Area Forecast Discussion
Issued by NWS Duluth, MN
FXUS63 KDLH 172002
Area Forecast Discussion
National Weather Service Duluth MN
302 PM CDT MON OCT 17 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 302 PM CDT Mon Oct 17 2016
Summary: The far southeastern forecast area, across parts of
Pine County, still has the potential for severe weather later
this afternoon and into this evening when an area of low pressure
lifts into northern Wisconsin. The models generally lift the low
across far southern Price County, or just to its south, putting
those areas within range of the storms that will likely develop
along and just north of the baroclinic zone that the low will be
following. Other parts of northwest Wisconsin could get some
storms, too, while light rain is likely over parts of northeast
Minnesota. Cooler weather will settle into the region tonight and
As of 3 pm, there was an area of surface low pressure over
west central Iowa, and an upper-level trough over the
northern/central High Plains. A quasi-stationary front stretched
from the low to the northeast, through southern Minnesota,
northwestern Wisconsin, and into Upper Michigan. Most of the
western Great Lakes to Northern Plains had cloudy skies. There
was unseasonably warm and humid air across the warm sector of the
front, with dew point temperatures well into the 60s and near 70
degrees across much of Wisconsin into southern Minnesota. On the
other hand, far northwest Wisconsin and the rest of Minnesota had
much cooler air with dew point temperatures in the middle 40s to
middle 50s. A powerful upper-level jet streak of 130 to 140 knots
was over the Central/Northern Plains from southern Wyoming to
southwest Minnesota. There were scattered showers and some
thunderstorms across southern Minnesota, lifting to the north.
The surface low will deepen and lift northeast along the
baroclinic zone of the somewhat stationary front this afternoon
and evening as the upper trough advances east into the Plains.
The surface low could track across the far southeast forecast
area in Price County,or just south and east of Price County.
Showers and thunderstorms will likely develop near and and just
north of the front as the low lifts into the region. A low to
mid-level band of frontogenesis will also develop across
northwest Wisconsin, and a shortwave lifting into the region
could help develop showers and some thunder near
the frontogenetical band across much of northwest Wisconsin.
While most of northwest Wisconsin will likely only have up to a
few hundred J/kg of most unstable CAPE, there could be around
1000 to 1500 J/kg of MUCAPE across southeastern Price County,
combined with ample deep layer wind shear of 50 to 70 knots.
Despite the lack of CAPE for most areas, there may be good
updraft organization with the storms, making it easier for the
storms to develop hail. Unseasonable atmospheric moisture will
see profiles of precipitable water values reach around 1.5 inches
across southern Price County, meaning the storms are capable of
brief heavy rain.
There is a lesser threat of strong winds, and even more
remote threat of tornadoes, across southern Price County. Besides
the ample deep layer wind shear, 0 to 1 km low-level wind shear
will increase to about 15 to 30 knots, which can help develop
supercell tornadoes. However, this greatly depends on the timing
at which the storms move into the area. If the storms hold off
more until evening, the instability will no longer be likely to
be rooted in the boundary layer because the of the typical,
nocturnal, near-surface inversion, which would help prevent any
tornadoes and lessen the potential for damaging wind gusts. If the
low and its storms reach Price County quickly enough later this
afternoon, there could be a short window for the potential of
tornadoes and damaging wind gusts before the nocturnal inversion
develops this evening. Rainfall will likely range from nearly 1
inch in the far southeast to about a 0.25" to 0.50" across the
rest of northwest Wisconsin.
Farther west, an upper-level frontogenetical band with humid air
in the layer will develop a band of light rain across parts
of northeast Minnesota this afternoon and linger into this
evening. The rain will at first be absorbed by the dry low-
levels, leading to more virga than rain at first, but rain will
become more likely once the low-levels absorb more humidity.
Northwest flow will usher in cooler air into the Northland
overnight and into Tuesday in the wake of the passing low.
Lingering overnight cloud cover will help bolster the overnight
lows, so leaned on the warmer NAM and Canadian regional models
with lows in the middle to upper 40s. Tuesday looks cooler and a
bit sunnier, with just scattered/broken upper-level clouds and
highs ranging from the lower 50s across far northern Minnesota to
around 60 degrees across northwest Wisconsin and nearby areas of
Minnesota. Expect afternoon wind gusts to around 15 mph.
.LONG TERM...(Tuesday night through Monday)
Issued at 302 PM CDT Mon Oct 17 2016
Near to above normal temperatures through the long term forecast
period with just a few chances for light precipitation.
On the synoptic scale a weak low will meander across northern
Manitoba into far northwest Ontario through mid-week, with a broad
longwave trough moving from west to east across the western half
of the country gradually merging with this upper low to result in
a deepening trough across the Midwest Thursday into Friday. While
there remains timing differences between models, the trough axis
is generally expected to swing through the upper Midwest Thursday
bringing colder air in aloft, around -5C. A very low chance for
light rain rain Thursday (or possibly more like sprinkles), with
skies clearing Thursday night leading to one of the coldest nights
yet for the Northland. Duluth may finally reach 32 degrees Friday
morning, which would be the latest first 32 degree or colder
reading since 1938!
Following this chill a broad mid-level ridge builds across the
Plains into the Midwest over the weekend leading to gradually
warming temperatures. A chance for rain/snow Friday night as a
weak mid-level impulse moves across southern Canada and the upper
Midwest in the fast west-northwest flow aloft, with another
similar disturbance possible towards the end of the weekend. In
either case precipitation amounts would be light. Highs in the mid
40s to mid 50s, lows in the mid 30s to near 40.
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1247 PM CDT Mon Oct 17 2016
Low clouds and fog causing the widespread IFR/LIFR conditions
will gradually lift through the afternoon. Across northeast
Minnesota light rain is developing and will impact HIB, BRD, and
eventually DLH through the afternoon leading to MVFR to VFR
conditions, but as the rain ends fog and stratus returns leading
to IFR/LIFR conditions overnight. INL will miss out on the rain
with mainly VFR conditions through the TAF period, with a brief
period of IFR stratus possible towards Tuesday morning.
In northwest Wisconsin IFR ceilings will continue through the TAF
period with showers and even a few thunderstorms developing in the
late afternoon and evening.
Winds will be light through the period and variable in direction
as a front drifts south through the region, leading to a light
northwest wind at 5-10 knots by late tonight/early Tuesday.
.PRELIMINARY POINT TEMPS/POPS...
DLH 47 57 42 53 / 50 10 10 10
INL 43 51 37 45 / 10 0 20 10
BRD 45 59 41 54 / 50 0 10 0
HYR 48 60 43 58 / 80 10 0 10
ASX 48 60 44 57 / 80 10 10 10