FXUS63 KFSD 051115
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
615 AM CDT Mon May 5 2025

.KEY MESSAGES...

- Locally elevated fire danger this afternoon west of I-29,
  mainly where tall dormant grasses are still prevalent. 

- Mainly dry conditions will persist through the week, with 
  only low (20-30%) chances of light rain south of I-90 midweek.

- Seasonably mild temperatures will dominate the week ahead 
  with highs in the mid 70s to lower 80s. Lows mainly in the 40s
  to start the week, but lows in the 50s will be more common by
  the end of the week.

&&

.DISCUSSION...
Issued at 330 AM CDT Mon May 5 2025

A stagnant pattern beneath a prominent Omega block over the 
Plains will make today a near carbon-copy of Sunday. East winds 
may be a touch stronger in areas east of I-29 this afternoon, 
but still relatively light at 10-15 mph. Meanwhile areas west of
I-29, and especially west of US Highway 81 will see more breezy
south-southeast winds, with gust to around 25 mph at times. 
Humidity levels remain low, generally bottoming out in the 25 
to 30 percent range this afternoon. This combination of breezy 
winds and low humidity could result in elevated fire danger in 
isolated areas where tall dormant grasses are still the dominant
fuel type. However, greening of new growth fine fuels appears 
sufficient to keep overall grassland fire danger on the low 
side.

Mid-week Tuesday-Thursday will see the cutoff upper low over 
the Desert Southwest move slowly east from the southern Rockies
into the souther/central Plains, while mid-upper level ridging 
remains prominent across the Upper Midwest. A northern stream
wave slides over the ridge through southern Canada, dragging a 
frontal boundary southward through the northern Plains Tuesday 
night. However, the boundary appears to wash-out as it attempts 
to push under the dominant upper ridge. At the same time, the
southern low treks slowly east across Oklahoma/Kansas, and much
of the precipitation remains confined to these areas. However,
ensembles still show low (20-30%) probabilities of measurable
light rain south of I-90 during the day Wednesday and again 
Thursday. If we see any rainfall, it should quite light as the 
probabilities topping 0.10" in these same periods remains less 
than 10%, with only 20-30% probability for exceeding 0.10" over 
the entire 48-hour period ending Friday morning. Temperatures
will remain seasonably mild through this mid-week period, with
low level temperatures continuing to support highs in the 70s.

As we move into Friday and the upcoming weekend, the southern
Plains low weakens as it moves through the lower Mississippi
Valley, while our local upper ridge is absorbed by a stronger
ridge expanding over the western half of the CONUS. This will
continue our dry pattern, while also allowing temperatures to
warm further as we progress through the weekend. NBM mean high
temperatures show widespread lower-mid 80s by Sunday, but these
values are below the 50th percentile of the NBM membership (and
closer to the 25th percentile in some areas), so some potential
for even greater warming for the upcoming Mother's Day weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 612 AM CDT Mon May 5 2025

VFR conditions will prevail through this TAF period. East to
southeast winds are expected to remain at or below 12kt for
areas along and east of I-29 corridor through the period,
"strongest" during the afternoon through sunset. 

Locations west of I-29 will see occasional afternoon gusts near
20-25kt, but these are also expected to diminish quickly around
sunset.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...JH