525
FXUS63 KABR 082239
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
539 PM CDT Wed May 8 2024

.KEY MESSAGES...

- Marginal risk (1 out of 5) for severe storms across east
  central SD through mid evening. Large hail (1 inch) and strong
  winds (60 mph gusts) are the main threats.

- Above average temperatures are looking likely over the weekend,
  along with drier conditions.

&&

.SHORT TERM /THIS EVENING THROUGH THURSDAY NIGHT/...
Issued at 316 PM CDT Wed May 8 2024

Starting to see an increase of shower and thunderstorm activity as
daytime heating increases and lapse rates steepen. Greatest
instability (albeit weak) is still expected across the southeast CWA
with MLCAPE values generally from 500-1000 J/KG. Shear remains
marginal in that area, with DCAPE values also forecast (RAP) to be
less than 800 J/KG over the next several hours. Any landspout/funnel
potential this afternoon looks to be best over southeast SD, under
the upper low center. Non-supercell TOR parameter on SPC meso page
showing a small area of 2-3 over southeast SD.

Any shower and thunderstorm activity across the region this evening
is expected to wane/push south later tonight and have configured
PoPs this way as well. As we head into Thursday, daytime heating may
once again lead to a few afternoon showers, but expecting coverage
to be much less than what we see this afternoon.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 316 PM CDT Wed May 8 2024

Starting off Friday, split flow continues as the northern stream
remains in a positive PNA pattern with the southern stream`s closed
low over the southwestern US. Ensembles are in agreement on a
positive tilted shortwave trough over extreme northeastern parts of
ND, northern MN, and into Canada 12Z Friday. This will plunge
southeast through the day, along with its surface low and front,
which leaves our CWA in northwest flow behind it. Ensembles and NBM
keep most of the precip well east of our CWA. Winds do increase
behind the system as NBM prob>35 mph ranges from 20-98%, highest
over the Prairie Coteau with Prob of 40 mph 60-80% over the Coteau
Friday afternoon and evening. Heading into the weekend on Saturday,
northwest flow continues over the Northern Plains, downwind of the
ridge. A low will be moving east through Saturday evening across
Canada into North Dakota. A surface trough sets up over the area by
early Sunday morning. GEFS seems to be the only ensembles trying to
bring a chance of precip with the other models keeping it more north
and northeast. NBM handles this well with an overall dry forecast.
This southern stream`s now open wave will continue its track
east/southeast into the central Midwest through the weekend which
could bring some slight pops (15%) into our southern/southeastern
CWA Sunday evening.

By early next week, the northern stream`s ridge will push east,
becoming less amplified as it does so, and winds aloft over the
Northern Plains becoming more zonal. A trough will then setup over
the Northern Plains as a surface low pushes eastward across Canada
through the midweek. Clusters agree on this pattern but there are
differences in timing and intensity so low confidence exists on
exact outcome. Latest NBM shows a general increase in pop from west
to east starting Monday evening through Tuesday morning with pop
values ranging from 15-30% with the first part of the system and 30-
40% with the surface trough/cold front Tuesday afternoon/evening.
Lingering chances of rain continue Wed post front (15-30%) as of
now. Prob of CAPE>500 j/kg and shear>30kts remains under 10% per
GEFS at this time for any organized severe. However, CAPE values of
200-300 j/kg during this time could be should be enough for
generalized thunder chances.

Temps will warm into the upper 60s into the lower 70s for Friday
with a gradual warmup through the weekend as highs on Sunday are
forecasted to be in the mid-upper 70s to the lower 80s. This trend
continues through early next week before a slight cooldown behind
the cold front Wed.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 539 PM CDT Wed May 8 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue. Thunderstorms this evening could
bring brief MVFR visibility is stronger storms to any of our TAF
locations. VCTS is included initially at all sites but MBG, where
much of the precipitation should be ending south of this evening.

&&

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

$$

SHORT TERM...TMT
LONG TERM...MMM
AVIATION...KF