Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 122334

Area Forecast Discussion
National Weather Service Duluth MN
534 PM CST Mon Feb 12 2018

Issued at 529 PM CST Mon Feb 12 2018

Updated aviation section for the 00Z TAFs below.


.SHORT TERM...(This evening through Tuesday)
Issued at 223 PM CST Mon Feb 12 2018

Increasing clouds and a chance for some light snow will be the main
focus for tonight. A positively-tilted shortwave trough will
eventually make its way across Montana and the Dakotas this evening
and overnight. Ahead of the wave, surface high pressure will make
its way across the Great Lakes, which will enhance southerly
return flow and warm air advection (WAA) behind it. This WAA will
bring some chances of light snow, mainly from the Brainerd Lakes
region, northeast towards the Minnesota Arrowhead region. Model
guidance disagrees somewhat regarding the amount of QPF this WAA
will generate, but the RAP soundings indicate some decent
dendritic snow growth, along with some better isentropic lift
within the dendritic snow growth layer. I decided to increase the
PoPs/QPF from the previous forecast to account for the dendritic
snow growth, but capped the QPF to two-hundredths or less of an
inch through the overnight period. In all, one-half inch or less
of snow will be possible for portions of the Northland through
Tuesday morning. The increased cloud cover should keep the wind
chills elevated enough to keep from reaching Wind Chill Advisory
criteria. Overnight lows will still be on the chilly side, with
temps between 0 and 10 below zero.

The mid-level shortwave will eventually arrive Tuesday morning, but
some drier air will lead to diminished chances of snow, with any
lingering precipitation winding down by the afternoon. Skies are
expected to become mostly sunny as well by the late
morning/afternoon hours. South to southwest winds look to be pretty
gusty Tuesday as stronger low-level winds develop along the mid-
level trough. 850 mb level winds are progged to reach between 40 to
50 knots. Both the 12.12z NAM and GFS model soundings indicate
boundary layer mixing to reach up to 900 mb, so some stronger
momentum transport is expected. Wind gusts could reach between 20 to
25 mph by Tuesday afternoon. Thanks to the WAA, temperatures Tuesday
will be much warmer compared to today, with highs in the lower to
middle 20s across the area.

.LONG TERM...(Tuesday night through Monday)
Issued at 223 PM CST Mon Feb 12 2018

The extended period will feature big temperature swings and an
absence of any strong storm systems.

Warm air advection will continue Tuesday night into Wednesday but we
expect most of the region to remain dry. It`s possible more stratus
will develop Tuesday night into Wednesday than is currently expected
and some drizzle/freezing drizzle would then be possible. However,
based on the amount of dry air in place initially we will continue
with the dry forecast. We expect highs Wednesday in the mid thirties
to around forty. The warm temperatures will be short lived as a cold
front will sweep through the region Wednesday night. There will be a
chance for light snow with the front and colder air Wednesday night
into Thursday but accumulation is expected to be less than an inch.
Northerly winds will continue to draw colder air into the Northland
Thursday with lake effect snow possible along portions of the South
Shore, mainly in the snowbelt of Ashland and Iron Counties. Some
accumulation will be possible there late Wednesday night into
Thursday night before winds back to more westerly. Highs Thursday
will be 10 to 25 degrees colder than Wednesday and range from 10 to
15 above in far northern Minnesota to the mid to upper twenties over
northwest Wisconsin.

Friday will be dry with highs in the teens. Temperatures will then
moderate into the weekend as warm air advection develops ahead of a
low pressure system. Highs Saturday and Sunday will range from the
mid twenties to mid thirties for most areas. There may be some light
snow on Saturday with the warm air advection with chances increasing
Sunday as the low nears the Northland. Although heavy snow looks
unlikely with this low, some light snow accumulation and possibly a
wintry mix will be possible.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 529 PM CST Mon Feb 12 2018

VFR to begin with, but MVFR possible as snow showers traverse
through the area tonight. Minor accumulations expected at most TAF
sites and potentially an IFR vsby restriction in the heavier
showers. Most guidance went VFR, but opted to go with MVFR due to
the nature of snow showers to quickly drop vsbys. LLWS may become
an issue towards the end of the TAF period as stronger winds move
overhead after 10Z.


DLH  -3  24  16  36 /  20  30   0   0
INL -10  23  15  35 /  30  20   0  10
BRD   0  25  15  37 /  40  10   0   0
HYR  -4  26  16  39 /  10  10  10   0
ASX  -1  29  19  40 /  10  20   0   0




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