Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 180540

Area Forecast Discussion
National Weather Service Pendleton OR
1040 PM PDT Thu Jun 17 2021

.AVIATION...06Z TAFS...Skies should continue to remain mostly clear
allowing VFW conditions over the next 24 hours. Diurnally driven
winds overnight, but tomorrow afternoon into evening winds
increasing across region 10-15kts, DLS nearing 20kts due to
passing shortwave trough. Goatley/87


.PREV DISCUSSION... /issued 758 PM PDT Thu Jun 17 2021/

SHORT TERM...Tonight through Saturday...Skies continue to be
clear, with temperatures into Friday expected 10-15 degrees above
average. Shortwave trough diving out of Canada and into PacNW
brings NW`ly flow Friday, with some increases in wind strength
expected across Kittitas Valley, Columbia Gorge, and Columbia
Basin, around 10-20kts.

Enhanced W-NW`ly flow continues to overspread the region on
Saturday. Although winds and RH`s remain outside of critical
status, an elevated concern for fire weather potential is possible
for the day. Pacific airmass should help to slightly cool overall
temperatures for the day, though they will remain around 10
degrees above averages. Goatley/87

SHORT TERM...Tonight through Saturday...A dry westerly flow aloft
will persist over the PacNW through Friday as high pressure over
the southwest continues to strengthen. The persistent high
pressure over the southwest will help to advect a warmer airmass
into the region, producing a warming trend into next week.
Tomorrow, a weak shortwave moving across the region will prompt a
weak marine push that will produce breezy winds through the
Kittitas valley, Columbia gorge, and spread into the Columbia
Basin and central OR. This will increase fire weather concerns
across the area, however, wind and relative humidity are not
anticipated to exceed critical thresholds. By late Friday and
through Saturday, flow aloft will begin to turn northwest as
shortwave trough moves across western Canada into central MT. This
will push a weak Pacific airmass into the intermountain west, but
will only slightly cool afternoon temperatures Saturday. Breezy
westerly winds will also redevelop across the forecast area and
will be slightly stronger than Friday. Fire weather concerns will
continue to be elevated for Saturday, however critical thresholds
will not be met as relative humidities will be slightly higher.
Afternoon temperatures will be in the upper 80s to mid 90s Friday,
while temperatures Saturday will generally be in the mid 80s to
lower 90s. Lawhorn/82

LONG TERM...Sunday through Thursday...Two words will be the the
dominant ones through the extended and dry.  Both the
deterministic and ensemble guidance are in very good agreement with
a large ridge early in the period, which will bring increasingly hot
weather through Tuesday.  There is a bit of disagreement, as to
whether Monday or Tuesday will be the hottest day in this stretch but
temperatures will likely be close to above 100 degrees in the Basin
Monday, Tuesday and possibly Wednesday, and highs in the 90s
elsewhere.  The ridge moves eastward on Wednesday as a trough
approaches the wast coast.  The southwesterly flow and approach of
the trough will bring in a marginal increase in moisture, and will
increase clouds and RHs, though they will remain low.  There will
also be a chance of thunderstorms, mainly over the mountains and
higher terrain on Tuesday, and Wednesday as shortwave energy moves
through.  The position and strength of the trough has been
relatively consistent in the deterministic and ensemble guidance. As
the trough moves inland on Wednesday, there will be some breezy
winds which could add to any fire weather concerns.  Toward the end
of the extended period and beyond, the ridge should build back in
and be even stronger, potentially bringing even hotter temperatures.

High temperatures Sunday will be in the upper 80s to lower 90s, and
will increase to the low 90s to near 100 by Tuesday and back into
the upper 80s in Central Oregon to the 90s elsewhere by Tuesday.
Overnight lows will mainly be in the 60s.


PDT  49  90  52  88 /   0   0   0   0
ALW  53  93  57  90 /   0   0   0   0
PSC  50  94  56  93 /   0   0   0   0
YKM  51  93  55  90 /   0   0   0   0
HRI  49  94  56  93 /   0   0   0   0
ELN  49  87  55  83 /   0   0   0   0
RDM  45  88  45  86 /   0   0   0   0
LGD  46  88  49  83 /   0   0   0   0
GCD  47  93  50  88 /   0   0   0   0
DLS  54  90  56  89 /   0   0   0   0




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