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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDLH 182352
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
652 PM CDT Sun Apr 18 2021

.DISCUSSION...(This evening through Saturday)
Issued at 349 PM CDT Sun Apr 18 2021

A strong cold front will bring in much colder air for a few days
along with some rain and snow into tonight. The Arrowhead has the
best chance at seeing several inches of snow tonight with some
light accumulation also expected in the snowbelt of the South
Shore.

A strong cold front stretched from the near Ely into central
Minnesota into northern South Dakota this afternoon. Light rain
was occurring along and behind the front but does transition to
snow as observed at KINL. Forecast soundings show dry low layers
and the combination of cold air advection and wet-bulb effects
will cool boundary layer temperatures from west to east this
afternoon into the evening. There remains some substantial
differences among the models handling the low pressure system. The
ECMWF and Canadian are slower and a bit further south with the
low tonight which results in more QPF over far northeast Minnesota
including the Arrowhead. The rest of the models are mixed but
several of the higher resolution models do support some higher QPF
but not as much as the Canadian/ECMWF. We did trend toward some
higher QPF and based on forecast soundings, expect the rain to
transition to snow through the evening. We issued a Winter
Advisory for much of the Arrowhead this evening into the early
morning hours for 2 to 5 inches of snow. The HREF supports these
higher snowfall totals and is actually a bit more bullish. A
period of gusty winds will occur both ahead of the front and after
it`s passage as winds turn out of the northwest. 850MB
temperatures will drop to -9C to -14C by 12Z Monday which will
cause lake effect snow to develop along portions of the South
Shore as well. We have snowfall along the South Shore tonight into
Monday morning of 1 to around 3 inches, with the higher amounts
most likely in northern Iron County. Overnight lows will drop
below freezing and any slushy snow or water on untreated roads
will freeze causing some slick spots.

Highs Monday will only be in the mid thirties to lower forties and
we increased cloud cover as cyclonic flow and the cold air support
more clouds and perhaps some flurries or light showers.

Lake effect snow chances will continue into Monday night along the
South Shore with some additional light snowfall expected.

We expect mainly dry conditions Tuesday into Thursday night with a
warming trend toward Thursday. Highs on Thursday will rebound into
the fifties and remain there into Friday. Another cold front and
area of low pressure will move through the region Friday night into
Saturday bringing a chance for light rain or perhaps some light
snow.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 652 PM CDT Sun Apr 18 2021

A cold front is passing through the region at this hour, located
in the vicinity of HYR. HYR will see a period of rain in the next
hour or two with some MVFR visibilities possible at times. MVFR
ceilings are expected at all terminals through the evening with
scattered showers of rain or snow possible. There is a possibility
that there may be some periods of VFR ceilings after midnight for
some terminals. Winds will be gusty from the northwest at all
terminals through the night. Gusts up to around 25 knots are
expected. Wind speeds will lighten up slightly Monday afternoon.
Diurnally-driven scattered snow showers may develop Monday
morning and last into the afternoon before a bit of drier air
moves in late-afternoon. Some MVFR visibilities may be possible
for brief periods.

&&

.MARINE...
Issued at 349 PM CDT Sun Apr 18 2021

A strong cold front will move across Lake Superior this evening
switching winds to north to northwest and causing them to increase.
Winds will increase to 15 to 25 knots with gusts of 30 to 35 knots.
The higher gusts are most likely from Little Marais to Grand Portage
late tonight. Waves will build as a result of the increasing winds
and be highest along portions of the South Shore. We continued the
Small Craft Advisories that were issued this morning. In addition to
the wind, an area of rain and snow will accompany the front. Much
colder temperatures will occur tonight into Tuesday with some lake
induced showers possible.

The wind and waves will gradually decrease Monday. Northerly winds
will continue Monday night but be around 15 knots or less for most
areas. A weaker pressure gradient will lead to even lighter winds
Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  27  39  24  39 /  60  10   0  10
INL  22  39  21  38 /  20  20   0   0
BRD  27  41  24  41 /  30   0   0  10
HYR  27  41  21  41 /  90  10   0  10
ASX  29  40  25  40 /  80  20  10  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Winter Weather Advisory until 4 AM CDT Monday for MNZ012-021.

LS...Small Craft Advisory until 1 PM CDT Monday for LSZ121-146>148-
     150.

     Small Craft Advisory until 10 AM CDT Monday for LSZ143>145.

     Small Craft Advisory until 7 PM CDT Monday for LSZ140>142.

&&

$$

DISCUSSION...Melde
AVIATION...JDS
MARINE...Melde