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454
FXUS63 KDLH 252045
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
345 PM CDT Mon Sep 25 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 325 PM CDT Mon Sep 25 2017

The Northland will remain under the influence of a deep upper-level
trough over the Intermountain West states, keeping the region under
persistent southwest flow. A sharp thermal gradient along a low-
level baroclinic zone will linger over the region through the early
evening and overnight. Expecting mainly chances of showers will
gradually increase later this evening and overnight as an area of
low pressure approaches from the south. Some scattered
thunderstorms will be possible later this afternoon and evening
over north-central Wisconsin as instability remains higher in
this area, with MLCAPE values between 500 to 1500 J/kg before
rapidly decreasing after sundown. The main focus for any
thunderstorm activity will be over Price, Sawyer, Iron, and
Ashland counties in northwest Wisconsin. Severe weather is not
anticipated during this time period, as deep layer shear appears
to be a bit low, with values between 25 to 35 kts possible.
However, we can`t rule out a strong thunderstorm or two. Chances
of showers will gradually increase overnight as the inverted sfc
trough of the sfc low pressure approaches the region. Heavy
rainfall will be possible overnight, given Pwat values between
1.0" to 1.5". Given that some locations in the CWA already have
seen decent amounts of rainfall per the CREST soil moisture, there
could be some localized ponding of water overnight. Due to the
very moist air mass in place and fairly light winds, areas of fog
will be possible tonight as well. Lows tonight will range from the
middle 40s north to the middle to upper 50s over northwest
Wisconsin.

Precipitation should be on-going Tuesday morning as the low pressure
center should be over northwest Wisconsin by around 12z to 15z
Tuesday. This low will lift northeast over western Lake Superior,
taking the baroclinic zone along with it. This will bring some
cooler temperatures to the region. Not expecting any
thunderstorms during the day Tuesday as instability greatly
diminishes overnight. Due to the expected rain, as well as the
abundant cloud cover, I decreased temperatures a few degrees for
Tuesday. Highs Tuesday will range from the lower 50s over north-
central Minnesota, to the lower to middle 60s over northwest
Wisconsin, so a bit cooler than today, and quite a bit cooler
compared to over the weekend.

.LONG TERM...(Tuesday night through Monday)
Issued at 343 PM CDT Mon Sep 25 2017

The gradual evolution to a progressive pattern will continue
Tuesday night. Scattered showers are expected to linger over
northern Minnesota and portions of northwest Wisconsin as low
pressure departs. Skies will gradually clear overnight and
temperatures will dip into the 30s over north-central and
portions of northeast Minnesota. Temperatures will remain near
normal for Wednesday with highs in the middle 50s northeast to
the low 60s south and west. Another cool front will move through
the Northland Wednesday evening which could bring another
sprinkle and an uptick in cloud cover. With the greatest cloud
cover arriving overnight, expect temperatures to trend a bit
warmer with lows from near 40 degrees northeast to the middle 40s
in central Minnesota.

An upper-level trough will dive southward out of Ontario and into
the Upper Midwest on Thursday with partly to mostly cloudy skies
and a chance of rain showers. The trough departs by Friday
afternoon with high pressure moving into the region. Highs Friday
will be a bit cooler from the middle 50s to near 60 degrees. As
the ridge axis passes to the east for Saturday allowing southerly
return flow to develop. Look for temperatures to nudge warmer
with sunny skies for Saturday. A deepening upper level trough
will move into the Northern Plains Saturday night with a
shortwave trough nosing into the Dakotas. The trough will be slow
to move eastward keeping a persistent chance of showers, and
possibly a thunderstorm, in the picture from late Sunday morning
into early next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1256 PM CDT Mon Sep 25 2017

Low clouds will linger across the Northland during this forecast
cycle. A surface low is forecast to develop over northern Missouri
this afternoon and lift northeastward along a nearly stationary
front through the area Tuesday afternoon. Scattered rain showers
and persistent IFR/MVFR ceilings are expected. Skies will begin to
clear after 18Z Tuesday as drier air wraps in behind the departing
low.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  51  56  42  60 /  90  80  20   0
INL  47  52  39  61 /  80  90  40   0
BRD  50  57  41  63 /  90  70  10   0
HYR  56  63  43  61 /  70  80  20   0
ASX  54  61  44  61 /  80  80  20   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from 10 PM this evening to 4 PM CDT Tuesday
     for LSZ121-140>147.

     Small Craft Advisory from 10 PM this evening to 10 PM CDT
     Tuesday for LSZ148.

&&

$$

SHORT TERM...JTS
LONG TERM...Huyck
AVIATION...Huyck