Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 302041
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
341 PM CDT TUE AUG 30 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 341 PM CDT Tue Aug 30 2016

Boundary continues to sag southward at mid afternoon, arcing from
just south of KHON and KFSD to around KSLB. So far, cumulus field
has enhanced some along the boundary, but have yet to see any
development of precipitation through around 20z. With temps in the
mid to upper 80s and dewpoint readings in the mid 60s, cap has
weakened to a point where would not be surprised to get an isolated
slow moving storm or two drifting south or southwest late afternoon
or early evening. The largest element of significance with any
random storm that develops would be some very spotty heavier
rainfall.  Otherwise, the boundary will work to clear the CWA this
evening, and with loss of diurnal support and weak mid-level trough
shearing southward, any precipitation chances will end very early
this evening. With moisture a bit slow to evacuate the Missouri
valley and winds remaining fairly light, did introduce some patchy
fog starting around 08z.

Wednesday a very pleasant late summer day with ridging building
surface and aloft.  Flow remains fairly weak even toward the
surface, so winds will be light. Highs fairly seasonable from upper
70s southwest Minnesota to mid 80s south central SD.


.LONG TERM...(Wednesday night through Tuesday)
Issued at 341 PM CDT Tue Aug 30 2016

Thursday and Friday will be highlighted by an upper ridge of high
pressure moving eastward across the plains. Dry weather will
therefore prevail with comfortable dew point temperatures. Given the
projected 850mb temperatures, preferred the warmer readings for
daytime highs for both Thursday and Friday, which were consensus raw
model values. For lows, Wednesday night will likely still be fairly
chilly along and east of I 29 with light winds and clear skies,
still under the influence of cool high pressure. The weighted model
average captured this the best and was followed, dipping locations
such as Spencer Iowa to near 50 degrees, while keeping Chamberlain
SD around 60 with a southerly flow in place throughout central SD.
Thursday night will be a tad warmer as a southeast or south wind
continues. These winds will increase on Friday into the breezy or
downright windy category. However fire weather conditions should be
somewhat muted as minimum humidity values are fairly high.

In the extended portion of the forecast, a large upper trough moves
into the western U.S. and sets up shop. This trough will spin
periodic short waves moving through the plains creating what appears
to be an active rainy pattern. Saturday night and Sunday night still
look rainy. And now the latest 12z runs of both the ECMWF and GFS
keep the storms moving across the area into Monday night. The
pattern finally appears to flush out late Tuesday as a surface
boundary moves through. Because of what appears to be an abundance
of clouds, temperatures during the day time will likely be held
down.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1136 AM CDT Tue Aug 30 2016

Potential for additional convection the more significant concern
as boundary drops southward through the afternoon. Convective
chances too low to mention for KFSD as will be near the most
possible northward extent of development, but a couple or three
hours around KSUX could manage a vicinity mention for the later
afternoon. Could potentially see brief IFR to MVFR conditions
within slow moving storms.  A little lingering low level moisture
may produce some MVFR visibilities near the Missouri River later
tonight due to light winds.


&&

.FSD Watches/Warnings/Advisories...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...Chapman
LONG TERM...MJ
AVIATION...Chapman



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