000
FXUS66 KPQR 071549
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
848 AM PDT SUN SEP 07 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 WAS BEGINNING TO DEVELOP AN
UPPER LOW OFF CALIFORNIA TODAY THAT WILL CAUSE THE THERMAL TROUGH TO
MOVE BACK TO NEAR THE COAST TODAY 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 AGAIN AT THE END OF THE WEEK.
&&
.SHORT TERM...FOG CHANNEL SATELLITE IMAGERY HAS SHOWN THE FOG AND LOW
CLOUDS ALONG THE COAST CLEARING FROM THE NORTH ALONG THE WASHINGTON
COAST AND THIS WILL CONTINUE SOUTH ALONG THE OREGON COAST TODAY AS
OFFSHORE FLOW CONTINUES TO DEVELOP. THE PERSISTENT EASTERN PACIFIC
UPPER RIDGE IN CONCERT WITH A DEVELOPING UPPER LOW ALONG THE
CALIFORNIA COAST ARE WORKING TOGETHER TO SHIFT THE SURFACE THERMAL
LOW BACK TO THE COAST TODAY. THE MARINE LAYER HAS ALREADY BECOME MORE
SHALLOW WITH FOG ON THE OREGON COAST...WHICH WILL CLEAR AS THE
OFFSHORE FLOW INCREASES TODAY. GRADIENTS ARE ALREADY MINUS 2.3 MB
KTTD TO KDLS AT 8 AM AND WE ARE STARTING TO SEE A LITTLE EAST WIND IN
THE GORGE AS WELL AS HIGHER ELEVATIONS OF THE CASCADES AND THE COAST
RANGE. THIS SHOULD ALLOW INLAND TEMPS TO REACH THEIR POTENTIAL WITH
REGARD TO 850 MB TEMPS...WITH MID OR POSSIBLY UPPER 80S INLAND.
THE THERMAL TROUGH WILL REMAIN NEAR THE COAST TODAY INTO MONDAY
MORNING...THEN BEGIN TO SHIFT EAST OF THE CASCADES LATE MONDAY AND
MONDAY NIGHT AS THE UPPER FLOW BECOMES MORE NORTHWESTERLY AND THE
NEXT SHORT WAVE MOVES INTO THE PACIFIC NORTHWEST. THIS WILL TURN THE
FLOW ONSHORE AND DEVELOP A MARINE LAYER AGAIN ALONG THE COAST...THAT
SHOULD PUSH INLAND TUESDAY MORNING. STILL A WARM DAY MONDAY INLAND
BUT COOLING NEAR THE COAST...WITH COOLING ALL AREAS TUESDAY. THIS
DISTURBANCE LOOKS DRY UNLESS SOME DRIZZLE IS SQUEEZED OUT OF THE
MARINE LAYER AT THE COAST ON TUESDAY. CLOUDS ON TUESDAY WILL BE A BIT
PERSISTENT ESPECIALLY AT THE COAST.
THE FLOW IS STILL ONSHORE TUESDAY NIGHT FOR INLAND PENETRATION OF LOW
CLOUDS AGAIN EARLY WEDNESDAY...THEN CLEARING WEDNESDAY AFTERNOON AS
THE SYSTEM MOVES EAST AND HIGH PRESSURE BUILDS IN. 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...VFR AT ALL INLAND SITES FOR THE NEXT 24 HOURS. LIFR FOG
ALONG THE COAST FROM TILLAMOOK SOUTH IS 100 TO 200 FT THICK
BUT...BASED ON SATELLITE TRENDS...SHOULD CLEAR KONP BY 17Z. SOME
PATCHY LIFR FOG NEAR KAST SHOULD ALSO CLEAR BY 16 TO 17Z. ONCE FOG
CLEARS THIS MORNING...VFR CONDITIONS EXPECTED AT COASTAL SITES FOR
NEXT 24 HOURS AS WELL.
KPDX AND APPROACHES...VFR FOR NEXT 24 HOURS. EASTERLY WINDS JUST
ABOVE THE SURFACE SHOULD MIX DOWN TO KPDX BETWEEN 18 TO 20Z. WIND 10
TO 12KT AT 060 DEGREES SHOULD BE PREDOMINANT WIND FROM MIDDAY THROUGH
LATE EVENING. DALTON
&&
.MARINE...NORTHERLY WINDS WILL CONTINUE OVER THE WATERS TODAY. WINDS
15 TO 20 KT WILL INCREASE TO 15 TO 25 KT BY EARLY AFTERNOON...WITH
GUSTS AS HIGH AS 30 KT POSSIBLE MAINLY SOUTH OF NEWPORT. CURRENT
SMALL CRAFT ADVISORY FOR WINDS COVERS THIS. ADDITIONALLY...SEAS WILL
ALSO BE ROUGH TODAY. SEAS WILL RISE FROM 7 FT THIS MORNING TO 8 TO 9
FT OVER MOST OF THE COASTAL WATERS BY THIS AFTERNOON...ALL THE WHILE
MAINTAINING A 6 TO 8 SECOND DOMINANT WAVE PERIOD. CURRENT HAZARDOUS
SEAS ADVISORY GOES UNTIL 11 PM TONIGHT...BUT THIS WILL LIKELY BE
EXTENDED IN THE AFTERNOON PACKAGE AS SIMILAR CONDITIONS WILL OCCUR
TONIGHT AND MONDAY. DALTON
&&
.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 THROUGH THIS TONIGHT.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 000111 PDX 00001 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.
