038
FXUS63 KABR 111736 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1236 PM CDT Tue Jun 11 2024

.KEY MESSAGES...

- There is a 20-40% chance of showers and thunderstorms Wednesday
afternoon into Wednesday night, mainly along and east of the James
River Valley. Some storms may become strong to severe, mainly along
and east of I-29.

- A storm system Friday night into Saturday will bring a 30-60%
chance of showers and thunderstorms. The storm system may produce
locally heavy rainfall over eastern SD and western MN.

&&

.UPDATE...
Issued at 1229 PM CDT Tue Jun 11 2024

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

UPDATE Issued at 908 AM CDT Tue Jun 11 2024

No changes planned, at this time, to the today period forecast.
Surface high pressure will set up over the region today.
Meanwhile, 925hpa thermal progs in the latest deterministic suite
of solutions suggest high temperatures today under a sunny sky and
west-component mixing layer winds should warm up a good 5 or more
degrees warmer than what resulted yesterday for highs. Going high
temperature forecast is in the ballpark.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 456 AM CDT Tue Jun 11 2024

Sfc high pressure and northwest flow today will bring dry weather.
The upper trough is expected to exit to the east this afternoon
leaving waa behind it in a building upper ridge. There should be
enough diurnal heating time for all areas to pop into the 80s.

Wednesday morning, weak low pressure sets up over western SD.
Southwest flow at the sfc will lead to downslope conditions along
the Coteau early. Strong capping in the morning may allow a few
benign showers ahead of the low, but it`ll be closer to noon when
the cap breaks. Models have continued to push the warm sector ahead
of the sfc low farther east with each successive run, but as of the
latest runs there`ll be a few hours where areas along the Coteau and
eastward could see ample instability (2000 to 4500 J/kg CAPE) and 45
to 50 kts of bulk shear when strong to severe storms could develop.
With lapse rates above 8 C/km, strong winds and large hail are
concerns. The threat of tornadoes is less impressive, but can`t rule
it out, especially along the Minnesota and Brookings county border
where there`s a sharp increase in helicity and the resultant tornado
parameter.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 456 AM CDT Tue Jun 11 2024

The long term portion of the forecast begins on Wednesday night with
a weak shortwave and frontal boundary sliding across the area.
Deterministic models have reduced pops during this time period, with
the GFS/NAM showing mostly dry conditions. While the NBM`s
probability of an hundredth of an inch is 20 to 35 percent, the
probability of prob of 0.05 inches is under 20 percent. NAM buffer
soundings indicate a substantial dry layer from the surface to 700
mb where the temp/dew point spread is 20 degrees or more. Wednesday
night into Thursday morning may feature very light rain, or perhaps
virga.

After a period of dry weather Thursday through most of Friday, the
weather pattern becomes active with a couple of storm systems
progressing across the region. The first storm system to impact the
area is an upper level trough that originates over the desert
southwest. The wave moves northeast into the northern plains, mainly
Friday night through Saturday. Southern and eastern South Dakota
appears to have the best potential of seeing moderate rainfall from
this system. The NBM`s probability of seeing an inch of QPF over a
24 hour period ending at 0Z Sunday is 20 to 30 percent, with the
highest chance over southeast SD.

A secondary storm system originating over the Pac NW should cross
the northern plains Sunday into Monday, bringing a 40-50 percent
chance of pcpn, mainly Sunday night into Monday morning. However,
there some support suggesting this wave may remain north of this
CWA, with perhaps dry conditions. Since the storm system is still
several days out, will maintain the higher NBM pops for now.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1229 PM CDT Tue Jun 11 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through Wednesday afternoon. Tonight
into Wednesday morning, there could be a few showers or
thunderstorms around. Too tough to nail down timing or coverage
right now, so left -shra/-tsra out of the TAFs for the time being.

&&

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

$$

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