Scientific Forecaster Discussion
fxus63 kdlh 192345
Area forecast discussion
National Weather Service Duluth Minnesota
545 PM CST sun Nov 19 2017
Short term...(this evening through monday)
issued at 231 PM CST sun Nov 19 2017
This afternoon, very light snow continues to progress eastward along
an axis of low-level warm air and moisture advection. Impacts with
this snow should remain minimal as only light accumulations have
been observed on area webcams. This band of snow should exit the
Northland later this afternoon as skies continue to clear over our
southwestern counties and drier air moves in. Clearing skies will be
the trend this evening before increasing from the north Monday
morning as a mid-level shortwave trough moves into the region.
Despite the increasing clouds, temperatures look to warm up Monday
as winds remain southerly, bringing warmer air into the region.
Highs Monday are forecast to reach into the middle to upper 30s over
the Minnesota arrowhead, to the lower to middle 40s over our
southern counties. There is some uncertainty regarding the high
temperatures Monday as some of the guidance differs quite a bit.
Some of the high-res, short-range guidance is going a bit cooler
compared to some of the synoptic guidance. Either way, temperatures
should be above freezing, so there should be some melting of the
snow pack tomorrow.
The next chances of precipitation, mainly in the form of a rain/snow
mix, will be along the international border when a mid-level
shortwave trough dives southeastward from the Pacific northwest.
Thaler qg Omega progs indicate the best lift over Manitoba and
western Ontario Canada, ahead of the wave. Also, there is a corridor
of stronger 850-700 mb q-vector convergence along the international
border region. The best chances of precipitation over the north
appears to hold off until early Tuesday morning.
Long term...(monday night through sunday)
issued at 231 PM CST sun Nov 19 2017
A cold snap will come early in the period, but more seasonal weather
is expected around Thanksgiving. A late week system could bring a
sloppy mix of rain and snow, sometime Friday into Friday night.
Another cold snap will hit the Northland with that passing system
going into the weekend.
A Canadian clipper will pass just to the north in Canada Monday
night and Tuesday. This low's Arctic cold front will blow through
the Northland late Monday evening through the early morning of
Tuesday. Brace yourselves! This front will not only bring relatively
strong and deep mixing, with 30 to 40 knots wind speeds within the
mixing layer. There will also be strong pressure rises. Cloud cover
will minimize radiational cooling (and the resulting boundary layer
decoupling) overnight and help maintain strong mixing. The cold air
will continue to pour into the Northland Tuesday, so the mixing will
continue through the day. We increased the wind forecast for Monday
night and Tuesday over the previous forecast. Expect widespread wind
gusts of 25 to 40 mph Monday night and early Tuesday, with stray
gusts to 45 mph. The strongest winds will be across central into
northeast Minnesota, and on the weaker range of those winds in
northwest Wisconsin. Expect little if any temperature recovery
Tuesday. Highs will be about 15 to 20 degrees colder than the day
before, but that's not the bigger story. Wind chills will be in the
single digits to lower teens.
The passing clipper and front will also bring light snow to far
northern Minnesota Monday night and Tuesday morning, and light lake
effect snow downwind of Lake Superior in northern Wisconsin. The
snowfall forecast is pretty light, about less than an inch.
High pressure will move into the Northland Tuesday night and
Wednesday, which will ease off the cold northwest flow. Wednesday
will be warmer, especially considering much lighter wind flow. A
weak area of low pressure will pass through the Dakotas into the
upper Midwest or Central Plains Wednesday into Wednesday night. It
might bring very light precipitation into the Northland. The latest
GFS and European suggest this precipitation would fall over the
areas of central into east central Minnesota. It would most likely
be very light snow.
Another area of high pressure will move into the Northland Thursday.
This will provide a somewhat sunny day. Colder air will be over
northern Minnesota compared to areas farther south. Highs should
range from the lower 20s near the Canadian border to the low 30s from
central Minnesota into northwest Wisconsin.
The models continue to indicate another Canadian clipper could
affect the Northland late this week. The latest GFS, European, and
Canadian are in better agreement compared to previous model runs.
There is increasing confidence the low will track across southern
Canada, when earlier model runs (like the european) were taking the
low through the Northland. This more northern track means warmer air
for the Northland, and keeping the heavier precipitation in Canada.
However, the Northland could still get a sloppy mix of rain and
snow. The clipper's Arctic cold front will bring another cold snap
going into the weekend. More light lake effect snow is possible
downwind of Lake Superior in northern Wisconsin over the weekend.
Aviation...(for the 00z tafs through 00z Monday evening)
issued at 544 PM CST sun Nov 19 2017
Warm air advection will continue into Monday morning with VFR
conditions occurring through the period for most areas. There
could be some patchy fog tonight that lower conditions to IFR or
MVFR but the probability of that is low.
An area of low pressure will pass through southern Canada moving
into northwest Ontario by 00z Tuesday, but the wind shift to
northwest will occur after the taf period. There could be some
light rain or light snow along the international border in the
afternoon but chances look too low to include at kinl at this
Preliminary point temps/pops...
dlh 20 40 19 22 / 0 10 10 10
inl 13 38 16 19 / 0 30 50 30
brd 22 44 20 24 / 0 0 10 10
hyr 20 44 22 25 / 0 0 10 10
asx 22 45 25 26 / 0 0 10 30
Ls...gale watch from Monday evening through Tuesday afternoon for