123
FXUS63 KABR 300824
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
324 AM CDT Mon Jun 30 2025

.KEY MESSAGES...

- Heat and humidity return by the end of the week with highs in
  the 90s and dewpoints back into the 60s. Heat indices may flirt
  with 100 degrees over portions of central SD on Thursday.

&&

.SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/...
Issued at 323 AM CDT Mon Jun 30 2025

Water vapor imagery shows shortwave energy dropping southward across
the Northern Plains. There are some showers and thunderstorms
associated with this feature across northern ND and southern Canada.
This is the activity that is projected to move southeast through the
day and eventually be responsible for the slight chance (15-20%)
PoPs across the eastern CWA this afternoon. Atmosphere is
characterized by steep lapse rates, although somewhat minimal
instability with MLCAPE values around 500-1000 J/KG. Moisture is
rather limited as well, so would not be surprised if any activity
that develops turns out to be sprinkles/virga, and/or light showers
with some thunder potential.

Through the short term period, surface high pressure will be working
its way from the northern Rockies this morning, eventually centering
itself over the area by this evening. Breezy northwest winds will be
felt today (25-35mph gusts) within the somewhat tight pressure
gradient with the approaching high. Winds will become light tonight
with the high overhead. Blended in some of the cooler NBM25 temps
given the clear skies and light winds.

High pressure will begin shifting southeast of the region on
Tuesday, allowing for return flow southerly winds to develop (mainly
central SD) and warming temperatures. 850mb temps warm back up to
over +20C across central SD by 00Z Wednesday. Highs look to be in
the upper 80s for the James River westward, or even hitting 90/low
90s across central/south central SD. Dewpoints remain fairly low
though on Tuesday and stay in the 50s. Thus, it won`t feel all too
humid out there, but that will change come mid/end of the week.

&&

.LONG TERM /TUESDAY EVENING THROUGH SUNDAY/...
Issued at 323 AM CDT Mon Jun 30 2025

The upper level pattern Wednesday is a northwest flow regime, and
as such we have cool temperatures/steep lapse rates aloft. Heights
may also be on a slow increase through the day and there isn`t
really much indication of a wave, however BUFKIT profiles show
enough destabilization for surface based convection. Mid-level
unidirectional flow and dry air support a localized wind/hail threat
though because of the lack of broad upper support deterministic
guidance is only generating a few blips of QPF, and as such the NBM
has smoothed out the POP down to between 10 and 20% which as history
would have it, feels just about the right amount of coverage for
this type of flow regime.

Thursday the ridge moves overhead, with southwest flow aloft for
Friday. As the ridge migrates east and flow becomes more southerly
in the mid levels, 700mb temperatures increase. Right now,
deterministic guidance is only in the +12 to +14C for a peak on
Friday, which is only about a standard deviation above climo, and
probably not a strong enough cap to preclude convection given the
temperatures/humidity forecast in advance of a cold front.

With evapotranspiration at full potential now that we have ample soil
moisture and crops well into the growing season, the 25th/75th range
for dewpoints is mid/low 60s to near 70. After the last heatwave
with dewpoints well into the 60s to occasionally low 70s with lower
evapotranspiration potential, we should overachieve in comparison to
the deterministic NBM. In regards to Thursday/Friday high
temperatures, NBM deterministic is currently running closer to the
25th percentile or less, with a nearly 10 degree spread between the
25th and 75th percentiles. As such, for both days heat, would
anticipate an increase in the next few runs and as such heat index
values, which are currently only running a few degrees either side
of 90.

As for the later days of the extended machine learning/AI systems
from NCAR highlight the northeast/Minnesota/eastern ND Friday,
however, this is not reflected in the CIPS severe probability
guidance.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1238 AM CDT Mon Jun 30 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. There`s an
area of -SHRA/-TSRA departing the KATY vicinity right at the start
of the TAF period, so no plans to include VC at this time.
Otherwise, breezy northwest surface winds may gust to around 25
knots during the day Monday.


&&

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

$$

SHORT TERM...TMT
LONG TERM...07
AVIATION...TMT