088
FXUS63 KABR 091517 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1017 AM CDT Tue Jul 9 2024

.KEY MESSAGES...

- Isolated afternoon showers and thunderstorms (15-25% chance of
  precipitation) possible over portions of northeastern SD and
  west central MN this afternoon into Wednesday afternoon.

- Hazy conditions continue this evening through Wednesday as
  northwest flow is bringing in periodic waves of smoke from
  Canadian wildfires. Much of this is expected to remain aloft,
  with little to no reductions in visibility at the surface.

- Heat and humidity are the top focus for the extended. Highs
  will be in the 90s (5-10 degrees above average) Friday through
  Sunday, with enough humidity to bring the afternoon heat index
  values into the mid and upper 90s with a few spots to 100F.

&&

.UPDATE...
Issued at 1010 AM CDT Tue Jul 9 2024

Not much in the way of changes needed to the forecast through 00Z
today. Watching smoke aloft move south across the Dakotas, with
models suggesting thicker coverage, and perhaps some potential for
near-surface smoke by morning. Highs are still on track for
readings in the 80s to near 90 degrees (central SD). Will also be
watching potential for afternoon pop-up showers/thundershowers
once again, although coverage of any non-severe storms is expected
to remain isolated/widely scattered and confined to areas east of
the Missouri River.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 327 AM CDT Tue Jul 9 2024

Elevated smoke continues to sink in from Canadian wildfires. There
are other significant wildfires over the western US over north
central WA, southern OR/northern CA, and southern UT, stuck under
the high amplitude 500mb ridge set up across the west coast up
through British Columbia. North to northwesterly flow will remain
over the Northern Plains through this evening, before the ridge
pushes into our area during the day Wednesday. The center of the
500mb high will remain over NV/southern CA/western AZ.

As for the local specifics, we once again won`t be able to rule out
mainly isolated (15-25%) chances of precipitation this afternoon
east of the Missouri River.  The mid 50s to mid 60s dewpoints remain
and daytime heating will again help allow summertime cumulus to
develop. Unlike the last couple of nights, showers and a few rumbles
of thunder could linger longer into the evening with assistance of
the weak shortwave currently set up over northern to central
Saskatchewan and Manitoba sinking across eastern ND by 00Z Wednesday
and our forecast area during the late evening and overnight hours.
Afternoon showers and thunderstorms will again be possible
Wednesday, mainly focused closer to the MN/ND border as that 500mb
ridge starts to become more dominant.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 327 AM CDT Tue Jul 9 2024

Really not that much to talk about that hasn`t already been
addressed over the last several long term discussions. The main
focus is on heat and humidity associated with an upper high
expanding northeastwards into the 4 Corners region which will come
to dominate the upper flow in the days to come.

We still see an initially tight thermal and pressure gradient at
850mb Thursday with high pressure over the eastern CWA. As that
feature retreats, that is when we begin to see the more widespread
heat and increase in humidity. NBM dewpoints remain in the mid/upper
60 to near 70 degree range for all 3 days (Fri - Sun). NBM 90th
percentile dewpoints only gets into the low 70s. As for
temperatures, there is a 10 to 30 percent chance of exceeding 100
degrees along and west of the Missouri (highest in
Jones/Stanley/Lyman) Saturday and a 30 to 60 percent chance for the
same area Sunday, with a 15 to 30 percent probability between the
James and Missouri river valleys. Those two factors combined only
gets us a heat index in the mid/upper 90s Saturday and Sunday
(Sunday afternoon features an hour or two with a few spots to 100).
HeatRisk also puts more emphasis on Sunday as well.

NBM does officially have a mention for thunder Saturday as the core
of the elevated mixed layer (700mb temperatures) takes until Sunday
to move overhead. There is also a weak wave that will ride over the
ridge around the Saturday timeframe, and the warm advection at 700mb
may also be the impetus for convection.

The ridge will be slightly suppressed for Monday/Monday night. Its a
rather subtle wave which enhances the flow aloft, with a more
northwesterly component and low chance for moisture. Additionally,
we see a drop in temperatures across the NBM and GEFS plumes. Still
quite a bit of range/uncertainty (6-8 degrees) for highs Monday w/
the NBM 25th/75th percentiles. We also see a rather significant
suppression of dewpoints for the first half of next week with the
NBM mean down into the low 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 637 AM CDT Tue Jul 9 2024

Terminals KABR,KATY,KPIR,KMBG

Smoke continues to push south from wildfires in Canada, staying
mainly elevated through the forecast period. MVFR visibility will
continue initially at ABR, with the main restriction just over the
weather station itself as visibility elsewhere across the airport
has improved to near VFR conditions prior to 12Z. VCSH have been
added to ATY for this afternoon, as they have the highest
(generally 20-30%) chance of precipitation.


&&

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

$$

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