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Office: FSD

FXUS63 KFSD 170334
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1034 PM CDT Tue Aug 16 2022

.SHORT TERM...(This Evening through Wednesday Night)
Issued at 251 PM CDT Tue Aug 16 2022

The fog from this morning has lifted to a large stratocumulus field
as boundary layer mixing has increased through the morning and early
afternoon today. Temperatures have steadily warmed into the 70s to
low 80s with some isolated gusts into the teens and low 20s, making
for a wonderful afternoon!

Outside of the nice conditions, the forecast area will stay in the
left entrance of an upper level jet streak, resulting in subsidence
via the jet streak circulation. This subsidence will slowly
dissipate the stratocumulus field by tonight, allowing low
temperatures to fall into the upper 50s to low 60s. With saturated
soils from yesterdays rainfall along with light to nearly calm winds
via the decoupled boundary layer, fog will again be possible
tomorrow morning. Fog will most likely be along the MO River where
the heaviest rain fell. Just like this morning, early morning
commutes may be affected due to lower visibilities. If the fog holds
on long enough, then high temperatures may need to be nudged down a
bit.

For now, Wednesday looks to be a beautiful day as 850 mb
temperatures warm into the mid to upper teens. Mixing that down to
the surface will result in high temperatures into the mid 70s to the
mid 80s. The warm temperatures, light winds, and clear skies will
make for lovely conditions, great for outdoor activities! Light
southerly flow will persist through the night, keeping lows a touch
warmer into the low to mid 60s.

.LONG TERM...(Thursday through Tuesday)
Issued at 251 PM CDT Tue Aug 16 2022

The next chance for rain comes for the later half of the week as an
upper low will track out of central Canada into the Northern Plains.
On Thursday, a shortwave trough ahead of the main wave will drag a
surface cold front into the region. While light showers are possible
throughout the day, ensembles support the notion from the previous
discussion that the highest chance for rain will come during the
evening and overnight hours on Thursday. In terms of amounts, the
GFS, Euro, and Canadian ensembles continue to show higher
probabilities of 50-80% for a tenth of an inch or more of rain.
Despite maintaining the same probabilities, the ensembles have been
trending slightly slower and more towards the west with the newer
06z/12z runs. Will keep an eye on trends but confidence is not high
enough to stray from the NBM at this point.

The main wave arrives on Friday, bringing better QG lift and the
highest probability for rain. Ensembles maintain the highest
probabilities of 60-90% chance for a tenth of an inch of rain or
more Friday afternoon and evening, with the highest probabilities
over southwest Minnesota. Trends have slightly upticked regarding
amounts as the Euro and Canadian ensembles now show a 30-40% chance
for a half an inch of rain or more. The GFS ensemble is the outlier
of the three with a slightly decreased probability for a half an
inch of rain or more, now at a 10-20% chance. This could possibly be
due to the ensembles tendency to overmix, thus resulting in less
moisture to lift.

The upper low will meander over the Upper Midwest throughout the
weekend, leading to near to below average temperatures. Ensembles
support the below average temperatures as the Euro and Canadian
ensembles show highs near to about 6 degrees below average. This
translates to highs for the weekend hovering mainly in the 70s. The
GFS ensemble continues to deviate from the other ensembles by
showing high temperatures near to above seasonal. This again may be
due to its overmixing bias. The upper low finally pulls away by the
start of the work week, allowing seasonable and quiet conditions to
prevail.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1028 PM CDT Tue Aug 16 2022

VFR conditions prevail through the period with the exception of
possible fog/low stratus development by daybreak Wednesday. This
will likely be confined along the MO River Valley, but can't rule
out some fog in other low lying areas and river valleys. Fog/low
stratus could drop ceilings and visibilities down to MVFR or IFR.
Although have a bit lower confidence in development than previous
forecast, have continued to include some MVFR fog mention in the
TAF at KSUX. Fog should lift through mid morning, with diurnal
cumulus returning for the afternoon and evening.

Winds remain light through the period, generally variable tonight
and turning predominately southerly Wednesday.

