Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 041622
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
921 AM PDT TUE AUG  4 2015

.SYNOPSIS...AN UPPER LOW CENTERED IN B.C. EXTENDS SOUTH INTO THE
PACIFIC NORTHWEST THIS MORNING...AND WILL CONTINUE AND EVEN SAG A BIT
MORE SOUTH OVER THE AREA THROUGH WEDNESDAY AND WEDNESDAY NIGHT BEFORE
MOVING EAST ON THURSDAY. THIS WILL BRING INCREASED ONSHORE FLOW AND
COOLER TEMPS TO THE AREA...AREAS OF NIGHT AND MORNING CLOUDS...AND
EVEN A CHANCE OF DRIZZLE TO AT LEAST THE NORTH COAST AREAS AT TIMES.
WEAK UPPER RIDGING WILL RETURN THURSDAY AND FRIDAY FOR A BIT OF A
WARM UP...FOLLOWED BY A DEEPER TROUGH FOR THE WEEKEND AND EARLY NEXT
WEEK FOR MORE CLOUDS...COOLER TEMPS...AND POSSIBLY A FEW SHOWERS.
&&

.SHORT TERM...AN UPPER LOW IS NOW CENTERED IN B.C. WITH AN UPPER
TROUGH THAT EXTENDS INTO WASHINGTON AND NORTHERN OREGON. THERE IS A
WEAK BOUNDARY THAT HAS MOVED INTO WESTERN WASHINGTON AND ONTO THE
SOUTH WASHINGTON AND FAR NORTH OREGON COAST...WHERE THE LOW CLOUDS
ARE THICKER THIS MORNING. SOME LOW CLOUDS HAVE REACHED THE SOUTH
CASCADE FOOTHILLS AND THE FAR NORTH OREGON CASCADE FOOTHILLS AND ARE
TRYING TO BUILD BACK INTO THE EASTERN SECTIONS OF THE PORTLAND AND
VANCOUVER METRO AREAS. THE CLOUDS IN THE PORTLAND AND VANCOUVER METRO
AREAS WILL MOSTLY CLEAR TODAY...BUT THE CLOUDS NEAR THE NORTH COASTAL
AREAS MAY TAKE SOME TIME TO THIN AND MAY NOT ENTIRELY CLEAR TODAY AS
THE CYCLONIC WESTERLY UPPER LEVEL FLOW CONTINUES.

ANOTHER PIECE OF ENERGY WILL CIRCULATE AROUND THE SOUTHERN PERIPHERY
OF THE UPPER LOW AND THROUGH WESTERN WASHINGTON AND NORTHWEST OREGON
TONIGHT AND WEDNESDAY...LOWERING 500 MB HEIGHTS SOME...AND
REINFORCING THE ONSHORE FLOW AND LOW CLOUDS. LOOK FOR BETTER COVERAGE
OF LOW CLOUDS AT LEAST IN THE NORTHERN INLAND AREAS WEDNESDAY
MORNING. THE MODELS PAINT SOME QPF NEAR THE COAST LATER TONIGHT AND
WEDNESDAY...AND EVEN SOME INLAND WEDNESDAY MORNING THAT LINGERS INTO
THE AFTERNOON ESPECIALLY OVER THE HIGHER TERRAIN.

THE CLOUDS IN THE NORTH MAY BE MORE PERSISTENT WEDNESDAY
AFTERNOON...WITH BROKEN CIGS PERSISTING ALONG THE COAST AND OVER THE
HIGHER TERRAIN AND SCATTERED TO BROKEN CIGS OVER THE NORTHERN
VALLEYS. WEDNESDAY WILL BE THE COOLEST DAY OF THE WEEK WITH 850 MB
TEMPS SUPPORTING THE MID OR UPPER 70S IN THE NORTH...80 TO 85 NEAR
EUGENE.

