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004
FXUS63 KABR 040215 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
915 PM CDT Fri May 3 2024

.KEY MESSAGES...

-- Changed Discussion --
- A banded rainfall event over the southern/eastern portions of
  the forecast area will relocate to mainly just the eastern
  portion of the CWA through late tonight. Rainfall amounts in
  excess of one half inch can be expected overnight.

- High pressure will bring dry and warmer conditions this weekend.

- A much larger system looks to affect the region on Monday, with
  widespread moderate rainfall. The threat for severe weather still
  appears low at this time (higher across NE/KS/OK), but we will
  continue to monitor trends.
-- End Changed Discussion --

&&

.UPDATE...
-- Changed Discussion --
Issued at 845 PM CDT Fri May 3 2024

A very favorable set-up for banded precipitation has unfolded (and
is ongoing), between strong low to mid-level fronto-forcing and a
100+knot upper level speed maximum. For a while, there were some
strong returns showing up within this band of rain, and some of
that could have been caused by bright-banding (occurs when the
radar assigns too high a reflectivity/rainfall rate to water
coated snowflakes falling through the melting layer). Legacy and
dual-pol rainfall estimates off the KABR 88D have maxed out at
~2.00-2.50 inches and ~1.50-2.25 inches, respectively. MRMS
estimates are lower (more reasonable) ranging from ~0.50-0.75
inches of rainfall along a stretch from northern Hand County
through Spink and Clark Counties up into Day County. There`s
plenty more forcing/lift to be had over the next ~6 hours or so,
particularly over northeast South Dakota into west central
Minnesota. Perhaps another 0.10 to 0.25 inch of rain could happen
along and east of a line from Miller, SD to Wheaton, MN. Low
temperatures still look okay for tonight.

UPDATE Issued at 647 PM CDT Fri May 3 2024

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

.SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/...
Issued at 315 PM CDT Fri May 3 2024

An upper level trough currently west of the region will track across
the Dakotas tonight, with a fairly potent shortwave affecting mainly
the eastern part of the CWA. The trough weakens as it exits the area
on Saturday, with ridging then building in Saturday night.

At the surface, the region is currently situated between a low
pressure system over southern Ontario and a low over Colorado. The
boundary between these two systems will be the focus for rain late
this afternoon and tonight as the aforementioned shortwave moves
over the area. Currently seeing some scattered shower activity over
mainly the western half of the CWA, but expect this area of rain to
become more of a line from southwest to northeast by this evening,
generally extending along and east of a line from west central
Minnesota to Murdo. The area of rain will then spread eastward
tonight. Right now, thunderstorm potential looks to stay south of
the CWA, but cannot rule out a stray thunderstorm maybe affecting
the southeastern CWA this evening. The highest rainfall amounts are
expected along and east of a line from Wheaton, MN to Murdo, where
one quarter to one half inch looks to occur. Should a thunderstorm
develop, there could be some locally higher amounts.  High pressure
will settle over the region Saturday and Saturday night, bringing a
return to dry conditions.

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

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 315 PM CDT Fri May 3 2024

This forecast period begins Sunday morning on a relatively quiet
note compared what were anticipating to be another round of active
and wet weather through the majority of next week. Upper level
ridging will build overhead on Sunday in response to an upper level
trough/low moving through the Great Basin and adjacent regions of
the western CONUS. Sfc high pressure will be positioned off to our
east while low pressure will be situated across the lee of the
Rockies and Northern High Plains on Sunday. Southerly low level flow
will intensify through the daytime as the pressure gradient
tightens. Increasing southerly winds through the day will
potentially reach advisory criteria, especially across our western
zones. NBM probabilities of seeing max wind gusts greater than or
equal to 34kts(40mph) is high(70-100%) along and west of the
Missouri Valley. At this point in time, the thinking is that this is
a bit on the high category or extreme, so will continue to take a
more conservative approach and keep an eye on trends with incoming
future guidance data. With a decent amount of sunshine to round out
the weekend and dry conditions expected, we should see a nice warm
up. 950mb temps are expected to reach about +13C to +19C which
translate to highs in the 60s to low 70s across the forecast area.

Unfortunately, all good things have to end sometime and we`ll see
the pattern shift quickly by Monday into a more active and wet one.
The aforementioned upper low is progged by both deterministic and
ensemble guidance to track northeastward out of the Rockies into
portions of the Northern High Plains and Northern Plains early next
week. This system looks to be rather vigorous on Monday as sfc low
will track into the Central Plains and shift northward into our
region. Severe weather parameters looks best across the Central
Plains and south of our region by Monday afternoon and evening,
however we can`t totally rule out some stronger activity in parts of
our area. As of right now, our forecast area is just outside of the
northern fringe of the better instability. MUCAPE values on the
order of about 300-500 j/kg is possible, especially across our
southern zones with far more higher values to the south in parts of
NE and KS. We`ll just have to keep track of the trends over the next
couple days to see if there`s any movement farther north with these
better ingredients.

The upper flow pattern remains unsettled at least through the middle
of next week and perhaps even through the end of this period.
Guidance progs a stagnant pattern locally with the upper low or
trough meandering and spinning just off to our northwest. Multiple
s/w`s in southwest flow aloft over our region will likely keep on
and off shower chances persisting through the week. Underneath the
more extensive cloud cover that anticipated, temperatures will be
held in check close to normal but probably falling short of average
for this time of year. Daytime values in the 50s and 60s can be
expected with overnight temperatures in the 40s.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 647 PM CDT Fri May 3 2024

Terminals KABR,KATY,KPIR,KMBG

Periods of MVFR cigs and MVFR/IFR vsbys will be possible under the
banded rain shield that extends from south central South Dakota
(KPIR) up through west central Minnesota (KATY). The whole band
of rain is translating east-northeast, and is forecast to be
clear of both KPIR and KATY by 06Z tonight. VFR conditions already
ongoing at KMBG and KABR are forecast to persist through the TAF
valid period. VFR conditions are forecast to establish at KPIR and
KATY overnight and then prevail at those two locations through the
rest of the TAF valid period.

&&

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

$$

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