Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 240333

Area Forecast Discussion
National Weather Service Sioux Falls SD
1033 PM CDT Sun Sep 23 2018

.SHORT TERM...(This evening through Monday)
Issued at 257 PM CDT Sun Sep 23 2018

A trough of low pressure will dig across the Northern and Central
Rockies tonight into Monday, then spread onto the Plains Monday
afternoon. This will keep southerly flow and mild temperatures in
place overnight, especially east of the James River. Most locations
will not fall below 55 degrees overnight tonight. Ahead of an
incoming cool front tonight conditions are too dry aloft to support
any shower or thunderstorm activity along and ahead of the front.
However behind the front some mid level moisture will support the
potential for development but most of that will be north of the area
through 12z.

A weakening right entrance region of the upper level jet will move
through on Monday which will swing cooler air into the region. The
cooler air aloft will likely aid in supporting some shower and
possibly isolated thunderstorm activity through the day and into the
evening. Instability does not appear high enough to support any
severe weather or heavy rainfall. The better chances for showers and
isolated thunderstorms should be north of Interstate 90. High
temperatures will start their downward trend with mid 60s west of
Interstate 29. From about Sioux City to Spencer and south warmer
southwest flow will hang in through mid day so highs might creep up
into the upper 70s, before falling late afternoon.

.LONG TERM...(Monday night through Sunday)
Issued at 257 PM CDT Sun Sep 23 2018

Tuesday will see the main wave swing through with some instability
showers possible as the cold air aloft deepens. Should be hit and
miss activity with no severe weather or heavy rain expected. Highs
will be in the 60s.

A broad trough will remain in place across the northern tier of the
United States which will support relatively fast flow aloft and
likely multiple weak waves. These will be difficult to time waves
but the overall affect of any shower or thunderstorm activity should
be short lived. At this time the better chance look to be Wednesday
night and Sunday but the chances for now are fairly low. Most
locations will see highs 55 to 65 with lows from the upper 30s to
mid 40s.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1033 PM CDT Sun Sep 23 2018

There will be a period of low level wind shear at KFSD and KSUX
overnight. A few showers will be possible in the vicinity of KHON
and KFSD on Monday with a frontal boundary, with ceilings
lowering into the MVFR range. Southerly winds will become
northwesterly on Monday with the passage of the front.




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