Sioux City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

523
FXUS63 KFSD 031103
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
503 AM CST Tue Dec 3 2024

.KEY MESSAGES...

- Milder temperatures for today. Breezy east of I-29.

- A cold front will move through tonight into Wednesday,
  bringing wind gusts of 30-40+ mph and falling daytime
  temperatures on Wednesday. Scattered flurries/very light snow
  will be possible on Wednesday and Wednesday evening. At this
  time, impacts are expected to be minor.

- Sub-zero wind chills return Wednesday evening and continue
  through Thursday morning.

- Much milder temperatures for Friday through Sunday.

- Cooler with low confidence precipitation chances for the
  beginning of next week.

&&

.DISCUSSION...
Issued at 350 AM CST Tue Dec 3 2024

As expected, winds have become southerly very early this morning as
surface high pressure over the area shifts to the east. With warm
air advection and cloud cover, temperatures have steadied out or
risen during the late night hours, with current temperatures mainly
in the teens. Strong warm air advection will continue to develop
across the region for today - this as the surface ridge axis shifts
from the Plains into the Tennessee Valley during the day and a
midlevel wave/ surface trough tracks into the western Dakotas. This
will result in a "thaw" across our area - although temperatures will
still remain below normal for this time of year. Highs look to rise
into the 30s to lower 40s (with warmest readings over south central
SD). Guidance does suggest that it will be a breezy day - focused
more so from the Interstate 29 corridor and eastward; this where the
SPG will be tighter and mixing will tap into stronger winds aloft
over that area. A weak cold front will slide through the area
tonight, and will see temperatures steady out or rise again as
mixing is enhanced somewhat as northwesterly winds pick up behind
the boundary. Look for lows generally mid 20s to lower 30s.

Enjoy the milder conditions while you can, because big changes are
in store for Wednesday. A strong low level jet dives into the
Northern Plains as an upper level trough deepens from the
Mississippi Valley and eastward. This will drive much colder air
into our area during the day on Wednesday. While early day
temperatures may rise into the upper 20s to mid 30s, temperatures
will fall in the afternoon - residing in the teens and lower 20s by
the evening. In addition, with the strong cold air advection,
enhanced mixing will tap into 40 to 45 kts winds aloft. This will
result in a potential for gusts just either side of 40 mph in some
areas during the afternoon. This may approach Wind Advisory
criteria, so will keep and eye on that. Could also see scattered
flurries/very light snow during the day into Wednesday evening with
any saturation in the DGZ, though are not expecting much in the way
of accumulation.

We are back in the ice box for Wednesday night and Thursday. Lows on
Wednesday night will drop to just either side of zero, with highs on
Thursday mainly in the teens. This will result in winds chills as
low as 10 below to 15 below later on Wednesday night into early
Thursday. A weak shortwave will track over the region on Thursday in
the northwesterly upper level flow, and some deterministic models
want to produce very light snow with this feature. That being said,
ensembles suggest only a 10-20% probability of receiving a few
tenths of snow during that period.

The roller coaster temperatures continue in the extended period, as
the upper level pattern slowly transitions to a west/southwesterly
flow and southerly surface winds return to our area. This will
result in a rather dramatic warm up, with highs climbing into the
30s and 40s (nearing 50 in some areas) for Friday through Sunday. By
Monday, may see temperatures cool back to just below normal. Both
deterministic models and ensembles suggest that precipitation
chances may return to the area sometime in the Sunday to Monday time
frame, though confidence is low in any one solution due to model
differences.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 455 AM CST Tue Dec 3 2024

Breezy southerly winds west of Interstate 29 early this morning
will become focused from the I-29 corridor and eastward by late
morning. Winds will then diminish this evening, though transition
to northwesterly late tonight as a front begins to move across
the region. As winds increase aloft, LLWS will develop at TAF
sites for tonight.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...JM
AVIATION...JM