924
FXUS63 KABR 281128 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
628 AM CDT Tue May 28 2024

.KEY MESSAGES...

- Dry conditions return to the forecast area today and Wednesday as
  high pressure takes hold. Increasing southeast winds expected on
  Wednesday with gusts of 25-45 mph. The strongest gusts will be felt
  across north central South Dakota and parts of the Missouri Valley.

- There is a 60-85% probability of precipitation west of the James River
  valley and 20-60% probability of precipitation from the James
  River valley over to the Minnesota/South Dakota border Wednesday
  night.

- There is a 55-95% probability of precipitation from east of the Missouri
  River valley over into west central Minnesota and 20-55%
  probability throughout and west of the Missouri River valley on
  Thursday.

- Temperatures are forecast to continue near to slightly below normal,
  in the upper 60s to mid 70s, Thursday and Friday before a
  gradual warming trend begins on Saturday and continues into
  Monday.

&&

.UPDATE...
Issued at 620 AM CDT Tue May 28 2024

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 419 AM CDT Tue May 28 2024

Ongoing shower activity early this morning across our eastern
forecast zones will be gone and exited from our CWA for the most
part toward day break. This will leave us with a dry day for a
change with sfc high pressure progged to gradually build in from the
north. Northerly flow at the sfc and aloft will pull in a cooler air
mass into our area, especially noticeable across our eastern zones.
Model guidance progs the cold air advection process to drive 850mb
temps down into the +5C to +7C range this afternoon from the James
Valley east into west central MN. A thickening CU field across the
east may also aid in keeping temps below normal for late May.
Farther west in the Missouri Valley, daytime readings will be closer
to normal. Overnight, high pressure will settle across the eastern
Dakotas and Minnesota. Clear skies and light winds in the east
should allow temps to bottom out around 40 degrees by Wednesday
morning, especially across the James Valley.

The sfc high pressure system will pull away eastward and farther
away from us on Wednesday. Increasing heights in the mid levels by
the latter half of today into Wednesday indicate an upper ridge will
be building across the Dakotas for midweek. This is in response to
the next upper level trough this is progged to shift into the PacNW
by tomorrow. Winds turn more south to southeasterly tomorrow
allowing a warmer air mass to displace the cooler one. Temperatures
should be back close to normal for daytime highs by afternoon. The
one concern on Wednesday will be the wind speeds. A tightening
gradient between the aforementioned high pressure east and
developing low pressure across the Northern High Plains will begin
to put the squeeze on across western and central SD by midday and
afternoon. Wind probabilities among ensemble guidance pegs north
central SD as having the best chances for seeing gusts approach or
exceed advisory criteria by the mid to late afternoon hours.
Generally speaking, a gusty afternoon with speeds between 25-45 mph
will be possible...with the highest gusts by afar across our central
and western CWA.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 419 AM CDT Tue May 28 2024

In-house ensemble-powered PoPs continue to ratchet up the chances
for showers and thunderstorms Wednesday night (60-85% probability
west of the James River valley and 20-60% probability from the James
River valley over to the Minnesota/South Dakota border) and Thursday
(55-95% probability from east of the Missouri River valley over into
west central Minnesota and 20-55% probability throughout and west of
the Missouri River valley). CAM solutions for Wednesday night,
however, do not presently support such high PoP values. So, the tug-
of-war between ensembles and CAMs begins, and the trend in PoPs in
these two camps of precipitation forecast will have to be monitored
closely over the next couple of days.

Once the frontal boundary and upper support for it pushes east of
the region Thursday night, the flow pattern aloft begins to flatten
and surface high pressure builds into the region. Transient/fast
flow aloft will make timing periods of surface fropas and surface
high pressure systems a bit tenuous from Friday onward. Right now,
there is actually some support amongst GSM camps for seeing a decent
fropa sweep through the CWA on Sunday (day 6) during peak/daytime
heating, and maybe there could be some convective potential there?
By the end of the period and beyond, the trend toward a (dirty)
ridge building over the western two-thirds of the CONUS and
temperatures warming into (at least) the 80s is still showing up in
the ensembles (box-and-whiskers/S.A anomaly tables) and
deterministic (850hpa and 925hpa thermal progs) model data. Worth
noting, for a couple of days now, the in-house ensembles
probabilities for temperature reaching 90F degrees or warmer over
central South Dakota next Monday has been hovering in the 10-20%
range. Beyond that, the same probabilistic data for days 8 through
10 increases to 20-50%. Another trend to monitor in the coming days.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 620 AM CDT Tue May 28 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast for all four terminals.

&&

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

$$

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