Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

FXUS63 KFSD 171949

Area Forecast Discussion
National Weather Service Sioux Falls SD
249 PM CDT Tue Oct 17 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 248 PM CDT Tue Oct 17 2017

Southerly flow will remain in place through the night ahead of a
weak cool front. While the flow will not be strong it should help
keep temperatures on the mild side. Lows will be in the 40s with a
good chance for lower 50s along the Buffalo Ridge where stronger
southwest winds will be possible.

Wednesday will be mild again, but the winds will be a little
stronger from the northwest, likely gusting to 20 to 25 mph at times
in the afternoon. Highs will be in the upper 60s to lower 70s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 248 PM CDT Tue Oct 17 2017

Wednesday night into Thursday will see upper level ridging increase
keeping rain chances very low and warm weather in place. As this
upper level ridge builds in Wednesday night, high pressure at the
surface will move into northwest IA late Wednesday night, allowing
for a little additional radiational cooling. In central SD southerly
winds will be on the increase and should keep temperatures mild.
Will lean a little more heavily on the CONSRaw output in central SD
which handles lows better with stronger winds at night and the
CONSMOS in northwest IA as it usually deals better with radiational
cooling. Thursday will become breezy everywhere with warm afternoon
temperatures. Mixing will not be perfect as low level flow may be
slightly southeast off of the cool exiting high pressure, but
gradient winds and mixing to 875-900mb should still lead towards
gusts around 35 mph, especially west of Interstate 29. Mixing to 900
mb should lead to highs in the 70s everywhere, maybe upper 60s in
northwest IA if winds remain a little more southeast than expected.

Thursday night into Friday will be the windiest period as a trough
of low pressure develops to the west. This will keep lows very mild
and near record warm levels in the mid and possibly upper 50s. This
will lead into a warm Friday with highs again in the 70s. At this
time there are some hints of a little increase in stratus potential
or at least some additional daytime cumulus so will not go too warm
until confidence that any cloud cover will be at a minimum.

Broad warm advection will be in place Friday into early Saturday
morning ahead of the incoming trough. Will maintain the mid level
chances for rainfall and isolated thunder as the set up is not great
but does appear that at least scattered development is expected.

From Sunday into Tuesday a strong northwest upper level jet running
about 150-170 knots at 250mb will bring a potentially much cooler
regime into the area. Sunday should still prove to be mixy with some
residual warm mid level air lingering. Monday and especially into
Tuesday the cooler air will settle in bringing highs back into the
55 to 65 degree range Monday and in the 50s and possibly colder
Tuesday. Confidence fairly good right now with only slight
differences amongst the models.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1244 PM CDT Tue Oct 17 2017

VFR conditions expected to prevail through the period. Southwest
flow is expected through the afternoon, turning southerly tonight.
Could see some patchy fog develop early Wednesday morning. Have
added mention of lower visibility at KSUX terminal.




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