069
FXUS63 KABR 062321
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
621 PM CDT Mon May 6 2024

.KEY MESSAGES...

- Strong to severe thunderstorms are possible across central South
  Dakota early this evening, where a Severe Thunderstorm Watch is in
  effect until 8 pm CDT. Another round of showers and non severe
  thunderstorms will occur across eastern South Dakota and west
  central Minnesota this evening into the early overnight hours.

- Strong winds will translate eastward this morning with gusts to
  around 50 mph across the entire area through Monday evening.

- The weather pattern will remain unsettled through Friday with
  periods of showers and thunderstorms. Below average temperatures can
  be expected through at least Friday, with perhaps a warming trend
  this weekend.

&&

.UPDATE...
Issued at 620 PM CDT Mon May 6 2024

The Severe Thunderstorm Watch continues until 01Z Tuesday for much
of central South Dakota. We will continue to monitor for the
potential isolated strong to severe storms this evening. Strong
winds remain, with gusts of 35 to around 50 mph, strongest over
central SD. A Wind Advisory remains in effect until 05Z Tuesday.
The main severe weather threat is over our central SD counties,
but severe weather parameters continue to weaken this evening.
Over eastern SD there will be scattered thunderstorms with gusty
wind and the potential for small hail, but the main threat will be
brief heavy rain. This is where Precipitable Water values are 1
to 1.3".

&&

.SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/...
Issued at 314 PM CDT Mon May 6 2024

A strong upper level shortwave trough currently just west of the CWA
will swing northward tonight, then will spin in place over western
North Dakota on Tuesday before weakening as it drops back over South
Dakota Tuesday night.

At the surface, an elongated low pressure system currently extends
from eastern Montana to the Texas panhandle, with the strongest part
of the low over northwestern South Dakota. In an area of somewhat
clearer skies where instability has been able to increase over
western South Dakota, thunderstorms have already developed. This
clearing area looks to develop further east into portions of central
South Dakota. Models indicate that there will be decent instability
in that area (2000-3000 J/kg), as well as shear of about 40 to 45
knots for about a 2 to 3 hour period between 21Z and 00Z. As the
surface boundary moves over that area during that time, it will
likely become the focus for thunderstorm development, with gusty
winds and large hail possible, along with a chance for a tornado or
two. As the system swings northeastward this evening, the boundary
will continue to be the focus for showers and thunderstorms, mainly
along and east of the James River Valley. Instability and shear both
weaken when this happens, so do not anticipate any severe weather.
The low becomes more west to east oriented across North Dakota on
Tuesday, with most of the precipitation coming to an end. Will keep
some small POPs in just in case some lingering showers remain. The
low broadens out and weakens Tuesday night, reducing precipitation
chances even further.

Strong southeast winds will continue late this afternoon and this
evening, with gusts in excess of 40 mph likely. A Wind Advisory
remains in effect for the entire area through midnight. May see a
brief respite in the gustiness overnight, then wind speeds will pick
up again on Tuesday, especially across central South Dakota. Will
reevaluate the situation later tonight for possible additional
headlines.

Low temperatures tonight will range from the mid 40s along and west
of the Missouri River, to the mid 50s across west central Minnesota.
High temperatures on Tuesday will range from the lower 50s across
north central South Dakota to the mid 60s across west central
Minnesota. Lows Tuesday night will be in the upper 30s to the mid
40s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 314 PM CDT Mon May 6 2024

The long term portion of the forecast begins on Wednesday with a
surface low pressure system and upper level trough crossing
southeastward across the region. The storm system will bring 40 to
50% chance for showers and thunderstorms, mainly Wednesday afternoon
through early Thursday morning. After a brief period of dry
conditions Thursday afternoon and night, a shortwave crossing
eastern SD and MN on Friday will bring a 20-30% chance of showers,
mainly along and east of the James River valley. The latest NBM has
trended drier west of the James, and slightly higher in northeast SD
and western MN. Based on guidance from the grand ensemble, pops
could be increased even more to 30-50% Friday afternoon.

The weekend still appears mostly dry with seasonal temperatures.
Upper level ridging west of the region will produce northwest flow
aloft. High temperatures should warm into the mid 60s to the lower
70s Saturday and Sunday. While the NBM and grand ensemble are mostly
dry, there are some hints of weak storm systems crossing the region
this weekend and into early next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 620 PM CDT Mon May 6 2024

Terminals KABR,KATY,KPIR,KMBG

Winds gusting 35 to 45kts will only slowly diminish to around
30-35kts on Tuesday. Look for improving conditions at PIR with
VFR conditions returning after the main area of rain/thunderstorms
exits north. Borderline VFR to MVFR ceilings will return 07-18Z
Tuesday. Scattered to steady showers and embedded thunderstorms
will move into both ABR and ATY. The result will be mainly MVFR
ceilings at ATY through 09Z Tuesday. While VFR conditions are
currently forecast after 05Z Tuesday at ABR, confidence is low, as
the site will be near MVFR ceilings during much of the next 24
hours.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until midnight CDT /11 PM MDT/ tonight for
     SDZ003>011-015>023-033>037-045-048-051.

MN...Wind Advisory until midnight CDT tonight for MNZ039-046.

&&

$$

UPDATE...KF
SHORT TERM...Parkin
LONG TERM...SD
AVIATION...KF