Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
606 PM CST Tuesday Jan 27 2015
Short term...(this evening through wednesday)
issued at 247 PM CST Tuesday Jan 27 2015
Main concerns in the short term are focused around the potential
for light snow along the Borderland tonight and Wednesday
morning...and the next shot of a wintry mix Wednesday and Wednesday
night. A mix of snow...sleet and freezing rain is possible...and
winter weather headlines may be needed.
Weak upper level ridge oriented from western Quebec into the upper
Midwest this afternoon with an associated surface ridge axis further
to the E/se. On the western edge of this ridge there is an area of
fairly strong warm air advection over the northern plains. Indicative of this warm
air are the upper 60 and lower 70 degree temperatures in western South
Dakota. Conditions are not as pleasant across the Northland with
much of the region enshrouded in cloud cover and temperatures in
the upper 20s and lower 30s. Still not too bad for late January.
The dome of warm air over the plains today will gradually shift
to the southeast as the ridge breaks down and the next upper short wave
and surface low move in from the northwest. A weak lead wave...ahead of the
main trough will pass through western Ontario and brush portions of
The Arrowhead and Borderland region with light snow tonight and
Wednesday morning. Only light snow amts are expected.
The brunt next winter system will begin to move into north-central Minnesota
late Wednesday morning with a mix of snow and freezing
rain/drizzle...that will spread to the south through the
afternoon. As the precipitation moves in...a colder air mass will
as well. But not before The Wedge of warm air in the middle levels
can alter the precipitation type to a wintry mix...mainly along
and south of a line parallel to Highway 2. The bulk of the
precipitation...namely heavy snow...with this system will fall north of
the international border...closer to the upper level forcing and
along a area of enhanced middle level f-gen. However...NE Minnesota and northwest
WI will see lighter precipitation...but still enough to cause potentially
hazardous travel/Road conditions during the day Wednesday and Wednesday night.
Could see 1 to 2 inches of snow across The Arrowhead...and light
ice accumulations possible from Waskish to the twin ports and into
northwest WI. Another round of winter weather advisories could be needed.
Long term...(thursday through tuesday)
issued at 247 PM CST Tuesday Jan 27 2015
A strong cold front will move through the Northland early Thursday
in the wake of a passing clipper system. There will be strong cold
air advection during the day. Partly to mostly cloudy skies should
ensure that the cold air advection results in falling temperatures through the
day...so highs will be in the morning. The nam12 and GFS model
soundings are showing a mixing layer packing quite a bit of
northerly wind. Not sure if the lapse rates will be sufficient
enough to draw down the 35 to 40 knots of wind those soundings are
showing in the mixing layer...but substantially increasing the
sustained wind and wind gust forecast over the previous forecast
seemed warranted. There will likely be at least widespread north-northwest winds
of 10 to 20 miles per hour with gusts up to 30 miles per hour. There could be snow
flurries and light accumulating snow...primarily in northwest Wisconsin due
to lake enhancement. Overall...Thursday looks like a blustery day
which will put an end to our recent relatively warm weather.
High pressure will move into the Northland Thursday night. The light
winds will promote radiational cooling...but lingering cloud cover
could promote the opposite. It appears there will be northwest to west-northwest winds
of 10 to 15 knots aloft through the night...despite the surface
winds becoming very light. The northwest winds aloft could maintain the
cloud cover. Nonetheless...lowered the Thursday night low
temperatures based on a wide blend. Lows will likely be near or up
to several degrees below zero.
Southwest flow will develop Friday in the wake of the passing high
pressure and in advance of an approaching clipper in Saskatchewan
and Manitoba. The influx of warmer air should allow temperatures to
recover 15 to 20 degrees by Friday afternoon. Highs will be about 5
degrees below normal.
Another weak clipper system will move through the Northland Friday
night and early Saturday. This could bring another dusting of snow
to the forecast area. The northern forecast area appears to have the best
chance of seeing this dusting.
A prolonged period of cold north to northwest flow will develop Saturday in the
wake of the clipper and its cold front...and continue through
Monday. This will lead to another cooling trend. Temperatures will
likely be 15 to 20 degrees below normal during this time. Wind chill
temperatures might flirt with readings of -20 degrees or colder at
night...both Sunday night and Monday night. The snowbelt region of
northwest Wisconsin will likely get light lake effect snow Sunday into
Monday due to the cold northwest flow over Western Lake Superior.
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 605 PM CST Tuesday Jan 27 2015
A challenging ceiling forecast exists across the Northland...at
least into the early morning hours. There is an area of VFR
conditions that runs from northwest to southeast that includes
kgpz/kxvg/kfoz/kinl. This clearing may impact kbrd/khib as well
for a time. However...an area of warm air advection will move through the
Northland tonight and develop MVFR and IFR ceilings where they are
absent this evening. Forecast soundings show a strong inversion
present so the current clouds may expand later tonight as well.
Area radars have been showing increasing echoes across northern
Minnesota and adjacent Ontario/Manitoba. Much of these returns
have produced little ground truth is likely mainly virga. NAM bufr
soundings as well as most of the model guidance suggest the best chance
for some light snow or possibly some sleet will be along the
international border this evening.
An area of low pressure and continued warm air advection will impact the
Northland Wednesday as well. We did not add any precipitation to the tafs
at this time...as the probability looks too low to include. As we
progress through the period...an addition of some mixed precipitation may
be needed in some of the tafs.
Preliminary point temps/pops...
dlh 25 33 23 24 / 0 30 50 10
inl 27 32 14 16 / 20 30 60 10
brd 27 34 21 22 / 10 20 40 0
hyr 24 34 27 27 / 0 10 50 20
asx 25 36 27 28 / 0 10 50 20