927
FXUS63 KABR 112017
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
317 PM CDT Thu Jul 11 2024

.KEY MESSAGES...

- While mainly dry weather will continue, isolated late evening
  and overnight showers and thunderstorms will be possible
  through at least the weekend due to weak disturbances moving
  through the region. Chances of precipitation are less than 40
  percent not only through the weekend, but through the middle of
  next week.

- High confidence in hot and muggy conditions Friday through
  Sunday. High temperatures will be in the 90s (5-10 degrees
  above average) with dewpoints in the mid to upper 60s. This will
  result in heat index values in the mid and upper 90s with a few
  spots to 100 degrees during the afternoon hours.

- Temperatures will moderate with lower humidity for the first half
  of next week.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 316 PM CDT Thu Jul 11 2024

Generally quiet conditions through the short term, with the main
highlight being the building heat beginning on Friday. Currently,
temperatures are rising through the 80s, and flirting with 90
degrees over portions of central SD. By Friday afternoon, 850mb
temps climb even a few more degrees, with decent southerly mixing
winds. Should be able to tack on a few more degrees compared to
today`s readings. With that, models are indicating dewpoints
climbing a bit higher than today as well. Current apparent T forecast
does show heat indices reaching 100 degrees across portions of
central SD. Somewhat marginal worthiness for headlines, but may want
to hold off until the weekend when even hotter conditons move in.
Held off on any headlines on this shift.

As for precipitation, there is a surface trough across the western
Dakotas and WY/MT border region. This will be a focus for widely
scattered thunderstorm potential into the evening hours. Some of
this activity may drift into central SD later tonight, potentially
aided by an increase of a 35-40kt southwesterly low-level jet across
southern SD. Did include slight chance (20%) PoPs for this
possibility. This trough remains in place through Friday, and we
reset the mechanism again for potential showers and thunderstorms
during the late afternoon over western into central SD. With a weak
mid-level disturbance also drifting eastward, some activity may
persist into central/northern SD into the evening/overnight hours.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 316 PM CDT Thu Jul 11 2024

The high heat and humidity will be the main focus in this period,
but along with that will come some chances for convection for some
of our forecast area. The Four Corner centered mid level anticyclone
will be the main driver of the upper flow pattern across the western
CONUS this weekend into early next week. This feature will in part
help to drive our increasingly hot conditions this weekend. While
this upper high remains to our southwest, our region will see more
quasi-zonal flow across the northern tier from the Northern High
Plains into the Northern Plains. Mainly weak embedded mid level
waves will periodically traverse through this flow across our
region. Lee side sfc troughing across the Plains will continue to
promote the influx of a warm and moisture rich air mass. Sfc dew
point temperatures will climb into the upper 60s to low 70s this
weekend. Combining this with temperatures topping out in the 90s to
perhaps near 100 degrees will lead to heat indices in the upper 90s
to low 100s in spots. Will have to consider heat headlines in future
forecast packages if this trend continues. The caveat still at this
point on location and timing of this highest heat/humidity will be
when and where convection takes place and how that may affect
ambient daytime conditions Saturday and Sunday.

The aforementioned embedded mid level shortwaves combined with a sfc
trough/frontal boundary will lead to development of scattered
convection across the region. Guidance progs the first wave in this
period will be cresting over the upper ridge late Friday into
Saturday across MT/ND and shifting eastward into parts of the
eastern Dakotas and Minnesota. Steepening mid level lapse rates and
increasing instability on the order of about 3000-5000 J/kg of
MUCAPE are progged to be present in the region. The one uncertainty,
moreso for our area, is the amount of convective inhibition that
could be present at this time, which would curtail any thunderstorm
activity. With that modest EML in place, we could be looking at more
of a capped environment for our forecast area, with perhaps the
exception of our northeast/east zones, which could be on the
periphery of the upper ridge. Just will have to continue watching
the trends as more hi-res guidance picks up on this wave and
hopefully more clarity comes with that. A somewhat continued active
pattern will persist into early next week as the pattern remains
fairly unchanged. Periodic, low-end chances for more convection will
be possible as these mid levels waves move through the region. The
passage of a stronger frontal boundary sometime early-mid next week
will bring accompanying precip chances along with a cooler and less
humid air mass.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1231 PM CDT Thu Jul 11 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. A stray shower
or two are possible across central SD late tonight, so have
included a VCSH mention at KPIR.


&&

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

$$

SHORT TERM...TMT
LONG TERM...Vipond
AVIATION...TMT