Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 140803
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
303 AM CDT Sat Oct 14 2017

.SHORT TERM...(Today and Tonight)
Issued at 301 AM CDT Sat Oct 14 2017

Today looks to be a cool and showery fall day across the region.
Stratus deck continues to edge in from the south early this morning
with the main trough evident on water vapor imagery over the
intermountain west. Overhead, a 130+ kt jet streak stretches
northeastward into the Great Lakes region. Showers are already
present over Nebraska and are expected to expand in coverage across
our area around and after sunrise as mid level warm air advection
and isentropic lift increase. Latest CAMs continue to advertise the
better shower activity will align along and north of I-90 after the
initial wave of showers pushes north, and thus this is where the
likely to categorical POPs exist. Further south across our southern
counties, expect showers to be more hit or miss in nature until
perhaps the evening hours as the system begins to pull east. High
temperatures won`t warm much this afternoon with extensive cloud
cover in place and winds eventually shifting out of the northeast.
Low to mid 50s will be common with perhaps slightly warmer high
temperatures across our far southeastern counties.

By this evening, the surface low begins to move northeast through
Iowa. As this happens, we begin to lose our isentropic lift and
shower activity will begin to come to an end from west to east,
although latest models have trended somewhat slower with this
process. The lower levels of the atmosphere remain fairly saturated
even as this happens and thus could see some areas of drizzle.
Overall, rainfall totals will range from between a 0.25-0.5 across
the north to near or less than a tenth of an inch across the far
south.

The other point of interest during the evening/overnight period of
the forecast is the increasing northeasterly winds. As the surface
low pulls away, the pressure gradient tightens behind the front with
winds responding accordingly. Increased winds some over previous
forecast with Bufkit soundings indicating some gusts in the 30 to
40 mph range.


.LONG TERM...(Sunday through Friday)
Issued at 301 AM CDT Sat Oct 14 2017

Mid-long range portion of the forecast will be dominated by dry and
warm weather, as upper jet and associated storm track shifts north
into southern Canada.

Will remain on the cool/normal side for temperatures Sunday, as the
cooler air lingers behind the retreating trough. Should see plenty
of sunshine, though could see scattered cumulus across the northeast
in the afternoon as a subtle trailing shortwave drops southeast into
Minnesota.

Modest ridging aloft Monday/Tuesday will bring the aforementioned
warming trend to the region early next week. The ridge flattens by
Wednesday as a trough swings through the Canadian Prairies. Unlike
yesterday at this time, when the Canadian model deepened this trough
and drove a cold front well into the Northern Plains, models are in
better agreement in keeping the jet energy well north of our area,
with just a glancing blow by the associated cool front Wednesday
night. Any cooling is quickly displaced northward again on Thursday,
so all-in-all, model consensus points toward a prolonged period of
above-normal temperatures for the upcoming work week, with any
precipitation chances remaining well north of the area. Given
projected 850-925mb temperatures, would not be surprised to see a
couple of days warm further than currently forecast, in particular
Wednesday and Friday, which could also be a little more breezy in
south-southwesterly flow ahead of approaching fronts. However, given
uncertainties in boundary timing and strength of the pre-frontal
thermal ridge, did not make significant changes to model consensus
at this time.


&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1055 PM CDT Fri Oct 13 2017

MVFR to IFR stratus will build northward overnight, eventually
impacting all terminals by mid morning Saturday. Scattered light
showers will overspread the area Saturday as well. Stratus will
begin to clear west to east late in the TAF period.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...Kalin
LONG TERM...JH
AVIATION...Ferguson


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