009 
FXUS63 KABR 301837
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
137 PM CDT Fri Jun 30 2023

.SHORT TERM...(This Evening through Saturday Night)
Issued at 136 PM CDT Fri Jun 30 2023

Precipitation chances, coverage and timing continue to be the most 
challenging aspects of the short term forecast.

At 1 PM CDT, amid a partly to mostly cloudy sky, there were isolated 
to scattered showers and thunderstorms happening over portions of 
western and central South Dakota. Temperatures have warmed into the 
70s across pretty much the entire CWA, with a few locations nosing 
up into the low 80s.

Compared to 24 hours ago, much of the hi-res short term guidance has 
shifted the coverage of showers and thunderstorms a bit further 
north and east across the CWA from late this afternoon through late 
this evening. Ensemble-based progs for precipitation on Saturday now 
point to the potential for isolated to widely scattered showers and 
storms developing north and west of the CWA Saturday afternoon and 
potentially moving down into north central South Dakota Saturday 
night.

There is little in the way of change in temperature guidance for 
tonight through Saturday night. The region is looking at both low 
and high temperatures right around normal for tonight through 
Saturday night.

.LONG TERM...(Sunday through Friday)
Issued at 136 PM CDT Fri Jun 30 2023

In the out periods, forecast challenges include convective 
potential/timing and severity Monday and Tuesday, along with 
temperatures.

The previously mentioned upper level ridge will be overhead on 
Sunday, giving way to northwesterly and then eventually westerly 
steering flow winds aloft Sunday night into Monday. Mid-level 
heights fall and mid-level winds begin increasing by 7 PM CDT on 
Monday. CIPS analogs show there is potential for severe weather in 
Monday/Monday night's synoptic-scale set-up, and the CSU machine 
learning 15-30% severe potential prog is centered on the CWA for 
Monday/Monday night. SPC hoisted a 15% probability of severe weather 
in their Day 4 SWO for this timeframe as well. A broad-brushed 
approach, at this point, to severe weather potential certainly 
checks all the boxes; mid-level forcing from approaching upper level 
trof/mid-level height falls, strong cold fropa for forcing, 40+ 
knots of deep layer shear and likely more than adequate instability 
under a un-capped mid-level thermal advection regime. Will be 
interesting to see if Independence Day's stout mid-level baroclinic 
zone (post-cold-frontal) can muster an additional potential bout 
with strong to severe (elevated) convection. Beyond Independence 
Day, the flow pattern appears to anchor itself on quasi-zonal 
westerly flow aloft, but no notable systems working through the 
region, at least not currently, for Wednesday through Friday.

Compared to 24 hours ago, guidance in both ensemble camps and 
deterministic camps is pretty consistent regarding temperatures. 
Sunday and Monday should prove to be rather toasty for high 
temperatures (>75% probability of high temps at or above 90F over 
most of the CWA both days). With Monday, there could be a cold fropa 
entering the arena across, mainly, north central South Dakota 
forecast zones, which could place high temperatures at or above 90 
degrees in jeopardy. So, a bit lower confidence in how things will 
turn out there on Monday. But, overall, the boundary should be 
moving toward or clear of the south/east CWA forecast zones by the 
end of peak heating on Tuesday. There could be some breezy to at 
times windy north/northeast mixing layer winds developing behind the 
fropa on Tuesday into Wednesday.

Standardized anomalies off the EC and GFS ensembles indicates 850hpa 
temperatures by mid-week (Tuesday/Wednesday) are at 2.0 standard 
deviations below normal. Gradually, low level return flow southerly 
component winds will develop by the end of the period, supporting a 
return of temperatures closer to normal for early July.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1220 PM CDT Fri Jun 30 2023

Terminals KABR,KATY,KPIR,KMBG

VFR skies/vsbys are forecast to prevail through the TAF valid
period, all the while, isolated to scattered showers with embedded
thunder will be possible this afternoon into late this evening at
KMBG, KPIR and KABR.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

SHORT TERM...Dorn
LONG TERM...Dorn
AVIATION...Dorn