Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 150848

Area Forecast Discussion
National Weather Service Duluth MN
348 AM CDT Fri Sep 15 2017

.SHORT TERM...(Today through Saturday)
Issued at 348 AM CDT Fri Sep 15 2017

An area of low pressure will be located over central Minnesota this
morning, but dissolve by afternoon. A surface trof will be found
over northwest Wisconsin and with a secondary trof over northern
Minnesota. A ridge of high pressure will be over western Lake
Superior through the day. Meanwhile, the southwest upper flow aloft
remains over the region. After the initial batch of showers and
storms over the Arrowhead, northwest Wisconsin and western Lake
Superior end, a much needed break from this activity occurs this
morning. By 21Z, the next round of rain should get underway,
especially over the western third of the forecast area. This is when
the parade of embedded upper level impulses begin to affect the
region. A mid level capping inversion will cover areas south of the
Iron Range with 700mb temps greater than 9C. With surface moisture
flux convergence lacking, the storms will be elevated in nature. Some
heavy rain is possible with the stronger storms as PWATS will be
over 1.5 inches. Lapse rates are not very steep and any hail that
accompanies the stronger storms will be limited.

A surface low gets organized in west central Minnesota by 06Z
tonight and moves into north central Minnesota late. The surface
trofs remain fairly stationary over northeast Minnesota and
northwest Wisconsin, while the ridge axis remains over western Lake
Superior. A closed mid level circulation will move from the eastern
Dakotas into northwest Minnesota tonight. This will continue to feed
embedded impulses into the region tonight with more showers and
storms. Area of focus for heavier rain amounts will be over northern
Itasca and Koochiching counties. This area missed out the heavy rain
from Thursday and is confirmed by CREST and SAC-SMA soil moisture
profiles of less than 20 percent. This area has also been in a minor
drought for the last month. Will hold off on any flood headlines and
mention to next shift. Much of northwest Wisconsin will be rain free
tonight as drier air aloft moves across this area with mean RH of 30
to 40 percent. The surface trofs dissipate late as an 850mb/surface
warm front lifts through the area ahead of the surface low. A weak
cold front begins to push through the region late tonight in concert
with the surface low. This will be the main focus area for showers
and storms.

On Saturday, the surface low and closed mid level circulations
meander around the same areas. The surface front will become quasi
stationary, and be the focus for additional showers and storms. There
will be limited upper level support and only expect showers with a
few isolated storms over the tip of the Arrowhead in the morning.
Thunderstorms become more numerous in the afternoon as upper support
form upper level divergence moves through the region. PWATS above
1.75 inches will be ahead of the front, dipping to 1.5 behind the
front. Heavy rains will be possible near the stronger storms. Model
differences prevail in the afternoon with the amount of instability
and thus severe potential. Model QPF is less limiting the excessive
rainfall potential.

.LONG TERM...(Saturday night through Thursday)
Issued at 348 AM CDT Fri Sep 15 2017

A comparatively active period is ahead for the long term with
several rounds of showers and thunderstorms possible.

A broad upper level trough is forecast over the Northern Plains
and Canadian Prairies Saturday evening with surface low pressure
over the Upper Midwest. The trough will deepen and become
negatively tilted as a shortwave rotates through its base
overnight. The surface low will kick off into northern Ontario as
the shortwave moves through the Northland. Look for showers and
thunderstorms to continue overnight as the low departs. Mainly
sunny to partly cloudy skies are on tap for Sunday as broad
subsidence moves into the region in the wake of the departing
low. High pressure will scoot through the Upper Midwest Sunday
night and Monday, continuing the brief quiet period. As the
surface ridge departs, a warm front should advance from the
Plains into the western Great Lakes as another deep trough of low
pressure moves into the Intermountain West. Strong southerly
return flow will enrich boundary layer moisture over the Dakotas
and Minnesota and isentropic upglide over the frontal surface
should yield increased cloud cover Monday afternoon. A few
isolated showers can`t be ruled out, however forcing appears
limited and the front moves east of the Northland before the bulk
of the moisture arrives. The western trough will deepen as
several shortwaves rotate through the central Rockies and into
the Plains states. Deterministic guidance is split on the
handling of surface low pressure and other details from Tuesday
night onward, but the trend is for a chance of showers and
thunderstorms each day from Tuesday afternoon through Friday. The
timing and placement of the precipitation varies by model, but
the overall signal is for unsettled weather. The southerly flow
and improved moisture profile should yield enough instability for
at least a chance of strong storms and heavy rainfall.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1206 AM CDT Fri Sep 15 2017

A frontal boundary has sagged south this evening and showers and
storms continue over portions of the Northland. IFR and MVFR
conditions will expand with time, especially over northern
Minnesota. The coverage of the showers and storms will also
diminish with time as the low level jet weakens and shifts east.
The MVFR/IFR ceilings will stick around through much of Friday
then an area of low pressure will move toward the area causing an
increase in showers/storms once again. IFR ceilings will at KDLH
should move in in a couple hours, they have been occurring at
KDYT and KSUW through the evening.


DLH  65  57  72  50 /  20  60  50  70
INL  58  52  64  44 /  90  90  50  50
BRD  74  63  70  48 /  20  50  50  50
HYR  80  63  79  54 /  10  10  30  70
ASX  71  59  80  55 /  10  20  30  60


WI...Beach Hazards Statement through this evening for WIZ001.

MN...Beach Hazards Statement through this evening for MNZ037.

LS...Small Craft Advisory until 4 AM CDT Saturday for LSZ144>147.

     Small Craft Advisory from 10 AM this morning to 4 AM CDT
     Saturday for LSZ140>143.

     Small Craft Advisory from 4 PM this afternoon to 4 AM CDT
     Saturday for LSZ121-148.



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