Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 060906

Area Forecast Discussion
National Weather Service Boise ID
306 AM MDT Tue Jun 6 2023

.SHORT TERM...Today through Thursday night... A favorable setup
for strong outflow thunderstorm winds tonight. Isolated wind
gusts up to 60 MPH will be possible especially along the Nevada
border. Outflow winds of 20-40 MPH will likely make it to the
Treasure Valley and across much of southeast Oregon later tonight.

Satellite showing the next upper level low pressure system over
central California at 08z, which is expected to remain mostly
stationary through tonight. However, the northern flank of this
system will reach the southern forecast area later this afternoon
providing the forcing for thunderstorm development. This area of
increased instability is already evident on satellite/radar this
morning across central Nevada where nocturnal thunderstorms have
already developed. Effective shear of 25-30 kts and SB CAPES
around 1500 J/KG will be sufficient for isolated strong to severe
storms to form around 21z basically southwest of the Western
Snake River Plain. Inverted-V profiles and high PW values support
strong to severe outflow wind gusts along with hail and heavy
rain. Outflow winds will continue northward into the Western Snake
River Plain and across much of southeast Oregon though convective
parameters will be less favorable the further north the storm
travel. Thunderstorms will be limited to southwest Idaho by early
evening were instability and shear remains somewhat marginal
through midnight.

Another round of strong thunderstorms is expected on Wednesday as
the low pressure system moves north into west-central Nevada. The
central mountain of Idaho and Harney county look to have the most
favorable conditions for stronger storms (50% chance). The
stronger storms will bring gusts winds, small hail and heavy rain.
The low center continues north into northwest Nevada by Thursday
afternoon and then southeast Oregon by Friday morning for
widespread showers and thunderstorms. Instability and shear are
lacking however, moisture will be quite favorable for periods of
heavy rain with the stronger storms. Temperatures will remain
above normal.

.LONG TERM...Friday through Tuesday...An upper level low will be
located over or very near our area to begin the long term period.
This low will weaken and move into western Oregon Saturday as a new
low develops over southern CA. This new CA low will then drift north
into NV Monday. This will bring a continuation of showers and
thunderstorms each aft/eve, occasionally lasting overnight. The best
chance for precipitation (30-70 percent) will be on the Idaho side.
Temperatures will be near normal during the period. Precipitable
water values will generally be near or above 1.0 inches (above the
90th percentile), which will continue the threat of heavy rain and
flash flooding. Gusty winds and small hail are also possible.


.AVIATION...Mainly VFR. Showers and thunderstorms, mainly
over the ID side and in the vicinity of KREO, will develop after
06/21Z, bringing areas of MVFR with reduced visibilities due to
heavy rain and lowered ceilings. There will also be mountain
obscurations and gusty outflow winds up to 40 kt. Surface winds:
variable 5-10 kt. Winds aloft at 10k feet MSL: Generally S 5-15 kt.





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