Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Text Only | 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
000
FXUS63 KDLH 212139
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
339 PM CST Tue Nov 21 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 334 PM CST Tue Nov 21 2017

A colder airmass has moved into the area today on the heels of last
night`s strong cold front passage.  The surface ridge now over
southern Saskatchewan will slowly slide southeast to over the area
tonight, and off to our east tomorrow.  This will leave the field
open for another fairly fast moving shortwave to move into the area
on Wednesday, bringing another dose of light snow Wednesday
afternoon and night.

With the surface ridge building into the area, winds should finally
diminish early this evening.  However, cloud cover extends to cover
much of Ontario, not clearing until Manitoba, and it will take time
for this to slide east of the area tonight.  Thus, have kept clouds
and flurries going this evening, with clearing not until after
midnight.  That said though, do anticipate clearing and good
radiational cooling, so have gone with some min temps tonight in the
single digits over much of the area, with slightly warmer values
where the clouds linger longer.  Lake effect clouds and snow showers
to linger overnight for portions of northwest Wisconsin.  A dusting
of light snow is possible there tonight.

Attention then turns to the incoming shortwave for Wednesday.  With
the dry air in place have gone with the slower advance of
precipitation into the forecast area, limiting it to the afternoon
hours.  The shortwave is fairly potent, though not extraordinarily
so, and should manage to bring a period of light snow to the area.
The NAM12 has gone a lot higher than the other models on QPF with
this wave, and since it seems to be the outlier have gone with a
blend of the more conservative models. This then produces about an
inch during the afternoon over portions of northern Minnesota.
This warm air advection wing is the most potent, so things really
diminish by the time it gets to northwest Wisconsin in the
evening.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 334 PM CST Tue Nov 21 2017

A dry Thanksgiving forecast, with a couple of clipper systems moving
just to our north for Friday into Saturday. Temperatures will be
rather variable over the Northland into next week as well.

Right off the bat, Wednesday night should see a chance of light snow
over the eastern portions of the forecast area, especially along
western Lake Superior. This is due to a weak mid-level shortwave
that will dive southward and impinge on a push of 850-700 mb layer
warm air and moisture advection. QPF amounts look to be pretty
light, so any new snow accumulations should only be around one-tenth
of an inch or so over northwest Wisconsin and adjacent areas of Lake
Superior. Once the wave moves out, which should be rather quickly, a
dry, but chilly, Thanksgiving is expected. A surface high pressure
ridge will be in control over the Northland, so winds will also be
light, so overall, a great travel day for Thanksgiving. Skies look
to be partly sunny for much of the day as well.

For Friday, conditions change over to mostly cloudy, with some
increased chances of precipitation. A strong surge of warmer air in
the low-levels will move into the region, which should bring in
temperatures nearly 10 degrees above seasonal average. This warmer
air is associated with an Alberta clipper, which should primarily
remain over southern Canada, keeping us in the warm sector. P-types
might be an issue over the Arrowhead region as some freezing
rain/freezing drizzle may be possible due to a deep warm nose that
develops in the 900-700 mb layer, with temps aloft between 7 to 10
degrees above zero, according to the NAM and GFS model soundings.
Available moisture seems to be very light at this time, with lighter
QPF expected when conditions are more favorable for icing.
Temperatures should increase by the late morning, which should
remove any threat of icing. Temperatures for Friday will increase to
above freezing everywhere in the Northland, including the Arrowhead
region, with highs ranging from the upper 30s/lower 40s north to the
middle 40s south. The best chances of precipitation will be Friday
afternoon, which should fall in the form of rain, limiting any snow
accumulations with this system.

For the upcoming weekend, most of the Northland should remain dry
except for along the Lake Superior snow belt, where some lake effect
snow will be possible Saturday and Sunday morning. The latest
guidance doesn`t show too favorable conditions for lake effect,
given a lack of deeper moisture and 1000-850 mb layer winds more
northwesterly than would be ideal for lake effect snow production.
So, we will have to keep an eye on this in subsequent forecasts. A
prolonged period of lake effect snow like what is forecast may
generate decent accumulations, however.

Monday and Tuesday look to be fairly dry, except for more chances of
light snow for Tuesday. Above freezing temperatures should return
again for most of the Northland Monday, with highs in the 30s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1135 AM CST Tue Nov 21 2017

Conditions continue to improve over the Northland TAF sites as
drier air filters into the region, leading to SCT to BKN cloud
cover over most locations, except for KINL and KHYR. Mostly VFR
conditions will continue through the afternoon and tonight, except
for KINL as a period of snow showers is expected this afternoon,
which may reduce visibilities down to MVFR. Also, gusty northwest
winds will continue into the evening today, with gusts between 20
to 30 knots possible. High clouds will move in for tomorrow
morning.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   9  24  16  31 /  10  90  30   0
INL   5  21  11  26 /  10  80  20  10
BRD  12  27  19  34 /   0  80  10   0
HYR  11  26  19  34 /  10  40  30   0
ASX  16  27  21  34 /  20  30  30   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 AM CST Wednesday for LSZ121-146>148.

     Small Craft Advisory until 10 PM CST this evening for LSZ140>145.

&&

$$

SHORT TERM...LE
LONG TERM...JTS
AVIATION...JTS



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