Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 221150

Area Forecast Discussion
National Weather Service Sioux Falls SD
650 AM CDT Sat Oct 22 2016

.SHORT TERM...(Today and Tonight)
Issued at 329 AM CDT Sat Oct 22 2016

Got a little warmer yesterday than what I was thinking and so with
that in mind, I bumped up highs today a little bit.  Considering the
amount of sun and the wind, it should be good for a few degrees more
than yesterday.  Shortwave ridge axis passes to the east and that
allows return flow to set up a little more this afternoon.  Models
continue to show a weak trof/front to pass through the area
overnight tonight but not expecting anything with the passage
other than a little cooler air for Sunday.

.LONG TERM...(Sunday through Friday)
Issued at 329 AM CDT Sat Oct 22 2016

Still looks seasonably pleasant Sunday and Monday. Breezy
northwesterly flow, especially east of the James River valley, will
prevail on Sunday behind a departing short wave which passed to the
north of the forecast area. Along with somewhat cooler temperatures
when compared to today, the humidity values are forecast to be too
high to give serious fire weather concerns, not that it will be
tremendously windy anyway. Still watching for the potential for
stratus Sunday morning. But all models continue to show the 925mb
moisture north of the forecast area and do not bring it down. Above
925mb, the 850mb level is quite dry. On Sunday night, chilly dome of
surface high pressure begins to slide to the east, therefore our
winds should become quite light. With dry air in place, trended lows
down a category compared to superblend. Monday will be pleasant with
a southeasterly flow of air with highs a few degrees either side of

The various models continue to be in pretty good agreement with the
short wave coming out of the Rockies next week. Monday night, the
aforementioned southeast flow of air continues warranting milder
lows then what superblend is advertising. So mixed in some warmer
raw model values. With the stout warm air advection and thetae
advection in the 850-700mb layer east of the James, a small chance
for showers and embedded thunderstorms exists late Monday night east
of the James where saturation becomes deep as the low levels moisten
up. This continues into Tuesday morning when the moisture depth
becomes even more saturated, giving a more organized chance for
showers and embedded TSRA. The short wave affects the forecast area
Tuesday afternoon and night, with QG forcing showing the wave moving
eastward very close to the forecast area. There is some instability
to be noted, not severe, but enough to just go predominant
thunderstorms in southeast SD, northwest Iowa and the far southern
reaches of southwest MN Tuesday afternoon and evening. Now the
isolated TSRA chances could be fairly widespread elsewhere,
encompassing nearly the entire forecast area Tuesday afternoon and
early evening with some decent elevated instability from 850-500mb
coupled with deep layer saturation and veering wind profiles.

The system will rapidly depart on Wednesday limiting rain chances
only to our eastern zones in the morning. Highs are tricky on
Tuesday and Wednesday. Although the overall air mass regime is
fairly mild, the blended guidances may be too warm both days given
the degree of cloud cover and potential rainfall. Most of the
moderate rainfall will once again fall east of the James River
valley, so its our east which needs watched the closest for
temperatures that could be too warm. Not a lot happening after
Wednesday with temperatures pretty close to normal and dry weather
late in the week.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 648 AM CDT Sat Oct 22 2016

Light surface winds this morning as shortwave ridge passes over
area. Return flow develops this afternoon in the way southeast
winds less than 15 knots especially in central South Dakota. VFR
conditions expected throughout the forecast period.




SHORT TERM...Heitkamp
AVIATION...Heitkamp is the U.S. government's official web portal to all federal, state and local government web resources and services.