Area Forecast Discussion
Issued by NWS Pendleton, OR

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007
FXUS66 KPDT 191709
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1010 AM PDT Tue Jun 19 2018

Updated aviation discussion

.UPDATE...Water vapor imagery shows an upper low over central
Montana and another low along the central British Columbia coast.
The low over Montana continues to circulate moisture into the
eastern half of the area and partly to mostly cloudy skies
continue over that portion of the area. Radar is not showing any
showers this morning but expect isolated to scattered rain showers
over the northern Blue Mountains and Wallowa county this
afternoon and early evening. Models show weak instability so have
not added any mention of thunderstorms there but an isolated
lightning strike or two is possible. Heavy cloud cover will help
limit the thunderstorm potential. Further west, a weak wave will
move through Washington this afternoon and create a slight chance
of showers and thunderstorms along the Washington Cascades this
afternoon and early evening. The rest of the area will be dry with
mostly sunny to partly cloudy skies. Winds will be light today
and tonight. Temperatures will be much warmer today with much of
the area 5 to 15 degrees warmer than yesterday. Forecast was
generally in good shape. Made some minor adjustments to
temperatures, pops and sky cover today and tonight. Forecast
update already out. Perry

.AVIATION...18Z TAFs...VFR conditions will prevail for the next 24
hours. FEW-SCT clouds at 060-100 kft today then becoming clear
overnight. Winds will remain 10 KT or less.

&&

.PREV DISCUSSION... /issued 158 AM PDT Tue Jun 19 2018/

SHORT TERM...Today through Thursday...An elongated upper level low
in MT is circulating moisture and light rain westward into eastern
OR/WA. The low will continue to drift east today. Light showers in
the Columbia Basin are dissipating. A band of showers is moving into
Wallowa County. These trends are reflected in latest HRRR model. I
expect showers to be limited from northern Blue Mountains  to eastern
Grant County eastward to Wallowa County this morning.

A weak wave will move into WA this afternoon/evening. This wave may
trigger a few showers and thunderstorms along the WA Cascades.
Convection will end overnight as an upper level ridge moves through
eastern WA and OR Wednesday morning. Wednesday afternoon a short
wave will  move into southwest OR. This will trigger some convection
late in the day...overnight and into Thursday. I expect
thunderstorms during this period to impact the CWA with the
potential for some strong storms, particularly Wednesday evening.
Coonfield

LONG TERM...Thursday night through Monday...The mid level shortwave
will exit to the east Thursday night. Scattered showers and isolated
thunderstorms from the Blue Mountain foothills eastward Thursday
evening will end by the overnight hours. Low amplitude ridging will
cross the area Friday for dry conditions area wide. GFS/ECMWF are in
reasonable agreement for the weekend, bringing the next system
across extreme northern WA/southern BC Saturday, digging south
across the intermountain West Saturday night/Sunday. Deep layer
moisture and dynamic support will remain north and east of the
center of the low. Thus, mainly dry conditions will prevail
Saturday, with perhaps a slight chance of showers along the
immediate Cascade crest of WA. Another low amplitude ridge is
progged to cross the region Sunday, exiting to the east Monday for a
continuation of dry conditions. Warm conditions can be expected
under the ridge for Friday, with a slight cooldown Saturday as the
low brushes the area, warming once again to above normal Sunday and
Monday.



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  83  59  90  64 /  10  10  10  50
ALW  84  60  92  66 /  10  10  10  30
PSC  86  60  93  67 /  10   0  10  30
YKM  86  62  88  66 /  10  10  20  20
HRI  87  60  94  68 /  10   0  10  40
ELN  86  62  89  63 /  10  10  20  30
RDM  84  54  88  56 /   0   0  20  50
LGD  76  51  83  59 /  20  20  20  40
GCD  75  54  85  59 /  10  10  10  50
DLS  90  65  93  68 /  10  10  10  30

&&

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

$$

83/80/80



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