Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 201000
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
300 AM PDT Thu Jul 20 2017

.SHORT TERM...Today through Saturday...An upper low is moving
ashore on Vancouver Island this morning and move into the Canadian
Rockies this afternoon. It will extend a trough down into our area
today before the low and trough lift northeast into Alberta tonight.
Models show showers moving into Western Washington this morning and
radar already shows some light showers over the Olympic Peninsula.
Any showers in our area will be confined to the Washington Cascade
crest region and will be ending by mid afternoon. Amounts will be
just a few hundredths of an inch at best. Conditions look too stable
for any thunderstorms to develop. A bigger concern will be the tight
pressure gradients over the Columbia basin and adjacent valleys
today through this evening. The Columbia Basin will have westerly
winds of 10 to 20 mph today and the Columbia Gorge and Kittitas
valley will reach 20 to 30 mph. This will cause a few fire weather
concerns due to the winds and low humidities. At this time it
appears that critical fire conditions will be over a limited area
for too short of a time period for a Red Flag Warning, but
conditions will have to be monitored closely. See the Fire Weather
discussion below for additional details.  As the low and trough
departs a dry and stable westerly flow will move over the area
through Saturday though by Saturday weak ridging will begin to build
into the Pacific Northwest. Tonight through saturday should be fair
and dry. Skies should be mostly clear aside from partly cloudy skies
over the Washington Cascades at time. Temperatures will be cooler
today with the trough passage and generally in the upper 70s and
80s. Tomorrow will be a couple of degrees warmer and then we will
warm Saturday as the ridge builds to the mid 80s to mid 90s. Perry

.LONG TERM...Saturday night through Wednesday. The extended period
will be a little more active with a slight chance of thunderstorms
each day mainly over central and northeast Oregon. This being the
result of an upper low moving into the Pacific northwest. Westerly
flow aloft Sunday will turn southwest in response to a weak upper
trough approaching the northern California coast. As this system
moves across the region later Sunday into Monday there will be a
chance of thunderstorms from central Oregon across the John Day
highlands and Blues. Further to the north expect clear to partly
cloudy skies. Sunday will be the warmest day with highs in the 90s.
For Tuesday and Wednesday a larger upper level low will be
approaching southern BC and the Pacific northwest. Southwest flow
aloft combined with some instability will support a slight chance of
thunderstorms over central and northeast Oregon. Temperatures will
be a little cooler with 80s to lower 90s. 94

&&

.AVIATION...12z Tafs. Mainly clear skies for the next 24 hours.
Westerly winds 10-20kt decreasing after sunset.

&&

.FIRE WEATHER...Previous discussion...Today, a marine push will
result in increasing wind from the Columbia Gorge to the Basin. The
greatest wind will occur after minimum RH`s are reached. Patches of
wind/RH criteria may be met, but coverage not sufficient for a Red
Flag Warning. Will continue to highlight the risk in the Fire
Weather Planning Forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  84  54  86  59 /   0   0   0   0
ALW  86  60  87  64 /   0   0   0   0
PSC  87  56  88  58 /   0   0   0   0
YKM  85  57  89  61 /   0   0   0   0
HRI  85  56  88  60 /   0   0   0   0
ELN  77  54  86  58 /   0   0   0   0
RDM  83  44  88  49 /   0   0   0   0
LGD  83  50  86  52 /   0   0   0   0
GCD  87  51  89  54 /   0   0   0   0
DLS  80  60  89  64 /   0   0   0   0

&&

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

$$

83/94/94/80



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