Area Forecast Discussion
Issued by NWS Pendleton, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS66 KPDT 301525

Area Forecast Discussion
National Weather Service Pendleton OR
825 AM PDT MON MAY 30 2016

.SHORT TERM...Today through Wednesday...Ridge of high pressure will
be building over the region providing mostly clear skies and light
winds through midweek. Temperatures will gradually warm each day
reaching its peak on Wednesday.


.PREV DISCUSSION... /issued 425 AM PDT MON MAY 30 2016/

SHORT TERM...Today through Wednesday...A weak disturbance is moving
well to the east of the CWA this morning with a northwest flow
behind it ahead of an upper ridge. Winds are diminishing and
becoming light this morning over most areas. The upper ridge will
build into the region during the next few days. Heights and 850 mb
temperatures will be rising resulting in a strong warming trend
through the short term forecast period. Today`s highs will be near
normal with maximum readings in the mid to upper 70s in the lower
elevations and mostly 60s in the mountains. Temperatures will warm
up by about 5 to 7 degrees on Tuesday and then another 7 to 9
degrees on Wednesday. Highs on Wednesday will climb into the upper
80s to the lower 90s in the lower elevations with mid 70s to mid 80s
in the mountains. On Wednesday the ridge will be suppressed a bit as
a weak disturbance moves to the north of the CWA. The flow will
become southwest which will cause an increase in moisture and
instability over the eastern mountains. As such decided to add a
slight chance of afternoon showers and thunderstorms over the
eastern and northeast mountains on Wednesday afternoon. Elsewhere it
will remain dry on Wednesday. Winds will be light through the short
term forecast period. 88

period will start off with a slight chance of evening thunderstorms
over the northeast Oregon mountains Wednesday as the latest guidance
was indicating fairly high amounts of CAPE and negative LIs over
this area...along with just enough lower and mid-level moisture. The
upper ridge that was over the region becomes suppressed south by
Wednesday night and Thursday as a weak disturbance quickly moves
through in the WNW flow. This disturbance is forecast to track
across north-central Washington...largely missing our Oregon zones.
This will act to increase mid level moisture and clouds...along with
knocking temperatures down several degrees...again mainly over the
Washington zones (mid to upper 80s). There will also be a slight
chance of showers during this period along the East Slopes of the
Washington Cascades. The fast westerly flow should allow the Yakima
and likely the Kittitas Valley to remain dry. The upper level ridge
then returns and builds quickly over the forecast area for Friday
through Sunday. Friday will be dry, warm and mostly sunny area wide.
Saturday will be very warm and generally dry with only a few
afternoon clouds around. There will be a slight chance for a PM
thunderstorm in the Oregon mountains as atmospheric instability
again gradually increases. High temperatures on Saturday will reach
the lower to mid 90s in the valleys/basins with upper 70s and 80s
mountains. Heading into Sunday the upper ridge remains in place but
the southerly return flow of moisture increases. This will mean
partly cloudy skies, a slight chance of afternoon thunderstorms over
the mountains and most of Central Oregon. Sunday looks to be the
hottest day of the extended period...with highs likely reaching the
mid-90s to low 100s in the valleys/basins with 80s mountains. This
is about 20 degrees above average for this time of year...and could
break record highs in some locations. Monday stays very warm with a
better chance for afternoon showers and thunderstorms for all but
the Lower Columbia Basin as moisture and instability continue to
rise. High temperatures fall back into the upper 80s to mid-90s with
upper 70s to mid-80s mountains. 77

AVIATION...12z TAFS...VFR conditions will prevail for the next 24
hours as an upper ridge builds over the region. Satellite shows
periodic mid and high level clouds moving over the top of the upper
ridge in a northwest flow...this trend will continue through the
day. There is a SCT-BKN layer near 7-8K FT AGL over KPDT and
KALW...which should dissipate later this morning. Otherwise expect
SCT-BKN high clouds between 15K FT AGL and 25K FT AGL for all other
terminals through the TAF period. Even these high clouds are
forecast to diminish this evening and overnight.

Winds will be AOB 12 KTs at all terminals through the period and
will follow a diurnal...terrain driven trend in direction.


PDT  75  47  81  51 /   0   0   0   0
ALW  76  51  82  51 /   0   0   0   0
PSC  78  48  84  53 /   0   0   0   0
YKM  78  45  83  52 /   0   0   0   0
HRI  78  46  84  51 /   0   0   0   0
ELN  75  43  81  49 /   0   0   0   0
RDM  75  39  82  47 /   0   0   0   0
LGD  70  44  76  47 /   0   0   0   0
GCD  73  41  80  50 /   0   0   0   0
DLS  82  53  88  54 /   0   0   0   0


.PDT Watches/Warnings/Advisories...


91/89/89 is the U.S. government's official web portal to all federal, state and local government web resources and services.