Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 200601
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
101 AM CDT SAT AUG 20 2016

.SHORT TERM...(This evening through Saturday Night)
Issued at 305 PM CDT Fri Aug 19 2016

The main story: a deep low will lift into the western Great Lakes
region tonight and Saturday, bringing moderate to heavy rain to
much of the region. The 12Z model runs generally delayed how
quickly the rain lifts into the Northland, but the track of the
low still indicates the heavy rains will fall over northwest
Wisconsin and areas to south and east. The NAM12 and regional
Canadian models are still outliers, showing substantially more
rainfall for northwest Wisconsin than other models, as well as
deeper low and more western track, but seem to be in better
agreement with the GFS, ECMWF, ARW, NMM, and SREF than earlier
runs.

As of 3 pm, the Northland was in the wake of cold front that
shifted to the south and east last night. Cooler northwest flow
was developing scattered/broken cumulus across much of the
Northland, and there was more substantial cloud cover across
northwest Wisconsin, where there were some showers. Temperatures
were in the upper 60s and lower 70s.

A potent upper level trough, over the northern High Plains and
Manitoba/Ontario, will dig into the Northern and Central Plains
tonight as its related surface low organizes near Iowa. The upper
trough will then lift into the western Great Lakes region
Saturday, while the surface low deepens and tracks towards Upper
Michigan. The synoptic lift generated by the upper trough, as
well as a strong frontogenetical band which will likely set up
on the western side of the low near the far southeast forecast
area, will bring a surge of rain into the Northland later tonight
and Saturday. Very cool air (850 hpa temperatures around 6 to 8
degrees Celsius) will wrap into the Northland on the western side
of the deepening low. Daytime heating, combined with the synoptic
lift, is also expected to overcast cumulus and plenty of rain
showers across the forecast for the late morning through early
evening. It will be wet, breezy, cool day for the Northland. Highs
will likely only reach the low and middle 60s, with my forecast
model blend incorporating some of the cooler model guidance, such
as the SREF. Temperatures could still be a bit too high. The low
will exit the region Saturday night, with lingering showers across
the eastern forecast area, especially downwind of Lake Superior.

Rainfall will likely range from 1" to 1.25" in northwest
Wisconsin near and east of Hayward and Ashland, to about 0.10" to
0.25" of rainfall across much of northeast Minnesota. May need to
increase pcpn if the models trend toward a more western track,
similar to the regional Canadian.

The threat of thunder looks fairly low. While the GFS and NAM have
up to several hundred J/kg of most unstable CAPE here and there,
think it is overdone considering the lack of heating because of
the cloud cover. Prefer the very low most unstable and mixed layer
CAPE in the SREF, which suggests a remote threat of thunder. While
cannot rule out a random weak storm here and there, it does not
even worth carrying isolated thunder for most areas. The exception
is in the very far southeast forecast area, with the forcing from
the expected strong frontogenetical band possibly generating some
thunder.

.LONG TERM...(Sunday through Friday)
Issued at 305 PM CDT Fri Aug 19 2016

The strong upper trough and surface low will continue to pull
away from the region with a ridge moving in on Sunday.
Temperatures will start out cool with 850MB temperatures from
around 5C in the Arrowhead to around 6C in our southern zones.
There may be some showers that linger Sunday morning over a
portion of northwest Wisconsin, then mostly dry conditions are
expected for the rest of the day. The cold temperatures aloft may
lead to some cumulus in the afternoon but forecast soundings are
quite dry so we did not increase clouds too much and left
afternoon showers out of the forecast for now. Highs are expected
from 65 to around 70.

Warm air advection will ramp up Sunday night and should at least
cause mid to upper level clouds to increase. We kept the forecast
dry despite the strong warm air advection as forecast soundings
remain quite dry, especially below 700mb. WAA continues into
Monday and highs will rise into the mid seventies to around
eighty. Lack of stronger forcing and weak mid level ridging should
keep Monday dry as well. We introduce some POPs Monday night into
Tuesday across portions of the CWA and increase them Tuesday night
into Wednesday as a shortwave trough and cold front move through
the area. A deep upper trough will be over the region into
Thursday with a broad upper trough remaining into Friday. There
will be a chance for some showers into Friday with the upper
trough. Temperatures will be cooler with highs only in the lower
seventies by Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 101 AM CDT Sat Aug 20 2016

VFR conditions remain across the terminals as of issuance time. A
band of light rain has set up in the vicinity of KHYR, which may
bring brief periods of rain to the site for the next few hours. A
low pressure system will move into the area from the southwest late
tonight and continue Saturday. This will cause an area of showers
and MVFR to IFR ceilings to spread into the area and expand in
coverage generally in the 09z - 15z time range.  Slow gradual
improvement to VFR after 00z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  50  67  49  77 /  40  10  10  10
INL  46  70  48  80 /  10   0  10  10
BRD  49  68  53  78 /  10   0   0  10
HYR  50  66  47  78 /  40  10  10  10
ASX  55  68  50  78 /  70  20  10  10

&&

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

$$

SHORT TERM...Grochocinski
LONG TERM...Melde
AVIATION...LE



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