Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 212345
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
645 PM CDT Fri Apr 21 2017

.UPDATE...
Issued at 645 PM CDT Fri Apr 21 2017

Please see the 00Z Aviation Discussion below.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 319 PM CDT Fri Apr 21 2017

An area of high pressure over eastern Dakotas will shift south
through Saturday, maintaining the clear skies across the Northland
through at least tonight, if not much of Saturday. The clear
skies, light wind flow, and low dew point temperatures tonight
will promote radiational cooling. Temperatures should drop into
the lower 30s. Some areas in northern Wisconsin and far northern
Minnesota could get into the 20s. It appears to be too dry to
warrant patchy fog in the forecast, but it is not impossible.

Breezy westerly flow will develop Saturday with the good heating
and resulting mixing. The increasing westerly flow aloft, ahead of
a cold front approaching from the north, could support gusts to
around 20 mph. Leaned on the warmest guidance for temperatures
considering the scenario and dry conditions. Manually increased
the highs for downtown Duluth and Canal Park because the westerly
flow will be strong enough to stave off a lake breeze, and to
account for downslope warming. Downtown Duluth and the city of
Superior should reach highs similar, if not warmer, than inland
areas in the higher terrain.

There will be increasing clouds from the north Saturday afternoon
as the cold front works its way into the Borderland areas. There
could be middle to late afternoon rain showers.

.LONG TERM...(Saturday night through Friday)
Issued at 319 PM CDT Fri Apr 21 2017

Main concern for the short term will be precip chances and type
during the forecast period.

A weak shortwave will move along the international border sunday
night bringing a chance for a rain and snow mixture to areas mainly
north of Highway 2.  There not as much moisture with this shortwave
so the precipitation will be scattered in nature.   On Monday and
Monday night, a stronger shortwave will move through MN along with
a deep low pressure area moving across the state Monday afternoon
and Monday night.  There is more moisture with this system so the
precipitation will be more widespread.  As like the previous night,
the rain will change over to a rain/snow mixture Monday night and
Tuesday morning.  There will be some accumulation but there are
still some differences with amounts.  The best area for snow
accumulation will be north of Highway 2.

A small area of high pressure will build into the forecast area
Tuesday afternoon keeping the area precip free through Thursday
morning.  The next strong system will affect the region Thursday
afternoon into Saturday.  Models to show major differences in
solution with the GFS having the low center in SW MN at 18z Fri
while the ECMWF has the center near GRB.  Canadian has the low in
Southern WI.  The GFS takes the low west of the forecast area Friday
night which would keep warmer air over the area.  The ECMWF has the
low center moving through the northern great lakes which will make
it colder.  So there are still major differences in ptype and
amounts.  Temperatures will be colder than normal next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 645 PM CDT Fri Apr 21 2017

VFR conditions through the TAF period with high pressure building
over the region. Winds will remain light and skies clear. The
latest RAP hints at radiation fog development at KHIB/KBRD late
tonight. Not confident at this point that fog will develop, but
will continue to monitor as the night progresses.

A backdoor cold front will move southward into the International
Border Saturday afternoon/evening. This will spread rain showers
into KINL and bring the possibility of MVFR ceilings towards the
end of the TAF period per the DLHWRF/NAM. There is some
instability ahead of the front, so a few thunderstorms cannot be
ruled out. Held off for now on including thunderstorms in the
KINL TAF. Gusty winds will develop at KINL/KHIB and KDLH as the
pressure gradient tightens due to the incoming front and the
exiting high.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  35  63  35  41 /   0   0  50  30
INL  35  60  30  45 /   0  20  40  20
BRD  35  65  39  54 /   0   0  20  20
HYR  29  64  37  52 /   0   0  10  20
ASX  31  67  35  43 /   0   0  40  30

&&

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

$$

UPDATE...WL
SHORT TERM...Grochocinski
LONG TERM...Stewart
AVIATION...WL


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