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000
FXUS63 KUNR 091126
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
526 AM MDT Fri Jun 9 2023

.DISCUSSION...(Today Through Thursday)
Issued at 342 AM MDT Fri Jun 9 2023

A slow moving, wet pattern will bring beneficial rains to much
of the area today and Saturday. Upper ridging across the central
CONUS and central Canada is in the process of breaking down, as an
upper low over the western CONUS phases into an approaching longwave
trough. A surface low sits across northeast WY, with eastern low
level flow across much of SD. A series of upper waves will push into
the CWA from the southwest, coinciding with peak heating and ample
surface moisture to result in thunderstorm development. Storm
initiation is first expected over the Black Hills around noon, then
coverage will expand primarily across northwest SD in a line moving
toward the northeast. Forecast soundings show plenty of instability,
with CAPE of 2000 J/kg; however, shear remains weak. While storms
are expected to be of the pulse variety, a few storms may be strong
for short periods, with small hail. PWATs will generally be 150-175%
of normal, and storm motion will be very slow today, which will
result in locally heavy rainfall. However, a Flash Flood Watch is
not anticipated due to relatively dry conditions/soil moisture that
have developed over the last 3 weeks. Will let the day shift
reassess with 12z runs. Storms will move into northwest to central
SD tonight, then push back westward Saturday morning as an upper
wave drops south across central Canada into ND. Western SD and
northeastern WY will get round two of precip through the day
Saturday, as cooler air pushes into the CWA along a Midwest backdoor
cold front. Precip will weaken Saturday night. QPF totals over a 48
hour period are expected to be above half an inch of rain. Many areas
will see over an inch...and wouldn`t be surprised if a few locations
received over 2 inches. Weak ridging will bring drier weather to the
region through early next week, but confidence in model output is
lacking with this pattern scenario. Near daily chances of precip are
still expected.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 522 AM MDT Fri Jun 9 2023

Cloud cover will increase through the morning with showers and
thunderstorms developing by the afternoon. Ceilings remain VFR
through the day, then areas of MVFR ceilings develop this evening
and overnight. IFR to MVFR conditions in vicinity of heavier
showers and thunderstorms.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...13
AVIATION...15