410
FXUS63 KFSD 092249
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
549 PM CDT Thu May 9 2024

.KEY MESSAGES...

- Warm and breezy northwesterly winds for Friday, with another
  round of isolated showers possible east of I-29. Little to no
  accumulation expected.

- Warmer and mainly dry conditions throughout the weekend.
  Continued warm with a couple rain chances next week.

- With the mostly dry conditions expected into the weekend,
  rivers across northwest Iowa will be able to lower their water
  levels for a couple days.

&&

.DISCUSSION...
Issued at 337 PM CDT Thu May 9 2024

Afternoon satellite imagery shows a scattered cu field across the
region, with some spotty weak showers out of the cu field possible
west of I-29, where moisture availability is marginally better than
it is for areas east of I-29. Temperatures are largely in the upper
60s to lower 70s, possibly warming another degree or two before
starting to decrease, with overnight lows in the mid to upper 40s.
After breezy northerly winds throughout the day, winds will weaken
as they turn westerly overnight, switching back to northwesterly
Friday morning as they increase in strength.

The northwesterly winds occur as a surface high pressure is slowly
meandering southwards into the central plains, which will help to
keep mostly dry conditions for the area on Friday. As the low-level
jet strengthens throughout the day, unidirectional winds from the
surface up to 850mb will allow for a portion of the 30-35 knot winds
to be brought down to the surface. Thus, expect gusty winds of 25 to
35 mph throughout the afternoon hours. Behind a weak front that
moves through during the morning hours, temperatures rise up into
the upper 60s to mid 70s throughout the afternoon hours. Soundings
from across the area show convective temperatures being reached area-
wide, so expect another cu field to develop during the afternoon
hours. As a narrow ribbon of warm-air advection forms behind the
front during the afternoon hours, areas east of I-29 may see enough
lift to form scattered showers, though moisture availability will
keep accumulations on the light side with under a tenth of an inch
expected. Given the breezy winds aloft, even weak showers may result
in gusts up to 45 mph.

Overnight into Saturday, the aforementioned surface high pressure
will have moved towards the Oklahoma/Arkansas area, shifting our
surface winds to be out of the southwest. This will allow for the
first day of seasonably warm temperatures to be advected into the
region, with high temperatures on Saturday expected to get up into
the mid to upper 70s, with lower 80s not impossible according to the
GEPS. A closed off upper level low moving off of the Rockies will
develop a surface low pressure over eastern Colorado by Saturday
evening, with 9.12Z deterministic and ensemble guidance indicating
our region will remain dry overnight into Sunday.

Sunday will see our seasonably warm temperatures continue as a warm
front overspreads the region, with the GEPS continuing to suggest
lower 80s are possible. Other ensemble guidance is not as convinced
keeping temperatures limited to the upper 70s, but as the GEPS is
ingested by the NBM there are some 80s that popped up for Sunday, so
will let the NBM ride for now. As a cold front stalls over southern
North Dakota by the afternoon hours from a surface low in southern
Canada, the aforementioned surface and upper level flow begin to
move into areas south of I-90. This will lead to increasing chances
for scattered showers and thunderstorms during the early afternoon,
expanding north of I-90 during the late afternoon hours. Ensembles
show there is around a 30-50% chance for at least 500 J/kg of CAPE,
though looking at deterministic solutions shows a wide range of
solutions, lowering confidence. Given little shear on the northern
side of the cut-off upper level low, and low confidence on amounts
of CAPE, while severe weather can`t be ruled out it certainly is not
a slam dunk severe weather set up.

The unsettled weather continues into Monday, but confidence in the
details and timing lowers for the extended portions of the forecast
as models solutions vary. Broadly speaking, zonal flow continues to
bring numerous shortwaves across the mid-level flow, which will
bring a couple chances for rain throughout the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 546 PM CDT Thu May 9 2024

VFR conditions will prevail through the period. Cumulus will
clear out this evening with weakening winds turning westerly.
Mid to high clouds spread back in early Friday morning with
northwest winds gusting again after sunrise. Expect gusts to
peak at 25 to 30 kts Friday afternoon with a low chance of
isolated showers east of the Interstate 29 corridor.

&&

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

&&

$$

DISCUSSION...APT
AVIATION...BP