Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 151547

Area Forecast Discussion
National Weather Service Duluth MN
1047 AM CDT Fri Sep 15 2017

Issued at 1044 AM CDT Fri Sep 15 2017

Updated to add chance of thunderstorms across nrn st. louis county
and the arrowhead as some possible storms are developing.

UPDATE Issued at 925 AM CDT Fri Sep 15 2017

updated to add pops for rw- this morning and trw- this afternoon
in areas mainly north of Highway 2 and the Brainerd Lakes region.
There are a few rain showers north of the iron range and in the
arrowhead this morning. This should continue into the afternoon
hours when the next shortwave may kick off some thunderstorms.

UPDATE Issued at 718 AM CDT Fri Sep 15 2017

Update for new 12Z Aviation discussion below.


.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

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 12Z TAFS through 12Z Saturday morning)
Issued at 718 AM CDT Fri Sep 15 2017

MVFR and IFR ceilings will improve to VFR for most terminals later
this morning, except at BRD where MVFR ceilings will continue for
much of the day due to its proximity to the stationary front. The
front will drift northward into the BRD/DLH area later this
afternoon. Showers and thunderstorms are expected to develop once
again north of the boundary and should affect most terminals this
afternoon or tonight. A strengthening low-level jet will raise the
potential for LLWS for many sites. Kept any LLWS out of INL for
this set as they may be too far north and west to experience the
strongest winds.


DLH  63  57  72  50 /  30  60  50  70
INL  57  52  64  44 /  90  90  50  50
BRD  79  63  70  48 /  30  50  50  50
HYR  80  63  79  54 /  30  10  30  70
ASX  69  59  80  55 /  20  20  30  60


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

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

LS...Small Craft Advisory until 4 AM CDT Saturday for LSZ140>147.

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



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