Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 270900

Area Forecast Discussion
National Weather Service Duluth MN
400 AM CDT Thu Apr 27 2017

.SHORT TERM...(Today through Friday)
Issued at 358 AM CDT Thu Apr 27 2017

We are not quite done with the strong upper low that has brought a
wintry mess to the forecast area for the last 36 hours, as we are
about to get another shot of precipitation across the 3-4
easternmost counties of the forecast area. A surface low over
southeast Wisconsin as of 3 am is slowly moving north-northeast,
and will move to far eastern Lake Superior this afternoon before
moving up into Ontario. It will bring a period of light to
moderate precipitation to the eastern portions of the forecast
area. The main question will be the precipitation type, which has
been somewhat problematic with this event. For now, the latest
analyses and short range model guidace suggests that the warm
layer aloft should be near or below freezing, once the
precipitaion gets here, as that should be in the next couple
hours. For now, it appears we will have a mixture of snow, sleet,
and a little freezing rain, which may end up being more snow and
sleet depending on how things are changing aloft. Have kept some
fairly high pops going, tapering off quickly to the west with some
freezing drizzle as far west as the I-35 corridor. Precipitation
should switch over to all snow this afternoon, this band sweeps
north of the area this evening. Cyclonic flow aloft along with the
continuing cold air advection will keep snow chances going for far
northern Minnesota tonight and Friday, but with little if any
accumulations expected. Temperatures will remain on the cold side
through Friday with highs only in the upper 20s and 30s for today,
and mid 30s to mid 40s for Friday. Even with the warmer
temperatures on Friday, it will still be well below normal with
Friday highs 10-15 degrees below normal for late April.

.LONG TERM...(Friday night through Wednesday)
Issued at 358 AM CDT Thu Apr 27 2017

The extended forecast period continues to feature temperatures
slightly to significantly below seasonal averages, along with the
potential for an impactful late April/early May winter storm.

Friday night through Saturday appears to be a quiet and dry period
with mostly clear skies throughout. A low-amplitude mid-level ridge
and an associated sfc high pressure system will dominate over the
Northland. Temperatures for this period look to be slightly below
normal, with highs ranging from the upper 40s over the Minnesota
Arrowhead to the lower to mid 50s from International Falls and
points south and west.

The primary concern for the long-term forecast period continues to
be the potential for an impactful winter storm Sunday and Monday
that could bring a wintry mix of precipitation to the region. This
system looks to develop from a mid-level shortwave trough that
develops out of the Four-Corners region of the Intermountain West
states. The sfc low pressure component of this system will develop
due to lee cyclogenesis and translate across the mid-Mississippi
River Valley over eastern Iowa and southern Wisconsin by Monday
morning. Plenty of moisture should be coincident with this system as
a good push of moisture transport and 850 mb theta-e advection will
be associated with this system. The best moisture looks to stay to
the east, but the Northland should be clipped by the northwestern
portion of the enhanced moisture plume. Cyclonic circulation around
the sfc low will bring northeasterly flow off of Lake Superior, so
temperatures over adjacent areas of the lake and upstream of the
flow should receive some chillier temperatures compared to the
inland areas. Moreover, the favorable northeast fetch off Lake
Superior will also lead to gusty northeast winds Sunday and Monday
over the head of Lake Superior. The consensus blends of the high
temperatures for Sunday and Monday appeared to be quite a bit warmer
compared to the deterministic values from the 27.00z GFS/ECMWF/CMC
models, so adjusted the highs down accordingly. Precipitation types
are uncertain at this time due to disagreement between the models,
but the general thought for now is a rain/snow mix due to a
favorable thermal profile as per the GFS model soundings. GEFS also
favor the rain/snow mixture, and the NAEFS ensembles indicate the
cooler temperatures, so higher confidence does exist for wintry mix
precipitation types. We can`t rule out some sleet or freezing rain
possibly mixing with the rain/snow, so those with travel plans on
Sunday and early next week should stay tuned to the latest forecast.
High temperatures will fluctuate through the extended period, while
lows remain generally in the 20s and 30s throughout the Northland.
Highs should remain well below seasonal averages, especially Sunday
and Monday, with highs in the lower to mid 40s Sunday, and in the
mid to upper 30s near Lake Superior and into the 40s further inland.

This system may linger over the region through Tuesday morning, most
likely across our eastern portions of the forecast area. Some
rain/snow showers could linger over the South Shore through Tuesday
afternoon, but these look to be fairly light in nature.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1141 PM CDT Wed Apr 26 2017

Expect MVFR ceilings through the forecast, with some isolated
pockets of IFR. Snow showers will be in the vicinity of BRD
through the first part of the forecast. Mixed precipitation will
be in the vicinity of HYR around 13Z. Confidence is low on
precipitation actually affecting these terminals, so VCSH used. As
the upper low departs late in the forecast, some additional
showers may be found in the vicinity of all terminals but BRD.


DLH  33  23  43  27 /  20  20  10   0
INL  30  22  41  22 /  50  50  30   0
BRD  37  24  47  27 /  10  10   0   0
HYR  36  23  46  27 /  40  10  10   0
ASX  36  24  45  29 /  50  20  10  10


WI...Winter Weather Advisory until noon CDT today for WIZ003-004-009.

LS...Small Craft Advisory until 10 AM CDT this morning for LSZ121-



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