Flood in Washington, April 9 to 12, 2019

Area Forecast Discussion
National Weather Service Pendleton OR
147 AM PDT Tue Apr 9 2019

.SHORT TERM...Today through Thursday...An unsettled west to
southwest flow with frequent embedded weather systems in the flow
will continue to keep mostly cloudy to cloudy skies with periods of
rain or showers. There has already been abundant rain during the
past few days which has resulted in rises on rivers and streams.
Some rivers are either already above flood stage or are expected to
go above flood stage within the next day or two. In addition, there
are many smaller streams in portions of the CWA that are either
bankfull or over their banks causing minor flooding. Flood warnings
are in effect as a result for the next few days. Showers will
continue through mid day and then begin to dry out from the west
behind a cold front. A transient ridge will move across the Pacific
Northwest on Wednesday. Then more wet weather is expected for
Thursday as another system moves into the region. Snow levels will
be fairly high so am not expecting snow except over the higher
mountains...with possible light accumulations. There will be some
minor instability this afternoon, but am not convinced that there
will be enough to break through the cloud cover and cause enough
heating for thunderstorms. Therefore they will not be included in
the forecast. It will be breezy to windy today, especially in
central and north central Oregon today. Then the winds will diminish
tonight. Temperatures will be about 3-5 degrees below normal during
the day and near normal at night for the next few days. 88

.LONG TERM...Thursday night through Monday. Long term period will
remain active and wet. Initially there will be a ridge offshore and
a large trough over the Rockies and Midwestern states with the PacNW
in between under north to northwest flow aloft. A digging upper-
level low/trough that will bring showers Wednesday into Thursday
will continue to drop south towards CA/NV Thursday night into
Friday, then towards the Four Corners by Saturday. Showers across
the mountains and central OR will taper off north to south across
the region Thu night into early Friday. Friday afternoon into early
Saturday looks to be drier at this point with transitory ridging
expected ahead of yet another approaching upper-level low/trough
that looks to bring more wet weather by later Saturday into Sunday.
This looks to be the first in a series of disturbances to impact the
region as moist cyclonic northwest flow sets up over the PacNW. Snow
levels Thu night/early Friday will be fairly low for this time of
year (3000-4000ft) but will rise slowly by Saturday (4500-5500ft)
before falling back down for Sunday and Monday. Seasonal temps with
highs in the 50s to lower 60s and lows in the 30s to lower 40s.
Breezy winds possible with each trough/frontal passage over the
weekend into early next week.

&&

.AVIATION...12Z TAFs...Scattered showers will continue this morning
but the steadier rain has shifted south and east of the TAF sites.
Westerly winds will increase to 15-30g30-40kts behind a departing
cold front today which, along with drier air, should help erode and
remaining IFR/MVFR this morning. More showers will likely develop
this afternoon with cool air aloft, especially near PDT/ALW with
some isolated thunderstorms possible. Showers will quickly taper off
this evening after sundown.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  37  55  39 /  40  20  20  50
ALW  58  40  57  41 /  60  20  20  60
PSC  64  41  63  43 /  20  10  20  20
YKM  61  38  59  39 /  10   0  20  30
HRI  61  40  61  41 /  30  10  20  30
ELN  56  36  55  34 /  10  10  20  30
RDM  50  33  51  36 /  30  10  20  30
LGD  49  35  48  36 /  60  40  20  60
GCD  49  34  49  36 /  70  30  30  50
DLS  58  42  57  42 /  20  10  40  30

&&

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

&&

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