Watertown, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

771
FXUS63 KABR 220530 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1130 PM CST Sat Dec 21 2024

.KEY MESSAGES...

- There is a low (15-25%) chance of a light wintry mix of
  precipitation, including rain and freezing rain over north
  central South Dakota Sunday morning into early Sunday afternoon,
  and freezing rain/sleet, or snow over northeastern SD into west
  central MN Sunday afternoon through early Sunday night.

- Temperatures will run around 5 to 20 degrees above normal Sunday
  through Saturday.

&&

.UPDATE...
Issued at 1126 PM CST Sat Dec 21 2024

Aviation discussion updated below for the 06Z TAFs.

UPDATE Issued at 841 PM CST Sat Dec 21 2024

The forecast is generally on track for this evening and minimal
changes are needed. Skies are mostly clear this evening with light
south breezes being maintained. Temps in some locations are
already approaching forecast lows, so did lower some areas a
couple degrees. Still expecting increasing clouds late tonight, so
don`t foresee temps dropping too drastically.

&&

.SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/...
Issued at 233 PM CST Sat Dec 21 2024

At 2 PM CST, under a partly to mostly cloudy sky, temperatures were
warming into the 20s and 30s. Portions of the west-river counties in
this CWA are nosing up into the low 40s. Winds are generally out of
the south around 10 to 20 mph with some occasionally higher gusts.

Surface low pressure will continue to deepen out to the west in the
lee-of-the-Rockies over the next 24 hours as the upper low along the
CONUS west coast moves inland. A surface low reflection of this
system will move east-southeast across the CWA mainly during the
first half of the day on Sunday. While the CWA is in the WAA side of
this system Sunday afternoon/evening, there could be enough
forcing/lift to make some precipitation reach to the ground in the
form of liquid precipitation. But, the better chances for meaningful
precipitation still reside to the north and eventually east of this
CWA. Everything hinges on surface temperatures Sunday morning
through Sunday evening, whether or not anything reaches the ground
as plain rain or freezing rain/sleet. Hi-Res and GSM ensemble
systems do not show much of a chance of measurable over this CWA.
There remains a 15-25% chance of achieving 0.01in of water
equivalent precipitation mainly north of U.S. Highway 12 during the
day on Sunday across north central SoDak and then into the early
evening across northeast SoDak/west central MN. From late Sunday
afternoon through Sunday night, low level CAA kicks in behind this
surface low passage, and enough cold air is introduced to where any
type of liquid precipitation (fzra/fzdz) that may be lingering
across nern SoDak/wc MN has the potential to convert to frozen/snow
precipitation. Again, low forecaster confidence in anything
hazardous coming from this lower-bound PoPs potential Sunday/Sunday
night. Surface high pressure will build across the CWA Sunday night.
Temperatures through the period should be near to a little above
normal.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 233 PM CST Sat Dec 21 2024

An upper-level shortwave moves out of SD Monday morning taking the
precipitation with it as an upper-level ridge moves over the state.
This ridge stays over SD through Wednesday evening moving occasional
pockets of mid-level WAA over SD. The WAA warms surface temperatures
to be 5-20 degrees warmer than normal Tuesday onward, with max
temperatures looking to be in the low 30s to upper 40s. As the ridge
moves out Wednesday afternoon into the evening, surface winds pick
up slightly because of a tighter pressure gradient, but the winds and
gusts still stay below 25kts.

The deterministic models and clusters then vary slightly moving an
upper-level trough east over SD Thursday onward as well as what
happens to the upper-level low connected to it. This then leads to
slight differences in precipitation chances for northeastern SD, as
some models have the low tracking to the northeast over NE that has
some light precipitation reaching northeastern SD. However, many
models and clusters are moving the low to the east over OK instead,
which keeps precipitation out of northern SD. The NBM PoPs have
values around 15 Friday and Saturday because of the slight chance
for light  in a few models. At the moment, with the mid-
level WAA and surface temperatures above freezing, any precipitation
that might fall looks to be as rain, though QPF stays out of eastern
SD keeping accumulations low.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1126 PM CST Sat Dec 21 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will persist through most of the TAF period. A
weak system will be sliding east across the Dakotas on Sunday,
and looks to bring areas of -FZRA/-SN to southern ND, potentially
sneaking into far northern SD. Confidence in this affecting
KABR/KMBG is low, so will leave out of the TAFs for the time
being. What`s more likely to occur from this system, is some MVFR
CIGs moving south into the area late in the TAF period and have
inserted mention of this for KABR/KATY.

&&

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

$$

UPDATE...TMT
SHORT TERM...Dorn
LONG TERM...Vernon
AVIATION...TMT