Watertown, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

990
FXUS63 KABR 230525 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1125 PM CST Fri Nov 22 2024

.KEY MESSAGES...

- There is a 15 to 25% chance of light snow over portions of north
  central and northeastern SD into west central MN Sunday through
  late Sunday night. Little to no accumulation is expected.

- Average to slightly below average temperatures this weekend and
  around 5 to 10 degrees below average early next week.

&&

.UPDATE...
Issued at 1123 PM CST Fri Nov 22 2024

See updated aviation discussion below.

UPDATE Issued at 910 PM CST Fri Nov 22 2024

Current forecast is on track, therefore no changes made at this
time.

&&

.SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/...
Issued at 310 PM CST Fri Nov 22 2024

An elongated sfc high pressure ridge extends from portions of
southern Canada south and east across eastern MT/western ND into the
eastern Dakotas and western MN this afternoon. Meanwhile, sfc low
pressure is located in WY along a northwest to southeast oriented
stationary front with an inverted sfc trough extending northeast
into the central Dakotas. This trough is sliding southeast and is
providing very little in the way of any noticeable weather in our
area, other than acting as a wind shift line with east to southerly
winds ahead of it and northerly winds behind the feature.

Going through tonight, rather quite weather conditions will continue
to persist. The aforementioned sfc trough will continue passing
southeast through our forecast area as low pressure shifts into NE.
The sfc ridge will shift eastward across ND into northern MN and
remain more or less anchored in this position through the day
tomorrow; nudging or ridging south and west into our eastern zones.
Thicker cloud cover to our north today will gradually sink southward
overnight. We will see clear to partly cloudy skies overnight,
especially in southerly located zones of our forecast area.
Temperatures will fall into the low to mid 20s overnight with some
upper teens in spots. One thing portions of our area could see by
daybreak is some low clouds and fog, particularly around the
Watertown and Mobridge areas as that sfc ridge nudges into the area.
At this point, it doesn`t look to be that dense, but something to
keep an eye out for. The low level air mass, with the help of that
ridge to our northeast, will keep temperatures on the chilly side
for Saturday with daytime readings in the upper 20s to low 30s east
to the mid to upper 30s west. A fair amount of cloud cover and
rather benign wind field at the sfc and aloft will also contribute
to maintaining the cooler than normal temperature trend.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 310 PM CST Fri Nov 22 2024

Starting out Sunday morning, models agree on a weak negative tilted
shortwave over Alberta/Saskatchewan with embedded shortwaves south
of this wave, on the downstream side of the trough that is
positioned over the Pacific Ocean. Just north of the trough we still
have this persistent low that will continue to spin off the Pacific
Northwest coast. The shortwave over Canada and the embedded waves
seem to phase together over the Northern Plains/Upper Midwest Sunday
night into Monday as it tracks east. With this Canadian wave, models
seem to agree on a chance of precip barely clipping the area, mainly
over our northern/northeastern CWA Sunday through Sunday night with
EC still being a bit broader in coverage than GEFS/GEPS. Latest NBM
has a 15-25% pops for this area during this time with Ptype being
snow. However, EC still holds on to the very slight chance (5% or
less) for freezing rain/drizzle over 8D3 area as EC soundings show
this warm nose layer and unsaturated air above it. The latest NBM
has added it in (covering portions of Roberts and Traverse
Counties). As the wet bulb temps cool aloft to below freezing here,
the Ptype will change to snow by the afternoon. Little to no
accumulation expected.

Behind this system, an elongated area of high pressure moves in from
the northwest and will be the dominant weather pattern through
Tuesday with overall northwest flow aloft. Middle of the week models
indicate split flow with a positive tilted weak ridge over the
Northern Conus/Canada and a positive tilted trough, with the axis
from the Rockies southwestward to CA, with its surface low forming
over the southern CONUS. By the end of the week, a shortwave in
Canada and its low/cold front is forecasted push east/southeast with
the CWA forecasted to be behind this dry cold front by ~Thursday
morning with a high following behind for Friday. However, this far
out models are quite messy on placement and timing of the overall
pattern aloft which results in low confidence on surface features
and strengths. For right now, the forecast remains dry next week
which will be great for holiday traveling.

Colder air moves in with this first high early next week as highs
will range in the upper teens 20s to lower 30 and lows in the single
digits to lower teens. This is about 5-10 degrees below average.
Jumping ahead to the end of the week into next weekend even colder
air is forecasted to surge southward, which could give us our first
taste of below zero temps. However, NBM 25-75th spread for
Friday/Friday night is about 10-12 degrees meaning low confidence as
models are all over the place as mentioned. For example highs could
either be in the teens or 20s and lows in the single digits below
zero to lower teens. This higher spread continues through the
weekend being further out in time. NBM Probability of low temps
below zero ranges from 20-55% Friday morning through the following
Sunday. CPC still highlights a moderate risk (40%) of much below
average temps for the northern part of the state from 11/29-12/2 and
a slight risk (20%) for the rest of the state from 11/20-12/5.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1123 PM CST Fri Nov 22 2024

Terminals KABR,KATY,KPIR,KMBG

IFR/MVFR cigs may develop across the area late tonight into
Saturday morning. Otherwise, VFR conditions will prevail.

&&

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

$$

UPDATE...Parkin
SHORT TERM...Vipond
LONG TERM...MMM
AVIATION...Parkin