Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 260319
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
719 PM PST SUN JAN 25 2015

.UPDATE...CURRENT FORECAST IS ON TRACK THIS EVENING. MAIN CONCERN IS
WIDESPREAD FOG AND/OR LOW CLOUDS IN THE LOWER COLUMBIA BASIN AND
ADJACENT VALLEYS. SO FAR THE FOG HAS STAYED OUT OF THE OREGON BLUE
MOUNTAIN FOOTHILLS...IN CENTRAL OREGON AND THE EASTERN MOUNTAINS. A
DENSE FOG ADVISORY REMAINS IN EFFECT UNTIL NOON MONDAY FOR THE BASIN
AND ADJACENT VALLEYS. IN THE SOUTHERN GRANDE RONDE VALLEY STRONG
WINDS HAVE PROMPTED THE ISSUANCE OF A WIND ADVISORY WHICH IS IN
EFFECT UNTIL 3 PM MONDAY WHEN PRESSURE GRADIENTS WEAKEN. OTHERWISE
CONDITIONS WILL BE QUIET AND MILD UNDER A STRONG HIGH PRESSURE RIDGE
ALOFT OVER THE WESTERN US. 88

&&

.AVIATION...06Z TAFS...EXPECT MVFR/IFR CONDITIONS AT ALL TAF SITES
EXCEPT AT KPDT...KRDM AND KBDN DUE TO FOG AND LOW CLOUDS. THE FOG
WILL LIFT AND/OR BURN OFF BY NOON MONDAY. WINDS WILL REMAIN MOSTLY
LIGHT AND VARIABLE THROUGH THE NEXT 24 HOURS. 88

&&

.PREV DISC... /ISSUED 325 PM PST SUN JAN 25 2015/

SHORT TERM...TONIGHT THROUGH WEDNESDAY...RIDGE OF HIGH PRESSURE
WILL CONTINUE OVER THE REGION THROUGH MONDAY AND THEN BEGIN TO
WEAKEN AND FLATTEN ALLOWING A WEAK SYSTEM TO MOVE ACROSS THE AREA
LATE TUESDAY AND WEDNESDAY. TEMPERATURES WILL REMAIN WARM THROUGH
MONDAY WITH SOME MORE RECORD HIGH TEMPERATURES POSSIBLE AND THEN
BEGIN TO COOL AS THE RIDGE BREAKS DOWN. THE INVERSION WILL ALSO
REMAIN THUS KEEPING TRAPPED LOW CLOUDS AND FOG IN PORTIONS OF THE
FORECAST AREA INTO WEDNESDAY WHEN THERE COULD BE SOME SCOURING OUT
OF THE FOG BUT NOT A COMPLETE SOURING. HAVE ISSUED A DENSE FOG
ADVISORY THROUGH NOON MONDAY FOR THE POTENTIAL OF LOW VISIBILITIES
DUE TO THE FOG. TEMPERATURES IN THE FOG AREAS WILL REMAIN COOL DUE
TO A LACK OF SURFACE HEATING AND THE INVERSION. VERY WINDY
CONDITIONS WILL CONTINUE FOR THE SOUTHERN GRANDE RONDE VALLEY
THROUGH MONDAY AFTERNOON FOR WHICH A WIND ADVISORY IS IN EFFECT.

LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...HIGH PRESSURE WILL
DOMINATE THE AREAS WEATHER THROUGH AT LEAST SATURDAY. A WEAK
DISTURBANCE WILL MOVE THROUGH WEDNESDAY NIGHT WITH A SLIGHT CHANCE
OF RAIN SHOWERS...BUT DRY CONDITIONS CAN OTHERWISE BE EXPECTED.
HOWEVER...FOG AND STRATUS WILL LIKELY PERSIST IN AND AROUND THE
LOWER COLUMBIA BASIN...WHICH WILL KEEP DAYTIME TEMPERATURES COOLER
THAN FOG-FREE LOCATIONS. THERE IS UNCERTAINTY ABOUT HOW MUCH FOG
WILL BE PRESENT IN CENTRAL OREGON...SO HAVE ONLY INCLUDED IT DURING
THE OVERNIGHT HOURS. THE MODELS BEGIN TO DIFFER ON SATURDAY NIGHT
AND SUNDAY WITH THE 12Z GFS FLATTENING THE RIDGE AND BRINGING A
FRONT AND PRECIPITATION THROUGH THE REGION WHILE THE ECMWF MAINTAINS
THE RIDGE UNTIL SUNDAY NIGHT. HAVE THEREFORE KEPT THE AREA MOSTLY
DRY BUT ADDED SOME RAIN ALONG THE CASCADES AND BLUE MOUNTAINS.
COBB

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  45  58  35  48 /   0   0   0  10
ALW  36  40  37  44 /   0   0   0   0
PSC  34  42  34  45 /   0   0   0  10
YKM  33  41  34  44 /   0   0   0  10
HRI  34  46  34  46 /   0   0   0  10
ELN  38  43  34  45 /   0   0   0  10
RDM  44  64  36  55 /   0   0   0  10
LGD  38  48  34  47 /   0   0   0  10
GCD  39  57  34  51 /   0   0   0  10
DLS  44  51  38  50 /  10  10  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...DENSE FOG ADVISORY UNTIL NOON PST MONDAY ORZ041-044.

     WIND ADVISORY UNTIL 3 PM PST MONDAY ORZ049.

WA...DENSE FOG ADVISORY UNTIL NOON PST MONDAY WAZ024-026>029.

&&

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

$$

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