Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 160017
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
617 PM CST Wed Feb 15 2017

.SHORT TERM...(This evening through Thursday)
Issued at 316 PM CST Wed Feb 15 2017

Look for scattered snow showers or flurries late this afternoon
into early evening in portions of northeast Minnesota and
northwest Wisconsin with warmer temperatures for Thursday.

Thin cirrus lingered over the forecast area for much of the day.
A ribbon of deeper moisture and FGEN forcing was located over
northeast Minnesota and was nosing into northwest Wisconsin at 3
PM. Light snow showers were reaching the ground over portions of
northern St. Louis and Lake counties. Added some chance POPs along
with this band through this evening. Kept accumulation low, only
a few tenths at most. The deepening cloud-layer moisture may
result in locally enhanced snow rates in northern Iron County
through mid-evening. Still think accumulations will be less than
one-half inch for the snowbelt areas of northern Iron County.

Meridional flow will continue over northern Minnesota and north-
west Wisconsin tonight. Moisture will remain limited, although the
cirrus layer may remain. A break in the cloud cover is possible,
especially over our western and northern zones and have nudged
overnight lows a little cooler tonight to account for the
potential clearing. Minimum temperatures tonight will range from
near zero in far northeast Minnesota to near 20 degrees our
southern zones.

The high amplitude ridge over the Rockies tonight will shift
farther eastward into the Northern Plains on Thursday. A compact
shortwave trough, and associated bolus of differential cyclonic
vorticity, will dive south from Manitoba across northwest Ontario
and into northern Minnesota by Thursday afternoon. With very
limited moisture, raised POPs above the consensus dry forecast
over the Arrowhead, but only into the slight chance POPs range.
Ahead of the aforementioned shortwave trough, winds will back
westerly over our western zones. Think some of the warmer air will
leak into northeastern Minnesota behind the departing trough
Thursday afternoon. Have raised temperatures above the consensus
blends for Thursday with highs in the upper 20s in northeast
Minnesota to near 40 in our southern zones.

.LONG TERM...(Thursday night through Wednesday)
Issued at 316 PM CST Wed Feb 15 2017

The long-term forecast begins with dry conditions across the
Northland as an upper-level ridge builds over the region. The
latest synoptic guidance indicates this ridge pattern will
continue through the upcoming weekend. The 15.12Z models are
progging a mid-level shortwave just grazing our northern counties
Saturday morning. The GFS/NAM model soundings are showing a very
shallow moist layer near the surface, with a large inversion and
very dry air vertically through the rest of the column. Consensus
blends gave no chances for precipitation along the Canadian
border. The GFS was the most bullish bringing any precipitation
along the International Border, but the other guidance is keeping
it dry, so will trend toward dry for now. Southerly flow will
continue through the weekend, keeping temperatures nearly 20
degrees above seasonal averages. Highs through the weekend in the
mid to upper 40s for most places, with perhaps even warmer
temperatures along our southern counties. Temperatures will depend
on the amount of boundary layer mixing. If the boundary layer can
mix deeper than what the GFS/NAM are progging, then temperatures
would become warmer than these values.

Models are starting to come together on a solution for a storm
system entering the region starting Monday morning and persisting
through Wednesday morning. A more potent 500 mb shortwave trough
will arrive Monday morning. The GFS is progging some strong
isentropic lift, with good moisture transport, as indicated by
surface streamlines and enhanced theta-e advection. GFS P-WAT
values do reach over 1 inch across northwestern Wisconsin Monday
afternoon. Moreover, a strong push of 850 mb warm air advection
will lead to additional forcing along with the shortwave. With the
good lift and moisture in place, likely to high chance POPs are
expected at this point. The thermal profile should support rain
chances during the day, and snow overnight when the profile cools.
Still too early to mention precipitation amounts, but could be
some rain/snow mix transition during the morning and evening hours
as the temperature profile chances. From Monday evening through
the rest of the forecast period, there is much uncertainty based
on differing solutions between the GFS/ECMWF/CMC models. For now,
simply kept the consensus blend of low end POPs across the
Northland from Tuesday morning through the day Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 611 PM CST Wed Feb 15 2017

A weak ridge of high pressure will move across the Northland
tonight with a weak trough of low pressure approaching the region
on Thursday. Mainly VFR conditions covered the area this evening
with a FGEN band of light snow occurring from western Lake
Superior into northern Wisconsin. The FGEN forcing will weak and
shift south tonight and we have already seen signs of it
weakening. Localized MVFR conditions will occur under this band
before it dissipates overnight.

Mainly VFR conditions are expected overnight but several of the
models suggest MVFR ceilings will develop Thursday/Thursday night
as low to mid level warm air advection continues.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  14  33  25  44 /   0  10   0   0
INL  11  35  25  45 /   0   0   0   0
BRD  20  39  27  48 /   0   0   0   0
HYR  15  36  24  46 /   0   0   0   0
ASX  15  36  25  45 /  20  10   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...Huyck
LONG TERM...JTS
AVIATION...Melde



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