Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
943 am MDT Sat Oct 25 2014
Discussion...update issued about an hour ago due to fog. Fog was
dense in the lower Treasure valley...necessitating the issuance of
a dense fog advisory through noon. A Wind Advisory remains in
effect for southeast Oregon this afternoon. Winds gusting to 50 miles per hour are
forecast there...especially at elevations above 5000 feet.
Otherwise...high clouds moving west to east across the area are
associated with warm air advection in advance of a large upper
level trough moving into the Pacific northwest coast at this time. A cold
front will move through tonight...bringing much cooler weather to
the area tomorrow. Showers will move in tonight and remain over
much of the area through Sunday night. We will continue to monitor
fog to see if forecast high temperatures today need adjusting. No
additional update at this time.
Aviation...IFR/LIFR conditions in fog in the lower Treasure
Valley West of Meridian into northern Malheur County this
morning...improving to VFR by 18z. Elsewhere VFR today with areas
of high-level ceilings. Surface winds...east to south 10-20 kts
becoming southwest 20-40 kts across southeast Oregon after 18z.
Winds aloft...southwest up to 50 kts at 10k feet mean sea level.
Outlook for tonight and Sunday...scattered showers spreading east
across Harney and Baker counties into southwest Idaho becoming
widespread over the mountains by 06z with areas of terrain
obscuration. Conditions improving in southeast Oregon after 12z and
the Snake River Valley after 18z with showers becoming mainly
isolated. Widespread showers continuing in the central Idaho
short term...today through Sunday...patchy dense fog formed in
the warm sector /including at Boise/ under clear skies and light
winds...but should not last over a couple hours. Winds from the southeast
to SW will increase by early this morning ahead of the cold front
nearing the coastal waters at 3 am so patches of dense fog are not
expected to last beyond 4 to 6 am and mainly across the lower
Treasure valley. Gusty SW winds will mix down to the surface with
up to 30 miles per hour winds and 50 miles per hour gusts later today over southeast Oregon
where a Wind Advisory remains in effect. Locally breezy over SW
Idaho as well but mostly gusts around 20 miles per hour. Colder air will
continue to filter in behind tonights cold frontal passage for
light snow in the mountains...around 3 inches as low as 7000 feet
through Sunday morning. Temperatures will be 15 degrees colder in
Oregon and 25 colder in south central Idaho Sunday vs. Today going
up today and down Sunday like a see-saw. This is due to the area
being in the warm sector today followed by a cool upper trough
swinging through Sunday.
Long term...Sunday night through Saturday...no significant changes
in the progressive pattern through next weekend. A weak shortwave
moves through the region Tuesday through Wednesday bring another
round of showers mainly over eastern Oregon and the central Idaho
mountains. High amplitude upper level ridge the ridge develops over
the intermountain region on Thursday then shift east over The
Rockies on Friday...leaving eastern Oregon and southwest Idaho under
a drier and slightly warmer southwest flow aloft. Another trough
moves into the region on Saturday though models remain split on the
timing and strength of this system. Temperatures will gradually warm
from slightly below normal on Monday to slightly above normal
Wednesday through Friday.
Idaho...dense fog advisory until noon MDT today idz012.
Or...dense fog advisory until noon MDT today orz064.
Wind Advisory until 8 PM MDT /7 PM PDT/ this evening orz061-063.
previous short term...vm
previous long term....js