Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 231805
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1205 PM CST Fri Feb 23 2018

.UPDATE...
Issued at 1148 AM CST Fri Feb 23 2018

Updated for the 18z Aviation Discussion below.

&&

.SHORT TERM...(Today through Saturday)
Issued at 401 AM CST Fri Feb 23 2018

Snow ongoing over the area this morning is piling up fairly
quickly, with 3.5 inches so far at the office as of 3 AM. This
broad area of snow with embedded bands of heavier snow is being
driven by a fairly strong shortwave that is moving across central
Minnesota, sweeping northeast in the strong southwest flow aloft.
For now, the most intense band of snow extends from the Bayfield
peninsula south across Hayward and farther south, which aligns
fairly nicely with a band of frontogenesis at 700mb and the
strongest warm air advection. In this band, visibilities are less
than a mile, and producing snowfall rates of an inch per hour.
This band is gradually shifting east, and should get out of the
forecast area by 13z. There are some weaker mesoscale bands, but
these are more transient and are not reducing visibilities as
much. The back edge of this precipitation is slowly lifting
northeast towards the forecast area, and while we are already
seeing some diminishment in the snowfall around the Brainerd
Lakes, expect that to spread northeast and the actual back edge to
move into the forecast area fairly soon. Snowfall reports that we
received around midnight and what we have seen here at the office
as well as visibility reports around the area imply that we are
going to see snowfall amounts around 6 inches for a very broad
area, including the Brainerd Lakes, much of northwest Wisconsin,
and around the Twin Ports. Where we have a Warning out along the
North Shore, snowfall amounts are likely to be in the 6 to 8 inch
range. However, snowfall reports will begin coming in here in the
next few hours and we will see how things work out. Temperatures
today to push up into the low 30s over northwest Wisconsin as the
low moves overhead, with much cooler values to the northwest.
Tonight we should see some clearing of skies, and with a surface
ridge building into the area we can expect good radiational
cooling conditions and have lowered minimum temperatures to below
zero for much of far northern Minnesota. Clouds should keep things
warmer for northwest Wisconsin, and have lows in the 10 to 15
degree range there.

.LONG TERM...(Saturday night through Thursday)
Issued at 401 AM CST Fri Feb 23 2018

Another strong and quick-hitting storm system Saturday night and
Sunday is the main focus for the long term this morning.

High pressure will drift east from the Western Great Lakes
Saturday. A deep trough of low pressure will move out of the
Rockies and into the Plains on Saturday with lee cyclogenesis
forecast over eastern Colorado. The trough will become negatively
tilted as it rotates eastward with time kicking the surface low
into the Midwest Saturday night. Gulf and Pacific moisture will
stream northward into the region ahead of the approaching system.
The deterministic models all bring the system through Wisconsin
and into Upper Michigan by early Sunday morning, and then farther
northeast to near James Bay by Sunday evening. This trajectory
favors a band of heavy snowfall from Iowa through eastern
Minnesota and western/ northern Wisconsin, and Western Upper
Michigan. With the abundant moisture available, we expect a 12 to
18 hour period of moderate to heavy snowfall from central
Minnesota and west-central Wisconsin northeast into the Arrowhead
and northwest Wisconsin. A wide swath of 6 to 10 inches of
accumulation is expected with far northeast Minnesota potentially
receiving a foot of new snow. Feel the inherited Winter Storm
Watch is adequate in timing and areal dimensions, so no changes
made with this forecast package. Anyone with travel plans late
Saturday night through Sunday should pay close attention to the
forecast and consider making adjustments to their itineraries, if
possible.

The active weather pattern continues into next week as a
shortwave trough scoots eastward across the Canadian Prairies
Monday night and Tuesday. This system may bring an inch or two of
snow to our northern zones. Attention then shifts toward the end
of the week where model solutions diverge in handling the next
wave. There is a possibility another fast-moving storm system
will bring several inches of snow to the Northland Thursday night
and Friday.

One potential upside to the active weather pattern is the warmer
temperatures. With the polar jet stream shifting northward
through our region, temperatures will remain near or slightly
above normal for much of the long range.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1205 AM CST Fri Feb 23 2018

Light snow will continue to wind down across the Northland this
afternoon, leading to a mix of VFR/MVFR ceiling reductions. There
could be some lingering flurries through the mid afternoon.
Otherwise, mostly MVFR ceilings will continue through much of the
afternoon. Overnight, an inversion may develop, which could trap
enough moisture to reduce visibilities down to high-end MVFR
categories. Some of the guidance is going even lower than this,
but confidence in that is low, so left out of the TAFs for now.
Dry conditions will persist overnight as surface high pressure
builds in.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  31   7  29  21 /  90   0  20  90
INL  27  -2  30  18 /  90   0   0  80
BRD  29   1  28  19 /  60   0  60  90
HYR  34  10  34  25 /  60   0  40  90
ASX  34  14  33  25 /  90   0  10  90

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from Saturday evening through Sunday morning
     for WIZ001>004-006>009.

MN...Winter Weather Advisory until noon CST today for MNZ011-012-018-
     019-025-026-033>037.

     Winter Storm Watch from Saturday evening through Sunday morning
     for MNZ012-019>021-034>038.

     Winter Storm Warning until noon CST today for MNZ020-021.

LS...None.
&&

$$

UPDATE...JTS
SHORT TERM...LE
LONG TERM...Huyck
AVIATION...JTS



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