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afddlh

Area forecast discussion
National Weather Service Duluth Minnesota
412 PM CST Thu Feb 23 2017

Short term...(this evening through friday)
issued at 411 PM CST Thu Feb 23 2017

Our major winter storm is still expected to affect the area tonight
through early Saturday. Models have pulled a bit of a right turn on
US with the storm track in the last 24 hours, shifting the storm
track farther southeast. Yesterday, the 18z Friday surface low
position was over southeast Iowa, that is now over north central
Illinois with the latest runs. The low track now GOES from the
Kansas City area at midnight tonight east to north central Illinois
at noon Friday, to northeast of Green Bay by midnight Friday night.
The models are relatively close together on the storm track, and so
I have better confidence in the forecast, but it could still shift
some more depending on the convection that develops over Iowa
tonight. This has caused the heavy snow band to shift farther
southeast from previous forecasts, so have once again reduced
snowfall totals over the forecast area. The heavy snow band is now
only catching my southeastern 3-4 counties, with lake effects
boosting snowfall amounts along the South Shore snow belt areas of
Ashland and Iron counties. Have decided to issue a Winter Storm
Warning for Ashland, Iron, price and Sawyer counties based on this
snowfall. Farther west the snowfall amounts taper off sharply, so
the twin ports are only looking at a dusting of snow, if anything.
Have only gone with an advisory for Bayfield and Washburn counties,
as they're looking at only 2 to 5 inches of snow. Wind conditions
are expected to get fairly breezy over northwest Wisconsin as well,
which could produce some drifting and even blowing of snow. Have
included blowing snow in the forecast where this is most likely.
Snow wraps up pretty quickly Saturday morning, with only lake
effects lingering into the daytime, so have set the headlines to
expire at 6 am. Some of those could be cancelled earlier, but for
simplicity have kept them all at the same begin and end time.

Long term...(friday night through thursday)
issued at 411 PM CST Thu Feb 23 2017

A return to cooler and somewhat seasonable temperatures late this
weekend into early next week in the wake of a winter storm exiting
the Midwest and colder northwest flow returning to the Northland.
This northwest flow pattern will result in numerous weak clippers
into the beginning of next week bringing some areas of light snow
but nothing more than an inch or so. Highs in the mid 20s (sun) to
mid 30s (mon) with lows falling to the single digits both Saturday
and Sunday night.

Early to mid week the pattern changes with a deepening longwave
trough at mid to upper levels over the Pacific northwest,
translating eastward towards the northern High Plains Tuesday. In
response to the mid-level wave, a surface low will develop somewhere
across the Great Plains and lift northeast towards the upper Great
Lakes. This storm may bring light to moderate snowfall amounts to
parts of the Northland Tuesday into Wednesday depending on the storm
track. While it's tough to provide much detail this far out, this
type of a storm track is more favorable for snowfall across more of
northern Minnesota and northern Wisconsin compared to the Friday
storm tomorrow because this tues-Wed storm will have a farther north
storm track. However, despite some colder temperatures to start off
the week, southerly flow ahead of the deepening low could result in
surface temperatures above freezing, leading to a mix of rain and
snow. Winds and colder temperatures aloft could lead to a period of
heavy snow somewhere near Lake Superior due to lake effect, but
depending on the storm track this could be focused on the North
Shore such as at the tip of the Minnesota arrowhead or across the
South Shore such as along the Bayfield peninsula. Or as the 00z
European model (ecmwf) depicted, lake effect snow for almost all areas inland of
Western Lake Superior as the low lifts out to the northeast. In
summary: rain/snow likely tues-Wed, light to moderate snowfall
amounts expected, with some locally higher amounts due to lake
effect impacts.

Late-week a clipper drops down in the northwest flow to bring a
chance for light snow to the region, possibly followed by repeat
clipper into the weekend.

Generally highs in the mid 20s to mid 30s through the work week with
lows in the teens to mid 20s - possibly some single digit lows north
of the Iron Range towards late-week.

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1149 am CST Thu Feb 23 2017

Conditions will improve to VFR at most sites for a period this
afternoon as the low level stratus deck dissipates and high-level
clouds increase from south to north. Winds will increase from the
north through the night into Friday morning as a low pressure
system approaches from the south. MVFR ceilings will develop dlh
and hib as the low approaches towards Friday morning, with a
lesser chance at brd and unlikely (but plausible) as far north as
inl. At hyr conditions may briefly improve to VFR late tonight,
but otherwise at least MVFR stratus deck will stick through
tomorrow morning. Snow will begin and ceilings will lower late
Friday morning, though at this point there still remains some
uncertainty as to how bad conditions will get at hyr during the
day Friday. At least MVFR to IFR stratus will persist through the
day, and if heavy snow develops IFR to LIFR conditions are
possible.



&&

Preliminary point temps/pops...
dlh 17 23 10 26 / 10 30 20 10
inl 9 21 5 23 / 0 0 10 10
brd 19 26 11 30 / 10 10 0 10
hyr 23 27 12 28 / 50 90 80 10
asx 23 27 15 28 / 40 90 90 40

&&

Dlh watches/warnings/advisories...
WI...Winter Storm Warning from midnight tonight to 6 am CST Saturday
for wiz003-004-008-009.

Winter Weather Advisory from midnight tonight to 6 am CST
Saturday for wiz002-007.

Minnesota...none.
Ls...none.
&&

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