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000
FXUS63 KDLH 122324
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
624 PM CDT Fri Apr 12 2024

.KEY MESSAGES...

- Warm weather is expected this weekend

- A few showers Saturday into Saturday evening

- A strong spring storm will bring accumulating rain, light
  snow, and gusty winds to the Northland next week

&&

.DISCUSSION...
Issued at 318 PM CDT Fri Apr 12 2024

Short Term:

Cumulus clouds dot the sky this afternoon with breezy northwest
flow. Surface high pressure tonight will cause winds to become
light and skies mostly clear after sunset. The broad ridging
within the omega block that`s dominating the weather pattern
across the CONUS will continue moving east on Saturday, with
southerly winds and warm air advection developing across the
region. This will bring noticeably higher temperatures for most
areas with highs reaching into the 60s and 70s. An exception to
this will be the North Shore where temperatures will remain in
the 40s and 50s with the onshore southerly flow.

While the weather should be mostly dry for most places, there
will be a bit of frontogenesis and a weak passing wave aloft
Saturday into Saturday afternoon that will bring a 20-30% chance
for some showers mainly north of US 2 in Minnesota, then
extending into northwest Wisconsin Saturday evening. Overall
moisture will be low, so totals will just be a few hundredths of
an inch for most places. However, a bit of weak convective
potential exists such that some heavier showers and perhaps a
few rumbles of thunder will be possible, which could lead to
some locally heavier rainfall amounts.

A weak cold front will pass through Saturday night, bringing a
wind shift to northwesterly by Sunday. Despite this being a cold
front, temperatures are not expected to cool drastically behind
it. Since we will remain under the influence of ridging aloft,
and with the presence of deeper mixing in the northwest flow,
temperatures shouldn`t struggle to reach into the 60s for most
places. Winds will be a bit breezy with gusts up to 20 mph and
the weather is expected to be dry with plentiful sunshine.

Long Term:

A strong low pressure system is expected to approach the Upper Midwest
moving across southern Minnesota into the U.P of Michigan late Monday
through Thursday morning. Locally heavy rainfall is possible
due to the slow nature of this system, with a 40 to 70 percent
chance of over an inch of rainfall across most of northeast
Minnesota and northwest Wisconsin. The strength of this system
for this time of year according to the NAEFS MSLP mean
percentiles is near the bottom percentiles compared to
climatology, indicating a very deep system for mid April. Some
global models (GFS,Icon, Euro) have an initial wave of moisture
approaching the Northland sometime Monday afternoon in advance
of the low pressure system off to our southwest. After this
initial slug of moisture streaming northward from the Gulf of
Mexico enters MN on Monday, a secondary batch of Gulf moisture
flows into the region just as the low starts to cross over
southeast MN. Precipitable water is forecast to increase to
around 1 inch, and the integrated vapor transport shows values
in the 90-99 percentile for this time of year. So this system
will certainly have plenty of moisture to work with. In fact the
WPC has highlighted the Brainerd Lakes to Hinckley areas for a
Marginal Risk of Excessive Rainfall for Monday, and the entire
Northland for Tuesday. Regarding the hydrologic impact, river
and stream rises are once again expected in the wake of recent
rises from snowmelt. While the frost in the ground has been
largely depleted, soils are still moist and enhanced runoff is
expected. However, the concern for widespread flooding is low at
this time given the rain being spread out over a long period of
time.

Regarding thunderstorm potential, there certainly is some CAPE
that will be in the area with the initial push of moisture
Monday into Tuesday, but the best forcing seems to be in
southern and southeastern Minnesota and western Wisconsin which
is where the SPC has highlighted the potential in their Day 5
Convective Outlook (tues- wed). Looking at the CSU Machine
learning probabilities there is a very slight chance around
5%-15% of severe storms for Tuesday in northwest Wisconsin. This
depends on numerous factors including how much buoyancy is in
the atmosphere and how far north the CAPE reaches depending on
the storm track. A more southern track would keep the severe
weather threat to our south while a more northern track keeps
the severe threat in play. Since this system will be so tightly
compact, winds look to be on the increase throughout the
forecast period as well. Widespread gusts in excess of 30 mph
are likely (60% to 80% chance)

Once this system departs there is a chance for some snowfall
with a secondary low-pressure system as there will be plenty of
cold air advection leading to a changeover to snow. The 12Z
global models show this system swinging down through our area
right after the first stronger low pressure system moves off to
the east. These two systems don’t phase completely, still the
result is a prolonged precipitation event for our area. The
global models seem to have some disagreement with precipitation
types as the GFS shows the changeover to snow a bit earlier
across the Arrowhead and North Shore Wednesday evening and for
the entire region by Thursday morning. However, the other global
models such as the ICON show the changeover much later due to
the slower progression of the system. However, if the snow
changes over later, then that would limit the amount accumulated
due to the high April sun angle and warmth of the ground. For
snow totals, the ICON shows nothing but the ECE and GEFS favor
some accumulation, especially across most of northeast Minnesota
and the Wisconsin South Shore. This makes sense as the GEFS/ECE
also shows temps for the area dipping down into the 30s and
upper 20s which certainly would be conducive for snow.

Regarding totals for rain, the global ensembles have good
clustering around 1-2” inches of rainfall for much of the
Northland. However, there are several members above and below
this cluster dependent upon the storm track and how much
convection will be embedded in the larger precipitation shield.
This system is a few days out so things can and will likely
change but just something to keep an eye on in future forecasts.
The good news is this moisture is welcome for the consistent
drought across the area.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 623 PM CDT Fri Apr 12 2024

Diurnal cumulus clouds are disappearing this afternoon giving
way to clear skies to start this evening. Warm air advection
will ramp up over night and tomorrow as southerly winds stream
back into the region. High clouds will increase and the northern
MN may see some light rain in the early morning hours (20-40%).


&&

.MARINE...
Issued at 318 PM CDT Fri Apr 12 2024

Breezy west to northwest winds persist for some of the nearshore
waters through this evening, with the highest potential for wind
gusts to 25 knots along the North Shore. Small Craft Advisories
will remain in effect through this evening. As high pressure
moves in from the west, winds are expected to become light and
variable from west to east this evening and overnight. Winds
will become east to northeasterly by Saturday afternoon with
directions and speeds a bit variable right along the shores
(generally a little less than over the open waters). Some breezy
conditions with gusts to 15 to 20 knots around the head of the
lake through Saturday evening. Winds will switch direction again
Saturday night with southwest winds Sunday morning, then
northwest Sunday afternoon with gusts 15 knots or less.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...Small Craft Advisory until 9 PM CDT this evening for
     LSZ140>143.

&&

$$

DISCUSSION...JDS
AVIATION...Britt
MARINE...JDS