Area Forecast Discussion
Issued by NWS Pendleton, OR

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734
FXUS66 KPDT 170610 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
958 PM PST Sun Dec 16 2018

updated the aviation discussion

.UPDATE...A disturbance over the pacnw tonight was continuing to
bring clouds and showers to the area but these will lessen
overnight from west to east except for the mountains. The winds
across the foothills of the blue mountains had decreased and the
wind advisory cancelled. Meanwhile gusty winds persist in the
Grande Ronde Valley. Otherwise snow level were above 4500k feet
and overnight temps are expected to fall into the 30s across most
locations and the short term forecast appears on track.

AVIATION...areas of mvfr and lcl ifr conditions in fog can be
expected at taf site kykm. Elsewhere areas of mvfr in fog was
possible at taf sites kpdt...kalw...and kpsc after 08z. After 14z
the fog should slowly lessen and conditions should improve to lcl
mvfr before rain arrives after 02z that could deteriorate conditions
after 02z.

&&

.PREV DISCUSSION... /issued 235 PM PST Sun Dec 16 2018/

SHORT TERM...Tonight through Wednesday...An active weather pattern
will continue through the short term. A warm front producing
precipitation and windy conditions over the forecast area today will
be followed by a cold frontal passage overnight. Snow levels will
lower behind the front to around 4000 feet by Monday morning but
decreasing precipitation means minimal snow accumulations expected.
Winds are also expected to decrease following the frontal passage.
The next weather system will rapidly follow Monday night and
Tuesday. Initial snow levels will be around 4000 feet Monday night
and there could be some significant snow accumulations before snow
levels rise to 5000 to 6000 feet late overnight and Tuesday. This
system will again increase southerly winds mainly over eastern
Oregon and the higher terrain which may need issuance of highlights
at a later time. Precipitation and winds will decrease Tuesday night
with just a few linger showers Wednesday along the Cascades and over
the far eastern mountains.

LONG TERM...Thursday night through Sunday...We`ll see one last warm
and wet atmospheric river event Thursday with widespread rain (snow
levels near 6000 feet). Before much colder, but still very season
appropriate air arrives Friday morning. With strong cold air
advection should see some efficient mixing of breezy winds to the
surface Thursday night and Friday morning before gradients quickly
relax, at this point only expecting 20 to 30 mph winds so may not
require any highlights for winds. Precipitation will largely be
trending down by the time the cold air really works in, so do not
expect much snow accumulation, however roads wet from previous rain
may become quite slippery for the morning commute with lows near
freezing. Saturday will be between systems without much activity.
Another much weaker fetch of Pacific Moisture arrives during the day
Sunday and while there is some warm air advection with it, think
snow levels will remain down close to the surface for most locations
with a chance for most to see some snow, but this is probably a
little too far out to get too excited about it. Peck

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  38  52  44  58 /  60  10  90  80
ALW  38  53  46  57 /  60  30  90  90
PSC  37  51  43  56 /  50  10  80  70
YKM  32  43  36  49 /  60  10  80  70
HRI  36  50  42  56 /  50  10  80  70
ELN  31  40  35  46 /  70  10  90  80
RDM  32  49  43  58 /  60  10  70  90
LGD  36  43  40  45 /  70  40  90 100
GCD  37  43  39  49 /  60  20  80  80
DLS  36  46  40  50 /  60  10  90  90

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 11 PM PST this evening for ORZ049.

WA...None.
&&

$$

97/97



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