Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Graphics & Text | 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

FXUS63 KFSD 261134

Area Forecast Discussion
National Weather Service Sioux Falls SD
634 AM CDT Wed Oct 26 2016

.SHORT TERM...(Today and Tonight)
Issued at 344 AM CDT Wed Oct 26 2016

Low stratus clouds will continue to advect southeast, and will
blanket the bulk of the area through at least the morning hours. The
trough over the upper Midwest slowly shifts southeast through the
day today, allowing ridging to build across the high Plains. Patchy
drizzle has been observed in northeast SD early this morning. Hi-res
models suggest that patchy drizzle will remain possible mainly across
east central SD into southwest MN in the low stratus deck through
around 9 am.

Mixing in the late morning into the afternoon will allow the
stratus to begin dissipating initially across south central SD
midday, then areas west of I29 during the afternoon. The question
will be how much of this stratus will break up for areas to the
east.  There is some suggestion that the wind shift/better mixing
may not make much headway into the forecast area until closer to
sunset. With clouds and cold air advection expected across the
greater part of the forecast area and for much of the day,
temperatures will be as cool as the upper 40s in southwest
Minnesota, while south central could see readings closer to the mid
60s if the stratus breaks and they have ample time to heat out.

Winds shift to the south southeast overnight, but will become light
at less than 7 mph. Lingering stratus across southwest Minnesota and
northwest Iowa may hold in part through much of the night. With low
level moisture persisting in this area and light winds, there may
also be some patchy shallow fog across northwest Iowa and adjacent
counties late tonight. If clouds linger a bit longer than expected,
fog threat may be minimal, but will go with patchy mention for now.

.LONG TERM...(Thursday through Tuesday)
Issued at 344 AM CDT Wed Oct 26 2016

Much warmer conditions for Thursday and Friday as a southerly low
level flow returns to the area and upper level ridging builds into
the central CONUS. Highs on Thursday look to range from the lower
60s over southwest MN to mid 70s over south central SD. By Friday we
are looking at highs into the 70s across the entire area with good
mixing as a cold front swings through the region in the afternoon.
It will be breezy in the afternoon thanks to a tightening gradient
and cold air advection. May have to watch our south central SD zones
on that day for Fire Weather concerns, with highs into the upper 70s
and afternoon relative humidity values approaching 30 percent.

The frontal passage will bring a return to more seasonable
temperatures for the weekend with highs back into the mid 50s to
lower 60s. Models are still pointing toward shower chances mainly
from I-90 northward on Saturday as a weak shortwave slides across
the region.

A brief warm up on Monday as upper level ridging builds back into
the region, before being broken down as upper level energy ejects
northward out of the Rocky Mountain states. While there are some
model differences in the handling of this system, most drive this
energy to the north of our area, keeping dry conditions in the
forecast through the end of the extended.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 628 AM CDT Wed Oct 26 2016

Low stratus and fog will be the main concerns in the TAF period.
Low stratus will continue to expand across the forecast area
through the next few hours, with IFR ceilings becoming widespread
this morning. Expect some mixing out of the clouds to begin around
midday in the Missouri Valley and South central SD, but
improvements to MVFR and low end VFR will likely hold off for much
of the day from around the I-29 corridor and points east. Patchy
will also remain possible this morning, with a small possibility
of patchy drizzle mainly in southwest MN through around 15z. Winds
will become light and shift south southeast tonight. The question
will be how much of the stratus will stick around tonight. If
enough clearing develops, patchy shallow fog will be possible late
tonight in northwest Iowa and adjacent counties. Not enough
confidence to put fog in FSD and SUX tafs at this time.




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