Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 171324

Area Forecast Discussion
National Weather Service Duluth MN
824 AM CDT Mon Apr 17 2017

Issued at 822 AM CDT Mon Apr 17 2017

Updated pops in NW WI to reflect the fast moving showers moving
through the region. They should clear WI by 16Z. Also increased
cloud cover this morning to reflect current conditions.


.SHORT TERM...(Today through Tuesday)
Issued at 317 AM CDT Mon Apr 17 2017

A mid-level shortwave with an associated weak sfc cold front will
continue diving to the southeast this morning through the forecast
area. There is some modest forcing with this shortwave, so chances
of precipitation will linger, mainly along the North Shore and
southeast into adjacent areas of Lake Superior. Lake induced fog and
chances of rain, possibly mixed with snow, will continue in these
areas before diminishing later this morning. Otherwise, expect
things to dry up for the afternoon today as sfc high pressure over
Ontario Canada and mid-level ridging briefly takes control over the
region. Easterly flow from the sfc high pressure will keep
temperatures cooler along Lake Superior, especially along the North
Shore. Highs today look to range from the mid to upper 30s along the
North Shore to the upper 40s and lower 50s further inland.

The main focus for the short-term forecast period is a more potent
system that will impact the Northland, starting Tuesday morning and
continuing into the afternoon. A mid- to upper-level trough will
develop over the Intermountain West areas of Montana and Wyoming and
translate to the east over the region. Very deep and robust lift
will accompany this system with strong isentropic omega progged in
the Thaler div Q guidance and upper-level divergence ahead of a
110+ kt 250 mb jet streak. Moreover, moisture transport looks to
be enhanced ahead of the system as a strong 60-70 kt 850 mb low-
level jet will enhanced moisture transport and theta-e advection.
Due to the strong moisture transport, precipitation will be very
efficient, leading to high amounts of QPF, especially through
Tuesday morning. There is still some uncertainty with the exact
onset of the precipitation, but the meso-model guidance looks to
ramp up precip between 06z and 09z Tuesday morning. Precipitation
types also look to a bit of a mixed bag as well, with a wintry mix
possible from the South Shore of Lake Superior, northeast towards
the Twin Ports and into the Iron Range and International Falls
areas, with freezing rain, sleet, rain and snow all possible in
these areas. Ultimately, this wintry mix will be brief,
transitioning to all rain by the late morning and afternoon. There
may even be a rumble of thunder possible along our southern tier
of counties Tuesday morning and afternoon. The heaviest QPF looks
to fall over the northwestern portions of the forecast area, with
the lightest in the southeast over northwest Wisconsin. Total
precipitation amounts may range between one-half of an inch up to
one inch. There may also be some light accumulations with the
snow, mainly right along the International Border corridor, with
up to two inches of new snow accumulation possible, but should be
localized. This system looks to continue over the east during the
late afternoon and evening hours Tuesday as well.

.LONG TERM...(Tuesday night through Sunday)
Issued at 317 AM CDT Mon Apr 17 2017

The upper flow will start out zonal across much of the northern
CONUS with a trough moving toward western Canada and western CONUS
on Wednesday. The upper trough will continue east and stretch from
the Four Corners region into the northern Rockies Thursday night. It
will then continue east with the main energy remaining south of the
region into the weekend.

Any lingering light precipitation will end Tuesday night as the low
pressure system continues to move away from the region.

A shortwave well ahead of the main upper trough will develop an area
of low pressure with a center into the Iowa/Nebraska border region
by 00Z Thursday. This low will continue east to northeast tracking
toward southern Lake Michigan by 12Z Thursday then toward the
eastern Great Lakes by 00Z Friday. The models are in decent
agreement on the track, but do show some differences in QPF. Light
rain may develop over southern portions of the Northland Wednesday
afternoon with a better chance Wednesday night. The ECMWF/GFS have
more QPF further north compared to the NAM/CANADIAN. The ECMWF does
show a 700MB thermal ribbon closer to northern Wisconsin compared to
the GFS but both show the low level thermal gradient much further
south. At this time we limit the mention of precipitation to just a
chance, with the best chance over portions of northwest Wisconsin.
Further adjustments will occur once the models come into better
consensus. A mix of rain and snow will be possible later Wednesday
night into early Thursday morning. Highs Wednesday and Thursday will
be near normal...from the mid forties to mid fifties.

The rest of the extended from Thursday night through the weekend
will be dry or only feature low chances for precipitation as the
main shortwaves pass north or south of the region. Highs Friday into
the weekend will be at or several degrees above normal. It does look
there will be a prolonged period of off lake winds although strong
lake breezes look unlikely.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 647 AM CDT Mon Apr 17 2017

An inverted trough extended north through northern Wisconsin into
northwest Ontario early this morning. A shortwave was also moving
through the area. There were scattered snow showers over portions
of the Northland and those will come to an end this morning.
Conditions varied widely, from VLIFR along portions of the south
and north shores of Lake Superior, to VFR from the Mille Lacs
Lake area to Siren and Park Falls. MVFR or low VFR ceilings were
moving south though and will impact all TAF sites this morning. We
do expect the IFR/MVFR ceilings to become scattered through the
day for most areas.

An area of low pressure will move toward the Northland tonight
causing precipitation to expand overnight. Mainly rain is
expected but snow or a mix will be possible over portions of far
northern Minnesota. Ceilings will lower to MVFR or IFR later
tonight into Tuesday morning. IFR conditions or lower will be
possible as early as this evening around Lake Superior as off
lake winds are expected.


DLH  45  34  51  33 /   0  70  80  10
INL  48  34  45  29 /   0  80  80  10
BRD  53  42  57  36 /   0  80  60   0
HYR  52  37  59  35 /  20  50  80  10
ASX  43  30  57  35 /  30  50  80  20




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