Area Forecast Discussion
Issued by NWS Duluth, MN

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303
FXUS63 KDLH 262124
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
424 PM CDT FRI AUG 26 2016

.SHORT TERM...(This evening through Saturday)
Issued at 424 PM CDT Fri Aug 26 2016

Main concerns during the short term revolve around rain and
thunderstorm chances late tonight through Saturday afternoon.

A somewhat complicated synoptic pattern this afternoon with a
pair of troughs approaching the Northland. The first was located
over the Canadian Prairies and Dakotas and the second over the
lower Missouri Valley. Showers were ongoing late this afternoon
over eastern South Dakota and southeast North Dakota, with a
second line of showers and embedded storms over central North
Dakota. The northern trough will advance toward the area tonight
and strengthen as it approaches. The 26.00Z runs of the High-Res
ARW and NMM cores seem to be handling the present situation the
best and leaned heavily on them for this package. Expect the
showers over the eastern Dakotas to push into my west later this
evening, and spread across the remainder of my Minnesota zones
through sunrise. Meanwhile, the southern stream system will spread
showers and thunderstorms across Iowa and into southeast Minnesota
and southwest Wisconsin tonight. Either the first band of showers
from the west, or the showers lifting northeast from the south,
should move through northwest Wisconsin Saturday morning.

Additional showers and storms seem likely late Saturday morning
through the afternoon along and well ahead of an approaching cool
front. There is a possibility some of the storms may be vigorous
on Saturday afternoon with brief heavy downpours and a small
chance of large hail or gusty winds. Confidence in timing and
coverage is a bit lower than earlier forecasts, so did trend
hourly POPs lower than the morning package. Mid shift will know
how the evening precip evolved and be able to fine tune forecast
overnight.

Rainfall amounts will vary greatly across the area, from less
than one-tenth of an inch on the low end, to an inch or more for
the areas which see the storms. Leaned on the bias corrected MOS
guidance and consensus blends for temps overnight and Saturday.

.LONG TERM...(Saturday night through Friday)
Issued at 424 PM CDT Fri Aug 26 2016

The extended begins with a slightly negatively tilted trough over
northern Minnesota lifting northeastward into Ontario late
Saturday night into Sunday. This will bring decreasing chances of
showers and thunderstorms as the night progresses on Saturday.
Behind the trough, a ridge of high pressure will build into the
region. Expect dry conditions for a portion of Sunday. Still some
uncertainty regarding precipitation chances Sunday afternoon/
evening as the GFS continues to show an elevated warm front
lifting northward across central Minnesota and northern Wisconsin.
Whereas the ECMWF/GEM/NAM keep things dry during the afternoon.
Opted to keep low precipitation chances, as baroclinicity
increases over this area due to strong WAA at 850 hPa and there is
around 1000-2000 J/kg of MLCAPE per the GFS and NAM. Shower and
thunderstorm chances continue through Monday and Monday night as a
cold front sweeps through. Will see a dry period on Tuesday as
high pressure builds across the region.

Still lots of uncertainty from Wednesday to Friday as a ridge
builds over the Northern Plains. The ECMWF is more progressive
with moving the ridge through by the the weekend, whereas the GFS
keeps this feature firmly in place. Both sets of guidance keep a
850 hPa baroclinic zone over Minnesota and Wisconsin on Wednesday
and Thursday. Any upper level shortwaves moving in from the
northwest could interact with this baroclinic zone to bring
showers and storms. High temperatures remain in the 70s from
Wednesday to Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1228 PM CDT Fri Aug 26 2016

VFR conditions expected for much of the upcoming forecast. High
pressure will build eastwards into the central Great Lakes by this
evening. This will keep southwesterly winds this afternoon with
fair weather cumulus lingering around into the evening. Based on
obs and the latest HRRR/RAP/NAM output expect cumulus ceilings
between 4-6 kft. Cumulus will dissipate during the evening due to
the loss of heating.

Winds will be light, but cloud cover will increase overnight as a
trough digs into the Northern Plains. There is a possibility of
radiation fog developing, but uncertain how widespread fog will be
due to the increasing cloud cover. For now kept a mention of fog
at KHYR, but may need to include at KHIB if cloud cover increases
slower than currently thinking. Kept in VCTS at KBRD/KINL from 14Z
until the end of the TAF. Think that showers/storms are possible
at other terminals after 18Z per the latest GFS/ARW/NMM.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  56  71  56  77 /  20  50  50  10
INL  55  71  53  78 /  40  60  50  10
BRD  57  73  57  79 /  40  60  30  30
HYR  54  72  57  78 /  30  50  30  20
ASX  55  73  57  78 /  20  50  50  10

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...Huyck
LONG TERM...WL
AVIATION...WL



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