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Area forecast discussion 
National Weather Service Duluth Minnesota
337 PM CST Friday Feb 12 2016

Short term...(this evening through saturday)
issued at 337 PM CST Friday Feb 12 2016

The Northland will continue to be under Arctic northwest flow through early
Saturday...but a surface high pressure ridge in the northern plains
will shift into the western forecast area around dawn...and put an
end to the Arctic flow Saturday afternoon.

The gusty northwest winds...as of this afternoon...will gradually weaken
tonight as the radiational cooling from the clear skies develops the
nocturnal inversion. The wind will help slow down the cooling rate
this evening...but the winds should become very light after
midnight...accelerating the cooling process. While most of the
Northland will be clear...there will be lingering cloud cover and
light lake effect snow showers downwind of Lake Superior across northwest
Wisconsin. The relatively dry flow and directional shear will
undermine the snow potential...so only an inch or so at most is
expected for parts of northern Iron County.

Tonight will be cold with bitter wind chills. Most of the 12z model
guidance for low temperatures for tonight are warmer than the
previous forecast...especially across northern Minnesota. The
forecast is generally warmer than the previous forecast...and it no
longer looks like a wind chill warning will be needed for northern
Minnesota. Widespread wind chills of 25 to 35 below zero are
expected...and the higher terrain of The Arrowhead could see around
40 below zero.

Long term...(saturday night through friday)
issued at 337 PM CST Friday Feb 12 2016

The main forecast concern for the long range is the potential for
accumulating snow Saturday night through Monday morning.

Northwest flow aloft is expected for much of long term period...
eventually shifting zonal and then southwesterly Wednesday night
as a long wave ridge builds and shifts east into the central
Continental U.S.. several shortwave troughs will move through the flow starting
on Sunday with the arrival of a fast-moving upper level
disturbance. The main area of DCVA will accompany the trough out of
eastern Montana and across the northern plains to northern
Illinois by Sunday night. The best forcing and moisture will be
found west and south of the Northland. A secondary trough will trail
behind the initial disturbance across the southern Canadian
prairies and into northern Minnesota Sunday night. At the
surface...an elongated surface trough will mark the passage of the
upper-level disturbances. Nudged probability of precipitation upward along my south and
west Sunday and Sunday night with 1 to 4 inches of accumulation
possible. Winds will back southwesterly and eventually southerly
at the surface and near-aloft...resulting in a favorable fetch for
lake enhancement along the North Shore. Have increased probability of precipitation and
quantitative precipitation forecast/snowfall along the high terrain of northeast Minnesota south
to Lake Superior. The changes yield likely probability of precipitation and snow
accumulation of up to 4 inches by Monday morning. As the secondary
trough arrives Sunday night...snow chances increase across the
northern third of the County Warning Area and have opted for likely probability of precipitation with that
feature.

Weak forcing for ascent will linger across northern Minnesota as
the system slowly departs Monday...keeping clouds and a chance of
light snow in place for most locales. Another series of shortwave
troughs will move through the northwest flow and into the area by
Tuesday. Cloud cover will increase once again and winds will
gradually veer northwesterly. A closed surface low will develop
near the stronger vorticity maximum as it moves from the northern plains to
the middle Mississippi Valley by Tuesday afternoon. Deterministic
guidance is split on handling these features with the GFS slower
and farther north...and the European model (ecmwf) and Gem faster and farther
south. Guidance is split on precipitation chances Monday night and
Tuesday so have opted for slight chance probability of precipitation across mainly my
south and west. Behind the departing surface low...northwest winds
and lingering clouds will support lake enhanced/lake effect snows
along the South Shore Tuesday through early Wednesday morning.

High pressure at the surface and ridging aloft should follow the
active pattern by Wednesday. The surface ridge will quickly move
southeastward across the Canadian prairies and into the western
Great Lakes by early Thursday morning. In the wake of the ridge a
warm front will lift north through the plains...with clouds
increasing once again and a slight chance of light snow Thursday
and Thursday night.

&&

Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1153 am CST Friday Feb 12 2016

Strong surface ridge over the Dakotas and Manitoba this morning
will continue advancing southeast into Minnesota during this
forecast cycle. With the exception of MVFR ceilings/visibilities at hyr...
kept VFR ceilings/visibilities from previous forecast in place. Think winds
will remain strong and gusty through much of the evening with
strong cold advection mixing higher momentum flow aloft down to
the surface. Winds should gradually ease late tonight as advection
slows and radiational cooling allows the surface layer to
decouple.

Lake induced clouds and snow showers will likely continue to
affect hyr/asx/pbh through this forecast cycle. Heaviest snow will
be found at asx...but think snow showers with temporary visibility
restrictions at hyr likely. Surface winds diminish over WI this
evening...but expect lake modified airmass should be able to tap
into north to north-northeasterly flow aloft maintaining lower
ceilings and snow showers at hyr overnight and Saturday morning.

&&

Preliminary point temps/pops...
dlh -18 6 -6 18 / 0 0 20 50
inl -25 5 -3 18 / 0 0 30 50
brd -21 9 2 21 / 0 0 90 100
hyr -20 9 -4 18 / 0 0 20 60
asx -9 8 -7 20 / 50 10 10 30

&&

Dlh watches/warnings/advisories...
WI...Wind Chill Advisory from 6 PM this evening to 9 am CST Saturday
for wiz001>004-006>009.

Minnesota...Wind Chill Advisory until 9 am CST Saturday for mnz010>012-
018>021-025-026-035-037.

Wind Chill Advisory from 6 PM this evening to 9 am CST Saturday
for mnz033-034-036-038.

Ls...none.
&&

$$

Short term...grochocinski
long term...huyck
aviation...huyck

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