474
FXUS63 KABR 151932
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
232 PM CDT Sat Jun 15 2024

.KEY MESSAGES...

- Thunderstorm development west-river this afternoon means the
  potential for strong to severe storms moving into the Missouri
  valley region this evening. There is a Slight Risk (2/5), with the
  main threats to include large hail (quarter to golfball) and
  damaging winds (60-70 mph). Storms are expected to weaken/diminish
  in coverage this evening as they cross the Missouri.

- Sunday night into Monday comes with another potential round of
  severe storms. Large hail will be the main threat Sunday night
  (southern portions of the region) with hail, strong winds, and heavy
  rain all being possible over a larger portion of the area on Monday.

&&

.SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/...
Issued at 225 PM CDT Sat Jun 15 2024

Continuing to monitor the potential for afternoon/evening convection
west river moving into the Missouri valley. Convection has started
to develop at the far western extreme of the state. HREF 2-5km
updraft helicity supports the risk for storms across the western CWA
in line with CAMS around 23-00Z but also continues to indicate
weakening in the 00-03Z timeframe which follows CAMS model storm
coverage. Again, looking at primarily a hail/wind threat, with
mainly dry conditions overnight east river. High pressure follows
for Sunday. With a southwest flow regime aloft, CAMS do show some
elements of convection developing during the day, however looking
at NAM profiles its evident that this is high based (AOA 12kft) and
will be little more than some high/mid clouds.  That high pressure
begins to shift northwards as the southwest flow regime directs a
subtle shortwave up into the region. The remnants of todays front,
by then in Nebraska, lifts northwards as a warm front and will
provide the focus for convection late Sunday night/early Monday
morning, with the HREF ensemble pointing towards around midnight in
south central SD and slowly lifting northeast. Already by 06Z
Monday, NAEFS PWATS are nearing 2-3 standard deviations above climo.
Generally, straight line hodographs above the front support rapid
individual storm motion and a hail threat (thus the SPC day 2 slight
risk), and while its still relatively far out for CAMS at this
point, they do suggest widespread storm coverage across the CWA.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 225 PM CDT Sat Jun 15 2024

An active flow pattern will keep a tight grip on our region through
most of this forecast period. An upper level longwave trough will
essentially remain in place across the PacNW/Northern High
Plains/Rockies region while an upper ridge plants itself across the
eastern CONUS and Deep South. This will promote an active
southwesterly flow aloft across the Northern Plains and Upper
Midwest through the majority of next week. The potential for severe
weather will be on the table at certain periods during the week
along with heavy rainfall.

Starting off on Monday morning, ongoing convection is expected to be
already underway across portions of our forecast area. A warm front
and/or stationary front is progged to be splayed out from southwest
to northeast from NE into southeast SD and southern MN. Shortwave
energy riding through the southwest flow aloft and in conjunction
with mid level warm air ascent invof of this sfc front will be the
focus area for showers and thunderstorms through the morning hours
as this activity shift north and northeast through the daytime
hours. Any severe weather threats during the morning will be in the
realm of a large hail possibility. Cyclogenesis taking place farther
to the southwest in the Lee of the Rockies earlier will promote sfc
low pressure to trek northeast along the sfc frontal boundary during
the day. Models prog this system to continue its course into eastern
SD and eventually into MN by the latter half of Monday into Tuesday.
Severe convection will be possible in our area during that time
frame. Ensembles fairly agree on decent ingredients being in place
across our eastern zones by Monday afternoon and evening for severe
storms. Joint probabilities of sfc CAPE greater than 500 J/kg, sfc
CIN greater than -25 and sfc-500mb bulk wind shear greater than
30kts is in a 50-70 percent range at this point. This remains fairly
consistent with SPC`s Day 3 slight risk severe weather outlook for a
majority of our CWA. At this time, large hail could be a primary
threat, but as the sfc low shifts through our area and east and
drags a cold front from west to east through our area, locally
damaging wind gusts could be possible.

The other potential caveat to this active pattern will be multiple
rounds of rainfall, some of which will be locally heavy that could
pose some flooding issues eventually given the anticipated
successive waves of energy that are expected to traverse the region
through the week. WPC`s excessive rainfall outlook pegs our eastern
forecast area as having the greatest chances for seeing heavy
rainfall on Monday and to a certain extent on Tuesday and Wednesday,
although those chances are much diminished compared to Monday.
Models do want to trend drier by late Tuesday into Wednesday as sfc
high pressure builds into the Dakotas and shoves all the active
weather and associated frontal boundaries south and east of our
region. This will probably be short lived however and return flow
sets up again by Thursday through the end of the period.
Essentially, the upper flow pattern will remain unchanged with
southwest flow aloft and a continued stream of shortwave energy
riding through the region and combining with sfc low pressure waves
and associated frontal boundaries to create an environment conducive
to more shower and thunderstorm chances.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1207 PM CDT Sat Jun 15 2024

Terminals KABR,KATY,KPIR,KMBG

We have some intermittent MVFR CIGS for KATY, otherwise VFR
conditions. There is just a low probability for convection near
the KMBG/KPIR terminals around 00Z.


&&

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

$$

SHORT TERM...Connelly
LONG TERM...Vipond
AVIATION...Connelly