Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDLH 102131
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
331 PM CST Sat Dec 10 2016

.SHORT TERM...(This evening through Sunday)
Issued at 331 PM CST Sat Dec 10 2016

the center of arctic high pressure will drift overhead this
evening and off to the east of the Duluth CWA by Sunday morning.
patches of stratus will linger this evening, especially along and
south of highway 2, and mid/high level clouds will rapidly
increase from west to east. however, before clouds increase too
much this evening, there should be several hours of mostly clear
skies across the northern third to half of the cwa, and this
should allow for maximized radiational cooling and temps to drop
very rapidly between 5 pm and midnight with rising temps the rest
of the night. we have significantly lowered temps for early
tonight in these areas, and undercut the coldest of guidance. Some
of the favored cold areas of interior northeast MN could easily
drop well into the teens below zero this evening for a few hours.

large scale forcing for ascent will rapidly increase later
tonight with the approach of the next wave, spreading light snow
across much of the forecast area by daybreak sunday. light to
occasionally moderate snow is then expected to continue in many
areas into sunday evening, with the strongest vertical motion
fields from midday sunday into early sunday evening. while qpf
amounts will not be terribly impressive, this should be very light
and fluffy snow with ratios between 20/25:1, which should amount
to a general 3-5 inches across most of the eastern half of the cwa
by the time things wind down sunday evening. we have hoisted a
winter weather advisory for areas along/east of the I35 corridor,
all of NW Wisconsin and the adjacent lake zones on the north
shore. Almost all hi-res model guidance continues to indicate a
rather high potential for moderate/heavy lake effect showers to be
advected on shore late tonight and sunday over the MN Arrowhead
region, and it`s entirely within the realm of possibilities that
locally heavier amounts to 6 inches, or perhaps more, could occur
just about anywhere along the north shore where the heavier
showers or lake-effect swirls/eddies come ashore. please refer to
the late morning AFD update for additional discussion on this
potential.

.LONG TERM...(Sunday night through Saturday)
Issued at 331 PM CST Sat Dec 10 2016

Main challenges for the long term are the successive waves of colder
Arctic air, lingering snow showers Sunday night, and the potential
for accumulating snow late next week.

A shortwave trough will be located over the Northland Sunday evening
with a surface low over Wisconsin. Light snow will be ongoing over
the Arrowhead and northwest Wisconsin Sunday evening and will
gradually taper off by Monday morning. Winds turn northwesterly and
eventually westerly on Monday, which could translate into some lake
effect snow showers over portions of the Bayfield Peninsula and
portions of northern Ashland and Iron Counties. The duration of the
LES should be short, owing to winds quickly becoming too westerly.
A strong Arctic cold front will swing through the region Monday
afternoon and evening. Scattered light snow showers are expected
to accompany the front as it passes through. Widespread
accumulation around an inch is possible, with the potential for
higher accumulation farther south across central and possibly
southern Minnesota. Overnight lows in the single digits below zero are
expected by Tuesday morning, with lower temps in typically colder
locales. Strong northwest winds will follow behind the frontal
boundary Monday night and Tuesday leading to wind chill values
dipping into the -25 to -30 range. A wind chill advisory may be
needed.

Strong winds are expected to develop over western Lake Superior
Monday afternoon as the low pressure trough associated with the
front moves across the lake. The winds will quickly become northwesterly
and continue to increase in speed Monday night and continue into
Tuesday. Sustained winds of 15 to 25 knots are expected with gusts
to 30 knots possible. A small craft advisory will likely be needed
Monday night through Tuesday.

Temperatures will remain cold on Tuesday with highs between -5 and
+5 degrees Fahrenheit, around 20 degrees below normal. Another
reinforcing shot of cold air will arrive Tuesday afternoon and
evening as another Arctic front dives southeastward out of central
Canada. Winds over western Lake Superior will increase once again
as the pressure gradient tightens due to passing low pressure over
northwest Ontario and building Arctic high pressure over the
western Dakotas. Gale-force wind gusts are possible over much of
western Lake Superior Tuesday night and through Wednesday night.
Wind chills will dip into the -25 to -35 range Tuesday night
through Thursday morning. Widespread low temperatures between -15
and -5 degrees are likely Wednesday morning, and even colder on
Thursday morning.

Cyclonic flow and lingering low-level moisture will support
scattered snow showers or lake effect snow over much of northern
Minnesota and portions of northwest Wisconsin Tuesday afternoon
through Thursday evening. We could see snow showers ebb for a time
late Wednesday night and early Thursday as the surface ridge slides
southeast into Iowa and northern Illinois.

Attention then shifts to gradually warming temperatures Thursday
through Saturday ahead of the next approaching storm system.
Deterministic and ensemble guidance are all pointing to a strong
storm system moving into the Plains Friday through Saturday night.
The presence of a storm system in the vicinity at this time range,
especially given the different mechanisms supporting the low, adds
confidence in accumulating snow somewhere in the region late next
week. Opted to raise POPs above the consensus blends Friday through
Saturday morning as this system moves in.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1148 AM CST Sat Dec 10 2016

Surface high pressure ridge was found across northern Minnesota
late this morning. Associated subsidence had eroded the stratus
deck over much of northern and northeast Minnesota. Stubborn MVFR
stratus layer persisted from near/north of BRD to DLH and
southeast to HYR. Think this stratus will gradually erode this
afternoon as well with ceilings returning to VFR conditions. Very
light snow showers are expected at DLH and HYR through early
afternoon and should diminish as ceilings increase/scatter out. A
developing storm system will move out of the Plains tonight and
into the Midwest on Sunday. MVFR ceilings will spread northward
ahead of the system overnight. Think the snow will arrive at BRD
and HYR first and then spread into DLH and HIB. Confidence is much
lower at INL for persistent light snow since the best forcing will
be farther south. With winds backing ESE at DLH overnight, think
lower ceilings and light snow showers may result from upslope
flow. Overall confidence in this forecast package is above average
through 09Z, then average thereafter.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   1  20   8  14 /  60  90  30  30
INL  -9  13   2   7 /  30  30  10  40
BRD   3  18   5  11 /  90 100  10  30
HYR   7  21  11  16 /  90 100  20  20
ASX   5  22  15  20 /  50  80  40  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from midnight tonight to 9 PM CST Sunday
     for WIZ001-006-007.along the North Shore zones and portions of
the South Shore zones

     Winter Weather Advisory from 3 AM Sunday to midnight CST Sunday
     night for WIZ002>004-008-009.

MN...Winter Weather Advisory from midnight tonight to 9 PM CST Sunday
     for MNZ020-021-037-038.

LS...None.
&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.