Scientific Forecaster Discussion
fxus65 kboi 222049
Area forecast discussion
National Weather Service Boise Idaho
249 PM MDT sun Sep 22 2019
Short term...tonight through Wednesday...upper trough along the
Oregon coast this afternoon will continue to dig toward Arizona.
Associated instability this evening over eastern Oregon should
easily support showers and thunderstorms. A few storms could
tap into shear, and higher winds aloft, and organize into longer
lived cells, with gusts to near 40 mph, and these could drift
into Idaho as the evening wears on. Best chance for precip is in
southeast Oregon, and over the higher terrain of southwest Idaho,
but can't rule out a shower in the lower elevations of southwest
Idaho too. As the trough splits - it rapidly diminishes the precip
chances by Monday morning, but a few showers are possible in the
Magic Valley, and over the Idaho mountains early Monday. Then
drier, cooler, northwest flow takes hold for Monday afternoon
through Wednesday. Expect breezy afternoons each day with this
pattern, especially in the Magic Valley - and temperatures near,
or slightly below, seasonal normals.
Long term...Wednesday night through Sunday...daytime temperatures
will gradually drop to nearly 20 degrees below normal by the end of
the period as a trough deepens over the intermountain west. Numerous
waves of precip from the cycling low pressure will spread rain and
snow showers across the region throughout the extended. Snow levels
will fall between 5000-6000 ft mean sea level over most of the cwa, taking a
plunge on Sunday to below 3500 ft across SW or.
Aviation...VFR. Cloud cover and isolated showers increasing in
coverage from west to east this afternoon, causing local MVFR and mountain
obscuration. Isolated thunderstorms across southeast Oregon through 23/06z.
Surface winds: S to southeast 5-15 kts, becoming northwest less than 10 kts
overnight. Winds aloft at 10kft msl: SW 10-20 kts.