000
FXUS66 KPQR 070338
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
836 PM PDT SAT SEP 06 2008
.SYNOPSIS...AN UPPER RIDGE OVER THE EASTERN PACIFIC WILL BE THE
PERSISTENT LARGE SCALE FEATURE THROUGH MUCH OF THE COMING WEEK. THERE
WILL BE SOME WEAK UPPER LEVEL SHORT WAVES RIDING OVER THE RIDGE AND
DOWN INTO THE ROCKY MOUNTAIN REGION THAT WILL AFFECT THE ONSHORE FLOW
AND MARINE LAYER AT TIMES. ONE SHORT WAVE WILL CUT BACK AND DEVELOP
OFF CALIFORNIA TONIGHT AND SUNDAY THAT WILL CAUSE THE THERMAL TROUGH
TO MOVE BACK TO NEAR THE COAST SUNDAY INTO MONDAY FOR WARMING AND
LESS MARINE INFLUENCE. A SERIES OF SHORT WAVES TO OUR NORTH WILL TURN
THE FLOW MORE ONSHORE MONDAY NIGHT AND TUESDAY AS AN UPPER TROUGH
CARVES OUT OVER THE ROCKY MOUNTAIN REGION AGAIN. THE UPPER RIDGE WILL
THEN REBUILD WEDNESDAY AND THURSDAY FOR ANOTHER WARMING PERIOD BEFORE
ONSHORE FLOW RETURNS NEXT WEEKEND.
&&
.SHORT TERM...THE MODELS CONTINUE TO SHOW THAT AN UPPER HIGH WILL
DOMINATE THE NE PAC MUCH OF THE COMING WEEK...WITH AN OCCASIONAL WEAK
SHORT WAVE RIDING OVER THE RIDGE AND MOVING S INTO THE ROCKY MOUNTAIN
REGION. MARINE CLOUDS HAVE MOVED BACK INTO THE IMMEDIATE COASTAL
AREAS THIS EVENING...AND AN ONSHORE PRES GRADIENT FROM ASTORIA TO
PORTLAND SUGGESTS SOME MARINE CLOUDS WILL MOVE BACK UP THE COLUMBIA
RIVER LATE TONIGHT. EXPECT THE MORE SOLID CLOUDS TO ONLY MAKE IT TO
ABOUT KELSO...BUT SOME BRIEF CLOUDS MAY FORM UP TO TROUTDALE EARLY
SUN MORNING. THE MODELS CONTINUE TO SHOW ONE WEAK SHORT WAVE DROPPING
THROUGH THE PAC NW TONIGHT WILL DIG BACK TO THE SW AND DEVELOP A WEAK
UPPER LOW OFF CALIFORNIA LATE TONIGHT AND SUN. THE MAIN IMPACT WILL
BE TO CAUSE THE THERMAL TROUGH TO SHIFT BACK TO NEAR THE COAST AND
REDUCE THE ONSHORE FLOW...TURNING TOWARD A NE OFFSHORE FLOW SUN. THIS
WILL FORCE THE CLOUDS TO CLEAR BACK OFFSHORE SOME IN THE AFTERNOON AS
INLAND TEMPS FINALLY RISE INTO THE 80S. RW
THE THERMAL TROUGH WILL REMAIN ALONG THE COAST SUNDAY NIGHT AND
MONDAY WITH NO LOW CLOUDS INLAND AND JUST PATCHY IF THAT ALONG THE
COAST. MONDAY SHOULD BE ANOTHER WARM DAY AND COULD BE WARMER THAN
SUNDAY. A WEAK UPPER SHORT WAVE MOVES INTO THE PACIFIC NORTHWEST FROM
THE NORTHWEST MONDAY AFTERNOON THAT WILL BEGIN TO TURN THE LOW LEVEL
FLOW ONSHORE BY MONDAY NIGHT. A COUPLE MORE SHORT WAVES FOLLOW MONDAY
NIGHT AND TUESDAY THAT PUSH THROUGH THE PACIFIC NORTHWEST... TURN THE
LOW LEVEL FLOW ONSHORE...BRING MORE MARINE CLOUDS TO THE REGION...AND
