Area Forecast Discussion
Issued by NWS Duluth, MN
FXUS63 KDLH 100929
Area Forecast Discussion
National Weather Service Duluth MN
329 AM CST Sat Dec 10 2016
.SHORT TERM...(Today through Sunday)
Issued at 329 AM CST Sat Dec 10 2016
An upper level short wave trof was clipping the Minnesota Arrowhead
at 08Z, while at the surface, high pressure was building in from the
Dakotas. Plenty of low level stratus was over the forecast area with
a few flurries. An area of snow showers was occurring ahead of the
trof over the tip of the Arrowhead. Only trace amounts of snow are
expected. Some holes/clearing was already taking place along the
western edges of the region as the high moves closer. The high will
drift over the region today allowing for a partly sunny to mostly
cloudy sky. There will be weak warm air advection through the day
which is indicative of the partly sunny to mostly cloudy sky.
However, max temps will not benefit much from the warmer air with
highs from around 5 above to around 10.
The high will drift into Ontario tonight as low pressure gets
organized in the lee of the Rockies. Model differences begin to
reveal themselves on the timing of the onset of snow and the
location of the low pressure. The ECMWF is the farthest
north/fastest, the GFS/NAM and GEM are slower and not as far north.
This also in agreement with the ARW/NMM for snow placement. Have
opted for the slower approach and lowered pops in the evening.
Models are a bit closer together late tonight with the location of
the low pressure and coverage of the snow. They are also in
agreement with the approach of potent short wave trof into North
Dakota by 12Z Sunday. Have kept the area along the international
border with the lowest pops as dry air from the high lingers. Higher
pops over the southern edge of the forecast area closer to the low.
Lower QPF amounts tonight have resulted in lower snow amounts
tonight with around one inch along the southern edge of the region,
with light amounts elsewhere.
On Sunday, the low pressure center moves to the southern end of Lake
Michigan. Meanwhile, the upper trof digs into western Lake Superior.
Plenty of lift associated with the trof and being on the northern
periphery of the surface low leads to a bit more snow. Highest
pops/snow amounts will be along the southern tier of zones, with
lighter amounts farther north. 1 to 2 inches is expected over the
northern half of the region, with 2 to 3 inches over the southern
portion. The wind will be fairly light throughout and will not have
an impact. Highs will be warmer with teens north to lower 20s in
.LONG TERM...(Sunday night through Friday)
Issued at 329 AM CST Sat Dec 10 2016
The focus remains on the very cold, Arctic air that will blast into
the Northland this upcoming week. There still seems to be pretty
good agreement through the at least the middle of the week, with the
coldest temperatures of the season likely coming for Wednesday with
subzero daytime high temperatures. The latest models in general
trended colder, so trended a bit colder in the forecast.
There will likely be lingering light snow across the Arrowhead and
northwest Wisconsin Sunday evening, from more substantial snow
across the Northland Sunday daytime, as an area of low pressure
moves across the Upper Midwest and Great Lakes region. The snow will
gradually taper off and shift east through the night. Additional
snowfall will generally be less than 1 inch, but parts of the North
Shore could get up to 2 inches.
A one-two punch of Arctic air will hit the Northland early this
week. The first cold front will come Monday afternoon and evening,
followed by another front (with even colder air) Tuesday afternoon
and evening. Expect a nose-dive in temperatures to about 25 degrees
below normal by Wednesday. Wednesday should be the coldest day, with
daytime highs up to several degrees below zero and wind chill
temperatures of about -15 to -25 degrees. Parts of the Northland
will likely see wind chills of -25 to -30 degrees during the early
morning hours Tuesday, Wednesday, and Thursday, possibly needing
the issuance of wind chill advisories.
The Arctic cold fronts will be accompanied by light snow,
especially Monday`s front. The strong-cold air advection and
synoptic lift from the falling heights with an approaching upper-
level trough will result in about a few-tenths of an inch of
widespread snow late Monday, and another dusting is likely Tuesday.
Also, the prolonged period of the very cold west-northwest flow over
western Lake Superior will result in some lake enhanced/effect snow
downwind over parts of the South Shore in northwest Wisconsin. The
wind direction is not ideal for substantial snowfall for northwest
Wisconsin (not enough of a northerly component), but the best
chances of snow will likely be for northern Bayfield Peninsula,
where the wind direction will favor the best fetch across the Lake.
There is less agreement between the GFS and ECMWF late this week
than earlier in the week. The GFS maintains the very cold west-
northwest flow on Friday, but the ECMWF has warmer southerly flow
and synoptic snow spreading into the region from a system farther
south in the US. Leaned on a blend of the two for now.
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1139 PM CST Fri Dec 9 2016
High pressure will continue to build southeast across the
Northland overnight, bringing some breaks in the cloud cover to
portions of the CWA. Cloud cover will vary between mostly clear
and cloudy, with VFR conditions gradually working in from the
northwest. Otherwise, until that happens, we will see MVFR CIG`s.
As is typical with this type of pattern, we will likely continue
to see some patches of MVFR clouds into Saturday morning.
Generally VFR conditions are then expected. Some light snow will
start to move in from the west/southwest Saturday evening, with
the greatest visibility restrictions in the KBRD area.
.PRELIMINARY POINT TEMPS/POPS...
DLH 7 4 20 11 / 0 50 60 30
INL 6 -5 13 5 / 0 20 30 20
BRD 8 7 18 6 / 10 90 90 10
HYR 11 7 21 12 / 10 70 80 30
ASX 11 7 22 16 / 20 40 60 40