Scientific Forecaster Discussion
fxus65 kboi 181542
Area forecast discussion
National Weather Service Boise Idaho
942 am MDT Wed Sep 18 2019
Discussion...upper level low pressure system over the Pacific
northwest today will continue widespread precipitation across
much of the forecast. Radar is showing the band of precipitation
over the Idaho/Oregon border slowly moving east-northeast this
morning. This area will weaken as it lifts out of the forecast
area with convective showers and thunderstorms developing behind
it. The stronger cells will produce heavy rain but should be
shortly lived. As the low moves over the forecast area tonight,
another precipitation band develops over south-central Idaho
bringing periods of moderate rainfall. Current forecast has these
trends covered well so no updates need at this time.
Aviation...widespread showers over eastern Oregon and the west
central Idaho mountains this morning. Precipitation will become
showery in nature this afternoon with isolated thunderstorms through
the evening. Expect mountain obscuration and areas of MVFR/local IFR
conditions. Snow levels 8k-9k feet mean sea level today lowering to 7k-8k feet
mean sea level Thursday. Surface winds SW-northwest 5-15kt with gusts up to 30kt in
thunderstorms. Winds aloft at 10k feet mean sea level southwest 20-30kt
becoming variable 5-10kt by 12z/Thu.
short term...today through Saturday...a stalled band of showers
continues west of a McCall-Ontario-Rome line early this morning.
The band is expected to remain nearly stationary until mid-
morning, then slowly drift eastward and weaken late this morning.
Showers and isolated thunderstorms will accompany an upper low as
it slowly moves into the pacnw this afternoon and evening,
including southeast Oregon and southwest Idaho. The upper low will
be centered over our area on Thursday for more showers and a
slight chance of afternoon thunderstorms. Snow levels will lower
to around 7500 feet by Thursday night with light snow
accumulations possible on the peaks. The low will finally start to
move to our northeast on Friday, although there is a chance for
showers to continue in southwest Idaho. Drier air will accompany a
weak upper ridge Friday night and Saturday. Temperatures will be
around 10 to 15 degrees below normal through Friday and 5 to 10
degrees below normal on Saturday.
Long term...Saturday night through Wednesday...models are in
good agreement. The next upper level trough from the Gulf of
Alaska is scheduled to arrive on Sunday, spreading showers across
our area by Sunday night. Showers are expected to end on Monday as
the trough exits to the south and stalls over Southern
California. Temperatures will be a few degrees below normal Sunday
and Monday and near normal Tuesday and Wednesday.