Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 191747 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1045 AM PDT SUN OCT 19 2014

.SHORT TERM...SATELLITE SHOWING SOME MID AND HIGH LEVEL CLOUDS
MOVING THROUGH THE REGION THIS MORNING. THIS SHOULD MOVE OFF TO THE
EAST BY AFTERNOON WITH MOSTLY SUNNY SKIES. STRONG LOW LEVEL
INVERSION LAST NIGHT ALLOWED PATCHY FOG TO DEVELOP. THIS WILL
DISSIPATE OVER THE NEXT SEVERAL HOURS. AIRMASS ALOFT HAS WARMED
FROM YESTERDAY WHICH SHOULD GIVE HIGH TEMPS TODAY A LITTLE WARMER
THAN SATURDAY. 12Z MODELS CONTINUE TO BRING NEXT UPPER TROUGH AND
FRONT THROUGH THE REGION MONDAY AND MONDAY NIGHT WITH CLOUDS AND
SOME LIGHT RAIN. 94

AVIATION...18Z TAFS...INTERMITTENT IFR CONDITIONS DUE TO FOG WILL
PERSIST THROUGH 19/19-20Z AT KDLS AND ESPECIALLY KALW TAF
SITES...BEFORE SCATTERING OUT EARLY THIS AFTERNOON. OTHERWISE VFR
CONDITIONS SHOULD CONTINUE OVER THE CWA WITH FAIR SKIES AND LIGHT
WINDS THROUGH 20/15Z...LATE IN THE TAF PERIOD ANOTHER STORM SYSTEM
WILL BE APPROACHING FROM THE WEST AND SHOULD START TO SPREAD
-SHRA/-RA INTO KDLS AFTER 20/12Z...WITH POSSIBLE MVFR CONDITIONS. 77

&&

.PREV DISC... /ISSUED 830 AM PDT SUN OCT 19 2014/

SHORT TERM...TODAY THROUGH MONDAY NIGHT...AN UPPER LEVEL TROUGH
DIGGING OUT OF THE GULF OF ALASKA INTO THE EASTERN PACIFIC WILL PUSH
THE UPPER RIDGE OVER THE REGION EAST TODAY. THIS WILL CAUSE THE FLOW
ALOFT TO BECOME INCREASINGLY SOUTHWESTERLY. THIS FLOW WILL CAUSE
TEMPS TO WARM ABOVE 3000 FT MSL. SOME OF THIS WARMTH WILL MIX INTO
LOCATIONS BELOW 3000 FT, BUT OTHER LOW ELEVATION AREAS WILL WARM
MORE SLOWLY AS MORNING INVERSIONS WILL BE SLOW TO BREAK. STILL
EXPECT AFTERNOON HIGHS TO BE ABOVE SEASONAL. SKIES WILL BE GENERALLY
SUNNY THOUGH VARYING AMOUNTS OF HIGH CLOUDINESS WILL OCCUR. WINDS
WILL BE GENERALLY LIGHT EXCEPT OVER THE AREAS ABOVE 3000 FT WHERE
LOCALLY BREEZY WINDS MAY BE POSSIBLE. ALSO THE SOUTH END OF THE
GRANDE RONDE VALLEY SHOULD BE LOCALLY BREEZY DUE TO GAP WINDS.
PATCHY FOG ALONG THE I-90 CORRIDOR IN KITTITAS COUNTY AND NEAR
SUNRIVER AND LA PINE IN CENTRAL OREGON EARLY THIS MORNING WILL
DISSIPATE BY MID TO LATE MORNING. THE UPPER TROUGH WILL PUSH TOWARDS
THE PACNW TONIGHT AND MONDAY, THEN SWING EAST OF THE CASCADES MONDAY
NIGHT. THIS TROUGH WILL PUSH A COLD FRONT WITH AN ASSOCIATED PRECIP
BAND SLOWLY INTO AND ACROSS THE REGION. THERE REMAINS SOME
UNCERTAINTY IN THE TIMING OF THE FRONT`S MOVEMENT INTO THE INTERIOR
NORTHWEST. FOR NOW WILL CONTINUE TO SPLIT THE DIFFERENCES IN THE
TIMING. THUS WILL KEEP THIS EVENING DRY AND ONLY GO WITH LOW CHANCES
OF PRECIP REACHING THE CASCADE CREST AND ADJACENT EAST SLOPES
OVERNIGHT. WILL ALSO CONTINUE TO INDICATE THE BAND MOVING SLOWLY
INTO THE AREA MONDAY WITH PRECIP CHANCES INCREASING THROUGH THE DAY
OVER OUR WESTERN ZONES. THE BETTER CHANCES OF PRECIP OVER OUR
EASTERN ZONES STILL IS EXPECTED TO OCCUR MONDAY NIGHT. 90

LONG TERM...TUESDAY THROUGH SUNDAY...MID/UPPER LEVEL SHORTWAVE
SWEEP ACROSS FORECAST AREA TUESDAY MORNING EXITS INTO IDAHO/MONTANA
IN THE AFTERNOON RESULTING IN DECREASING POPS IN THE EASTERN
MOUNTAINS AND DRY CONDITIONS FROM DAYBREAK ONWARDS FOR LOWER
COLUMBIA BASIN AS WELL AS CENTRAL AND NORTH CENTRAL OREGON, THE
KITTITAS AND YAKIMA VALLEYS AND THE SIMCOE HIGHLANDS. TUESDAY NIGHT
AREAS EAST OF CASCADES WILL HAVE DRY CONDITIONS ALTHOUGH SOME
SLOP OVER RAIN WILL BE POSSIBLE ALONG THE EAST SLOPES OF THE
WASHINGTON CASCADES AND ALONG CRESTS OF THE CENTRAL AND NORTHERN
OREGON CASCADES. ON WEDNESDAY A COLD FRONT AND ASSOCIATED MOISTURE
PLUME MOVES INLAND BY VIRTUE OF A LONG WAVE TROUGH OVER THE
NORTHEAST PACIFIC BRINGING A BROAD SOUTHWEST FLOW ALOFT ACROSS
PACIFIC NORTHWEST FOR INCREASING CHANCE OF RAIN IN THE EAST AND RAIN
LIKELY IN WESTERN SECTIONS OF CWA. WEDNESDAY NIGHT AND THURSDAY THE
SOUTHWEST FETCH OF MOISTURE CONTINUES OVER REGION WHILE THE COLD
FRONT REMAINS STALLED IN FORECAST AREA RESULTING IN RAIN LIKELY FOR
MOST OF FORECAST AREA. MODELS START TO DIVERGE THURSDAY NIGHT
ONWARD. BOTH MODELS INDICATE A RIDGE OF HIGH PRESSURE TRYING TO
BUILD OVER WESTERN STATES, BUT THE ECMWF SHOWS A MUCH STRONGER RIDGE
THAN THE GFS SO I KEPT MAINLY DRY CONDITIONS FOR FRIDAY. THE WEEKEND
LOOKS TO BE DRY THANKS TO THE RIDGE.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  75  45  71  47 /   0   0  10  50
ALW  72  50  73  50 /   0   0  10  50
PSC  72  46  70  49 /   0   0  10  40
YKM  68  45  63  44 /   0   0  40  40
HRI  72  43  70  47 /   0   0  10  40
ELN  69  46  65  45 /   0  10  50  40
RDM  76  41  64  37 /   0  10  50  50
LGD  72  45  72  46 /   0   0  10  60
GCD  73  43  70  43 /   0   0  20  60
DLS  74  51  66  47 /   0  10  60  50

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING WAZ026.

&&

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

94






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