273
FXUS63 KABR 141545 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1045 AM CDT Wed May 14 2025

.KEY MESSAGES...

- Fire danger will remain elevated today for the forecast area east
of the James River Valley with southerly winds gusting to 25 mph and
minimum relative humidity around 25 to 30 percent.

- Showers and thunderstorms are expected Wednesday afternoon through
Thursday morning (45-85% chance). A few storms could be on the
strong to severe side.

- A 50-80% chance for showers and thunderstorms persist Thursday
night through Friday night with a 50% chance or greater of seeing at
least an additional half inch or more of rainfall.

- The probability of low temperatures falling to 36F degrees or
colder Saturday night is 40 to 60 percent in areas along and north
of the US Highway 212 corridor.

&&

.UPDATE...
Issued at 1031 AM CDT Wed May 14 2025

As of 10:30 am, overall clear skies (other then some high clouds)
mainly east of the Missouri River. A slow moving to nearly
stationary front currently is positioned north to south through
central SD with more scattered to mostly cloudy skies behind the
front over north central SD and scattered rain showers. Temps
across the area range in the mid to upper 70s to around 80 and
dewpoints in the 50s. Showers and thunderstorms are expected to
fire up over central SD this afternoon, progressing to more of a
linear system tonight/overnight. A few storms have the potential
to be strong to severe with quarter sized hail and wind gusts
between 60-70 mph as the main threat. A tornado or two cannot be
ruled out, with the greater threat more south of the CWA. Overall
forecast remains on track.

UPDATE Issued at 643 AM CDT Wed May 14 2025

The aviation discussion has been updated below for the 12Z TAFS.

&&

.SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/...
Issued at 444 AM CDT Wed May 14 2025

As of 09z, a surface low and a frontal boundary are over western SD,
with some storms along the boundary. This front will be moving east
through the day towards central SD. Southern flow to the east of the
frontal boundary helps to push some moisture into central SD, with
dew points potentially getting up into the 50s and 60s. However,
northeastern SD and west central MN will not receive as much
moisture, leading to minimum humidity values getting into the 25-30%
range over and east of the James River Valley. Winds and winds gusts
also look to stay just below 25mph. While there are some elevate
fire weather concerns, most places see conditions below the criteria
for fire weather headlines.

There will be some instability to the east of the front, with MUCAPE
over 500 J/kg and some areas of south central SD seeing higher
values by the afternoon. With the available moisture and instability
as well as the lift from the frontal boundary, storms have the
chance to develop. The CAMs show the frontal boundary reaching
central SD early Wednesday afternoon between 18z to 20z. The biggest
obstacle for severe storm development is that the strongest shear is
behind the frontal boundary and not in the same area as storm
development. There is however a small area in which some weaker
shear and instability overlapping in front of the boundary, which
could lead to supercell and severe weather development. The storm
mode looks to start as more isolated cells, with a larger
possibility for severe hail development along with severe winds.
However, as the afternoon goes on, the lapse rates look to decrease
and storm mode becomes more linear, which leads to a decreased
potential for severe hail.

With the front moving rather slowly, the models show that it takes
until the early evening before the storms move east of the Missouri
River. As the evening progresses, the storms over south central SD
look to become more dominate while the storms to the north start to
weaken. Storms or no, precipitation will continue to move east along
with the front through the night with some models having
precipitation wrapping along the backside of the surface low over
central and eastern SD during the day Thursday.

&&

.LONG TERM /THURSDAY EVENING THROUGH TUESDAY/...
Issued at 444 AM CDT Wed May 14 2025

The main forecast challenges in this period will be focused on
precipitation chances and low temperatures through the end of the
week into early next week. The overall upper flow pattern will turn
more active throughout the course of this period, which will lead to
more opportunities for showers and thunderstorms. Breezy to windy
conditions throughout the period will be a notable feature as we
have successive low pressure systems progged to move through the
region. A much cooler temperature pattern will develop and persist
with below normal temperatures for a change.

Beginning Thursday night and persisting through Friday night, medium
to long range guidance is in fair agreement and in support of a low
pressure system at the sfc and aloft tracking through the region.
Our forecast area will see a 50-80% chance for showers and
thunderstorms during this time frame. Ingredients don`t look
conducive for strong convection, so just anticipating more garden
variety type activity that will be more tame, but any storms will be
capable of producing locally heavy rain. This system will start to
shift northeast and pull out of our CWA on Friday with leftover wrap
around showers in a trowal/deformation zone type scenario through
the end of the day. Rainfall exceedance probabilities in a 24 hr
period from 00Z Fri-00Z Sat depict most of our forecast area having
a 50-80% of seeing a half inch or more for areas along and east of a
McIntosh to Gettysburg to about Miller with the highest probs across
the James Valley and Sisseton Hills areas. Robust west to northwest
flow on Friday will drive a cooler air mass into the region. 925mb
temps will fall into a +3C to +8C range and with overcast skies and
rain in the area, daytime highs will be held in the 50s. This will
set up a couple of chilly overnight periods late Friday into early
Saturday and late Saturday into early Sunday. Cloudy skies Friday
night will likely keep temperatures from bottoming out no lower than
the upper 30s to around 40. However, some clearing is expected the
following night which will potentially set up some patchy frost in
spots, especially across our eastern zones. Probabilities of seeing
temperatures reaching or falling below 36F is about 40-60% from the
James Valley and points west and northwest into north central SD.
Cloud cover or lack thereof will play an important role in this so
it bears watching.

By the end of the weekend into early next week, another upper trough
is progged to dig into the Four Corners region and then track
northeast into the Northern Plains and Upper Midwest. This will lead
to another shot of rainfall for us by the end of the weekend all the
way through until about the middle of next week. The air mass
doesn`t get turned over much through this period so anticipate a
continued below normal trend in temperatures.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 643 AM CDT Wed May 14 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail through the majority of today. A cold
front shifting west to east will produce a line of SHRA/TSRA
across central SD late this afternoon, likely affecting KPIR/KMBG
at some point. Vsby and cigs may drop into MVFR/IFR in heavier
showers. Strong to severe storms are possible, with hail and
gusty surface winds around 50 knots or higher. At this point, this
activity doesn`t look to reach the KABR/KATY terminals until
after sunset or closer to midnight.


&&

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

$$

UPDATE...MMM
SHORT TERM...12
LONG TERM...Vipond
AVIATION...Vipond