029
FXUS63 KABR 290118 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
818 PM CDT Tue Apr 28 2026

.KEY MESSAGES...

- Chances for light rain are possible over the next few days
  mainly over far south central South Dakota through this
  evening (30-50%) and more widely scattered (20-40%) for
  Wednesday and Thursday. Thunderstorms are possible Wednesday
  afternoon and evening, no severe weather is anticipated.

- High temperatures 5 to 15 degrees below normal expected
  through the work week. Highs will be in the 50s through that
  period. Weekend highs will increase slightly into the 60s.

&&

.UPDATE...
Issued at 816 PM CDT Tue Apr 28 2026

An area of showers continues to move southeast across southwest
SD, and if it holds together, its movement may bring it across
the far southwest CWA over the next few hours. Have therefore
expanded PoPs (20-40% chances) across the southwest counties a
bit more in areal coverage. Skies have also cleared nicely
across central SD this evening, so reduced sky cover there.

&&

.DISCUSSION...
Issued at 143 PM CDT Tue Apr 28 2026

A broad troughing pattern continues over the Central and Northern
Plains, on the southern side of a broad low spinning over Canada.
Models indicate a weak embedded shortwave, with its axis over WY,
tracking eastward and over SD/NE through late this afternoon and
evening, with the CWA on the backside of it by early Wednesday
morning. Another embedded and stronger shortwave has been the main
focus for rain showers further south in Nebraska. Shortwave pulses
on the PVA side of this northern wave is producing the bulk of the
rain showers over southwestern SD with the northern edge of this
rain currently over south central SD, mainly Jones and Lyman Counties
per radar. This will be the main focus for ongoing chances of rain
where we have better better 1000-500mb. NBM is a little bit more
aggressive on the northern extend of this rain (and pop chances) than
CAMS, which continue to keep the bulk of it south of the CWA through
this evening.

Late this evening through early Wed morning, another
weak embedded shortwave over MT/WY will bring more chances of light
rain with CAMs indicating spotty convective showers moving in from
western SD and tracking southeast. However, CAMs show these either
weakening or dissipating as they move in over the western CWA.
Additional development of spotty showers (HRRR) are possible over
portions of south central and east central SD however hi res models
are not too thrilled and very spotty and NBM does not have anything.
These will be moisture starved so most likely sprinkles at most or
virga. Ran with ECAM between 00-12Z with pops up to 15% at most. So
low confidence on if they will even form and where they will
initiate if they do. HREF Probability of 0.01" through 12Z Wednesday
is 30 to 50% over portions of south central SD with the highest prob
over Stanley and Jones with most of this QPF through this evening
NBM runs 40-70% for this same area so NBM running a bit more hot
with pop chances and QPF. The 10-25% chance will be pretty splotchy
over the rest of the CWA (with the exception of far northeastern
SD/western MN) per these convective shower possibilities.

This broad trough overhead for Wednesday plus additional shortwave
energy/pulses and daytime heating, CAMs indicate the development of
very spotty elevated convective showers/thunderstorms tracking
northwest to southeast between 18-03Z across the CWA as HREF
composite reflecting>40 dbz paintballs as well. Instability will be
weak with MUCAPE of 500j/kg or less and mid level lapse rates less
then 7C. However bulk shear will be around 30kts out of the
northwest. So thunderstorms could be possible with no severe weather
anticipated. Any stronger rain shower or thunderstorm could produce
sub severe winds given an inverted V sounding. Another embedded
positive tilted shortwave moving in out of Canada and tracking over
the CWA will bring isolated spotty convective showers once again
Thursday. However forcing and instability is really not there, so if
showers do form they will be weak with pops of 15-20%.

Finally, for the end of the week as this upper low/trough pushes
more eastward and over the eastern CONUS, models indicate split flow
over the western CONUS with a ridge over the Pacific Northwest and
trough over southern CA/Mexico. The Northern Plains will continue in
overall northwesterly flow aloft between the ridge to our west and
trough to our east. This should overall produce dry weather Friday
and Saturday with more shortwaves moving across the region early
next bringing slight chances of pops (15-20%).

With this overall broad troughing pattern, 850mb temps continue to
be below average through the end of the week, hovering a bit above
or below 0C, with values as low as the 10-20th percentile. Highs for
Wednesday through Friday will range overall in the 50s with temps
warming into the 60s for the weekend. Climate Predication Center 6-
10 day outlook (5/3-5/7) indicates below average in precip and temp.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 629 PM CDT Tue Apr 28 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. There is an
area of -SHRA moving southeast across southwest SD this evening,
but will leave out of KPIR TAF at this time due to low
confidence in them affecting the terminal. Will amend if needed,
although any -SHRA would likely only bring brief MVFR VSBY. On
Wednesday, isolated -SHRA forecast across the region, but areal
coverage and confidence too low to include in a TAF at this
time, even in PROB30 fashion. But again, due to the light nature
of shower activity, perhaps only a brief drop to MVFR VSBY is
currently expected. May need to include PROB30 or TEMPO/VC
conditions for Wednesday in later TAF issuances.

&&

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

&&

$$

UPDATE...TMT
DISCUSSION...MMM
AVIATION...TMT