460
FXUS63 KABR 292309 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
609 PM CDT Sat Jun 29 2024

.KEY MESSAGES...

- Winds out of the southeast will gust 35 to near 45 mph Sunday
  afternoon west of the Missouri River.

- There is a marginal risk, level 1 out of 5, of severe weather late
  Sunday night into Monday morning. The main concern in the
  strongest storms will be winds around 60 mph.

- Monday afternoon and evening, the region will be in a slight risk,
  level 2 out of 5, of severe weather. This time period looks to be
  the next best chance for organized severe storms. Predictability
  on details is still low, but no threats (wind, hail, tornado) are
  ruled out at this point.

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

&&

.UPDATE...
Issued at 604 PM CDT Sat Jun 29 2024

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

&&

.SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/...
Issued at 247 PM CDT Sat Jun 29 2024

The surface high over the western half of ND is extending a ridge
across our forecast area this afternoon, before the high sinks
across eastern SD by 06Z Sunday and along the ND/MN border before
shifting to western MN by daybreak Sunday through the early
afternoon hours. Between this exiting high and organizing area of
low pressure across the Rockies, we`ll have an increasing pressure
gradient, and adequate mixing Sunday afternoon. There is a warm nose
near 700mb, limiting some of the mixing. The 500mb currently across
the interior western U.S. will be across the Plains States Sunday
afternoon through Sunday evening. Still, we should tap into some
winds in the 30-40kt range for gusts (strongest west of our forecast
area). Mainly dry weather will continue through the day Sunday,
although we will continue to monitor the trends for the potential of
a few (20% chance or so) of small pop up showers.

Our chances for showers or even a few thunderstorms increases late
Monday night into Tuesday morning, but will remains mainly around
20% or less. Clouds will steadily increase. This will be while the
large area of high pressure at the surface only slowly shifts east
from WI to WI and MI, and an elongated area of low pressure begins
to better organize from southern Alberta/southern Saskatchewan
through eastern MT into WY and the far western portions of the
Dakotas.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 247 PM CDT Sat Jun 29 2024

By Monday morning the region will be solidly in a southwest flow
aloft/mid level WAA advection pattern with an ongoing 30-40 kt LLJ.
Plenty of gulf moisture will be streaming northward into the
region. It is pretty uncertain if the LLJ will drive nocturnal
convection overnight Sunday into Monday morning. This certainly
could have some influence on the subsequent daytime heating and
destabilization of the boundary layer by Monday afternoon. That
said, best NBM probability of thunder chances (30% or greater)
through 18 Z Monday are mainly concentrated in North Dakota and
along the IA/NE border.

Assuming lingering convection and clouds are not a factor going into
Monday afternoon, it looks like a decent set up for a fairly
organized severe weather event. 700 MB temperatures do increase early
on (ensemble probs of 700 temps exceeding 14 C are around 40-60%
from Mobridge through Pierre) suggesting an initial CAP. However,
rapid 500 MB height falls/cooler air promptly follow and erode any
existing CAP by 21-00Z Monday. As for forcing, multiple waves of
upper level energy are expected to track across the region. An
especially defined shortwave will move through during the late
afternoon/evening hours along with a corresponding surface
trough/cold front. Mean ensemble CAPE values range in the 1000-2000
J/KG realm along with bulk shear of 30-40 KTS. Favorable low level
hodograph curvature will be in place out ahead of the cold front,
with (the expected) more straight line geometry behind the front.
These initial progs would suggest that supercellular development is
possible with sufficient shear/cold pool balance to sustain storm
development, especially for any storm that can develop out ahead of
the front. For the models that trend toward the lower CAPE
potential, it would suggest weaker, more shallow supercells. SPC has
the entire region outlooked under a slight risk (2 of 5).

There could be lingering shower and thunderstorm development into
Tuesday under the passing upper level long wave trough, cold air
advection and steep low level lapse rates.

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. There is strong upper level
forcing with this next system, but definitely lacking well defined
surface pressure/frontal boundaries.

The active pattern may break as models suggest building high
pressure across the SW CONUS and a high amplitude ridge developing
by the weekend into next week. Differences in timing and strength do
exist between models however.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 604 PM CDT Sat Jun 29 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to continue over the next 24 hours.
Winds will increase out of the southeast during the day Sunday.

&&

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

$$

UPDATE...Dorn
SHORT TERM...KF
LONG TERM...Serr
AVIATION...Dorn