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442
FXUS63 KUNR 111007
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
407 AM MDT Tue Jun 11 2024

.KEY MESSAGES...

- Near to above average temperatures with chances for
  an afternoon/evening storm or two on Wednesday and Thursday.

- Stormy weather returns by Friday with chances for daily
  storms through early next week

&&

.DISCUSSION...(Today Through Monday)
Issued at 110 AM MDT Tue Jun 11 2024

 WV imagery depicts broad low pressure swirling in the northern
Pacific. Far to the south, a cutoff low spins off the coast of
SoCal. Slightly closer to home, upper air analysis depicts a weak
upper ridge building over the northern Rockies in the wake of the
shortwave that was responsible for our storms today. Dry air in
the mid-upper levels has filtered into the region behind the
shortwave and attendant front with mostly clear skies as a result.
The airmass at the surface is still pretty soupy with
temperatures in the mid to upper 50s and dewpoints in the low 50s.
The airmass is pretty shallow and the westerly winds are likely
strong enough to dissuade any fog from developing overnight.

Weak ridge builds into the region today with warm temperatures
and dry weather expected. Zonal flow sets up over the region with
strong 250mb jet streak displaced just to the north of the CWA.
This will facilitate near to above average temperatures. Moisture
will be very limited so widespread convection is not expected but
an isolated afternoon/evening thunderstorm can`t be ruled out
Wednesday and Thursday as weak disturbances ripple through the
flow. Wednesday will be the warmest day of the week with
widespread highs in the 80s. Some areas may breach the 90 degree
mark for the first time this year, especially in south central SD.

Upper low over the northern Pacific will begin to make its way
onshore with a trough digging south into CA. The cutoff low off
the coast of SoCal will get integrated into the flow. This will
give us our next real chances at thunderstorms Friday into the
weekend. Individual ensemble runs diverge slightly past this
weekend but cluster analysis depicts broad troughing over the
western US by early next week with associated unsettled and cooler
weather possible.

&&

.AVIATION...
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(For the 12Z TAFS Through 12Z Wednesday Morning)
Issued At 407 AM MDT Tue Jun 11 2024

VFR conditions are expected through the TAF period.
-- End Changed Discussion --

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...Johnson