Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 141706

Area Forecast Discussion
National Weather Service Duluth MN
1206 PM CDT Mon Aug 14 2017

Issued at 1206 PM CDT Mon Aug 14 2017

Showers continued from the Arrowhead into the Iron Range and into
northwest Wisconsin as an upper trough moves through the area. A
few more showers were developing elsewhere as well and we
expanded POPS this afternoon into early evening and added more

UPDATE Issued at 642 AM CDT Mon Aug 14 2017

Updated aviation section below for 12Z TAF TAF issuance.


.SHORT TERM...(Today through Tuesday)
Issued at 347 AM CDT Mon Aug 14 2017

An upper level short wave with a closed mid level circulation, will
cross Minnesota this morning, and then into northwest Wisconsin this
afternoon as the mid level circulation opens into a trof. Several
embedded impulses will accompany this system and have increased pops
across much of the area as a result. Even though there is some
instability suggested by the models, cloud cover may affect the
overall potential for thunder. Regardless, do have a mention of
thunder over portions of northwest Wisconsin this afternoon. The
greatest potential for thunder will be over northern St. Louis east
through northern Lake and Cook counties which each of the models agree
upon. Thermodynamic profiles do not support any mention of hail, nor
excessive rain.

Monday evening finds the short wave moving through the eastern
portion of the Wisconsin forecast area before departing. No change
was made to the prior forecast in the early evening as a result.
Brought the pops down for the rest of the evening. No thunder is
expected as instability is diurnally driven. Elsewhere, upper level
and surface ridging are arriving from the west with a clearing sky.
As the high settles overhead late tonight, expect fog to develop and
affect much of the region and linger until 14Z/9am Tuesday.

A dry day is expected Tuesday as the ridging remains over the area.
The models are trying to flatten the upper ridge in the afternoon
with an approaching short wave trof. However, moisture is lacking and
thus a rain free day.

.LONG TERM...(Tuesday night through Sunday)
Issued at 347 AM CDT Mon Aug 14 2017

Tuesday night-Wednesday night a potent upper level shortwave and
associated surface low moves across the upper midwest, bringing a
period of showers and a few thunderstorms to the forecast area.
Models are fairly consistent in depicting that this feature will
affect our area, but the strength and track of the low vary a lot
between models and over the last few runs.  That said though, have
raised pops between 09Z Wednesday through 12Z Thursday over the
consensus to depict this greater confidence in this event happening.
The GFS looks overamplified aloft and too strong and too far north
with the surface low, so am favoring a more moderated solution
between the ECMWF and NAM solutions.  Since I am favoring a more
southerly solution to the surface low, have reduced the thunder
somewhat.  Thursday the precipitation chances slowly ramp down as
the system moves off to the east.

Beyond Thursday there are some pretty large differences in the
synoptics of the forecast.  By Thursday evening the general pattern
of low pressure system just to our east and ridging over the west
coast/Rockies is fairly consistent.  However, the GFS has a potent
secondary shortwave moving out of the Rockies that is much weaker in
the ECMWF.  Over the following 24-36 hours the GFS ramps this
feature up into a fairly strong system that moves a surface low
across the mid Mississippi River valley that just does not exist on
the ECMWF.  This makes a pretty big difference in the models by
Saturday, producing large uncertainties in the forecast beginning on
Friday and continuing through the weekend and early next week.  Have
stuck with the consensus forecast for now, and will have to wait and
see on how these features resolve in the next few days.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 642 AM CDT Mon Aug 14 2017

An area of low pressure over eastern South Dakota as of issuance
time will move east across southern Minnesota and Wisconsin today
and tonight. It will bring chances for showers and perhaps a few
thunderstorms to the area with MVFR ceilings and visibilities. The
MVFR ceilings will move southeast out of the area this afternoon
and evening as the low pressure system moves farther away from the
area. High pressure will build into the area tonight, causing
skies to clear and winds to become light and variable. With recent
rainfall, fog is expected to develop after 05z, with IFR
visibilities possible after 09z. LIFR visibilities are also
possible, but have left out for now as cloud cover could reduce
this possibility.


DLH  67  53  74  57 /  70  10   0  30
INL  76  52  79  57 /  10  10   0  30
BRD  70  53  75  60 /  30   0  10  70
HYR  67  51  77  58 /  90  10   0  30
ASX  69  53  75  56 /  90  10   0  20


WI...Beach Hazards Statement until 8 PM CDT this evening for WIZ001.

MN...Beach Hazards Statement until 8 PM CDT this evening for MNZ037.



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