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919
FXUS63 KABR 201738 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1238 PM CDT Thu Jun 20 2024

.KEY MESSAGES...

- There is a 50 to 90 percent chance for showers and thunderstorms
  today through Saturday. Some storms may be strong to severe across
  parts of south central South Dakota this afternoon and evening, then
  across much of the area Friday afternoon and evening.

- A more quiet stretch of weather is anticipated by the second half
  of the weekend into early next week. Dry conditions look to take
  hold Sunday through Monday with much warmer temperatures and muggy
  conditions setting in.

&&

.UPDATE...
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Issued at 1234 PM CDT Thu Jun 20 2024

Issued a Flood Watch for portions of the area mainly south of Hwy
212. Portions of the watch area have a slight to moderate risk
for excessive rainfall through Friday. 1 to 3 inches of rain has
already fallen in the last 18 hours in Hand and Buffalo county.
More rain, locally heavy at times in thunderstorms, is expected
through Friday night.

UPDATE Issued at 1030 AM CDT Thu Jun 20 2024

Made a few tweaks to hourly pops to slow down northerly advance of
precip. Otherwise, the forecast remains on track this morning.
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&&

.SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/...
Issued at 406 AM CDT Thu Jun 20 2024

Through the near term period, the region will be situated between
upper level high pressure over the southeastern part of the country,
and a trough west of the Rockies. Shortwave energy will be ejected
from the trough over the Northern Plains, though none of it looks to
be particularly strong.

At the surface, high pressure is currently northeast of the CWA, and
a low pressure system is approaching from the southwest. In the
region between these two system, rain is occurring and is extending
from southwest to northeast over the CWA, with most of the rain east
of the Missouri River. This area of rain will continue to track
northeast through the remainder of the overnight hours, then will
become reinforced over the CWA as a warm front associated with the
low to the southwest sets up across the southern part of the state
today, then from southwest to northeast over the CWA tonight and
Friday. Will see 500 to 1000 J/kg of instability and 40 to 50 knots
of shear develop across mainly the southern part of the state later
this afternoon and evening, so may see a few stronger thunderstorms
over the far southwestern CWA. This is noted by a Marginal Risk. By
late Friday afternoon, 1500-2000 J/kg of shear and 40 to 45 knots of
shear develop across parts of the southern CWA, so will again see a
chance for strong to severe storms. This is highlighted be a Slight
Risk across the southern half of the CWA, and a Marginal Risk across
the north for the Friday afternoon/evening time frame. Large hail
and strong wind gusts will be the main threats.

Rainfall amounts will likely be the highest across the southeastern
CWA, where some areas may see amounts in excess of two inches today
through the day Friday. Amounts will become less to the north and
west, but much of the CWA has a good chance at seeing at least one
half inch of rainfall.

High temperatures today will be in the upper 60s to lower 70s. Low
temperatures tonight will be in the mid 50s to lower 60s. Highs on
Friday will be in the 70s.

&&

.LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/...
Issued at 406 AM CDT Thu Jun 20 2024

The active pattern will persist into the beginning of this forecast
period. The upper flow pattern is expected to remain southwesterly
as an upper trough across the Western CONUS shifts out into the
Central Rockies...while an upper ridge remains across the Deep
South. By late Friday into Saturday, the upper shortwave trough is
progged to lift northeast into the Central Plains and Upper Midwest.
This will be followed by a secondary upper trough sliding southeast
across southern Canada into the Western Great Lakes Lakes during the
course of the weekend. Models then indicate an upper ridge will
develop across the Northern High Plains and shift across our region
by late in the weekend into early next week. By the end of the
period, we`re left with more or less quasi-zonal upper flow if not
northwesterly flow as the upper ridge tries to re-assert itself
across the western CONUS.

Friday night into Saturday morning will remain unsettled as sfc low
pressure tracks northeast across a frontal boundary that will be
draped across portions of southern/southeastern SD into southern MN
early on but lift north-northeast into east central SD and central
MN by daybreak Saturday morning. Periods of showers and
thunderstorms look likely(60-90 percent) across the forecast area
with decreasing chances going forward in time overnight through
Saturday morning. Strong to severe storms will be possible across
portions of our forecast area late Friday into Saturday morning.
NAM12 MUCAPE values are rather impressive south of our CWA across
southeast SD into southern MN, but even our southern and eastern
zones are showing 1000-2500 J/kg of MUCAPE Friday night into early
Saturday. 0-6km bulk shear in these areas could be on the order of
about 30-50kts. The collection of ensembles indicate joint
probabilities of SFC CAPE greater than 500, SFC CIN greater than -25
and sfc-500mb bulk shear greater than 30kts highlight a 30-60
percent chance from our far southern zones(I-90 corridor) northeast
into east central SD/west central MN. SPC currently highlights our
southern zones from central/south central SD into parts of east
central SD with a slight risk for severe weather. Heavy rainfall
could be a concern for our eastern zones(east of the James Valley)
through Saturday morning. NBM probabilities of 1 inch or more of
rainfall in a 24 hr period ending Saturday morning remain highest
across east central SD into the northeast corner of SD and into west
central MN. Here...chances currently sit at about a 50-70 percent
chance of seeing that amount of rain.

The pattern returns more tranquil for the most part the remainder of
the period. With that aforementioned upper ridge building in early
next week, temperatures are expected to warm significantly above
normal. In fact, daytime readings on Monday are anticipated to reach
the mid 80s to mid 90s across the CWA. Humid conditions will remain
in place, so it will be a fairly muggy start to the week. The region
may see another disturbance work across the Dakotas Monday night
into Tuesday which could give us a chance for showers and storms
along with slightly cooler temperatures.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
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Issued at 1234 PM CDT Thu Jun 20 2024

Terminals KABR,KATY,KPIR,KMBG

A chaotic mix of cigs is around the region today as rain and
embedded thunderstorms spread north and east. Vsby may be reduced
in heavier rain through Friday.
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&&

.ABR WATCHES/WARNINGS/ADVISORIES...
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SD...Flood Watch through Saturday morning for SDZ018>020-022-023-036-
     037-048-051.

MN...None.
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&&

$$

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