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fxus66 kpdt 300527 

Area forecast discussion
National Weather Service Pendleton or
1030 PM PDT Wed Mar 29 2017

Updated aviation discussion

Update...updates to the forecast through Thursday afternoon were
mainly to lower pops in some zones and tone down quantitative precipitation forecast amounts for
most of the area. The warm front that brought widespread rain
earlier today has moved out of region...and satellite and
surrounding WSR-88D are showing clearing behind the system. A
weak cold front will track across eastern Oregon tonight. Earlier
model runs appear to have been too high on the
wsr-88ds west of the Cascades are only showing scattered showers
at this time unlike the widespread precipitation the models were
advertising. Light to moderate precipitation early Thursday
morning will mainly be over central and northeast Oregon.
Precipitation amounts through 18z will range from a trace to a
quarter of an inch. Snow levels will be around 4000 feet...and
some of the higher mountains and valleys will get about 1-2
inches of new snow.

After the passage of the upper level trough on Thursday...high
pressure building at the surface and aloft will result in breezy
to windy conditions. The strongest winds will be in the eastern
Columbia River gorge and the Kittitas Valley were sustained winds
will be 25-30 mph...possibly stronger in the afternoon and
evening. Confidence is not high that winds will meet advisory
criteria for more than an hour or two so will hold off on any wind
advisories for now. Wister


Aviation...06z tafs. Conditions will predominantly be VFR for the
next 24 hours...although krdm and kbdn may experience brief MVFR
tonight due to light rain. The chance of precipitation at the
remainder of the taf sites is minimal but there will be showers in
the vicinity of kpdt and kalw. The main aviation concern will be
the increasing westerly surface winds on Thursday...10-20 knots
gusting to 30 knots. Kdls may observe northwest winds 25g35 knots in the


Hydrology...rainfall amounts varied significantly across the
region over the past 24 hours...and the northern Blue Mountains
received significantly more than most of the forecast area with
amounts of 0.75 to over one inch in a few locations. The Umatilla
river and Walla Walla rivers are responding with levels expected
to be near bankfull on Thursday. The grande ronde river at Troy
is showing sharp rises and is forecast to rise to flood stage
Thursday morning. A Flood Warning is in effect for the grande
ronde river at Troy as well as the John Day river at Service
Creek. The John Day river is not showing sharp rises...and there
is question on whether it will get above flood stage. Will keep
the Flood Warning for now and monitor precipitation amounts
tonight and Thursday. Wister


Preliminary point temps/pops...
PDT 40 52 33 54 / 40 40 20 0
alw 43 54 38 54 / 40 30 20 0
psc 43 60 34 60 / 10 20 10 0
ykm 39 62 32 62 / 10 10 0 0
hri 41 59 34 59 / 20 20 20 0
eln 38 56 33 59 / 10 10 0 0
rdm 35 47 20 52 / 40 30 10 0
lgd 39 49 32 51 / 80 60 20 10
gcd 36 48 30 54 / 90 70 20 0
dls 43 60 37 62 / 20 20 0 0


PDT watches/warnings/advisories...

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