FXUS65 KBOI 242045

Area Forecast Discussion
National Weather Service Boise ID
245 PM MDT Thu May 24 2018

.SHORT TERM...Tonight through Saturday...An upper level ridge will
move across the area overnight, as our next upper level low moves
onshore over northern CA. This low is expected to help create
strong to possibly severe convection across the area late tonight
and tomorrow. SPC has placed most of our forecast area in a
"marginal" risk for severe thunderstorms. This category means that
isolated severe storms are possible. A convective complex is
expected to develop across northeast CA and northwest NV this
evening, and move north into southeast Oregon overnight as it
weakens. After a break Friday morning, new storms will develop
Friday afternoon across southeast Oregon and southwest Idaho, and
these storms will last into the evening. It is this round of
storms that has the best chance to be severe. Threats include
large hail (up to 1.5 inches), strong winds (up to 70 mph), and
heavy rain (total amounts could be over 1 inch in isolated cases).
A dry slot will move into the southeast part of our forecast
area, reducing the chance of convection south and east of
Mountain Home. Tomorrow will also be the warmest day of the
period, with highs in the upper 80s in the valleys. As the upper
low moves into northwest NV Saturday, cooler air will be drawn
southward over the region. Highs Saturday will be around 10
degrees cooler than Friday. Moisture is high through the period,
with PW values between 0.6 and 0.8 inches.

.LONG TERM...Saturday night through Thursday...An upper level low
moving through southern NV through the weekend will bring showers
across the area with afternoon thunderstorms. SE Oregon will begin
to dry out Monday and remain dry through Tuesday. Showers linger in
SW Idaho through the end of the period, but do remain confined to
mostly the higher elevations. A short wave ridge does build over the
region Tuesday afternoon, but yet another upper level trough begins
to impact our CWA by Wednesday increasing shower activity.
Temperatures will hover right around normal for this time of year.


.AVIATION...Mostly VFR. Isolated showers and thunderstorms this
afternoon, but with a lot less coverage. A line of showers pushes
into SE Oregon after 07z hitting KBNO by 10z. MVFR/IFR within
heavier showers. Surface winds, variable 10kts or less with gusts in
and around thunderstorms 20-30kts. Winds aloft to 10k feet MSL,
westerly 10-15kts through 00z then south-southeast 15-25kts.






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