Area Forecast Discussion
Issued by NWS Duluth, MN
FXUS63 KDLH 052052
Area Forecast Discussion
National Weather Service Duluth MN
252 PM CST Mon Dec 5 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 252 PM CST Mon Dec 5 2016
A developing low pressure system will lead to a period of rain and
snow across the Northland this evening into tonight, with heavy snow
likely for parts of northern Minnesota.
On the synoptic scale a mid-level shortwave trough is currently
ejecting out of the Rockies into the central Plains, with a
resulting surface low starting to develop along the North
Dakota/Minnesota border per 3-hour pressure fall analysis. With the
low to the west, a warm front will lift north across northern
Minnesota and northwest Wisconsin tonight with seasonably strong
warm air advection aloft. This warm air advection combined with the
mid-level PVA from the shortwave trough will result in precipitation
rapidly developing and expanding across the Northland this evening,
with radar returns and surface observing stations already reporting
rain/snow falling in east-central Minnesota at of 3pm. Temperatures
at the surface are near-freezing, and until the colder air aloft
wraps around the low late tonight surface temps will likely be
steady if not rising slightly behind the warm front. Since temps
shouldn`t be too much above freezing, the precipitation rate should
overcome any melting causing by warm air near the surface thus
precipitation should be mainly snow. However, where large-scale
forcing will be weaker, such as in northwest Wisconsin, precip will
probably fall as more of a rain/snow mix resulting in limited
As the low lifts north a well-modeled dry slot will likely work its
way in after midnight towards Tuesday morning. This could result in
areas of light freezing drizzle within the dry slot due to the loss
of ice aloft, but given the true origin of the cold air that will
begin to wrap around the low tonight is from southern Saskatachewan,
think there will be enough ice in the column to result in more
flurries than freezing drizzle. The low will lift north towards Lake
of the Woods Tuesday with colder air continuing to wrap around it,
causing light snow showers off and on through the day. Along the
north shore strong southeasterly winds will likely lend to a bit of
lake enhancement late tonight into Tuesday, so the highest snowfall
amounts for this storm will likely be along the higher terrain of
the north shore.
With this rapidly deepening low so close, winds will increase
tonight into tomorrow. Southeast winds will be breezy this evening,
becoming south to southwesterly on Tuesday. Winds will be 10-15mph
overnight, increasing to 15-20mph on Tuesday afternoon with gusts
over 30 mph. Tonight, these winds will aid in keeping areas along
the Lake Superior shoreline above freezing and thus resulting in
lower snowfall amounts as rain mixes with snow. However, late
tonight into Tuesday these stronger winds will result in a some
blowing and drifting snow, especially in north central Minnesota
such as Walker and the Brainerd Lakes region.
Total snowfall amounts around 3 to 5 inches across northern
Minnesota tonight, mainly along and north of Highway 2 in northern
Minnesota. South of Highway 2 - Cass, Crow Wing, Aitkin, and Pine
counties in MN and much of northwest Wisconsin - lesser snowfall
amounts are expected, 1-3". In the Twin Ports and along the north
shore there will be a sharp gradient in snowfall between communities
right along the shoreline such as Two Harbors (1-2" at most) and up
in the higher terrain such as near Finland (4-6"+). In Duluth a
sharp gradient will be observed, with 1-2" downtown and 3-6" up
"above the hill" such as at our office near the airport.
.LONG TERM...(Tuesday night through Monday)
Issued at 251 PM CST Mon Dec 5 2016
Focus for long term lake effect snow is first significant fall
system Friday into the weekend wed night to thu night along with the
first cold blast of the season
The surface low will be along the the Canadian border with the gfs
locating it near the Lake of the Woods and the ecmwf locating the
center just south of INL tuesday night. Both models move the low
center into the northern great lakes by wednesday morning. The
northerly flow will continue to pull in the colder air and moisture
into the forecast region. This will keep snow showers across most
of the area. As indicated by the mid shift, formation of a gravity
along the northshore of Lake Superior is still possible so will keep
the current fcst in that area for Wednesday and Wednesday night.
With the northerly flow and much colder air (850T < -10C) and lake
temps around 4C-6C, snow showers will develop along the snowbelt
areas of northwest Wisconsin. The snow showers will be heavy at
times Thursday as the best conditions will affect the region.
Less favorable wind conditions along with decreasing moisture will
decrease the snow showers Thursday night before ending Friday
morning. Another short wave will move through the forecast region
Friday night and Saturday bringing a possibility of snow showers.
Another Low pressure system will move through the region late
Saturday night and Sunday bringing another round of light snow.
Temperatures will remain below normal through the period with below
zero readings possible over the weekend across the northern areas.
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 252 PM CST Mon Dec 5 2016
VFR at all sites except for IFR cigs at INL. The main concern of
the forecast period will be the snow`s affect on the TAFs. The snow
will move north into BRD/HYR/DLH by late afternoon and early evening
across HIB/INL. Once the snow commences, conditiions will drop of
IFR to LIFR in heavier snow showers. Conditiions should improve to
MVFR with occasional IFR Friday morning.
.PRELIMINARY POINT TEMPS/POPS...
DLH 26 27 16 20 / 100 50 30 30
INL 29 29 18 24 / 100 50 50 50
BRD 22 24 15 18 / 70 60 20 20
HYR 29 29 17 21 / 80 60 30 20
ASX 33 33 21 24 / 60 40 30 30
MN...Winter Weather Advisory from 6 PM this evening to 6 AM CST
Tuesday for MNZ010-011-018-019-026.
Winter Weather Advisory from 6 PM this evening to noon CST
Tuesday for MNZ012-020-021.
Winter Weather Advisory until 6 AM CST Tuesday for MNZ037.
LS...Small Craft Advisory from 6 AM to 3 PM CST Tuesday for LSZ121-
Gale Warning from 3 PM Tuesday to 9 AM CST Wednesday for LSZ121-
Small Craft Advisory from midnight tonight to 3 PM CST Tuesday