FXUS66 KPDT 142250 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
350 PM PDT SUN MAR 14 2010
UPDATED AVIATION DISCUSSION
.SHORT TERM...TONIGHT THROUGH WEDNESDAY AFTERNOON...A MID/UPPER
LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE OVER THE FORECAST AREA
TONIGHT AND MONDAY FOR DRY CONDITIONS. WINDS ALOFT WILL BACK TO THE
SOUTH ON MONDAY NIGHT IN RESPONSE TO A STRONG MID/UPPER LEVEL LOW
DEEPENING BETWEEN 130-140W WHILE THE MID/UPPER LEVEL RIDGE IS OVER
IDAHO/MONTANA. THIS PUTS THE FORECAST AREA WELL EAST OF INCREASING
MOISTURE APPROACHING THE COAST OVERNIGHT AHEAD OF A COLD FRONT
PUSHED TOWARD THE PACIFIC NORTHWEST BY THE LOW. AS SUCH AREAS EAST
OF THE CASCADES WILL REMAIN DRY MONDAY NIGHT...EXCEPT FOR A LOW
CHANCE OF RAIN ALONG THE CENTRAL WASHINGTON CASCADE CRESTS
OVERNIGHT. THE LOW SWEEPS THE COLD FRONT INLAND DURING THE DAY ON
TUESDAY WITH THE FRONT MOVING INTO THE WESTERN SECTIONS OF THE
FORECAST AREA TUESDAY AFTERNOON. THE FRONT WILL USHER IN A CHANCE OF
RAIN ALONG THE EAST SLOPES OF THE CENTRAL AND SOUTHERN WASHINGTON
CASCADES AND THE OREGON CASCADES TUESDAY WITH RAIN LIKELY NEAR THE
CRESTS IN THE AFTERNOON. THE FRONT THEN MOVES ACROSS THE REST OF THE
FORECAST AREA TUESDAY EVENING. AS SUCH POPS ON TUESDAY EVENING WILL
BE IN THE LIKELY CATEGORY BUT QPF AMOUNTS ARE GOING TO BE ON THE
LIGHT SIDE AT LOWER TERRAIN ELEVATIONS. THE NORTHEAST MOUNTAINS OF
OREGON ARE LIKELY TO RECEIVE 0.10-0.20 INCHES OF RAIN FROM THE
FRONTAL PASSAGE. SNOW LEVELS WILL DECREASE TUESDAY NIGHT TO AROUND
2500 FEET AFTER MIDNIGHT SO RAIN WILL TRANSITION TO SNOW AT PASS
LEVELS BY MID EVENING. THEN A WEAK...LOW AMPLITUDE MID/UPPER LEVEL
TROUGH MOVES INLAND ON WEDNESDAY. THIS SYSTEM WILL MAINLY BRING MID
AND HIGH LEVEL CLOUDS OVER THE FORECAST AREA ON WEDNESDAY WITH DRY
CONDITIONS PREDOMINATING...EXCEPT FOR A CHANCE OF SNOW SHOWERS ALONG
THE EAST SLOPES OF THE CENTRAL WASHINGTON CASCADES. POLAN
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. CONFIDENCE IN THE
MEDIUM-RANGE MODELS IS FAIRLY STRONG THROUGH THE END OF THE WEEK BUT
FADES LATE IN THE PERIOD. HIGH PRESSURE WILL STRENGTHEN OFFSHORE
EARLY IN THE EXTENDED PERIOD LEAVING WA/OR UNDER A NORTHERLY FLOW
ALOFT. A SHORTWAVE MOVING SOUTH ALONG THE ROCKIES MAY BRING A FEW
SHOWERS IN EXTREME NE OREGON BUT MAY ALSO BRING INCREASING WINDS TO
PORTIONS OF THE AREA--NOTHING SIGNIFICANT BUT LOCALLY BREEZY. THE
RIDGE WILL SHIFT EASTWARD WITH THE AXIS OF THE RIDGE ALONG THE
CASCADES BY FRIDAY. THIS WILL RESULT IN A DRY AND WARMING TREND
THURSDAY AND FRIDAY. AT THIS TIME...WILL KEEP TEMPS SLIGHTLY ABOVE
SEASONAL AVERAGE BUT FUTURE SHIFTS MAY GO WARMER IF MODELS INCREASE
HEIGHTS EVEN MORE. WILL ALSO KEEP FRIDAY NIGHT AND SATURDAY DRY WITH
LITTLE WEATHER CHANGE...ALTHOUGH MODELS ARE HINTING AT A WEAK WAVE
OVERRIDING THE RIDGE. THE 12Z ECMWF HAS BACKED OFF ON THE STRENGTH
OF THE SHORTWAVE COMPARED TO ITS PREVIOUS RUN. UPSTREAM OFF THE
EASTERN PACIFIC...THE ECMWF IS MUCH STRONGER THAN THE GFS WITH AN
UPPER LOW THAT EVENTUALLY APPROACHES THE COAST OVER THE WEEKEND.
THE GFS ENSEMBLE IS A COMPROMISE OF BOTH SOLUTIONS. KEEPING THIS IN
MIND...FORECASTING CLIMATOLOGY ON POPS AND TEMPERATURES ON SUNDAY
SEEMS TO BE THE BEST OPTION. JOHNSON
&&
.AVIATION...00Z TAFS. MID AND HIGH LEVEL CLOUDS WILL INCREASE
TONIGHT WITH BASES AROUND 7-10,000 FT AGL ALONG WITH HIGHER LEVEL
ALTOCUMULUS AND CIRRUS CLOUDS. WINDS WILL REMAIN 10 KT OR LESS AT
MOST TAF SITES. JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 35 62 40 63 / 0 0 0 10
ALW 38 62 43 64 / 0 0 0 10
PSC 32 64 37 65 / 0 0 0 10
YKM 32 61 37 62 / 0 0 0 10
HRI 32 64 35 65 / 0 0 0 10
ELN 30 59 36 57 / 0 0 0 30
RDM 27 62 38 59 / 0 0 0 10
LGD 31 59 38 58 / 0 0 0 10
GCD 26 58 33 60 / 0 0 0 10
DLS 36 62 38 57 / 0 0 10 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
MONDAY : GREEN
TUESDAY : GREEN
WEDNESDAY : GREEN
GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
$$
99/85/85
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