Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 210900
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
400 AM CDT Fri Apr 21 2017

.SHORT TERM...(Today through Saturday)
Issued at 400 AM CDT Fri Apr 21 2017

A warming trend today into tomorrow as an area of high pressure
moves across the region. Mainly sunny today after some morning fog,
clear overnight, then increasing clouds from north to south Saturday
associated with a cold front approaching from the north.

Early this morning clouds and a few areas of stratus should quickly
dissipate after dawn due to the relatively shallow nature of the
fog/stratus and drier air advecting in from the west as observed on
preliminary non-operational GOES-16 low level water vapor channel
imagery. High pressure builds in across the upper Midwest today, and
strong solar heating should help temps rise to near 60 in some
spots, enough to cause a lake breeze to develop. While many parts of
region has seen two rounds of soaking rain over the past three days,
the solar heating and relatively drier air moving from the west will
result in relative humidity values falling to around 30-35 percent
in the afternoon, perhaps lower in a few spots such as the Wisconsin
Pine Barrens. However, light winds will mitigate any fire weather
concerns.

Clear skies overnight with the area of high pressure centered over
southern Minnesota into central Wisconsin. Lows in the upper 20s to
mid 30s, just about normal for this time of year.

A cold front approaches from the north Saturday with fairly weak
large-scale lift, and with the area of high pressure in place to the
south the front will slow down and gradually move across the
international border in the afternoon. This may result in some light
rain showers with a bit of elevated instability in place, though
significant dry air at both low levels and mid/upper levels will
likely result in more virga than rain. West winds may become gusty
ahead of the front in northern Minnesota Saturday afternoon with a
few gusts to 20 mph possible. Dry again, though increasing clouds
where winds are expected to be strongest will result in relative
humidity values not falling as far as Friday. Still, parts of east-
central Minnesota and northwest Wisconsin could see relative
humidity values fall to 25 to 35 percent in the afternoon. Warmer,
with highs reaching into the low to mid 60s.


.LONG TERM...(Saturday night through Thursday)
Issued at 400 AM CDT Fri Apr 21 2017

An active extended period is in store for the Northland. An upper
ridge will extend through the Rockies into western Canada early in
the period, then a series of northern stream shortwaves will create
a quasi-zonal flow over the weekend before a longwave trough
develops over the western CONUS midweek. The longwave trough will
then move east into the central CONUS next weekend.

A cold front will continue to move south Saturday night moving
through the Northland, the front will then return north as a warm
front Sunday into Sunday night. A strong baroclinic zone will be
associated with and behind the front but little upper level support
for lift will occur until a stronger shortwave starts to affect the
area Sunday night continuing into Monday night. There will be a
chance for light rain or snow Saturday night behind the front,
impacting much of the Northland. Some light snow accumulation will
be possible over far northern Minnesota as boundary layer
temperatures cool. There will be a continued chance for
precipitation on Sunday over portions of the Northland as FGEN
continues. The precipitation will become mainly rain as temperatures
warm through the day. The coverage and intensity of the
precipitation will increase Sunday night, continuing through Monday
night as the stronger shortwave arrives. Surface low pressure will
start to deepen in eastern Wyoming on Sunday moving through South
Dakota into Minnesota on Monday. The low will then continue east
lifting into eastern Ontario on Tuesday. The models do show some
differences in the track and strength of the low but still remain in
reasonable agreement considering the time period. A wintry mix or
just snow is still expected both Sunday night and Monday night over
mainly northern portions of the Northland. Some snow accumulations
will be possible...but both the GFS and ECMWF have trended warmer
than runs 24 hours ago.

A weak ridge of high pressure will provide either dry conditions or
only low chances for precipitation Tuesday night into Wednesday
night. Considerable model differences occur Thursday through next
weekend. There will be a strong low pressure system in the region
and both the GFS and ECMWF show it impacting the Northland but have
significant timing and track differences.

Highs Sunday through Friday will be below normal for most areas.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1257 AM CDT Fri Apr 21 2017

High pressure will build into the region from the Northern Plains
tonight through Friday. This will keep mostly clear skies across
much of northeast Minnesota tonight with light winds. This
combined with recent precipitation, has resulted in radiation fog
development. Expect fog to persist across northeast Minnesota into
the morning hours. Will see visibilities range anywhere from VLIFR
to VFR as is typically the case with radiation fog. Fog may
develop at KHYR if skies clear. Currently think that MVFR/IFR
cloud cover will remain in place KHYR until early Friday morning,
which will limit the amount of radiational cooling. So, for now
held off on mentioning fog at KHYR.

Will see a return to VFR conditions around 14Z to 15Z once fog
dissipates with light winds through the rest of the forecast.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  55  32  63  34 /   0   0  20  40
INL  61  36  61  28 /   0  10  30  30
BRD  61  35  64  37 /   0   0  10  20
HYR  56  29  63  36 /   0   0  10  20
ASX  53  30  65  35 /   0   0  10  40

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 9 AM CDT this morning for LSZ140>142.

&&

$$

SHORT TERM...JJM
LONG TERM...Melde
AVIATION...WL


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