Area forecast discussion
National Weather Service Pendleton or
1040 PM PDT Friday may 24 2013
Updated the aviation discussion
Update...showers from earlier today were decreasing with the loss
of daytime heating. Otherwise a disturbance will track across our
southern portions of the region tonight. This will increase middle/high
level clouds and a few showers are possible over the John Day
Highlands/ochocos overnight. Thus the zones were updated to reflect
this and the remainder of the forecast appears on track for now.
Aviation...other than local MVFR ceilings at taf site kykm...a
disturbance will pass across southern Oregon that may produce local
MVFR ceilings at taf site kpdt before returning to mostly VFR
conditions across the area by 18z. A low pressure system will
approach Oregon and Washington Saturday night and areas of MVFR
ceilings will develop in showers and especially at taf sites
kykm...krdm...kdls after 02z.
&&
Previous discussion... /issued 138 PM PDT Friday may 24 2013/
Short term...tonight through Memorial Day...the large low pressure
system is currently elongating and shifting northward and is
currently over Washington. Isolated to scattered showers are across
much of Washington with a band of showers moving east in the
foothills and the Blue Mountains of Oregon. Expect showers to
gradually taper off tonight. Some instability this afternoon and
evening may lead to a thunderstorm or two. The best shear for storm
development is in central and northeast Oregon. Central Oregon
however will lack upper level support due to the low moving further
away but will keep an eye on northeast Oregon. Don't anticipate
severe...but can not rule out a strong storm if enough clearing
happens this afternoon and evening.
The low will move out of the area with some drying and warming
expected on Saturday. The overall pattern will remain a trough
through the weekend with individual disturbances rotating through.
The next one is expected to move into the Oregon portion of the
region Saturday night into Sunday. The second system looks to impact
the region on Memorial Day...though models are disagreeing on the
exact timing of the system. Both systems will bring a chance of rain
and some instability for the potential of afternoon thunderstorms
over northeast Oregon and southeast Washington. Snow levels will
rise through the weekend so precipitation will be in the form of
rain except for the highest of peaks. Dmh
Long term...Monday night through Friday...models in good agreement
in continuing persistent unsettled weather pattern through the
period. With some differences in timing and strength of each
disturbance...will keep slight chance of showers in the basin with
higher probability of precipitation over the mountains through Wednesday. By
Thursday...models begin to differ quite significantly as GFS keeps a
broad upper trough centered over the forecast area. Meanwhile...
European model (ecmwf) develops an upper low over Washington and moves it southeast
into Idaho Friday. At this time...will stick closer to the GFS/S
drier forecast as it has been a little more consistent. In
fact...European model (ecmwf) indicated the aforementioned low developing over Idaho
the previous run. Temperatures will generally be below normal but
gradually warming to near normal late in the period. Earle
&&
Preliminary point temps/pops...
PDT 41 66 46 68 / 20 10 10 30
alw 44 68 50 71 / 20 10 10 20
psc 42 71 47 74 / 20 10 10 10
ykm 43 66 46 70 / 20 10 10 10
hri 42 70 47 73 / 10 10 10 20
eln 42 64 44 68 / 20 10 10 10
rdm 34 66 39 64 / 10 20 30 40
lgd 36 64 40 67 / 20 20 20 40
gcd 35 64 42 65 / 10 20 20 40
dls 45 69 49 71 / 10 10 20 30
&&
PDT watches/warnings/advisories...
or...none.
Washington...none.
&&
Threat index
Saturday : green
Sunday : green
Monday : 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...
www.Weather.Gov/Pendleton
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