Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 140847

Area Forecast Discussion
National Weather Service Duluth MN
347 AM CDT Mon Aug 14 2017

.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 06Z TAFS through 06Z Monday night)
Issued at 1228 AM CDT Mon Aug 14 2017

An area of low pressure will continue to move eastward into the
region overnight. As it does, it will bring rain showers and
perhaps an isolated thunderstorm for the rest of the night and
into Monday. Low clouds and visibilities have been slow to develop
so far this evening, but we should continue to see further
deterioration of CIG`s and VSBY`s as the night wears on. Some MVFR
and even IFR conditions will be possible later tonight and on
Monday morning. We should then see a gradual improvement in
conditions by Monday afternoon, as the low pressure system pulls
off to the east.


DLH  67  53  74  57 /  70   0   0  30
INL  76  52  79  57 /   0   0   0  30
BRD  70  53  75  60 /  20   0  10  70
HYR  67  51  77  58 /  80  10   0  30
ASX  69  53  75  56 /  80  10   0  20




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