Scientific Forecaster Discussion
fxus66 kpdt 241102
Area forecast discussion
National Weather Service Pendleton or
300 am PST Wed Jan 24 2018
Short term...today through Friday night...an upper level trough
off the pacnw coast will move inland in a piecemeal fashion through
Friday keeping unsettled weather over the area. On Friday night a
more organized system in the form of a warm front will begin to lift
north across the region. For today into this evening expect
relatively warm conditions ahead of a cold front with fairly
widespread precipitation especially north and east. Snow levels over
the Washington Cascades will rise above 3000 feet and the heavy snow
occurring there now will change to rain this morning. By the time
snow levels lower again this evening and rain changes back to
snow...qpf amounts will be lighter so additional snowfall amounts
after this morning will be light. Still 1 foot plus amounts have
occurred near the crest in the past 24 hours. Over the Blue
Mountains snow will continue today with snow levels slowly rising to
around 4500 feet. The Winter Weather Advisory for the northern
Blue Mountains will continue until 18z. A brief lull in the heavier
precipitation is expected this afternoon until the cold front moves
in this evening then an additional 2-3 inches of snow may fall
before precipitation ends tonight.
The other issue today is the winds. Beefed up winds along the Blue
Mountain foothills today to 20-30 mph with higher gusts so the next
shift could easily issue an advisory if needed...mainly near the
base of the mountains. Otherwise with this forecast package will
issue wind advisories for the grande ronde and Wallowa valleys for
gusty south winds into the mid evening hours. The hrrr model is also
showing some 40-45 mph peak wind gusts in The Bend area this
afternoon but none of the other available models are showing
anything near that strong. So for now will keep that area at 15 to
30 mph but will continue to monitor the model and observation
Once the front passes tonight there will be a drying trend but with
weak impulses moving inland Thursday and Friday scattered rain and
snow showers will be possible with snow levels 1500-2500 feet. On
Friday night as the warm front approaches a general area of snow
will begin to overspread central and north central Oregon and
portions of south central Washington. 78
Long term...Saturday through Tuesday...models all show a warm
front bringing copious precipitation amounts to the forecast area
Saturday with snow levels in northeast Oregon and southeast
Washington rising to 2500-3500 feet by Saturday afternoon and rising
to 4000-4500 feet in central Oregon. As such central Oregon will
start Saturday morning with snow changing to rain before midday.
Snow levels in the southern east slopes of the Washington Cascades
will rise to 2000-3000 feet Saturday afternoon while snow levels in
Kittitas County will remain 1500-2000 feet through Saturday.
Saturday night and Sunday an upper level ridge of high pressure
builds over the region for dry conditions Sunday in central and east
central Oregon while the rest of the forecast area holds on to
chance of rain through Sunday. Monday will be dry as well due to the
ridge continuing. Monday night and Tuesday models are showing the
ridge weakening and allowing a cold front to bring a chance of
mainly snow, but with rain possible in the Columbia Basin on Tuesday.
Aviation...06z tafs...a weather system will continue to impact the
forecast area over the next 24 hours. Conditions will be VFR to MVFR
but some local IFR is possible especially around kdls and kykm
through Wednesday morning. Will also see some increasing south to
southeast winds impacting kbdn, krdm, kpdt and kalw with some 15-30
kt winds possible at times.
Preliminary point temps/pops...
PDT 52 32 44 33 / 80 100 30 20
alw 56 36 47 36 / 80 90 40 30
psc 54 34 48 35 / 60 70 30 20
ykm 47 30 44 27 / 30 20 40 30
hri 55 34 47 33 / 60 80 30 20
eln 44 26 38 25 / 50 30 50 30
rdm 50 30 46 27 / 50 40 40 30
lgd 44 29 39 30 / 80 90 40 30
gcd 48 27 39 28 / 60 80 40 30
dls 50 34 47 34 / 70 30 50 50
or...Winter Weather Advisory until 10 am PST this morning for orz502.
Wind Advisory from 10 am this morning to 10 PM PST this evening
Washington...Winter Weather Advisory until 10 am PST this morning for waz030.
Winter Weather Advisory until 10 PM PST this evening for waz520.
Winter Storm Warning until 10 PM PST this evening for waz520.