Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Pendleton or
315 PM PDT Wednesday Mar 12 2014
Updated aviation discussion
Short term...tonight through Friday night...a generally flat upper
ridge will linger over the region tonight and Thursday. A weak
disturbance will move out of British Columbia into Montana tonight.
Other than some thin high clouds, this disturbance will have little
affect on our portion of the Pacific northwest. Overnight lows will
again be cool due to good radiational cooling. The upper ridge will
build slightly Thursday as another disturbance begins to move out
of the Gulf of Alaska. Thus expect mostly sunny and dry conditions
with seasonally mild high temperatures Thursday. This next disturbance will
approach the Pacific northwest Thursday night and swing across the
region Friday. This system will push precipitation to the Cascade crest
towards and after midnight, while some light precipitation may make it to
the Blue Mountains overnight. This system's cold front will move
through on Friday, and most areas will see some precipitation due to this
front. Will indicate highest probability of precipitation along the Washington Cascade east
slopes Friday morning, and over the Blue Mountains and adjacent
foothills Friday afternoon. Winds will be breezy to locally windy
behind the front late Friday morning and Friday afternoon. There may
also be an outside chance of a stray thunderstorm over southeast
Washington Friday afternoon. Snow levels will run around 4000 feet
Friday morning and 5000 feet Friday afternoon. Overall snow
accumulations should be light, about 1 to 3 inches above 5000 feet.
Will see conditions stabilize and generally dry out Friday night. 90
Long term...Saturday through Wednesday...overall confidence in the
medium range models is rather low. While models are in agreement
with the position and strength of the ridge over the western U.S.
Saturday and Sunday...there are significant differences in the
timing and strength of a developing trough off the eastern Pacific.
The European model (ecmwf) and the Gem develop the trough Sunday morning between
140w-150w then deepen into a closed low along 140w Monday morning
and move it inland by Wednesday...unlike the GFS which keeps the
trough open as it traverses across the eastern Pacific Sunday and
Monday and pushes it into California on Tuesday. In addition...the
European model (ecmwf) and Gem bring a weak shortwave across Washington and northern
Oregon early Monday morning. Because the GFS is the outlier...I am
leaning towards the European model (ecmwf) and Gem but the ecwmf has not been very
consistent as well. For now...will anticipate light showers over the
Cascades and from the Blue Mountain foothills east to the Idaho
border along with breezy/windy conditions on Monday. There will be a
break on Tuesday with a better chance of rain and mountain snow on
Aviation...00z tafs. Clear skies, unlimited visibility, and winds
less than 10 knots are expected through 15z/13th. High cirrus clouds
will increase after 15z. Wister
Preliminary point temps/pops...
PDT 32 59 40 58 / 0 0 0 60
alw 37 59 43 58 / 0 0 0 60
psc 28 60 40 62 / 0 0 0 30
ykm 28 60 36 59 / 0 0 10 40
hri 27 60 38 62 / 0 0 0 30
eln 27 57 37 55 / 0 0 10 50
rdm 21 61 33 57 / 0 0 10 20
lgd 28 57 34 52 / 0 0 10 50
gcd 28 59 32 55 / 0 0 0 40
dls 32 61 42 61 / 0 0 20 40
Thursday : green
Friday : green
Saturday : green
Green: none or limited need for watches, warnings, or advisories.
Yellow: a few watches, warnings, or advisories possible or in effect.
Red: numerous watches, warnings, or advisories possible or in effect.
For additional weather information, check our web site at...