418
FXUS63 KABR 170433 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1133 PM CDT Thu May 16 2024

.KEY MESSAGES...

- Above average temperatures can be expected on Friday with highs
  in the 80s. A few locations may reach 90 degrees.

- A frontal boundary crossing the area late Friday afternoon and
  Friday night will be the focus for a 40 to 70 percent chance
  (northern SD) for thunderstorms. Some may be severe across parts
  of central South Dakota, with gusty winds around 60 mph the
  main threat.

- Strong west to northwest wind gusts between 30-45mph will be
  possible on Saturday. Highest probabilities for the strongest
  gusts are across our northern tier of counties along the ND
  border.

&&

.UPDATE...
Issued at 628 PM CDT Thu May 16 2024

Made some hourly tweaks to pops based on latest radar trends.
Isolated to scattered thunderstorms will continue to move east
across the northern cwa this evening.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 339 PM CDT Thu May 16 2024

Weak disturbance aloft passing across the Dakotas while at the
surface, a boundary/wind shift is noted across western SD. We`ve
seen a cumulus field develop across central SD over the past couple
hours, with a couple towering/agitated areas across Corson/Dewey
counties. We do have two weak cells showing up on radar (as of 3PM),
with weak instability (500-1000 J/KG MLCAPE) and shear (~25kt 0-6km)
in place. Mid-level lapse rates are modest, around 7 C/km. Latest
HRRR runs do continue to show widely scattered activity across
central SD over the next couple hours, and has taken a noticeable
shift southward with potential activity, something to watch as
current precip chances do not quite go that far south. Had already
earlier this afternoon added 20% chances to north central SD as the
cumulus field was growing and HRRR starting hinting at possible
development. Previous forecast did not have things going until later
in the afternoon and closer to 00Z. Really don`t expect things to
get out of hand, as severe parameters stay mostly in check through
the evening, but would not be surprised to get some gusty winds over
40 mph with any stronger cores that develop.

As we head into Friday, will be watching the arrival of a cold front
into the western Dakotas by late afternoon/evening. Better upper
level support as well, with only modest low-level moisture return.
The strong cold front will provide good lift for convection though,
and CAMs continue to show development reaching the western CWA
around 00Z. Severe parameters show mostly a wind threat with any
storms that move into central SD Friday evening, with steep lapse
rates developing in a deeply mixed environment. Marginal risk (level
1 out of 5) continues to be in place across central SD as the front
makes its way through the region during the evening hours.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 339 PM CDT Thu May 16 2024

This period will begin Saturday morning with a cold front departing
east of our forecast area while sfc high pressure shifts south and
east out of the Rockies and Northern High Plains toward Nebraska and
Kansas during the day. Cooler and drier conditions will be setting
in for the first half of the weekend. In addition, much stronger
winds out of the west-northwest are expected on Saturday. With a
tight pressure gradient in place, strong wind gusts in excess of 40
mph will be possible for some of our forecast zones. In fact, the EC
ensemble data suggests the probabilities of wind gusts exceeding 40
mph is highest(40-50 percent) from north central SD eastward along
our northern tier of counties along the ND border into the James
Valley. NBM probabilities of gusts exceeding 40 mph are higher in
these same locales on the order of a 70-95 percent range. So, this
lends some confidence that windy conditions will be the feature of
the day on Saturday. At this point, we would anticipate wind gusts
will be somewhere in the range of 30-45mph. We`ll have to watch
trends over the next 24 hrs to see if a wind headline would be
warranted.

An unsettled pattern returns by early next week. A reinforcing mid
level trough will shift into the western CONUS maintaining
southwesterly flow aloft across our region. Deterministic and
ensemble solutions prog a disturbance to shift northeast into parts
of the Central and Northern Plains on Sunday into Monday. Shower and
thunderstorm chances will be on the upswing Sunday into Sunday
night. The western CONUS upper trough is progged by guidance to
shift into the north central CONUS by the middle of next week. This
will maintain our unsettled weather with more on again, off again
chances for showers and storms through the end of the period.
Temperature trends through this period should maintain near normal
to slightly above normal values with overnight lows in the 40s and
50s and daytime highs in the 60s and 70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1131 PM CDT Thu May 16 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected through Friday afternoon. Showers and
thunderstorms will move into central SD Thursday evening.
VCTS/TSRA may need to be added to KMBG after 0z Friday, but
confidence in timing and extent is too low at this time to add a
mention.

&&

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

$$

UPDATE...Wise
SHORT TERM...TMT
LONG TERM...Vipond
AVIATION...Wise