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074
FXUS63 KABR 301910
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
210 PM CDT Sun Jun 30 2024

.KEY MESSAGES...

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- Winds out of the southeast gusting 30 to near 45 mph to expand to
eastern SD/west central MN Monday while shifting out of the south
and diminishing slightly.

- There is a Marginal Risk (level 1 out of 5) of severe weather for
around daybreak Monday mainly west of the Missouri River. The main
threats will be large hail and strong wind gusts.

- There is a Slight Risk (level 2 out of 5) for severe weather from
mid afternoon Monday through Monday evening. At this point all
severe weather threats are possible, including damaging winds, large
hail, and even a tornado. The highest risk for a tornado will be
over central SD.

- The active weather pattern of showers and thunderstorms persists
through the workweek.
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&&

.SHORT TERM /THIS EVENING THROUGH MONDAY NIGHT/...
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Issued at 210 PM CDT Sun Jun 30 2024

Winds will remain elevated as we move into Monday. Winds gusting 30-
35kts have been common west of the MO River, with a few higher
values. The 2 to 3mb pressure falls in 6 hours due to the tight
pressure gradient between the surface high over eastern MT/WI and
low across WY will continue to spread east this evening. While will
will relax around 5kts, they will remain gusty through Monday. The
low across WY will push into the western Dakotas early Monday
morning.

Storms over western ND overnight may clip our western, but mainly
far northwestern counties 09-13Z Monday. While the main threat for
strong to severe storms in the form of hail around 1" in diameter or
winds around 60mph will be across far western ND, there is still a
Marginal Risk (level 1 out of 5) of severe weather for counties
mainly west of the MO River.

Low level moisture will steadily increase during the daytime hours
Monday, with relative humidity values staying at or above 60
percent during the day Monday. The 12Z runs of the NSSL WRF and NAM
Nest have been a little more robust with the showers and a few
thunderstorms developing over our eastern SD counties and remaining
through much of the daytime hours. We have steadily increasing
chances of precipitation increasing from 20 to 70 percent) through
the day. There are differences in when thunderstorms will develop or
move over central SD Monday. The latest HRRR and and a couple of the
FV3 runs indicate the potential as early as 21Z, others hold off
until late afternoon with the storms developing over eastern
WY/Black Hills of SD sliding into our western counties around 00Z.
Much of this could be a result of the warmer air aloft capping some
of the convection. The NAM is near 14C over central SD, while the
HRRR is closer to 11C (weaker capping). There is plenty of room for
change in this period, so we will continue to highlight that people
be prepared for strong to severe storms as early as mid afternoon
with golf ball sized hail and winds over 60-70mph, along with a
tornado threat over central SD (2% tor off the latest SPC convective
outlook). CAPE values peak across central SD 15Z Monday to 00Z
Tuesday, with 0-3km computed cape values of 1500 to around 2000
J/kg, diminishing significantly after 00Z. A similar trend is noted
with shear and lapse rates, diminishing as storms move east.

Winds will diminish to less than 15kts Monday night as the surface
trough tracks east and resides either near the SD/MN border or all
into MN by 12Z Tuesday.
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&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
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Issued at 210 PM CDT Sun Jun 30 2024

A passing upper level long wave trough, cold air advection and steep
low level lapse rates may result in daytime heating showers and
thunderstorms Thursday afternoon. Expect anything that can get going
will be isolated in nature. Perhaps just enough CAPE (~ensemble mean
500 J/KG) to get a stronger pulse storm or two, but the severe
threat is low at this time.

High pressure will make a brief appearance Tuesday night/Wednesday
morning, but won`t last long as the next system moves into the
region Wednesday night and Thursday. A strong closed low system is
expected to develop and slide across the north plains Thursday
afternoon. Current model timing and location of this system varies
pretty significantly, so forecast confidence is low. A few solutions
bring a more defined surface low with a warm front lifting over our
eastern CWA resulting in a longer period of unstable air over the
region. While other solutions have a very ill defined surface
pressure pattern or keep the low east of our CWA altogether,
resulting in a cooler, more stable airmass. It is a pretty large,
slow moving system however, so rainfall may linger into Friday
afternoon before exiting the region. Models are generous in their
QPF, and the WPC values are currently over an inch for the eastern
2/3 of the CWA.

Models really diverge toward the weekend and early next week. Some
solutions try to build high amplitude ridge over the southwest
CONUS, placing us into a persistent northwest flow aloft. Whereas
other models maintain a more zonal flow first, before making the
transition to northwest flow aloft.
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&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1226 PM CDT Sun Jun 30 2024

Terminals KABR,KATY,KPIR,KMBG

Winds will shift from out of the southeast to out of the south
with gusts 25-35kts expanding from PIR/MBG this afternoon to
ABR/ATY by late this evening. VFR conditions will continue until
12Z Monday, with low level moisture increases and we fall to MVFR
at all locations by 15Z. Included low level wind shear at ABR
07-14Z Monday as the winds above the surface increase to 40kts.
Otherwise, any mention of precipitation has been kept out of the
TAFs for now, with around a 30 percent or less chance by 15Z at
ATY. This will be added as the time period nears.


&&

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

$$

SHORT TERM...KF
LONG TERM...Serr
AVIATION...KF