Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 231751
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1251 PM CDT Sun Apr 23 2017

.UPDATE...
Issued at 1001 AM CDT Sun Apr 23 2017

The northwest to southeast band of light to moderate snow
continues to fall across northern Minnesota. At 10 AM CDT, there
is a heavier band of snow that extends from the Leech Lake area
southeast to Aitkin that will continue to move to the east-
southeast this morning. This could dump a quick inch or so for
most locations in its path. This snow could last into the early
afternoon before mixing with rain, then becoming all rain in the
afternoon.

&&

.SHORT TERM...(Today through Monday)
Issued at 459 AM CDT Sun Apr 23 2017

Rain and snow showers associated with a robust band of
frontogenesis and convergence stretched from western North Dakota
into northern Minnesota and Upper Michigan early this morning. The
strongest portion of the band was located over northern Cass
County through southern St. Louis and southern Lake Counties and
east into western Lake Superior. The areas where precipitation is
the strongest have changed to all snow, with a rain/snow mix,
leaning toward the rain side, favored on either side of the band.
The surface boundary was located south of the precipitation and
stretched from northern South Dakota across central Minnesota and
northern Wisconsin into Upper Michigan.

Convergence aloft will weaken this morning as the southwesterly
low-level jet weakens and winds north of the boundary veer
easterly and weaken. The precipitation intensity and coverage is
expected to decrease with diminishing forcing for ascent. The
frontal surface aloft will drift northward later today and
tonight, shifting the focus for additional precipitation toward
the Borderland. A weak shortwave trough will advance eastward
across North Dakota and the southern Canadian Prairies, along the
northern periphery of a developing low in the Rockies. Increasing
southerly winds in the low and mid-levels will strengthen
convergence over northern Minnesota, increasing frontogenesis once
again, as the shortwave moves through. Look for precipitation
coverage and intensity to increase once again tonight generally
north of the Iron Range. Falling temperatures and diabatic
contributions from the precipitation should result in a change to
all snow for some areas of far northern Minnesota overnight. A
rain/freezing rain/snow mix is favored farther south. The surface
low will emerge from the Rockies tonight and advance northeastward
through the Dakotas and into northern Minnesota by Monday
evening. Precipitation will rotate eastward across our area
through the day, and should trend back toward all rain by late
afternoon.

Temperatures will trend cooler today as cold air advection
continues at the surface, aided by easterly winds off Lake
Superior for areas along and inland from the lake. Should skies
clear across our southern zones, temperatures should be able to
rebound into the middle to upper 50s, with low 50s to upper 30s
for the rest of the Northland. Temperatures will remain cool along
the North Shore and northern Minnesota on Monday due to cloud
cover and precipitation. Meanwhile, temperatures recover into the
60s for southern areas.

Snow accumulation during the next 36 hours of a couple inches is
possible, but mainly on unpaved surfaces. The best potential for
accumulating snow is generally from Grand Rapids to the Twin Ports
and along the North Shore today, to areas north of the Iron Range
and east to the Boundary Waters and far northeast Minnesota on
Monday.

.LONG TERM...(Monday night through Saturday)
Issued at 459 AM CDT Sun Apr 23 2017

An elongated area of low pressure will extend into central
Minnesota by Monday evening, as an upper level shortwave moves
through the Northland. Widespread precipitation is expected across
the northern 2/3 of the CWA. Have added a small chance of
thunderstorms to areas of east central Minnesota Monday evening,
with some weakly unstable air forecast to be in that area. Some
minimal MUCAPE and a ridge of higher dewpoint and theta-e air will
also stretch into the southern to southeastern portion of the
CWA. The chance of precipitation will diminish across the area by
Tuesday morning, but the next wave will start to affect the region
already by Tuesday afternoon. The surface low is expected to
approach Rochester, MN by 00Z Wednesday, with widespread
precipitation developing across the southeast half of the region.
The low will move to central/northeast Wisconsin by 12Z Wednesday,
with precipitation gradually trailing off to more scattered
precipitation on Wednesday. High pressure will build into the
Northland on Thursday and Thursday night, with dry weather
expected for the latter half of the week. The next main system to
affect the region will move into the western Great Lakes over the
weekend. We may need to continue to increase POPs as the system
approaches, as the GFS and ECMWF are both indicating the potential
for a fairly major system moving into the region. There will be
significant variation in temperatures during this relatively
active long term period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1251 PM CDT Sun Apr 23 2017

A band of snow showers will lift north across northern Minnesota
today resulting in MVFR to at times IFR ceilings at HIB this
afternoon then INL tonight, but otherwise VFR conditions should
prevail this afternoon into this evening at most sites as drier
air moves north into the region. Late tonight into tomorrow east-
northeast winds increase and MVFR ceilings will develop along the
Lake Superior shoreline and spread inland, impacting at least DLH
but also possibly HIB and BRD. East winds will gust to near 25
knots at all sites tomorrow morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  35  30  43  37 / 100  30  70  60
INL  42  29  40  32 /  20  60  90  80
BRD  46  35  58  39 /  90  10  70  50
HYR  47  36  62  45 / 100  10  40  40
ASX  38  32  57  43 / 100  20  50  50

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 PM CDT Monday for LSZ121-146>148.

     Small Craft Advisory until 10 PM CDT Monday for LSZ144-145.

     Small Craft Advisory from 10 PM this evening to 10 PM CDT Monday
     for LSZ140>143.

&&

$$

UPDATE...JTS
SHORT TERM...Huyck
LONG TERM...DAP/Huyck
AVIATION...JJM


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