Special Weather Statement, NWS Pendleton, OR

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
500 PM PDT MON JUL 18 2016

.SHORT TERM...Tonight through Thursday afternoon...A low pressure
system near the wa/or coast will continue to spin disturbances
across our area into tonight. The disturbances will combine with
daytime heating to produce thunderstorms across the two state area
and some of the storms may become strong and produce gusty
winds...hail...frequent lightning with the greatest chances of this
occurring is southeast of a line from Madras Oregon to Walla Walla
Washington. The convective activity should decrease tonight but with
an upper level jet overhead some showers should persist into Tuesday
morning mainly over the southern and eastern sections of our area
along with the area mountains. As the low pressure remains nearly
stationary over the pacnw several disturbances will continue
drifting across our region and another round of developing
thunderstorms is forecast Tuesday afternoon and again Wednesday
afternoon before decreasing in coverage and intensity overnight.
While the low pressure remains along the wa/or coast the moisture
lessens over the region and the showers should be limited to the
area mountains over the eastern third of the area including the east
slopes of the wa cascades on Thursday afternoon. Temperatures
through the period should remain near normal.

.LONG TERM...Thursday night through Monday night...A mi/upper
level trough will be on the coast Thursday evening and introduce mid
level moisture and marginal instability Thursday evening for a
slight chance of Evening thunderstorms in central and NE Oregon as
well as far SE Washington. The trough moves across forecast area
over night and Friday morning for a chance of showers in the Blue,
Elkhorn and Wallowa Mountains and a slight chance of showers along
the foothills of the Blue Mountains. Flat zonal westerly flow aloft
takes over Friday afternoon for dry conditions. A mid/upper level
ridge of high pressure  then builds over the region and continues
through Saturday night. Models differ on whether or not a mid/upper
level short wave moving through the forecast area on Sunday will
produce any showers during the day on Sunday. As such I decided to
keep a dry forecast due to uncertainty. Sunday night through Monday
night a dry SW flow aloft continues for dry conditions Sunday night
through Monday night.  Polan

&&

.AVIATION...00Z TAFS...VFR conditions are expected to predominate
for the next 24 hours. However, visibility and/or ceilings could
deteriorate briefly to MVFR/IFR in concentrated showers and isolated
thunderstorms KRDM, KBDN and KPDT late this afternoon into this
evening. Winds will be light except for gusty and erratic winds near
showers and thunderstorms. A few isolated strong to severe
thunderstorms are possible late this afternoon and early this
evening in east central and NE Oregon and in SE Washington (eastern
Walla Walla County, Columbia County and eastward to Idaho). The
strongest thunderstorm cells may produce gusty winds and hail to
1.00 inch in diameter up until around 03Z/19th.  Polan

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  56  81  57  85 /  30  20  20  10
ALW  59  82  61  86 /  30  20  20  10
PSC  60  86  61  90 /  30  10  10  10
YKM  56  84  56  87 /  30  10  10  10
HRI  59  84  60  89 /  30  10  10  10
ELN  56  80  55  82 /  40  10  10  10
RDM  46  77  45  83 /  40  30  20  10
LGD  53  80  54  80 /  40  20  20  20
GCD  51  81  52  85 /  30  20  20  10
DLS  59  81  61  85 /  30  10  10  10

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

97/99/99

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PENDLETON OR
520 PM PDT MON JUL 18 2016

ORZ049-502-503-190045-
NORTHERN BLUE MOUNTAINS OF OREGON OR-
SOUTHERN BLUE MOUNTAINS OF OREGON OR-GRANDE RONDE VALLEY OR-
520 PM PDT MON JUL 18 2016

...SPECIAL WEATHER STATEMENT...

AT 519 PM PDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
STARKEY...OR 12 MILES SOUTHWEST OF LA GRANDE...MOVING NORTHEAST AT 40
MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 30 MPH WILL BE POSSIBLE WITH
THIS STORM.

THIS STRONG THUNDERSTORM WILL BE NEAR...
  HILGARD AROUND 530 PM PDT.
  LA GRANDE AND ISLAND CITY AROUND 540 PM PDT.

LAT...LON 4520 11786 4519 11787 4516 11785 4508 11833
      4531 11855 4548 11801 4522 11785 4520 11783
TIME...MOT...LOC 0019Z 237DEG 34KT 4522 11829

JS