868
FXUS63 KUNR 191050
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
450 AM MDT Wed Jun 19 2024

.KEY MESSAGES...

- Below normal temperatures continue through Thursday.

- Mostly dry conditions today, but unsettled weather returns
  Thursday through the weekend.

- Warming trend over the weekend.

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 224 AM MDT Wed Jun 19 2024

Current surface analysis show surface high pressure situated over
far southeastern MT this morning. Water Vapor and upper air models
show upper wave that moved through the northern plains now
situated over western Ontario, with upper trough over the PAC NW
and southwest flow over our region. Current temperatures sit in
the 40s over western SD, while the Black Hills and northeastern WY
have dropped into the 30s over some areas. Light winds along with
near freezing temperatures over some areas may allow for some
frost to develop early this morning, mainly over northeast WY and
the Black Hills.

Surface high passes over the region this morning and afternoon,
allowing for mostly dry and cooler conditions to continue.
High temperatures will stick around the mid 60s to low 70s. Some
isolated showers may pop up this afternoon over northeastern WY,
the Black Hills, and northwestern SD, but expect most of the
region to remain dry today. On the back side of the high later
today, low level southeasterly flow returns, allowing for warmer
air and moisture advection. Increasing theta-e will bring a better
chance for precipitation tonight into Thursday. Ample shear in the
region, however MU CAPE of 200-500 j/Kg tonight should limit
severe potential and keep general storms and showers through
Thursday. Better chance for severe potential remains on Friday, as
a disturbance makes its way across the northern plains. Still good
40-50 kt 0-6km shear over the region on Friday, with better
available energy, especially closer to south central and central
SD, with models showing ML CAPE values in the 1000-2000 j/Kg
range. Severe potential will likely depend on timing and
placement of the wave as it moves through the northern plains
Friday.

Following passage of the shortwave, conditions will
improve later Saturday into Sunday. Upper models show ridge
building over the Rockies in this timeframe, sliding over the
northern plains early next week, bringing warmer and dry air over
the region. Highs should climb back into the 80s by Sunday, and
perhaps low 90s on Monday. Early next week, ridge breaks down into
more zonal flow over the forecast area, though right now models
show any disturbances well north of the region.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 449 AM MDT Wed Jun 19 2024

Areas of MVFR ceilings from near the Black Hills into central
South Dakota will dissipate this morning. A few showers and
thunderstorms are possible late this afternoon into tonight with
local MVFR/IFR conditions. Gusty southerly winds will be found
across the area today.

&&

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

$$

DISCUSSION/KEY MESSAGES...Dye
AVIATION...7