264
FXUS63 KABR 202329 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
629 PM CDT Thu Jun 20 2024

.KEY MESSAGES...

- Rain and thunderstorms spread north and east tonight. Some storms
may be strong to severe across parts of south central South Dakota
this evening, then across much of the area Friday, especially along
and south of Hwy 212.

- A Flood Watch is in effect through Friday night for southern
portions of the forecast area, mainly south of Hwy 212.

- Above normal temperatures (highs in the upper 80s to 90s) and
muggy conditions are expected Sunday and Monday.

&&

.UPDATE...
Issued at 622 PM CDT Thu Jun 20 2024

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 245 PM CDT Thu Jun 20 2024

Precipitation has remained mostly south of Hwy 212 so far today.
There are a few showers showing up on radar farther north, but the
bulk of the activity remains closer to the primary boundary - a
developing warm front stretching east northeast from a Colorado low
across northern NE. A 30 to 40kt llj in the warm sector and some
ample shortwave activity riding the upper ridge will help kick off
some strong to severe thunderstorms through this evening. However,
the strongest part of the jet looks to remain across NE and maybe as
far north as the NE/SD border. A more anemic 20 to 25kt llj may push
into central and east central SD. Weak convection with heavier rain
is the most likely scenario tonight, but there is a marginal to
slight risk (1 to 2 out of 5) for severe storms south of Hwy 14.
Anything severe could be more likely if an MCS traverses out of
Wyoming and the Black Hills and clips this forecast area with strong
winds.

WPC pushed a moderate risk for excessive rainfall into Lyman and
Buffalo counties for tonight. Given the convection, chances for
locally heavy rainfall are present, especially with PWATs a full
standard deviation above normal. Could still see an additional 1 to
3 inches of widespread rain across the southern cwa into east
central SD through Friday night with embedded areas of more intense
accumulations. Therefore, issued a flood watch through Friday night
due to the wetter antecedent conditions and thunderstorm potential.

The warm front will stretch farther northeast on Friday and be the
focus point for strong to severe storms. The timing has really
waffled on storm development but could be as early as 17z or closer
to 21z. There is a slight risk for severe storms along and south of
Hwy 212 Friday. Less sold on anything much developing too far north
of the front, but there is a low potential for a couple of tornadoes
right on the front aside from risks of strong winds and large hail.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 245 PM CDT Thu Jun 20 2024

Saturday starts the long term with a shortwave over the area. This
will move east fairly quickly before a ridge builds in for Sunday.
This ridge stays over the region a little longer than in previous
model runs, lasting at least into Monday afternoon before we
transition to more westerly/zonal flow. Tuesday a quick shortwave
makes its way across the area. Another ridge starts to build in for
the end of the period.

We start the long term with some possible lingering showers over far
northeastern SD and west central MN Saturday morning. Monday evening
is going to be our next chance for some rain ahead of that shortwave
trough. Chances are pretty limited, with highest being 25 to 35%
over eastern SD and west central MN. Accumulations are also expected
to be low, toping out at about a tenth of an inch over east central
SD.

Temperatures to start the period will be warming, peaking on Monday
with highs east of the James River about 5 to 10 degrees above
average and west of the James River about 10 to 15 degrees above
average. Highs return to about average for the rest of the period.
Winds are expected to be around normal for the entire period.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 622 PM CDT Thu Jun 20 2024

Terminals KABR,KATY,KPIR,KMBG

A blanket of clouds is over the region. Prevailing conditions are
characterized as generally MVFR or lower. Guidance indicates that
later tonight after 06Z, the prevailing condition at all four
terminals will drop into some form of IFR (cigs) and remain there
until sometime later on Friday when some improvement is expected.
With the current batch of showers and thunderstorms just about
done affecting terminal airspace, it appears that there will be a
several hour break before more showers/thunderstorms begin picking
up/moving in from the southwest later this evening into the
overnight hours. Keeping an eye out for heavy rainfall, which
could lead to reduced (MVFR/IFR) visibility overnight.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch through Saturday morning for SDZ018>020-022-023-036-
     037-048-051.

MN...None.
&&

$$

UPDATE...Dorn
SHORT TERM...Wise
LONG TERM...KK
AVIATION...Dorn