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000
FXUS63 KABR 281138 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
638 AM CDT Sun Apr 28 2024

.KEY MESSAGES...

- Active pattern continues with chances for moisture today,
  Tuesday, and Thursday. Rainfall amounts for today and tonight
  range at about an inch in northeast South Dakota/western
  Minnesota while western/north central SD will see around quarter
  inch or less.

- Less moisture is expected with the other systems during the week.

- Below to near normal temperatures through the extended.

&&

.UPDATE...
Issued at 629 AM CDT Sun Apr 28 2024

Aviation discussion updated below for the 12Z TAFs.

&&

.SHORT TERM /TODAY THROUGH MONDAY AFTERNOON/...
Issued at 350 AM CDT Sun Apr 28 2024

Next round of rainfall is moving northward across NE and has
recently moved into far southern SD. Main surface low center is down
in KS, set to move north-northeast through the day while spreading
rainfall northward into the CWA. Models may have slowed down precip
onset a bit compared to 24 hours ago, but still expect precip to
overspread the region through the morning hours. Little to no
instability to speak of, so just looking at general rainfall with
this system. Forecast rainfall totals are fairly close to NBM means,
which are around 1 inch across the eastern CWA, to around 0.25 or
less across central/north central SD. Higher end scenarios
(75th/90th percentiles) top out around 1.25-1.50 inches for eastern
areas, while central SD is more around 0.75 inches. There is some
question where exactly the western edge of precipitation sets up
with this system, which models show could be around the CWA border
with UNR. In this scenario, it`s interesting to note some drier
outcomes (25th percentile) show only about 0.10 or less (maybe
nothing at all?) across north central SD and west of the Missouri
River.

Late tonight into early Monday morning, temperatures try to cool
into the mid to upper 30s. NBM lows were generally from 34-36
degrees across the CWA, but felt this might be a touch too cool
given the cloud cover and lack of strong cold air advection. Leaned
more towards NBM 75th, which still gave lows from 35-38 degrees.
This is still cool enough to entertain the mention of a rain/snow
mix perhaps, especially for higher terrain areas like the Leola and
Sisseton hills regions. NBM probs for precip type (snow) generally
show 30-50% from the Leola hills south to Hand/Hyde counties,
eastward into the Coteau region. Official wx grids do show a
rain/snow mix by early Monday morning, but with little to no
snow accumulation.

System begins to depart the region on Monday, but it will take some
time to erode the cloud cover from west to east according to HREF
low-level cloud cover ensemble means. By Monday afternoon, it still
shows the eastern CWA stuck in clouds while central SD beings
clearing out. Where sun does manage to emerge on Monday (central
SD), look for temps to rebound into the 60s as lower level
temperatures begin to warm from 925-850mb with an approaching warmer
air mass.

&&

.LONG TERM /MONDAY EVENING THROUGH SATURDAY/...
Issued at 350 AM CDT Sun Apr 28 2024

Start out the long term with one departing system, weak ridging
overhead and an approaching trough from the west. This upstream
trough deepens over Montana, ejecting a shortwave eastwards that
quickly crosses South Dakota Tuesday, before making a sharp turn
northwards up into northern Minnesota. The resulting surface low
will have a tight gradient and southeast low level flow as it moves
in from the west Tuesday morning, and a north south cold front that
crosses into Minnesota by the afternoon. There will be limited
moisture return, despite a well defined warm tongue. Its within this
warm tongue, and along the cold front, where we see the potential
for convection. NAM BUFKIT profiles support skinny elevated CAPE in
a high unidirectional shear environment, with the core of highest
CAPE in southeast Minnesota. NAM MUCAPE is around 2-3k j/kg in the
aforementioned corridor, however NBM 25th/75th range is much lower,
between a few dozen to around 500j/kg. Winds on the back side of the
system is the result of cold advection (about a 5C drop in 850mb
temperatures) though pressure rises are only about 3-5mb over 6
hours.  West of Mobridge continues to be the focus for highest winds
with the NBM 25th/75th range between ~45 and 50-55mph, but elsewhere
that range is much lower.

The next system to contend with is a more typical type Colorado low
that tracks into Kansas and Iowa, similar to the more recent
systems. Pretty similar outcomes between deterministic guidance in
the track/timing of the low, though NBM 25th/75th range of QPF is
still about 1/2" with a similar range between GEFS plumes.

As for temperatures, with the moisture and airmass changes, still
looking at readings near to below normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 629 AM CDT Sun Apr 28 2024

Terminals KABR,KATY,KPIR,KMBG

MVFR/IFR (predominately IFR) CIGs are forecast through the TAF
period. -RA/RA & -SHRA/SHRA will spread northward across the
region this morning, already affecting KPIR at 12Z. MVFR/IFR VSBY
is possible in RA/SHRA.

&&

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

$$

UPDATE...TMT
SHORT TERM...TMT
LONG TERM...Connelly
AVIATION...TMT