Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 141806
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1206 PM CST Sun Jan 14 2018

.UPDATE...
Issued at 1206 PM CST Sun Jan 14 2018

Updated for the latest 18Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Monday)
Issued at 407 AM CST Sun Jan 14 2018

A clipper will bring a round of 1-3 inches of snowfall across
much of the Northland today with locally higher values along the
north shore this afternoon then along the south shore as lake
effect snow lingers into Monday. While temperatures will warm up
slightly ahead of the clipper today, colder air moves in behind
this clipper bringing a return to subzero temperatures into early
next week.

On the synoptic scale a mid-level shortwave trough will dig into
the Upper Midwest today, slowing down considerably as it becomes a
closed low and transitions east from Minnesota into Wisconsin on
Monday. Colder air moves in behind this clipper with 850mb temps
approaching -25C. A strong area of high pressure will build in
from the west Monday, with a 1050+ mb high centered over the
northern Plains late Monday. (This is approaching three standard
deviations above normal compared to climatology.)

Today into this evening the primary concern is a brief period of
moderate to potentially heavy snowfall as the clipper arrives.
Large-scale forcing from the warm air advection ahead of the cold
front and the incoming mid-level vort max is producing lift on the
order of around 20mb/hr per QG large-scale analysis of guidance,
which signals decent large-scale lift. Thermodynamic profiles
depict a nearly isothermal layer from around 900mb through 700mb,
and while the best vertical lift will be centered above this snow
growth layer, the deep layer within the snow growth zone may lead
to large aggregates to develop causing lower visibility and
slightly higher snowfall rates. Guidance has also been trending a
bit higher over recent runs, with the SREF mean rising from 1.9"
to 3.0" over the past four runs. Both convection-allowing and
parameterized guidance are in good agreement on precip values,
with only minor timing differences apparent across the range of
guidance. In total around 1 to 3 inches of snowfall are expected
late today into tonight, with much of that falling within a 2 to 4
hour window.

Along the north shore lake enhancement from the low level
southerly winds will lead to locally higher snowfall amounts,
around 3 to 5 inches. A Winter Weather Advisory was issued
yesterday for the southern Cook county/north shore zone, and no
changes were made to the advisory.

As the upper low shifts from Minnesota into Wisconsin on Monday,
low level flow will become favorable for fairly long fetch lake
effect snow showers for the south shore. Around 3 to 6 inches of
snowfall with locally higher amounts are possible in addition to
the clipper snow for a total of 4 to 8 inches. Locally higher
amounts are possible depending on how lake effect snow bands set-
up. A Winter Weather Advisory has been issued for Bayfield, Iron,
and Ashland counties late today through Monday night, though the
advisory is mainly for the lake effect snow Monday into Monday
night.

Colder air moving in from the west combined with increasing
northwest winds will lead to very cold wind chills late tonight
through early this week. A Wind Chill Advisory has been issued for
north-central Minnesota for tonight, with additional advisories
possible for Monday night.

.LONG TERM...(Monday night through Saturday)
Issued at 407 AM CST Sun Jan 14 2018

Snow showers linger over the Gogebic Range through Tuesday. High
pressure builds for Wednesday with warm air advection bringing in
much warmer air where highs get back into the 20s to even the 30s by
late in the week.

Models begin to diverge on specifics after Thursday. A few short
waves are progged to pass near the area which could bring increased
chances for precip, but nothing significant. There is a signature
towards late in the weekend that appears on all models of a fairly
robust system moving through the Great Lakes region, but that is
still 7 days out.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1206 PM CST Sun Jan 14 2018

Widespread IFR/MVFR conditions are spreading east into northeast
Minnesota and northwest Wisconsin, as of early this afternoon.
This is from snow and lower ceilings from an approaching Canadian
Clipper. There will be short periods of LIFR conditions due to
low visibilities from the snow this afternoon, but anticipate
mostly IFR and MVFR. The snow will gradually taper off late this
afternoon into tonight, but there will be lingering snow flurries
across much of the region into Monday with cold northwest flow.
Expect mostly MVFR and conditions flirting with MVFR later tonight
through Monday morning with widespread ceilings of 2 to 4 kft.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   8  -4   6  -8 / 100  90  30  20
INL   7 -13  -1 -20 / 100  80  20   0
BRD  11 -11  -2 -16 / 100  70  10  10
HYR   9   1  12  -2 / 100  90  50  30
ASX  11   4  15   5 /  90  90  70  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 AM CST Tuesday for WIZ002>004.

MN...Wind Chill Advisory from midnight tonight to noon CST Monday for
     MNZ010-018-025-026-033>036.

     Winter Weather Advisory until midnight CST tonight for MNZ021.

LS...Small Craft Advisory until 8 PM CST this evening for LSZ140>143.

&&

$$

UPDATE...Grochocinski
SHORT TERM...JJM
LONG TERM...Wolfe
AVIATION...Grochocinski



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