Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 202342
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
642 PM CDT TUE SEP 20 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 317 PM CDT Tue Sep 20 2016

Even though high pressure was covering the forecast area at 19Z/2pm,
scattered rain showers were moving through the southern third of the
area. Rainfall amounts have been fairly light with 0.01 to 0.03
inches of rain being reported. This rain was the result of a
vorticity max moving from west to east over the region and
accompanied by some frontogenesis in the 1000mb-850mb range. Expect
this area of lift to move northeast of the area by this evening and
bring an end to the rain.

Models are still disagreeing on how to handle the surface low in the
central plains, its path, the location of a warm front, baroclinic
zone, and the amount of QPF. They are in better agreement with the
front being draped over southern Minnesota tonight. A weak piece of
vorticity is forecast to move along the front which will result in
the rain being restricted to well south of the forecast area
tonight. Have therefore adjusted pops to have a mention in just
northwest Wisconsin and not until late tonight. This is seen in the
latest hires ARW/NMM/HRRR as well as the GFS.

Model differences continue on Wednesday with the ECMWF/NAM going dry
in northwest Wisconsin in the morning, while the GFS/GEM brings rain
into northwest Wisconsin from the south. Since the GFS/GEM solutions
are the only ones with this rain, have leaned toward the drier
solutions including the ARW/NMM. The NAM/GFS/ECMWF all have a strip
of showers moving through northern Minnesota in the morning and have
adjusted pops to account for this. These showers will be driven by a
vorticity maxima moving along the international border.

The NAM/GFS come into agreement with the northward progression of
showers from central Minnesota and Wisconsin. The ECMWF is farther
west with its QPF and a bit drier over northwest Wisconsin. The GEM
is more bullish on the QPF, but generally in the same location as
the NAM/GFS. The hires ARW/NMM are not as supportive with either a
westerly or northerly solution and keep the rain restricted to the
southern tier of Wisconsin zones. They all appear to keep the warm
front suppressed to southern Minnesota/Wisconsin. Used a blended
approach to pops which keeps the rain over the southern half of the
region and the northern half dry.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 317 PM CDT Tue Sep 20 2016

Multiple chances for rainfall through the long term period with
temperatures right around normal for late September. Not expecting
any frost/freeze for the next seven days as we approach the
climotological normal time for the first freeze.

On the synoptic scale the fast zonal to west-southwest flow aloft
across the upper Midwest will break down as a ridge builds across
the northern Plains in response to a deep upper low developing
across the desert southwest mid to late week. This ridge should
result in an area of high pressure across parts of Manitoba into
northwest Ontario, which should result in some clearing skies across
the international border mid to late week. Elsewhere across the
Northland the remnants of stationary front across northwest Wisconsin
will lead to cloud cover and a chance for showers and storms.
Precipitation chances appear to be mainly limited to northwest
Wisconsin Wednesday night into Thursday with the potential for heavy
rainfall along the front, but Thursday night into Friday chances
will be lower as the ridge builds in from the west. Highs in the
upper 50s to mid 60s late week, lows in the mid 40s to upper 50s.
The exception will be across the international border Thursday
night when clear skies will result in lows falling to near 40.

A warm front will lift north across the Plains and mid-Mississippi
river valley late Friday into early Saturday - some uncertainty to
the exact speed with the ECMWF being faster and GFS/GEFS/GEM-Global
a bit slower. This warm front will bring showers and possibly a few
storms - though instability looks fairly limited at only 0-300 j/kg
MUCAPE. A brief dry slot will build in for a period Saturday, then
the cold front moves from west to east across the upper Midwest
Saturday night into Sunday bringing widespread showers and scattered
storms. Again, limited instability with this round of precipitation
with less than 500 j/kg MUCAPE. Mid-level shortwave trough moves
across the upper Midwest Sunday night with clearing skies from west
to east behind it as high pressure builds in across the Plains. East
winds ahead of the cold front will negate most of the warm air aloft
behind the warm front Saturday, resulting in highs in the upper 50s
near Lake Superior and in the low 60s elsewhere. Seasonable Sunday
with highs in the low to mid 60s. Lows in the mid 40s to mid 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 642 PM CDT Tue Sep 20 2016

Expecting VFR conditions through the overnight with ceilings
around 7 to 10 kft. Will see an area of low pressure move
eastward from Wyoming into the Central Plains and gradually
northeastward into western Iowa by the end of the TAF period. This
will lift a warm front into northern Wisconsin and central
Minnesota. Expect showers and perhaps a few thunderstorms as the
front lifts northward tomorrow. With showers moving in will see
ceilings in the MVFR range at KHYR as suggested by the latest
NAM/RAP. Other terminals will remain VFR, with showers possible at
KDLH/KBRD.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  50  63  49  59 /  10  30  50  30
INL  44  64  43  65 /  10  10   0   0
BRD  52  67  52  64 /  10  50  50  40
HYR  53  69  56  64 /  10  60  80  60
ASX  53  66  52  62 /  10  40  80  50

&&

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

$$

SHORT TERM...GSF
LONG TERM...JJM
AVIATION...WL



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