172
FXUS63 KUNR 060804
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
204 AM MDT Thu Jun 6 2024

.KEY MESSAGES...

- Breezy northwest winds continue today especially across
  northwestern into south central SD

- Warm weather expected through early next week with some chances
  for showers and storms returning over the weekend.

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 203 AM MDT Thu Jun 6 2024

Current upper air analysis depicts upper low centered over MB/ON
with 300 mb jet streak over ND/MN/eastern SD. Skies over the CWA
are clear with temps in the 40s to 50s and light northwest winds.
Sfc low that was over MB this afternoon has drifted eastward with
high pressure building in from the west.

Breezy northwest winds continue today as the upper level jet
lingers overhead. The strongest winds aloft will be to the
northeast of the forecast area with low chances for advsy level
gusts mixing down in some spots across northwest SD. Due to
limited coverage and duration as well as low confidence in these
gusts materializing: have opted to not issue any wind headlines
for today. We could still see gusts of 30 to 40 mph this
afternoon, especially over northwestern into south central SD and
our usual "squeeze" spots near the Black Hills.

Northwest flow pattern will continue through the weekend with
mostly dry and warm conditions across the forecast area. 700 mb
lee shortwave develops late Thursday/Friday and ejects over NE by
midday Friday. ML CAPE of 1000-1500 J/kg will stay mostly in NE
with values of 500-1000 J/kg over far southern SD. The better
shear will remain to the north and east of the best CAPE values
but there could be enough to result in a few strong to marginally
severe storms over southern SD Friday afternoon. Limiting factor
for convection will be high CIN (around -70 to -100 J/kg) and
meager moisture. Chances for showers and storms across southern SD
will continue through Saturday.

Forecast uncertainty increases through early next week as the
models aren`t quite in agreement as to the evolution of the upper
level pattern. There are some hints in the most recent
deterministic runs of the Euro and GFS of an upper low flattening
out the ridge and putting the northern plains under a more zonal
flow pattern with the Canadian having troughing over the northern
plains. However these features haven`t been consistent in the
model to model runs. Which is to say: forecast confidence
decreases by early next week as to the exact evolution of the
upper level flow. How this upper level pattern develops will
determine the likelihood of storms early next week as well as
temperatures later in the week (though ensemble output has been
fairly consistent as to much warmer air moving into the region by
late next week).

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1025 PM MDT Wed Jun 5 2024

VFR conditions are expected through the forecast period.

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...13