National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KABR 141742 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1242 PM CDT Sun Apr 14 2024

.KEY MESSAGES...

- Mild today and Monday with highs 10 to 20 above normal today and
  15 to 25 degrees above normal for Monday. Light winds today, however
  Monday will see increasing winds raising the fire danger to the very
  high category.

- A strong low pressure system will bring showers and thunderstorms
  to the region Monday night through Wednesday morning. Some storms
  could become strong to severe Monday night, especially for south
  central South Dakota. The current probabilities of rainfall
  exceeding 0.5 inch range from 50% along and west of the Missouri
  River to over 90% for eastern South Dakota and west central
  Minnesota. Strong and gusty winds can also be expected through the
  time period.

- Colder temperatures, around 10 to 15 degrees below normal, can
  be expected for the latter half of next week. High temperatures
  during this time will only rise into the 40s and 50s.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1238 PM CDT Sun Apr 14 2024

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

UPDATE Issued at 945 AM CDT Sun Apr 14 2024

No changes planned to the today period. Current forecast is doing
fine.

UPDATE Issued at 618 AM CDT Sun Apr 14 2024

See the updated aviation discussion below.
-- End Changed Discussion --

&&

.SHORT TERM /TODAY THROUGH MONDAY AFTERNOON/...
Issued at 240 AM CDT Sun Apr 14 2024

High pressure in Canada/North Dakota will continue to ridge down
into northeast SD/western MN today. The gradient on the western
fringe of this high will tighten however, with increasing southeast
low level flow into the evening. That gradient continues to
intensify tonight, as low pressure develops over Wyoming while the
high essentially remains in place. Will have a 10mb gradient from
southwest to northeast across the state by Monday afternoon, with
pressure falls increasing to 6mb/6 hours by the evening. 1/2km winds
pick up Monday at 00Z to 35kts where the gradient is tightest, and
is generally around 30kts across the CWA by Monday morning. CAM
Ensemble 25th to 75th percentile wind gusts range between 30 to
40kts at the start of peak heating, but then trend towards the upper
20 to low 30kt range through the course of the day... meaning a
brief episode of stronger winds will preceded the more ubiquitous
gustiness through the rest of the day.

As for shower and thunderstorm potential... mid level warm advection
will steepen lapse rates. Weak ascent will support convection with
generally skinny mid level CAPE. We`re right on the edge of the
highest CAPE values with the CAM ensembles right around 1000j/kg in
Jones county with a gradient extending to the northeast to generally
negligible values in northeast SD/western MN Monday evening. CAMS
also hint at two waves of shower activity. First, right along the
ND/SD state line extending into ND, with another cluster developing
in central SD and expanding northeast...so attempted to extrapolate
these solutions into the POPS for Monday.

&&

.LONG TERM /MONDAY EVENING THROUGH SATURDAY/...
Issued at 240 AM CDT Sun Apr 14 2024

The upper level pattern will be transitioning to a diffluent flow
aloft ahead of a closed low system. At the surface a tight pressure
gradient will be in place with southeast winds tapping into gulf
moisture. A ribbon of 50+ F dewpoint air will extend from southeast
South Dakota into parts of northwest South Dakota, including our
south central South Dakota counties. CAPE values will be on the
rise, although still limited. Probability of CAPE greater than 100
J/KG is high across our south central counties (60-80%), roughly 50%
of ensemble solutions are suggesting CAPE up to 500 J/KG, but
probabilities really drop off (~<30%) for values over 1000 J/KG.
Meanwhile, a 30-40 KT LLJ sets up late Monday night into early
Tuesday morning and 0-6 km wind shear increases to around 30 kts.
All of the above may be enough to produce the first severe storms of
the season for our CWA. Jones/Lyman counties are under an SPC slight
risk with 2/3 of our western CWA under a marginal risk. As of now
the primary concern is hail, but definitely an early season storm
system that is worth keeping an eye on.

Tuesday the entire low pressure system becomes stacked as the
surface low works into the plains states. Plenty of moisture
wrapping around the system with PWAT values persistently around the
1.00 inch mark. This is at or exceeding the 90th climatological
percentile on both the NAEFS and ENS charts, especially across the
southern and eastern CWA. That said, these wrapped up systems do
tend to have streams of drier air that get wrapped up, and models do
show the occasional break in QPF, so periods of on and off rain are
likely.

Windy conditions are expected throughout the entirety of this low
pressure system, however as the low tracks east Tuesday during the
late afternoon/evening we become positioned on the backside of the
system. It is at this time winds will switch to the northwest and
increase substantially. A strong pressure gradient, CAA and steep
low level lapse rates will allow for gusts in excess of 45 mph for
much of the region. Winds persist into Wednesday, but will gradually
taper through the day.

The later half of the workweek and the weekend will then feature
temperatures 10-15 degrees below normal. High temperatures on Friday
will struggle to get into the low to mid 40s for most locations.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
-- Changed Discussion --
Issued at 1238 PM CDT Sun Apr 14 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail. Winds will continue their shift
around to southeast through the course of the TAF period. The
strong southeast winds the develop tonight, off the surface, will
create a potential low level wind shear situation at KPIR. A low
pressure system will bring isolated showers and thunderstorms to
the region as early as Monday morning.
-- End Changed Discussion --

&&

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

$$

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