270
FXUS63 KABR 301522 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1022 AM CDT Thu May 30 2024

.KEY MESSAGES...

- A storm system moving through the region today will lead to a
  40-80 percent chance for showers and thunderstorms. Although
  severe storms are not expected, there could be a few stronger
  storms that develop by afternoon across northeast SD and west
  central MN as a cold front moves into the area.

- There is a 50-70+% chance for showers and thunderstorms between
  Sunday afternoon and late Sunday evening. Other mentionable
  potential periods of precipitation include Saturday night
  (20-45% chance) and Tuesday afternoon/evening (20-40% chance).

- Temperatures are forecast to rise above normal over the weekend
  and into next week (highs in the 80s).

&&

.UPDATE...
Issued at 1017 AM CDT Thu May 30 2024

Scattered showers and a few thunderstorms ongoing across parts of
the CWA this morning. Still expecting a frontal boundary to track
across the eastern half of the area this afternoon and evening and
become more of the focus for additional showers and thunderstorms.
No changes made to winds or temperatures at this time.

&&

.SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/...
Issued at 407 AM CDT Thu May 30 2024

The overall theme in this forecast period will continue to reflect
an active weather pattern at times across our forecast area through
the end of the week. A sfc low pressure system, currently located
across portions of northern ND early this morning, with a trailing
occluded frontal boundary extending southward into parts of western
and central SD is in part responsible for the ongoing scattered
showers and thunderstorms across the western and central Dakotas.
Most of this activity has remained rather benign so far as
ingredients remain rather lacking for any strong to severe storms.
Things may change and evolve into more of an active situation,
convectively speaking, as we get into the daytime hours today.

A pretty stout low level jet has set up early this morning,
especially across our eastern zones. KABR VAD Wind Profile indicates
50kts observed just off the deck. Some CAM solutions generate
scattered convection developing closer to daybreak in the James
Valley, perhaps on the nose of this low level jet that begins to
impinge on portions of northeast SD. Perusing the convective
parameter progs going through the morning hours today, we do see
instability remaining fairly low and deep layer shear unimpressive.
By midday into the afternoon, a narrow ribbon of some higher
instability builds across our eastern zones(I-29 corridor and east).
Now, this instability is far from mentionable with MLCAPE values up
around 1000-1200 J/kg. 0-6 km bulk shear values are lacking ahead of
the sfc boundary on the order of about 20-25kts. However, low level
lapse rates are expected to be steep around 7 C/km for a short time
this afternoon in our eastern zones. All this to say is we`ll likely
get convection to develop along and out ahead of the advancing sfc
frontal boundary, but most storms should remain sub-severe. CAMs
depict a scattered line of thunderstorms setting up across the James
Valley closer to midday and shifting east with time through the late
afternoon hours. Wouldn`t be surprised if a couple storms get strong
enough for some small hail and localized gusty winds, but
ingredients are better for more organized severe weather just to
our south in southeast SD and eastern NE this afternoon.

Breezy southeast sfc winds ahead of the aforementioned boundary in
the east will be persist through the late morning, while winds turn
west to northwest behind the front across central SD by mid morning.
Stronger northwest wind gusts will be possible through the afternoon
across north central SD with speeds reaching 25-35mph. The sfc
frontal boundary will get shunted eastward as the upper level trough
currently across the Northern High Plains shifts eastward across the
US/Canadian border region. Rain chances will end from west to east
through the morning into the afternoon, lingering the longest across
our eastern zones through late this afternoon into the evening. Sfc
high pressure briefly tries to build into the area tonight into
Friday. However, with the sfc front stalling out south of our area
and perhaps some lingering s/w energy working through the mid level
flow across southern SD on Friday, we could see some showers
returning to parts of the area by midday and the afternoon.

&&

.LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/...
Issued at 407 AM CDT Thu May 30 2024

Clusters analysis continues to support a semi-progressive upper flow
pattern with the best precipitation chances attached to mid/upper
level systems progged for Sunday and Tuesday. Still a lot of time to
conjecture over whether or not there is a severe weather threat
attached to either of these systems. But, timing-wise, right now,
models are still working frontal boundaries through the CWA Sunday
and Tuesday during peak-heating. So, there`s that. Beyond Tuesday,
it still looks like an upper level ridge will be trying to establish
across the western two-thirds of the CONUS, including over this CWA,
while a longwave upper trof hangs out over the east coast of the
CONUS.

Also, regarding precipitation chances, will have to see what happens
Saturday night, when a low level jet is forecast to develop down
near the Nebraska/South Dakota border and spread north overnight.
Other things needed for convection include low/mid-level WAA and a
good low level moisture feed. And, some upper level jet support
(lift) would be helpful. Will have to see if all these ingredients
can come together to promote nocturnal convective development late
Saturday night/early Sunday morning.

Otherwise, the temperature forecast remains a toasty one in the out
periods. The probability of seeing the temperature warm to 90
degrees or higher has increased now, for Sunday, to 40 to 55% across
portions of the southwestern forecast zones. Seems like high
temperatures climbing into the 80s is a good bet for much of the CWA
for much of the out periods.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 640 AM CDT Thu May 30 2024

Terminals KABR,KATY,KPIR,KMBG

Mainly between now and 00Z, there could be a mix of VFR and MVFR
clouds around. If KPIR sees any MVFR stratus, it would only be for
a few hours. KMBG, KABR and KATY could be in and out of MVFR cigs
for many hours today, before conditions return to prevailing VFR.
There are also showers and thunderstorms in the forecast today
(raining right now at KMBG and KPIR) at all four terminals. But,
once a west to east-moving front over the region passes each
terminal, precipitation chances pretty much dwindle to nothing.
Ahead of this frontal passage, strong southerly (15 to 25 knots
with gusts to 30-35 knots) winds will persist. Behind the fropa,
west to northwest winds develop, considerably lighter, and remain
the prevailing wind in the TAF valid period.


&&

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

$$

UPDATE...Parkin
SHORT TERM...Vipond
LONG TERM...Dorn
AVIATION...Dorn