033
FXUS63 KABR 050509 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1209 AM CDT Sun May 5 2024

.KEY MESSAGES...

- Dry conditions tonight and Sunday.

- Southeasterly winds will increase Sunday afternoon. Highest gusts
  of 40 to 50 mph expected across central South Dakota. A Wind
  Advisory is in effect Sunday afternoon and evening west of the
  Missouri River.

- A much larger system will affect the region late Sunday night and
  Monday, with widespread showers and thunderstorms. Portions of
  south central South Dakota could see a few strong to severe
  thunderstorms on Monday.

- An unsettled and at times wet pattern looks to persist through at
  least the middle of next week. Temperatures will begin to turn
  cooler after Monday with daily readings near to slightly below
  normal.

&&

.UPDATE...
Issued at 845 PM CDT Sat May 4 2024

No changes planned to the tonight period forecast.

UPDATE Issued at 620 PM CDT Sat May 4 2024

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

&&

.SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/...
Issued at 315 PM CDT Sat May 4 2024

Upper level ridging will be in place over the region tonight and
Sunday, then gets pushed eastward Sunday night as a fairly strong
trough begins to slide across the Rockies.

At the surface, high pressure will be over the area tonight, with
winds going fairly light and thereby allowing temperatures to fall
to somewhat chilly values. A broad low pressure system will reach
the Rockies on Sunday, pushing the high eastward. The pressure
gradient between these two systems will tighten across western South
Dakota Sunday morning, then across the central part of the state
during the afternoon and evening. Wind gusts look to exceed 40 mph
west of the Missouri River during this time, so have issued a Wind
Advisory from midday Sunday through midnight Monday. The windy
conditions may continue into the overnight hours as well, but will
reevaluate that time period on Sunday. As the low tracks across the
Rockies to the western High Plains, will see precipitation out ahead
of it reach the western part of the CWA late Sunday night. A 40-50
knot low level jet will develop over central South Dakota, along
with 30 to 35 knots of shear. However, instability will be minimal,
so cannot rule out some thunderstorm activity, but do not expect any
severe storms Sunday night.

Low temperatures tonight will be in the mid to upper 30s. High
temperatures Sunday will be in the mid 60s to lower 70s. Lows Sunday
night will be in the upper 40s to lower 50s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 315 PM CDT Sat May 4 2024

By Monday morning, the focus will be on the storm system coming out
of the Rockies and into the Plains. There continues to be fair
agreement among deterministic and ensemble guidance progging a
vigorous negatively tilted upper trough shifting northeast off the
Rockies into the Central and Northern Plains on Monday into Monday
night. All four clusters from the cluster analysis feature this
500mb trough across the Northern High Plains/Northern Plains on Day
3. The NAEFS MSLP Mean Percentiles indicate a very deep sfc low
pressure system shifting eastward out of MT into the Dakotas on
Monday into Tuesday. The NAEFS Mean PWAT values remain at the 97.5
percentile on Monday across the central Dakotas. NBM QPF
probabilities of reaching or exceeding a half inch in a 24 hour
period ending Tuesday morning remain between about a 40-60 percent
range across our forecast area with higher percentages located
across our central and eastern forecast zones. So, confidence still
remain highs the weather pattern will turn active and unsettled for
our forecast area as precipitation moves through the region.

When it comes to the chances of severe weather, confidence isn`t
quite as high on those parameters for our area at this point in
time. The GEFS/GEPS/ENS mean CAPE values still remain below 1000
j/kg across our CWA on Monday. Joint probabilities for CAPE>500
J/KG, CIN>-25 J/KG, and 0-500mb bulk shear>30 kts are only about 5-
15 percent off the Grand Ensemble...and that`s mainly across our
western and southern forecast zones(northeast SD and west central MN
excluded). Both the mean values and joint probabilities continue to
remain much higher to our south across parts of the Central Plains
and our forecast area remains just on the northern fringe of any
instability. The CIPS analogs on Day 3(Monday) for 24-hr probs for
severe does continue to bring the 10 percent contour into southeast
parts of South Dakota, but not into our CWA. All this continues to
coincide with SPC`s Day 3 Severe Weather Outlook that indicates a
slight to enhanced risk from the SD/NE border southward into the
Central and Southern Plains. A marginal risk does touch our very far
southern zones in portions of Lyman and Buffalo Counties. So, we`ll
just have to continue to watch these trends for any changes during
the next 24 to 36 hours.

Rain chances nonetheless will be on the rise Monday and Monday night.
Areas of showers and storms will be possible across the forecast
area along with a decent amount of wind. This wound up storm system
will generate a lot of wind. There is quite an impressive low and
mid level jets that set up Monday and Monday night. 850mb winds are
progged to be between 40-50kts while 500mb winds could be on the
order of about 50-70kts. Strong south to southeast sfc winds across
our forecast area will be consistently sustained between 25-35mph
with possible gusts between 40-50 mph. Winds do begin to abate some
but remain persistent into Tuesday and through midweek. Guidance
continues to show very little progress on movement of the 500mb low
across the Northern Plains through Wednesday...showing basically a
slow and meandering movement south and east across our region.
Unsettled conditions will continue with on again/off again chances
for showers through the work week. With a fair amount of cloud cover
expected under this upper flow pattern, temperatures will be at best
near normal if not below normal most of next week after Monday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1207 AM CDT Sun May 5 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast across the area through the TAF valid
period. Look for southeasterly winds to increase into the 20 to 35
knot range across central South Dakota Sunday morning, before
gradually spreading over into northeast South Dakota late in the
day, and continuing through Sunday night.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory from 1 PM CDT /noon MDT/ this afternoon to
     midnight CDT /11 PM MDT/ tonight for SDZ003-015-033-045-048.

MN...None.
&&

$$

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