Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 252148

Area Forecast Discussion
National Weather Service Duluth MN
448 PM CDT Tue Oct 25 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 448 PM CDT Tue Oct 25 2016

As of 330 PM...there was a surface ridge of high pressure
stretching from western Hudson Bay through the Great Lakes. An
upper-level ridge was moving through the Plains, and a shortwave
trough was also moving through the Plains just behind the upper-
level ridge. A surface low was over southwest South Dakota. There
was some rain across parts of southern/central Minnesota into the
eastern Dakotas.

The surface low will be moving east through Nebraska and Iowa
through tonight, then Iowa and northern Illinois Wednesday. While
this low will be well to our south, increasing moisture amidst the
southeast flow, combined with lift from the approaching shortwave
trough, will bring rain as far north as parts of the Northland
later today and through tomorrow. The precipitable waters values
will increase to about 0.8" to 0.9" across the south, about the
90th percentile of climatology for this time of year. The rain
shield will have difficulty spreading north and east into our
forecast area tonight because of the relatively dry easterly flow.
It will take some time for the atmosphere to saturate, so some of
the rain will be virga at first. Leaned on the models reflecting
this theory, such as the NAM12/RAP/HRRR/WRFARW.

The rain will mostly fall tonight and Wednesday morning, with the
heaviest rains well south of Highway 2, about 0.5" to 0.75".
Whereas most of the Arrowhead, Iron Range, and Borderland areas
may barely get 0.02". Parts of the North Shore, like Duluth, Two
Harbors, and Silver Bay will benefit from some extra moisture from
Lake Superior. The Duluth area should get about 0.30" and the Two
Harbors and Silver Bay areas about 0.10".

Temperatures will be cool tonight and Wednesday, with lows mostly
in the 30s tonight and highs in the low 40s Wednesday. The
soundings suggest there could be brief periods of a rain/snow mix
or wet snow late tonight and Wednesday morning, primarily over the
inland Arrowhead and parts of northwest Wisconsin. However,
thought the chances looked fairly low. Subsequent shifts will need
to keep a close eye on the snow potential.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 448 PM CDT Tue Oct 25 2016

The main concerns during the long term period involve sensible
weather with the departing system Wednesday night and another
shortwave passing through Friday and Saturday.

Surface low pressure will be located over northern Illinois
Wednesday evening, with a shortwave trough over Wisconsin and
Upper Michigan. A second shortwave trough will quickly approach
from the southern Canadian Prairies and is expected to phase with
the departing southern system. Look for showers to linger through
Thursday morning over my northeastern zones, ending slightly
earlier over northwest Wisconsin. Longwave ridging builds behind
the departing shortwaves Thursday afternoon through Friday morning
yielding a period of quieter conditions. A longwave trough will
move onshore over the West Coast Thursday night and Friday
morning, kicking a shortwave east across the southern Canadian
Prairies and Northern Plains. Deterministic guidance is split over
the timing and intensity of the feature, and the placement of the
subsequent surface low. Continued trending toward the consensus,
which keeps low chance POPs over the area Friday through Saturday
morning. ECMWF is farther south and a bit more vigorous with
precipitation potential, with the NAM/GFS/GEM farther north. Think
the trend over the next few days may increase POPs and shift the
focus a bit farther south, closer to the ECMWF solution. Time will
tell. Fast zonal flow, with another weak shortwave, follows the
Friday night/Saturday system with weak high pressure ridging over
the region. Quieter weather Saturday night and Sunday will
transition toward a more active period late Sunday night into the
upcoming work week. The slow-moving longwave trough over the
western CONUS will gradually shift eastward into the Plains and
eventually the Upper Midwest. All of the medium-range
deterministic models develop surface low pressure in response to
the longwave trough crossing the Rockies. As usual, the specific
solutions vary on the timing, location, and intensity, but all
feature a potent system moving into the region. Was comfortable
with a consensus for now.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1256 PM CDT Tue Oct 25 2016

VFR conditions continue into this evening, eventually lowering to
MVFR and possibly IFR late tonight and Wednesday. Developing low
pressure will move toward the Northland tonight bringing clouds
and rain showers into the area. Ceilings are expected to lower to
MVFR at BRD and HIB this evening and lowering at the remaining
terminals overnight. Light rain will spread eastward out of
western Minnesota and the Dakotas as the low pressure moves into
Iowa and the eastern Dakotas late tonight. The onset of the
rainfall is somewhat uncertain, with rain beginning at BRD this
evening and spreading east and north with time. Think INL will be
last to see the showers, if at all. With precipitation arriving
during the overnight, think we`ll see visibilities lower to MVFR
and possibly IFR. Best bet at lower visibilities will be at BRD
where, rain will fall for the longest duration. Ceilings at DLH
may lower into IFR range overnight with upslope flow off Lake
Superior. Confidence is too low to include in a prevailing group
at this time. Overall confidence in the forecast is above average
until 26.01Z, then average until 26.08Z, and below average


DLH  37  43  37  49 /  30  70  20  10
INL  35  45  39  49 /  10  30  40  10
BRD  41  44  38  54 /  90  80  10   0
HYR  39  43  35  50 /  70  90  10   0
ASX  37  45  37  50 /  20  80  20  10


LS...Small Craft Advisory until 10 PM CDT Wednesday for LSZ143>145.

     Small Craft Advisory until 4 AM CDT Thursday for LSZ141-142.

     Small Craft Advisory from 11 PM this evening to 4 AM CDT
     Thursday for LSZ140.



SHORT TERM...Grochocinski
AVIATION...Huyck is the U.S. government's official web portal to all federal, state and local government web resources and services.