River Flood Warning 8, NWS Pendleton, OR

Area Forecast Discussion...Update
National Weather Service Pendleton OR
1000 AM PDT Thu Mar 16 2017

Updated Aviation Discussion

.SHORT TERM...Today and tonight...A cold frontal passage occurred
overnight which will place the forecast area under a dry and cooler
westerly flow through tonight. Skies will be mostly sunny today but
then some increasing high clouds overnight with the potential for
some patchy fog.

.HYDROLOGY...As stated in the short term discussion...a cold front
that swept across the region last night and early this morning has
lowered snow levels and precipitation is diminishing behind the
front.  This leaves the current Flood Warnings for portions of
Kittitas and Yakima counties as well as Flood Warnings for the
Klickitat, Grande Ronde and Umatilla. Conditions will improve today
but it may be slow for water levels to respond. Unfortunately, the
dry and cooler conditions this afternoon through Friday morning will
be followed by rain and increasing snow levels Friday afternoon
through Saturday...and Hydrologic statements may be in order.  Wister

.AVIATION...18z TAFs...VFR conditions expected to persist at all
terminals through the next 24 hours. Skies are mostly clear for most
of the forecast area late this morning and are forecast to remain
this way through the afternoon and evening hours. Expect only a few
to sct mid level CU clouds, mainly over the mountains. Later tonight
and into Friday morning the next weather system will begin to
approach the area. This will bring increasing mid and high level
clouds to the area. Rain and some lower CIGS will overspread the
forecast area from west to east Friday afternoon.

Winds will be slightly breezy mainly early this afternoon at
KDLS...KPDT and KALW where some gust to near 20 kts will be
possible. Otherwise from this evening into tonight and Friday
morning winds will be AOB 12 kts. 77

&&

.PREV DISCUSSION... /issued 415 AM PDT Thu Mar 16 2017/

SHORT TERM...Today through Saturday. A cold front is making its way
across the forecast area and is located in a line along the
northern Blue Mountains south to the Ochoco Mountains.  The front
will exit the region by mid day.  Precipitation has tapered off
dramatically behind the front...and snow levels are falling.  Based
on surface temperatures...snow levels are currently around 4000 feet
along the east slopes of the Washington and northern Oregon
Cascades. This is good news for the areas who have experienced mass
snow melt runoff the past week and have faced flooding or near
flooding.  By noon today...any showers will be isolated to
scattered along the WA Cascades and the northeast mountains with
snow levels around 2500 feet.  It will be about 5-7 degrees cooler
today compared to yesterday with highs in the 40s over the mountains
and 50s elsewhere. It will be partly cloudy and chilly tonight with
lows in the mid 20s to mid 30s.  The dry conditions will not last
long as a warm front spreads precipitation east of the Cascades
Friday afternoon and Friday night. Snow levels will rise...but the
east slopes of the WA Cascades above 3000 feet will likely observe
about 1-3 inches of snow before snow levels rise to 5000 feet Friday
night.  Increasing snow levels and rain could mean water levels will
rise again Friday night and Saturday.  The warm front lifts north
across Washington Friday night...and precipitation will taper off
across most of central Oregon.  However...an approaching cold front
will bring widespread rain on Saturday with snow levels gradually
decreasing late in the day.  From Friday afternoon through
Saturday afternoon...QPF amounts of 0.5-0.75 inch are forecast for
the east slopes of the WA Cascades...the northern Blue
Mountains...and the Wallowa Mountains.  Elsewhere...QPF of 0.1-0.5
inch are expected with the central Oregon zones receiving the low
end of QPF. Southwest winds will increase to 20-30 mph in many areas
ahead of the cold front.  Wister

LONG TERM...Saturday Night Through Wednesday...An upper level
trough will move through the CWA Saturday evening with decreasing
precipitation and windy conditions. This will keep rain and higher
mountain snow showers over the east slopes of the Cascades and
northeast Oregon mountains Saturday evening.  Sunday will be dry and
cooler with an building ridge offshore and rising heights over
eastern WA and OR. Monday afternoon a warm front will move north
into the southern part of the CWA then spread across the rest of the
CWA Monday night. A deepening offshore trough will provide abundant
moisture for rain Monday night and Tuesday. The associated cold
front will move through eastern WA and OR Wednesday with
rain and high mountain snow. Coonfield

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  53  33  56  45 /   0   0  20  70
ALW  55  36  57  48 /   0   0  20  70
PSC  57  34  53  45 /   0   0  30  60
YKM  56  30  51  40 /   0   0  40  70
HRI  57  33  52  44 /   0   0  30  60
ELN  50  29  45  36 /   0   0  40  80
RDM  53  32  58  46 /   0   0  30  20
LGD  52  33  61  48 /  10   0  10  70
GCD  54  35  63  50 /  10   0  10  40
DLS  56  34  50  45 /   0   0  50  70

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

91/77/77