Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1140 PM CST Monday Feb 8 2016
issued at 859 PM CST Monday Feb 8 2016
Have been getting reports of heavy snow out of northern Iron
County near Hurley...of 4 inches from 6 to 8 PM. On radar...we are
catching the top edge of a lake effect snow band streaming
straight down into northern Iron County this evening...producing
the enhanced snowfall. With colder 850mb temperatures falling
aloft...only slowly diminishing low level relative humidity boundary values...and
continued north 1000-850mb winds...expect the lake effect snow
bands to continue overnight...only slowly diminishing during the
day on Tuesday. Thus...have upgraded the Winter Weather Advisory
for Iron County to a lake effect snow warning...for the same time
Short term...(this evening through tuesday)
issued at 320 PM CST Monday Feb 8 2016
Northwest flow in the wake of a clipper will continue through today
and into tomorrow. Snow showers gradually diminish from west to east
as drier air moves in aloft...except along the South Shore of Lake
Superior where lake effect snow showers will continue into tomorrow.
Temperatures slightly below normal...lows 5 to 10 below zero in
northeast Minnesota and around zero to 5 above in northwest
Wisconsin. Highs Tuesday in the single digits...with locations north
of the Iron Range struggling to reach zero.
On the synoptic scale a broad low pressure system over Lake Michigan
will gradually slide eastward over the lower Great Lakes. Tonight
into Tuesday an area of strong high pressure begins to spread
southward from Manitoba into the Red River valley and upper
Mississippi Valley. This will result in continued north-northwest
flow at the surface and aloft through the short term period with
850mb temperatures gradually falling from around -15c this afternoon to
around -20c by Tuesday afternoon. While drier air is gradually
working its way in from the northwest as seen by the thinning clouds
on visible Satellite Lake effect snow showers are expected to
persist along the South Shore of Lake Superior. The lake temperature/air
temperature difference is ideal for les and will continue to be good
through tonight when lake effect snow showers are expected to
intensify as winds shift to become more northerly. Skies become
mostly clear tonight in north central Minnesota as high pressure
builds in...then mostly sunny tomorrow with weaker winds compared to
Tonight...lake effect snow showers ramp up this evening along the
South Shore....likely producing heavy snow rates at times. Elsewhere
gradually clearing skies from west to east with temperatures plummeting to
below zero. Decided to go with a Wind Chill Advisory from the Iron
Range north...wind chill values hit -25 to -30 or so late tonight
into tomorrow morning. While winds may go to near calm with the high
moving in decided to issue anyway since this is the first time
International Falls will fall below zero since Jan 20 and many
locations will likely reach advisory criteria /-25/. Decided to be
optimistic with the sky cover given the thin nature of the cloud
cover this afternoon.
Tuesday...as drier air moves in aloft and high pressure builds in
skies become mostly sunny from west to East. Lake effect snow
showers should diminish along Iron/Ashland County...and the Winter
Weather Advisory may need to be cancelled early should the intense snow
showers expected to ramp up tonight not develop as expected. An
additional 1-2 inches possible through the morning and early
afternoon along northern Iron/Ashland counties. Highs in the single
Long term...(tuesday night through monday)
issued at 320 PM CST Monday Feb 8 2016
A steady supply of cold air will remain over the Northland into
at least the first half of next weekend due to northerly flow aloft.
An upper ridge will extend from the southwest Continental U.S. Into
Alberta...moving little from Tuesday night through Friday. A surface
ridge of high pressure will be over/near the area as well keeping
most areas dry into the first half of the weekend. The exception
will be the chance for lake effect snow along portions of the South
Shore which will continue.
The best chance for lake effect snow will be Tuesday night into
Wednesday evening...then the low level flow will back on Thursday.
Stability and fetch are quite favorable for lake effect snow...but
inversion levels are not very high and drier air will move over
Western Lake Superior as well. We have another 2 inches to maybe 5
inches of snow Tuesday night through Wednesday...with the highest
amounts over northern Iron County. It is possible the advisory may
need to be extended...but the impacts of the drier air may reduce
the expected snowfall. A northerly flow will redevelop Thursday
night into Saturday bringing another chance for lake effect snow
along portions of the South Shore.
Temperatures will be well below normal through Saturday.
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1135 PM CST Monday Feb 8 2016
A mixture of MVFR and VFR conditions across the forecast area as
of 05z. Most sites VFR with periods of MVFR ceilings and
visibilities in -sn in the last couple hours. This is expected to
slowly taper off from northwest to southeast as drier air builds
into the area. All locations except khyr expected to be VFR by
12z...with khyr lingering longer due to lake effect clouds
streaming across the terminal through approximately 21z. North-
northwest winds generally 10-15kt g20kt to also slowly
diminish...and should drop below 10kts for all sites by 01z.
Preliminary point temps/pops...
dlh -3 6 -12 5 / 40 10 10 0
inl -11 1 -19 2 / 20 0 10 0
brd -3 8 -12 8 / 10 0 10 10
hyr 1 7 -8 7 / 70 10 10 10
asx 5 8 -2 8 / 90 40 30 30
WI...lake effect snow warning until 3 PM CST Tuesday for wiz004.
Winter Weather Advisory until 3 am CST Tuesday for wiz001-002.
Winter Weather Advisory until 3 PM CST Tuesday for wiz003.
Minnesota...Wind Chill Advisory from 3 am to noon CST Tuesday for mnz010>012-