patchy fog
to develop.

Looking ahead to Thursday, July 4, temperatures will be near
normal once again with highs in the middle 70s to low 80s. A
shortwave trough with a weak area of surface low pressure will
propagate eastward from the central Plains into the Upper
Midwest during the day. Rain and a few thunderstorms are
forecast to accompany the system as it slowly moves eastward.
Instability will be limited due to forecast cloud cover and
relatively warm temperatures aloft. Look for MLCAPE in the
250-1000 J/kg range with very limited deep layer shear of 20 to
25 knots. Forecast soundings show deep moisture and PWATs are
forecast to be 1.25 to 1.5 inches over central Minnesota into
northwest Wisconsin. Locally heavy rain will be possible with
the storms given a slow propagation and "warm rain" processes.
The main mitigating factor for the risk of heavy rain will be
the general lack of focused ascent. A warm front will remain
south of the Northland, over southern Minnesota and southern
Wisconsin. If the front advances farther north than currently
forecast, the risk of heavy rainfall over portions of the I-35
corridor and northwest Wisconsin would increase.

Aside from increasing cloud cover, morning festivities on
Independence Day should be unaffected with rain chances trending
higher in the afternoon and evening. Areas of northern
Minnesota, generally north of US-2, have the lowest chance of
additional precipitation on Thursday.

Showers and storms are expected to persist over portions of
central Minnesota and northwest Wisconsin on Friday as the
upper-level trough gradually propagates eastward. Rain chances
will decrease by evening as a narrow axis of ridging passes over
the Northland. Rain chances return to the forecast on Saturday
as another trough of low pressure aloft and surface low pressure
propagate eastward across the region. Deterministic guidance
seems to be a little slower with the arrival of rain chances
over the past 24 hours. If the trend continues, much of Saturday
may end up dry with rain holding off until late afternoon or
evening.

There will be several additional chances of showers and
thunderstorms Sunday through next week. The upper-level flow
remains progressive with numerous shortwave troughs and
vorticity maxima moving generally west to east across the
Canadian Prairies and the Upper Midwest. Temperatures will
remain near normal for early July.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 610 AM CDT Wed Jul 3 2024

Scattered showers and a few thunderstorms are forecast late
this morning through early this evening. INL has the greatest
chance of a thunderstorm and have maintained the VCTS mention
with this forecast. Added VCSH to HIB, DLH, and HYR. Think BRD
will be west of the showers. Gusty west winds today subside
tonight. IFR visibility with light winds likely at HIB, INL,
BRD, and HYR after 04.09Z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 426 AM CDT Wed Jul 3 2024

A weak cool front will advance eastward across western Lake
Superior today. Winds will turn southwesterly in the wake of the
front. Wind speeds will increase to 10-20 knots with gusts of
15 to 25 knots. The long fetch along the North Shore will allow
waves to build to 2 to 5 feet near and east of Grand Marais. A
Small Craft Advisory remains in effect from Grand Marais to
Grand Portage primarily for the hazardous waves. Wind speeds and
waves will diminish this evening and should remain relatively
light while backing northeastward for Independence Day Thursday.
By Thursday evening, the pressure gradient will tighten north
of a strengthening area of low pressure over southern Minnesota,
northeast Iowa, and southern Wisconsin. Northeast winds of 5 to
15 knots with gusts of 10 to 20 knots are forecast by Friday
morning. Waves may become hazardous near the Twin Ports by late
Friday morning. Winds and waves will gradually diminish through
the afternoon and evening as the surface low to the south moves
farther away from the region.

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...Small Craft Advisory from 10 AM this morning to 10 PM CDT this
     evening for LSZ140.

&&

$$

DISCUSSION...Huyck
AVIATION...Huyck
MARINE...Huyck