Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 42
000
FXUS63 KFSD 060831
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
331 AM CDT Wed Jul 6 2022

.SHORT TERM...(Today and Tonight)
Issued at 330 AM CDT Wed Jul 6 2022

Satellite shows widespread high clouds associated with convection
moving northeast across northeastern NE. Under the shroud of
cirrus though, obs show light winds, which combined with the
moisture from recent rain, is leading to very low stratus and fog.
Isolated dense fog has been observed in southwestern
MN/northwestern IA, so will monitor trends in case an advisory is
needed. Otherwise, temps are in the 60s to lower 70s.

Today, southwesterly flow through the mid and upper levels brings
another wave toward the area. 06.00z model runs have shifted the
main vort axis closer to the I-90 corridor than previous runs, and
thus have increased pops slightly from previous forecast south of I-
90 through tonight. For tonight, held on to previous pops and
overall increased slightly. Larger scale deterministic models show a
wide variety in evolution of the vort max through tonight and the
potential for another vort lobe/wave ejecting out of eastern
WY/western SD. For example, the NAM and Canadian to some extent hold
on to the day`s vort max along the Hwy 14 corridor, while the GFS
diminishes the main vort lobe and is much more aggressive in the
next wave through early Thursday. This factors in to just how far
north moisture return and WAA can reach, and thus impacts pops. This
dichotomy is seen across the hi-res models today and tonight with a
majority of models keeping precip focused south of I-90 or along the
Hwy 20 corridor, varying widely on if/when/where precip moves in
from the northwest with the secondary wave. Regardless, expect
scattered showers/storms across the CWA today and tonight.

Regarding severe weather, the most robust instability has moved
south of the area. However, an isolated strong to severe storm is
possible this afternoon and evening. This will be highly dependent
on how far north warmth and moisture (thus instability) travels.
This gradient may approach the I-90 corridor in south central SD,
slanting southeastward toward the Hwy 20 corridor in northwestern
IA, which would keep the severe risk along and south of this line.
With MUCAPE values generally below 1500 J/kg, mid level lapse rates
under 7 deg C/km, and bulk shear values generally 35 knots or less,
main severe hazards would be hail to the size of half dollars and
wind gusts to 60 mph in the strongest updrafts. Isolated heavy
rainfall remains a threat, with PWAT values in/above the top 2.5% of
climatology (with most model guidance showing values over 1.70"
through the evening). Areas which have seen robust recent rainfall
and/or see multiple rounds of storms today would be at the greatest
risk of localized flooding.

With periodic precipitation and cloud cover across the region,
temperatures today may be a touch on the higher side for some
locations. Do expect 80s to prevail, and high humidity making it
feel sticky out. Lows tonight remain warmer than average in the
upper 60s to near 70 with clouds, subtle WAA, precip, and
southwesterly flow aloft. Surface winds remain easterly through
tonight.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 AM CDT Wed Jul 6 2022

Aforementioned disagreed upon waves continue to more through on
Thursday. Subtle CAA, continued precip, and mid level flow beginning
to shift more northwesterly, lead to a slightly cooler day on
Thursday with highs in the lower/mid 80s. Although precip lingers,
severe weather threat should remain to the south and west of our
area with the shift to more northerly flow and other waves tracking
to the south.

Northwesterly flow regime builds for the end of the week and into
the weekend as ridge axis amplifies in the west in response to
troughing on the coasts. We`ll continue to see more short waves
swing through this flow, even as the axis starts to slide east
during the first half of the weekend. Temperatures should follow a
warming trend through the weekend, eventually climbing back into the
90s as low level southerly flow and WAA return. Subtle model
differences in timing, but all show a cold front swinging through to
end the weekend/kick off next week, with the mid level ridge
flattening as a low pressure deepens in Canada. The short waves keep
isolated/scattered storm chances in the forecast through the
weekend, with more scattered activity likely toward Sunday night.

Ridge once again amplifies across the western CONUS, with low
pressure/trough centering over the Great Lakes/Northeast. Expect
temps near seasonal into mid week, with a brief reprieve in
shower/storm chances.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1053 PM CDT Tue Jul 5 2022

Aside from a bit of stratus to our west, latest observations across
the region show quiet conditions and light winds in the wake of
today`s storms. May see a bit of low level stratus form prior to
daybreak along and north of I-90, which may cause cigs/vsbys briefly
fall to MVFR levels at KHON/KFSD. Otherwise, look for VFR conditions
and easterly winds to largely prevail for the remainder of the TAF
cycle. Could see another round of showers and storms Wednesday
afternoon/evening - though confidence in timing and exact location
remain low at this time.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...SG
LONG TERM...SG
AVIATION...SST


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