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000
FXUS63 KABR 130923
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
423 AM CDT Sat Apr 13 2024

.KEY MESSAGES...

- Warm weather continues into Monday. Highs in the 80s today
will be 25 to near 30 degrees above normal.

- There is the potential for fain and weak thunderstorms with the
system early next week, with about a 50% chance for an inch total
moisture.

- Colder temperatures, around 10 to 15 degrees below normal, can
be expected for the latter half of next week.

&&

.SHORT TERM /TODAY THROUGH SUNDAY AFTERNOON/...
Issued at 422 AM CDT Sat Apr 13 2024

Warmer air will push in today, allowing temperatures to rise into
the low 80s. As noted in the previous discussion, the NBM continues
to run on the lower end of the 5 degree spread in the 25-75th
percentiles for high temperatures not only today, but for Sunday
too. Confidence is lower on temperatures from PIR to MBG, which could
end up 2-4 degrees higher than the current forecast of 82-85
degrees. There are a couple of concerns, particularly with the
timing of the slightly cooler air moving into north central SD late
this afternoon. 850mb temperatures should top out 14 to 20C (highest
over central SD) on westerly winds before winds shift out of the
northwest. The surface low set up across southern Saskatchewan/near
the MT/ND border through western SD will shift east near the MO
river by 15Z and the James River Valley by 21Z before exiting into
southern MN and southeastern SD by 03Z Sunday. Very dry air will
move into central SD this afternoon, with relative humidity level s
falling into the teens. Grassland Fire Danger Index Values will be
in the high category today (level 3 of 5, 1/low-5/extreme). The
shifting winds could raise concerns for any ongoing fires, from out
of the south to southeast early this morning to out of west between
15 and 18Z across central SD. Winds across the entire forecast area
will by out of the west or northwest by 23Z. The strongest wind
today will be over the Prairie Coteau of northeastern SD this
morning with gusts of 25-35kts, highest over the downslope areas
given the winds out of the south. These strongest winds will
diminish during peak heating, when relative humidity levels there
drop into the 25 to 35 percent range. Given the timing differences,
will not issue any fire weather headlines at this time, but will
monitor our southeastern counties (particularly Deuel County) where
the gusty winds stay the longest this morning/early this afternoon.

Behind the area of low pressure, and on northerly winds, 850mb
temperatures will fall into the 6 to 13C range by 18Z before warmer
air starts to shift back in again. The surface high over southern
Saskatchewan at 12Z Sunday will move over far northeastern SD and
into MN Sunday afternoon. Highs Sunday in the 70s to near 80 degrees
look reasonable, but wouldn`t be surprised if temperatures ended up
being 2-5F higher than the current forecast (with the greatest
change over central SD/where warm air advection will take hold
sooner).

&&

.LONG TERM /SUNDAY EVENING THROUGH FRIDAY/...
Issued at 422 AM CDT Sat Apr 13 2024

Not much overall change to the forecast. Start with a ridge
overhead, northwest zonal flow across southern Canada into the
eastern CONUS and a cut off low over California/Nevada. The ridge
overhead stays in place through the day Monday, while the upper low
moves into the 4-Corners region. 850mb temperatures are still at the
high end of a standard deviation above climo (just shy of 2 standard
deviations), with a gradient in those temperatures aloft from
southwest to northeast across the state.  Low level flow becomes
increasingly southeasterly as a lee low forms in northeast Colorado.
Despite the ridge, mid level warm advection will support skinny mid-
level CAPE with the potential for some showers and weak
thunderstorms.

The upper low ejects into the Central Plains Monday night, taking
into Tuesday night before it makes the Western Lakes region. Can`t
really discern any trend in this storm track and NBM POPs, P-Type
and probabilities of 1" total are about the same. There has been a
slight upwards bump in temperatures for the rest of the extended
however, with the colder airmass for the latter half of next week.

The only real hazard through the extended will be the aforementioned
southeast winds Monday-Tuesday. This is similar to the last windy
system, with the strongest 1/2km winds during a period of neutral
advection. There will again be about a 20mb gradient across the
state from east to west, transitioning to a 10mb gradient from north
to south as the low moves to our south. The gradient lingers into
Wednesday when we do see cold advection enhancement of winds to the
surface...as such a windy 24-48 hour period. GFS 1/2km winds not
quite as strong as the last one however, at only 30-40kts. There may
be a window Monday afternoon where fire weather is still a concern,
despite the slow spring green-up, something we will need to watch as
the system gets closer.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1123 PM CDT Fri Apr 12 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected through Saturday.


&&

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

$$

SHORT TERM...KF
LONG TERM...Connelly
AVIATION...Wise