Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1120 PM CST sun Mar 1 2015
issued at 716 PM CST sun Mar 1 2015
Removed the late afternoon wording. Otherwise...a few flurries are
still possible yet this evening. Rest of the forecast in shape.
Short term...(this evening through monday)
issued at 300 PM CST sun Mar 1 2015
At 300 PM...there was an upper level trough over the northwest Ontario
and the northern plains. The Northland had 5 to 15 miles per hour westerly
winds. There were clear skies over the Minnesota arrowhead and
parts of northwest Wisconsin...but there was increasing cloud cover from
the west. Temperatures were in the low to middle 20s.
Through this evening...the upper level trough will move through
the region. The trough and cool west-northwest flow will likely bring a
period scattered/broken cloud cover and scattered snow flurries through the
Late tonight and early Monday morning...a surface high pressure
ridge will move through the Northland and provide a period of
mostly clear skies and light winds. Overnight lows will be
bolstered by the winds and cloud cover earlier in the
evening...but begin to plummet when the light winds and clear
conditions develop later in the night. Overnight lows should be
near 0 degrees for most areas.
Late Monday morning and Monday afternoon...there will be
increasing southerly flow as low pressure trough moves into the
northern High Plains. The sunny skies and mixed southerly flow
should help temperatures reach higher than what some of the
guidance is suggesting. Considering the sun angle is improving by
the day...sunny days are resulting in warmer than guidance
temperatures due to the the albedo effect from dark body Pine
trees. Therefore...increased the highs over most guidance and the
previous forecast. Highs should at least reach the middle to upper
20s...if not higher.
Long term...(monday night through sunday)
issued at 300 PM CST sun Mar 1 2015
Confidence is increasing on widespread accumulating snow event
Monday night through Tuesday...with the snowfall amounts in
excess of 3 inches expected over northern wis zones at this time.
There remains good model agreement that the northern stream of a
long wave trough digs across Manitoba/Ontario Monday
night...meanwhile phasing with the southern stream wave over the
western Great Lakes region Tuesday. Although there remains
uncertainty in the track of the southern stream surface low as it lifts
over Iowa and into Wisconsin...the strengthening inverted trough
will sweep over the Northland and bring at least few inches to
much or all of the forecast area.
The bulk of the forcing/moisture and snowfall accumulation will be
across the northern wisc zones...closer to the surface low center.
However...latest NAM bufr soundings at kdlh/khyr suggest precipitable water
values increase to around 0.4" by Tuesday morning...with deeply
saturated profiles to accompany the frontal passage and support
several inches of snowfall.
In addition...a surge of Arctic air will spread over the region as
winds turn out of the northwest and the northern stream low continues to
deepen over Ontario through Tuesday afternoon. The steep lapse
rates and strong pressure gradient will allow for gusty winds to
30 miles per hour and areas of blowing snow...mainly for the Minnesota zones.
The low becomes wrapped up and finally cuts off over James Bay by
Wednesday morning. The Northland will remain in the cold
cyclonic flow with lingering clouds/flurries Wednesday.
Long range models are in good agreement that a warm quasi-zonal
flow returns for the end of the week with the hint at near to
above freezing temperatures for Friday and through the upcoming
weekend for much of the region.
Aviation...(for the 06z tafs through 06z Monday night)
issued at 1120 PM CST sun Mar 1 2015
Last batch of MVFR clouds moving through northwest WI at the start of the
forecast. These clouds will depart by 09z...then VFR. Southerly
flow through the day with gusty surface winds expected to affect brd
Preliminary point temps/pops...
dlh 3 25 15 24 / 10 0 40 90
inl -1 25 15 20 / 10 0 50 30
brd 2 29 17 22 / 10 10 60 80
hyr 0 27 15 26 / 10 0 50 90
asx 4 27 16 27 / 10 0 40 90