Funnel Cloud in Idaho, May 20, 2019

Area Forecast Discussion
National Weather Service Boise ID
918 AM MDT Mon May 20 2019

.DISCUSSION...Showers continue across the area this morning, with
wet and cool conditions persisting. Models continue to show an
increase in instability this afternoon, especially across the
northern third of the forecast area, and into the Magic Valley.
Some isolated thunderstorms possible through the evening hours.
The next area of low pressure continues to nose into the Pacific
Northwest this afternoon, helping to regenerate showers across
Oregon. Unsettled conditions then continue tonight and into
Tuesday. No changes planned to immediate forecast.

&&

.AVIATION...VFR/MVFR with local IFR in rain and low stratus.
Mountains obscured. Isolated thunderstorms developing this
afternoon. Snow levels: 7000-8000 ft MSL dropping to 5500-6500 ft
after 21/12z. Surface winds: variable 12 kts or less. Winds aloft at
10k ft MSL: west-northwest 10-20 kts.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Thursday...An upper low positioned
over the Great Basin will slowly slide eastward today. Showers
and thunderstorms will development on the backside of the low,
over southwest Idaho and far southeast Oregon. Stronger showers
and thunderstorms will bring heavy rain and wind gusts to 30mph.
By early evening precipitation coverage increases across southeast
Oregon as a separate low pressure system approaches the Oregon
coast. Widespread rainfall will continue through Tuesday as this
low tracks from southwest Oregon into northern Nevada. Seeing good
model agreement that the bands of heavier precipitation initially
set up over east-central Oregon and the west-central Idaho and
Boise mountains through early Tuesday, filling in across southeast
Oregon during the day Tuesday. The low drops into southern Nevada
by Wednesday morning, before lifting northeastward on Thursday.
This track will gradually pull the focus of precipitation eastward
so by Thursday the chance of showers is centered across the
higher terrain of southwest Idaho, while southeast Oregon trends
drier. Snow levels will be lowest across southern zones which are
closest to the low track. Expect accumulations as low as 6k feet
across the Steens and Owyhee Mountains and down to around 7k feet
across the west-central and Boise mountains. Temperatures will run
10-15 degrees below normal through Thursday.

LONG TERM...Thursday night through Sunday...Active pattern will
continue through the period with several low pressure systems
moving through. Another low pressure system moves southward from
western Canada Friday with the cold front bring showers and
thunderstorms to the region. Over the weekend, the low will move
south along the West Coast, maintaining showers and gradually
warming temperatures. Through the holiday weekend, each morning is
likely to start off dry and develop showers and thunderstorms in
the afternoon. The low will finally move over the forecast area on
Monday for widespread precipitation and below normal
temperatures. Temperatures will remain 10-15 degrees below normal
through the period with some warming by the weekend while snow
levels will hover around 7500-8500 ft MSL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise

DISCUSSION...KB
AVIATION.....AL
PREV SHORT TERM...DG
PREV LONG TERM....JS