Area Forecast Discussion Issued by NWS Duluth, MN
000
FXUS63 KDLH 161743
AFDDLH
Area Forecast Discussion
National Weather Service Duluth MN
1243 PM CDT Sat Mar 16 2024
.KEY MESSAGES...
- A cold front will bring very strong winds to the Northland
today, with breezy conditions persisting into Sunday.
- Isolated to scattered light snow showers are possible (20-40%
chance) at times today, with the best potential for pockets of
a quick dusting of snow north of US Highway 2 in Minnesota.
- Lake effect snow develops along the South Shore in the wake of
the cold front from later today into early Monday. A Winter
Weather Advisory has been for Iron County, with a 50-80%
chance of seeing 6+ inches in the northern portion of the
county.
- Near-critical fire weather conditions are expected today, and
are again possible Sunday into the first half of next week due
to low humidities and breezy winds.
&&
.DISCUSSION...
Issued at 455 AM CDT Sat Mar 16 2024
Today - Tonight:
A vertically stacked low over northern Ontario early this
morning will continue to trek to the southeast throughout the
day today, dragging a cold front through the Northland.
Radar still shows light rain showers ongoing along and ahead of
the front across the MN Arrowhead and into the South Shore where
temperatures are still in the upper 30s to low 40s. Behind the
front today, breezy northwest winds and cold advection will
usher colder temperatures into the area as a tight pressure
gradient leads to daytime wind gusts up to 35 mph, though some
higher gusts could be seen along the North Shore this afternoon
into evening. Have held off on any Wind Advisory issuance for
the North Shore as gusts should primarily stay below 45 mph,
with the probability for gusts reaching this threshold are only
about 30-40%.
In addition to the winds, steep low-level lapse rates will
provide a potential for isolated to scattered post-frontal snow
showers this morning and today to have some convective elements.
While amounts look light (less than an inch over northeast MN
and less elsewhere), the convective nature of the showers could
result in some very brief visibility reductions to a mile or
less at times. These snow showers should come to an end later
this evening into tonight. Overall, conditions will be pretty
brisk, with highs in the 30s in MN and upper 30s to low 40s in
NW WI, but the breezy winds making conditions feel like below
freezing. Wind chills tonight also dip into the single digits
above and below zero.
South Shore Lake Effect Snow:
The lake-effect snow machine gets going this evening across
portions of the South Shore (Bayfield, Ashland, and Iron
Counties) and continues into early Monday morning as much
colder 850 mb temperatures (-13C to -18C) advect in behind the
departing low pressure, with northwesterly to northerly winds
grabbing moisture off of Lake Superior along with some lake-
induced instability. There is still some spread in the model
guidance with regards to exact snowfall amounts with the lake-
effect snow, but the trend in amounts has increased over the
last few model runs. This spread is noted by forecast amounts
ranging from an inch in western Ashland County to upwards of 8
inches in northern Iron County through 7 AM on Monday.
Probability-wise, the chances for 6+ inches of snow are 50-80%
in northern Iron County, with probabilities quickly dropping off
into southern Iron County and eastern Ashland County. Therefore,
have issued a Winter Weather Advisory for Iron County to account
for these higher totals. If snow amounts continue to trend
higher, I can`t rule out the need for expanding the Advisory
into Ashland County or potentially an upgrade to a Winter Storm
Warning for Iron County. The potential for Warning-criteria
level snowfall (8+ inches) in northern Iron County generally
ranges from about 20-40% at the moment. Lake-effect snow comes
to an end on Monday as drier air advects into the region.
Several Days of Near-Critical Fire Weather Conditions:
Despite a cooler airmass working into the region for the next
several days (high temps on Sunday in the mid 20s to low 30s and
generally upper 20s to 30s much of next week, a general lack of
precipitation for most of the Northland along with dry
antecedent conditions and breezy winds will combine to produce
the potential of several days of near-critical fire weather
conditions from today through mid-next week as precipitation
chances look minimal (10-40% chances) with a couple weak
shortwave troughs passing through.
Minimum humidity values today as low as 35 percent in central to
east-central Minnesota will lead to near-critical fire weather
conditions. Additional low or lower humidity values Sunday
through the first half of next week may lead to additional
near-critical fire weather conditions on a daily basis depending
on the strength of the winds each day.
Additional Snow Chances Next Week:
Global ensemble guidance increasingly diverges regarding
solutions for potential snowfall late next week, with the
upper-level pattern varying between an upper-level trough or
weak NW flow/ridging Thursday and Friday. Therefore, confidence
in amounts and locations of precipitation remain low, but
forecast temperatures would support any precipitation primarily
in the form of snow.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1242 PM CDT Sat Mar 16 2024
Northwest winds behind a cold front have become strong, with
gusts of 25 to 30 knots today. Speeds decrease slightly tonight,
but gusts will remain in the 20 to 25 knot range. Isolated to
scattered snow showers on radar in northeast MN will continue
this afternoon, mainly affecting KINL and KHIB. Have included
TEMPO groups for both sites for visibilities dropping to IFR
convective showers. Otherwise, expect MVFR ceilings for KINL,
KHIB and KDLH, with MVFR for KBRD and KHYR. Ceilings to lower to
MVFR this evening and overnight, but are likely to improve to
VFR once again around mid morning Sunday.
&&
.MARINE...
Issued at 346 AM CDT Sat Mar 16 2024
Westerly winds over western Lake Superior will shift to
northwesterly by this morning as a cold front passes through the
region. Winds increase and become very gusty today into at least
Sunday morning, with widespread wind gusts to around 35 knots.
Waves of 3 to 8 feet are also expected along the South Shore. A
Gale Warning remains in effect until early Sunday morning. Winds
turn northerly and weaken slightly on Sunday. However, gusts of
20 to 30 knots and lingering elevated wave heights along the
South Shore will likely result in hazardous conditions to small
craft. Additional Small Craft Advisories will likely be needed
after the Gale Warning ends on Sunday morning.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...Winter Weather Advisory from 7 PM this evening to 1 AM CDT
Monday for WIZ004.
MARINE...Gale Warning until 7 AM CDT Sunday for LSZ121-140>148-150.
&&
$$
DISCUSSION...Rothstein
AVIATION...LE
MARINE...Rothstein