Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1201 PM CST Tuesday Mar 3 2015
issued at 555 am CST Tuesday Mar 3 2015
Updated aviation section below.
Short term...(today through late tonight)
issued at 332 am CST Tuesday Mar 3 2015
Incoming winter storm with snow and blowing snow today is the
primary concern in the short term...with a secondary focus on the
very cold air expected to push in late tonight.
Snow has started to move in from the south this morning with the
latest radar loop showing the returns increasing south of Highway
two and the column quickly becoming saturated as the area of snow
lifts to the north. The latest rap mesoscale analysis shows a band of
700mb f-general along the northern edge of strong warm air advection...and the corridor of
strongest snowfall directly in line with this forcing. This area
of f-general will define where the heaviest snow will occur this
morning...and is still expected from around the Brainerd
Lakes/Lake Mille Lacs area northeastward to the twin ports and into
portions of northwest Wisconsin. A broad area of 3 to 5 inches is
expected in this zone. Other areas to the north/NW...and even to
the southeast...south of State Highway 70 in WI will see around 1 to 2
inches. The most favorable time for accumulating snow will still
be this morning from around 5 am to 11 am.
The surface cold front...currently moving into far northwest Minnesota will move
across the Northland this afternoon and allow the winds to shift
from SW to northwest. This front will also bring with it very gusty
winds. Still expecting sustained winds around 10 to 20 miles per hour and
gusts around 30 miles per hour late this afternoon through the evening. The
combination of the initial snow this morning...and blowing snow
later today will keep conditions hazardous through midnight
tonight. No changes...spatial or timing...have been made to the
winter weather advisories.
The snow will taper off during the evening and overnight hours
tonight from west to east with the cold air behind the front
pouring in across the upper Midwest. 850mb temperatures from -25 to -28
degree c are expected with this air mass. This will allow surface
temperatures will fall into the single digits and teens below
zero...and the combination of gusty northwest winds will produce wind
chills in the -25 to -35 f range. Will likely need a Wind Chill
Advisory over much of the forecast area tonight/Wednesday morning.
Long term...(wednesday through monday)
issued at 332 am CST Tuesday Mar 3 2015
Wednesday to be a cold and blustery day with the strong surface low
moving northeast across Quebec. An inverted trough will extend west
from this low...and slowly sag southeast across the forecast area
during the day. A strong surface high will build down the plains
during the day as well. Expect that we will see flurries or light
snow in the vicinity of the trough axis...and am carrying some small
probability of precipitation for this along with cloudy skies. With the pressure gradient still
fairly steep surface winds will remain in the 10-15mph range with
gusts in the 20-25mph range...especially in exposed areas.
Wednesday night the surface ridge builds into the area a little more
and allows the pressure gradient to weaken...and the clouds and
flurries are pulled off to the east with the surface low. There may
be some lake effect snow affecting the South Shore east of Ashland...
but wind trajectory is not the most favorable and have kept probability of precipitation
low. Temperatures to bottom out in the negative teens for many
locations...and with the light northwest winds it looks like we may
need a Wind Chill Advisory for Wednesday night and Thursday morning.
For now will discuss in severe weather potential statement...and will have to re-evaluate as we get
Thursday some strong warm air advection sets in aloft and highs
should rise into the 10-15 degree range...if not warmer. Otherwise
quiet weather is expected with the surface ridge in the vicinity.
Another shortwave is due to move through Thursday night and Friday.
For now am not carrying any snow chances but would not be surprised
to see flurries. Currently have highs Friday up in lower to middle
30s. Initially this warming seems overdone compared to Thursday.
However...pure mixing techniques would indicate middle 20s to low
30s...and then you add in some sunshine and our dark trees and
suddenly those low to middle 30s seem more reasonable.
The weekend looks questionable with a series of shortwaves dropping
down across the area in upper level northwest flow. Models are
bringing some warm 850mb temperatures into the area aloft...but with
the increased cloud cover associated with the clippers...and our
decent snowpack...am wondering if we might not get a bunch of
stratus and fog and cooler temperatures instead of sunshine and middle
30s. Have left consensus alone in this low confidence situation...
but we will need to watch this carefully.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1158 am CST Tuesday Mar 3 2015
The storm system that brought the accumulating snow to the
Northland will continue to pull off throughout the day and into
tonight. Strong cold air advection and gusty winds will be found in the wake of
the departing system. Vlifr to IFR conditions will quickly
transition to MVFR and even some VFR as the day wears on. With the
passage of a system such as this...there are often some lingering
cloud streets and spotty flurries or snow showers. This could mean
some local MVFR ceilings/visibilities tonight or even on Wednesday morning.
Preliminary point temps/pops...
dlh 25 -9 4 -11 / 100 10 10 0
inl 24 -15 3 -19 / 60 10 10 0
brd 22 -11 5 -14 / 100 10 10 0
hyr 27 -8 6 -15 / 100 10 20 10
asx 28 -4 7 -8 / 100 20 20 10
Minnesota...Winter Weather Advisory until midnight CST tonight for mnz011-
Winter Weather Advisory until midnight CST tonight for mnz020-
WI...Winter Weather Advisory until midnight CST tonight for