Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 150517
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1117 PM CST Tue Feb 14 2017

.UPDATE...
Issued at 919 PM CST Tue Feb 14 2017

A very dry atmosphere is in place over the forecast area which has
been successfully eroding any clouds that try to move inland from
Lake Superior. This is true along both shores. With a dewpoint
depression of 12 degrees at IWD and 15 degrees at both ASX and
K4R5 on Madeline Island, this has precluded any lake effect
processes from getting started. Latest RAP/HRRR/NARRE keep Ashland
and Iron county from seeing any snow developing tonight until
09Z, then just over Iron county. Have also adjusted downward the
snow amounts to less than one half inch. Rest of the forecast on
track.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 238 PM CST Tue Feb 14 2017

Mid-level shortwave trough will continue to advance south-
southeastward through the region, which will continue to support
small chances of relatively light lake effect snow showers across
the Lake Superior snow belt area this evening and overnight. The
14.12z synoptic models are progging a nearly north to south 110+
knot upper-level jet streak persisting over the region.
Northwesterly flow will continue through this evening, with some
gusts up to 20 mph possible before weakening overnight as a sfc
high pressure ridge axis translates through the region. Continued
high chance to likely POPs along and near the Gogebic range this
evening and overnight as cold air advection on the windward side
of the system becomes entrenched across the Northland. Lake to
850 mb delta-Ts should be suitable for this lake enhancement, with
lake temperatures near 2 C, and 850 mb temperatures between -10
and -15 degrees C. New snow accumulations are expected to remain
fairly light, with nearly an inch possible along the Gogebic
range, but isolated amounts greater than one inch possible. Lows
tonight should drop into the single digits above zero along the
International Border, and the lower teens across NW WI.

The lake enhanced snow should wind down Wednesday morning as the
1000-850 mb mean layer RH decreases, as indicated by the
GFS/NAM/ECMWF RH progs. Winds will be light during the day Wednesday
as the high pressure ridge axis advances through the region.
However, model soundings are indicating some pessimistic cloud cover
for Wednesday. Continued with the previous forecast package and kept
more cloudy skies for Wednesday, despite the ridge axis in place.
Highs Wednesday in the lower to mid 20s most places, with warmer
temperatures towards the southwest.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 238 PM CST Tue Feb 14 2017

Late week and through the weekend will be very warm, with
temperatures approaching record highs and record warm lows. Partly
to mostly sunny through the weekend with increasing clouds and the
next chance for precipitation late Sunday into Monday.

On the synoptic scale a broad mid-level ridge will build into the
Great Plains and Midwest late this week. A weak mid-level shortwave
trough moves across the ridge well to the northwest of the region
early in the weekend before the ridge builds back in over the
weekend. At low levels, this warm period will have a few weak
warm front passages through the long term period, which will
result in occasional clouds through late week, but Saturday should
be mostly sunny before clouds return late Sunday. With such warm
temperatures, snow melting and the possibility for clearing skies,
some fog/stratus will be possible this weekend. While it will
take until late in the weekend for higher dew points to work their
way in, at least some localized fog will be possible Friday and
Saturday nights.

Early next week a much more organized pattern emerges as a mid-level
trough ejects out of the Great Basin region into the northern high
plains with a resulting surface low developing somewhere across the
Dakotas and lifting northeast. While the latest ECMWF takes this low
track directly towards western Lake Superior, the GFS has a much
farther north and west track and the Canadian is a bit slower with a
track in the middle. So, while there are still uncertainties with
regards to the exact pattern, in general the warm temperatures ahead
of this low and a surge of moist and warm air from the south ahead
of the low late Sunday into Monday will lead to rain transitioning
to snow. Gusty winds are possible depending on the exact low track,
with a closer and deeper track increasing the likelihood for
stronger winds. Way too early to discuss specific rain/snow amounts,
but a period of rain appears likely before colder air arrives when
the low passes.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1117 PM CST Tue Feb 14 2017

VFR is expected through the forecast as high pressure arrives from
the eastern Dakotas, and floats over the terminals through the
end of the forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  10  24  15  31 /   0  10   0   0
INL   4  22  11  34 /   0  10   0   0
BRD  12  28  18  38 /   0   0   0   0
HYR  12  25  13  33 /   0   0   0   0
ASX  15  25  13  32 /   0  10  10   0

&&

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

$$

UPDATE...GSF
SHORT TERM...JTS
LONG TERM...JJM
AVIATION...GSF



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