338
FXUS63 KABR 250540 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1240 AM CDT Sat May 25 2024

.KEY MESSAGES...

- The unsettled weather pattern continues with chances of showers
  and thunderstorms Saturday afternoon into Sunday (35-80%
  chance) and Monday 25-35% chance) before things dry out for much
  of the rest of the forecast.

&&

.UPDATE...
Issued at 1233 AM CDT Sat May 25 2024

The aviation discussion has been updated below for the 06Z TAFs.

UPDATE Issued at 901 PM CDT Fri May 24 2024

Weak vort/disturbance noted on water vapor across eastern MT into
western ND, responsible for scattered showers over said region.
Upstream KBIS radar showing activity moving eastward along the
southern portion of ND, with trajectory perhaps taking it into
the far northern CWA over the next few hours. Latest HRRR runs,
along with various hi-res output does show potential for isolated
or widely scattered light showers moving eastward along the ND/SD
state line over the next several hours. Added slight chance PoPs
to account for this. Some of this cloud cover may keep lows up
just a couple degrees from previous forecast lows. That said,
still a cool night in store with lows in the upper 30s to low/mid
40s.

&&

.SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/...
Issued at 304 PM CDT Fri May 24 2024

Occluded low pressure will exit the region this evening. Strong
northwest winds associated with the cold air advection in the upper
low will diminish as well this evening. Some areas along the ND/SD
border did receive a mix of rain and snow as temperatures fell into
the 30s. That`s leaving a big question mark for overnight lows as
clouds clear out. Dewpoints are in the upper 30s and 40s this
afternoon, so don`t have lows falling below 37 degrees right now,
but that`s dependent on places like McPherson county seeing some
rebound after the last of the precip exits over the next couple of
hours. If there`s no recovery, a frost advisory may be warranted.

Heights rise on Saturday and winds shift to the south and east on
the northeast side of another Colorado low. Shortwave energy moving
through the upper flow may generate some showers and thunderstorms
as early as 11am across south central SD before more thunderstorms
develop in increasing instability in the afternoon. Expecting just
general thunder due to limited moisture and temperatures, but 30 to
80% chances for convective showers push east and north on the
shortwaves through the afternoon as a weak sfc trough/boundary
develops.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 304 PM CDT Fri May 24 2024

Sunday morning starts the long term with a shortwave moving across
the area. Deterministic models show this lasting through at least
the first part of Monday afternoon. Monday evening, a ridge starts
to build into the region and looks to last through mid week. We are
starting to see a shortwave ride that ridge across the area on
Thursday. By Friday evening we are on the upwind side of the ridge
and a low reaching down from southern Canada starts to move into the
region.

Sunday will have some chances (25-65%) for rain with that shortwave.
While some storms could form, it is unlikely they will become
severe. Wednesday evening, rain chances (15-25%) return for the rest
of the term as the Thursday (20-40%) shortwave rolls through
followed by the incoming trough on Friday (30-40%). With mid level
lapse rates between 6.5 and 8.5 C/km and MLCAPE values around 1000
to 2000 J/kg (depending on model), some storms have the potential to
become severe Thursday afternoon and evening and potentially again
Friday evening. This is still 6 to 7 days out so things could
change.

Temperatures for the first part of the long term will be rising back
up to around normal with highs in the high 70s to low 80s expected
Wednesday and Thursday. With the increased rain chances Friday,
highs look to be closer to the mid 70s. At the moment, winds look to
remain around normal for the entire period.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1233 AM CDT Sat May 25 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected through the TAF period. LLWS (low-level
wind shear) is forecast at KATY Saturday morning. Also, guidance
suggests a few scattered -SHRA/-TSRA are possible near and south of
KPIR around 22Z or after. For now, have a VCSH mention as confidence
on areal coverage and placement of any precipitation is low. As for
KPIR`s wind forecast, some uncertainty here too as a surface frontal
boundary looks to be splayed out over the region during the afternoon
hours, with NE winds north of the front, and SE winds south of the
front. This front may hang out in the KPIR region during the
afternoon, with potential for winds to waffle from SE to NE at
times.

&&

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

$$

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