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275
FXUS63 KABR 251734 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1234 PM CDT Tue Jun 25 2024

.KEY MESSAGES...

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- Periodic chances(20-40%) for showers and thunderstorms late this
  afternoon and evening and again late tonight. A couple of storms
  will be capable of becoming strong to severe this evening.

- Two rounds of moisture for late in the week. Showers and weak storms
  for Wednesday night/Thursday (30-70%) and then again early
  Friday (30-80%).

- Very cool temperatures for the upcoming weekend (5-15 degrees below
  normal) with lows down into the upper 40s possible Sunday
  morning.
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&&

.UPDATE...
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Issued at 1232 PM CDT Tue Jun 25 2024

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 1017 AM CDT Tue Jun 25 2024

No changes planned to the today period forecast at this time.
Going gridded database is doing okay right now.
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&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 414 AM CDT Tue Jun 25 2024

This period will be marked by on again/off again chances for showers
and thunderstorms, especially this morning and tonight. Dry
conditions should eventually take hold during the day on Wednesday
as sfc high pressure gradually builds in from the northwest. Returns
on radar early this morning evidence of a bit of a continued
agitated upper flow pattern. Showers and some thunderstorms have
been moving across parts of central SD since late last evening and
now some activity has started shifting east into western James
Valley. Weak embedded mid level shortwave energy is working across
SD in the fast westerly flow aloft. A weak sfc boundary is draped
northeast into our area from sfc low pressure situated across
western SD/eastern WY. This disturbance will in part allow for the
persistence of this precipitation across the forecast area the
remainder of the pre-dawn hours and through about mid/late morning.
It will stay scattered that not everyone sees rainfall with PoPs
remaining about 20-40 percent at best.

Several hours of dry conditions are anticipated from around midday
through at least late this afternoon. Temperatures will be cooler
but still quite warm and humidity levels will be lower but remain
still somewhat humid to versus what we experienced on Monday. High
temperatures should top out in the 80s for most locations to around
90 degrees in a few other spots. This daytime heating will lead to
increasing instability through the afternoon ahead of a weak cold
front that is progged to shift south and east out of ND later today
and into tonight. MLCAPE values of 1500-2500 J/kg and 0-6 km bulk
shear values >40kts should be sufficient ingredients to work with to
kick off some convection as the aforementioned fropa comes through
and a s/w upper trough axis works southeast across the Dakotas into
MN tonight into early Wednesday. The strongest of any storms that do
get going would be capable of producing large hail and localized
strong wind gusts. Have painted mainly our northwest zones into
central and eastern zones with some low end PoPs for this
anticipated activity late this afternoon into the early overnight
hours.

That activity should be clear of our forecast area by daybreak
Wednesday morning. Sfc high pressure will gradually build in from
the northwest during the day. Cooler temperatures, but still
seasonal values for late June and less humid conditions can be
expected for the end of this period.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 414 AM CDT Tue Jun 25 2024

Plume of monsoon moisture drifts up from the 4-corners region to
link up with a wave embedded within a weak ridge that traverses the
region early Thursday. NAM BUFKIT profiles point to a moist
adiabatic profile with PWATS of about an inch and a half. Mid-level
warm advection associated with this feature brings 700mb
temperatures up to around +13C, so convection will likely be
elevated. Probability of a quarter inch is still only 20-40% though
the highest probability has now shifted towards the Pierre area.

This is ahead of a stronger shortwave that traverses eastern Montana
into North Dakota, with the surface reflection being a cold front
that passes through the CWA late Thursday night/early Friday. NBM
CWASP has shifted east in comparison to 24 hours ago, and is in
line with the latest deterministic guidance having the front along
the eastern CWA border by 18Z with low level westerly/cold advection
stabilizing the low levels.

High pressure follows, with an anomalously cool airmass. NBM box and
whiskers for Sunday morning are consistent with about a 3-6 degree
range in lows with the deterministic value right around 50 (and even
upper 40s).

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
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Issued at 1232 PM CDT Tue Jun 25 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals. Low probability for
thunderstorms this afternoon/evening and again late tonight.
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&&

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

$$

UPDATE...Dorn
SHORT TERM...Vipond
LONG TERM...Connelly
AVIATION...Dorn