ALSO BRING SOME COOLING. MARINE CLOUDS TUESDAY COULD BE SLOW CLEARING
ESPECIALLY AT THE COAST. TOLLESON
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
AFTER A SHORTWAVE PASSES EAST OF THE AREA TUESDAY
NIGHT...GUIDANCE CONTINUES TO INDICATE A STRONG RIDGE WILL REBUILD
OVER THE PACIFIC AND PERSIST THROUGH MOST OF NEXT WEEK. THIS WILL
BRING OFFSHORE FLOW AND A RETURN OF DRY WEATHER AND WARM TEMPERATURES
FOR WEDNESDAY AND THURSDAY WITH HIGHS INLAND INTO THE 80S. LONG TERM
MODELS START TO FLATTEN THE RIDGE SOMEWHAT THURSDAY NIGHT INTO
FRIDAY. ONSHORE FLOW SHOULD RETURN FRIDAY THROUGH THE WEEKEND...FOR
CLOUDY MORNINGS INLAND AND A RETURN TO MORE NORMAL TEMPERATURES.
BROWN
&&
.AVIATION...STRONG HIGH PRESSURE OFFSHORE EXTENDS INTO BRITISH
COLUMBIA TONIGHT WITH THERMAL TROUGH ALONG SOUTH OREGON COAST. HIGH
PRESSURE CONTINUES OFFSHORE INTO BRITISH COLUMBIA SUNDAY WITH
THERMAL TROUGH OVER WESTERN OREGON. NORTHERLY FLOW WILL DEVELOP OVER
AREA TONIGHT WITH SLIGHT OFFSHORE COMPONENT OVER INLAND AREAS. NORTH
TO NORTHWEST FLOW WILL CONTINUE ON SUNDAY. SHALLOW MARINE AIR MASS
ALONG THE COAST TONIGHT WILL EXTEND INLAND ALONG THE COLUMBIA RIVER
TO THE WEST OF PORTLAND LATE TONIGHT AND EARLY SUNDAY. THERE WILL BE
WIDESPREAD IFR/LIFR CONDITIONS WITH THE MARINE AIR. THE MARINE AIR
WILL BREAK UP ALONG THE NORTHERN COAST SUNDAY MORNING AND ALONG THE
CENTRAL COAST DURING THE AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS WILL CONTINUE IN THE KPDX AREA
TONIGHT AND SUNDAY. LOCAL MVFR VISIBILITIES ARE POSSIBLE AROUND
DAYBREAK SUNDAY UNTIL MID MORNING.
&&
.MARINE...HIGH PRESSURE OFFSHORE EXTENDING INTO BRITISH COLUMBIA
TONIGHT AND SUNDAY. THERMAL TROUGH ALONG SOUTH OREGON COAST TONIGHT
WILL SHIFT OVER WESTERN OREGON SUNDAY. SMALL CRAFT WINDS WILL
CONTINUE OVER THE WATERS TONIGHT AND SUNDAY DECREASING NEAR SHOWER
AFTER MIDNIGHT. WINDS WILL INCREASE NEAR SHOWER AGAIN SUNDAY
AFTERNOON. SEAS WILL REMAIN BELOW 10 FEET. SEAS OF 6 TO 8 FEET
COMBINED WITH SHORT PERIODS WILL GIVE HAZARDOUS SEAS TONIGHT AND
SUNDAY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...SMALL CRAFT ADVISORY FOR WINDS CAPE SHOALWATER TO FLORENCE
THROUGH MON.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO
FLORENCE TONIGHT THROUGH SUNDAY EVENING.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST --00-1 PDX 00000- SLE 00000- EUG 00000-
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