&&

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

$$

SHORT TERM...Meyers
LONG TERM...Meyers
AVIATION...SG



Office: UNR FXUS63 KUNR 170425 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1025 PM MDT Tue Aug 16 2022 .DISCUSSION...(This Evening Through Tuesday) Issued at 125 PM MDT Tue Aug 16 2022 Lingering moisture with diurnal heating and weakly unstable profiles will allow for a few isold TS this afternoon over mainly NW SD, perhaps into the BH. However, forcing is quite weak and when combined with height rises, convective chances will remain quite limited. Stronger upper level wave will support better chances for storms across the NW SD Wed afternoon and evening. Have adjusted pops up and further south and bit south as models continue to trend stronger with the shortwave trough. Precip amounts will generally be less than a quarter inch where rain materializes. CAPE will remain quite limited less than 1000 J/KG, however bulk shear over 35 knots will be more than enough for a few rotating updrafts over NW SD. Cool front will move through the region Thur with perhaps a shower or storm in the far east. It will be breezy with with north winds of 20 to 30 mph, breeziest on the SD plains. Upper low will briefly stall over the upper Midwest with the FA on the backside with subsident flow. Cooler and drier NNE ll flow will then help settle the main frontal zone south of the region this weekend with most rain chances south of the FA where the better moisture and main storm track will be. This will also support cooler conds with highs in the 70s and 80s. Gradual warm up can be expected of the first part of next week, with dry weather and seasonal temps. && .AVIATION...(For the 06Z TAFS Through 06Z Wednesday Night) Issued At 1022 PM MDT Tue Aug 16 2022 Local MVFR conditions may develop over south-central SD from 10z- 14z Wednesday due to stratus/br. Otherwise, VFR conditions will prevail through 18z Wednesday. After 18z Wednesday, isolated/scattered thunderstorms with local MVFR conditions are expected over northeastern WY into the Black Hills/northwestern SD. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION...JC AVIATION...Helgeson
Office: ABR FXUS63 KABR 162321 AAA AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 621 PM CDT Tue Aug 16 2022 .UPDATE... Issued at 619 PM CDT Tue Aug 16 2022 The forecast remains on track this evening. No major changes are planned. && .SHORT TERM...(This Evening through Wednesday Night) Issued at 214 PM CDT Tue Aug 16 2022 Again today pcpn chances are the main challenge. At the sfc a very subtle boundary is situated from nw MN, southwest into eastern ND. Meanwhile on water vapor imagery a decent looking s/w is rotating e- se across central ND. The combination of increasing instability and some UVM from upper wave/sfc convergence should lead to isolated storms over eastern ND and perhaps northern SD toward evening. Without much of a nocturnal LLJ (WAA feed), suspect most activity will die out around or near sunset. A pulse severe storm is possible, but with such low deep layer shear values, wouldn't expect much organization to any storms that do form. Wednesday looks dry but another wave aloft will track toward the forecast area for Wednesday night and Thursday, with a renewed chance for some showers and storms at that time. Highs on Wednesday will favor 80s east, to 90s west. Overnight lows tnt should be right around 60. .LONG TERM...(Thursday through Tuesday) Issued at 214 PM CDT Tue Aug 16 2022 Not much overall adjustment to the extended which will feature a pronounced upper low drifting south out of Canada and lingering across eastern South Dakota and Minnesota. Initial instability and shear does not appear to be high enough for severe weather, with profiles just showing skinny CAPE and relatively light winds throughout the profile. Moisture in the form of showers/rain will linger across good portions of the CWA well into Friday with mainly dry conditions thereafter as ridging builds to the west. The fetch from Canada (cooler airmass and shallow cu) will result in temperatures at or slightly below average, with blended guidance maintaining a slight tinge of humidity. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 619 PM CDT Tue Aug 16 2022 Terminals KABR,KATY,KPIR,KMBG VFR conditions are expected through Wednesday afternoon. Showers and thunderstorms may move near KMBG this evening. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Wise SHORT TERM...TDK LONG TERM...Connelly AVIATION...Wise