THE UPPER TROUGH/LOW SYSTEM MOVES OFF TO THE EAST WEDNESDAY NIGHT AND
THURSDAY...BUT SOME LINGERING ENERGY IN THE NORTHWEST FLOW ALOFT WILL
KEEP SOME CLOUDS ACROSS ESPECIALLY THE NORTHERN PORTIONS OF OUR
FORECAST AREA INTO THURSDAY...AND SOME LINGERING SHOWERS OVER THE
SOUTH WASHINGTON CASCADES ARE NOT OUT OF THE QUESTION. THURSDAY
AFTERNOON SHOULD SEE CLEARING OVER MOST OF THE AREA. TEMPS WILL START
TO REBOUND...BUT MAY REMAIN NEAR NORMAL IN THE NORTH. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
BROAD UPPER-LEVEL TROUGH AND CONTINUED ONSHORE FLOW SHOULD KEEP
TEMPERATURES OUT OF THE 90S LATE THIS WEEK INTO THE WEEKEND...BUT
WEAKENING ONSHORE FLOW AND WINDS BECOMING MORE SOUTHERLY ON FRIDAY
WILL ALLOW TEMPERATURES TO BE A BIT WARMER ON FRIDAY THAN EARLIER IN
THE WEEK. SOUTHERLY FLOW ALSO INTRODUCES A CHANCE FOR THUNDERSTORMS
IN THE OREGON CASCADES...MAINLY ALONG THE CREST. THE SHIFT TO MORE
SOUTHERLY WINDS OCCURS AHEAD OF A UPPER LEVEL LOW DIGGING DOWN OUT OF
ALASKA OVER THE WEEKEND... BRINGING A CHANCE FOR SHOWERS SATURDAY AND
SUNDAY. THERE IS SOME DISAGREEMENT BETWEEN THE MODELS ON TIMING AND
AMOUNT OF RAIN WITH OF THIS SYSTEM...CREATING UNCERTAINTY WHICH
SHOULD BECOME RESOLVED AS WE APPROACH THIS WEEKEND. HAVE KEPT
TEMPERATURES A BIT CLOSER TO CLIMATOLOGY ON SATURDAY AND SUNDAY...BUT
IF SYSTEM PLAYS OUT AS FORECAST RIGHT NOW TEMPERATURES WILL LIKELY BE
A BIT COOLER THAN CURRENTLY FORECAST. -MCCOY
&&

.AVIATION...MVFR STRATUS CONTINUES ALONG THE NORTH COAST...THE LOWER
COLUMBIA RIVER...AND NEAR THE COLUMBIA RIVER GORGE THIS MORNING.
EXPECT THE STRATUS ALONG THE LOWER COLUMBIA AND NEAR THE GORGE TO
LIFT AND DISSIPATE THROUGH THE MORNING WITH CIGS TURNING VFR THIS
AFTERNOON. STRATUS ALONG THE NORTH COAST WILL BE SLOWER TO
DISSIPATE...BUT A BRIEF PERIOD OF VFR CIGS ARE POSSIBLE LATE THIS
AFTERNOON. OTHERWISE...WIDESPREAD VFR CONDITIONS ARE EXPECTED TO
CONTINUE THROUGH THIS EVENING OVER THE CENTRAL COAST AND THROUGH
TONIGHT OVER MUCH OF THE INTERIOR. MVFR MARINE STRATUS WILL RETURN TO
THE COAST THIS EVENING...WITH IFR CIGS AND VSBY POSSIBLE AFTER 06Z.
ONSHORE FLOW LOOKS TO BE SLIGHTLY STRONGER TONIGHT...SO SUSPECT MVFR
STRATUS WILL PUSH FURTHER UP THE COLUMBIA AND REACH THE PORTLAND
METRO TERMINALS AFTER 11Z.

KPDX AND APPROACHES...VFR THE NEXT 24 HOURS. HOWEVER...MARINE STATUS
LOOKS TO PUSH FURTHER UP THE COLUMBIA RIVER TONIGHT AND COULD BRING A
BRIEF PERIOD OF MVFR CIGS BETWEEN 14-17Z. /64
&&

.MARINE...NO SIGNIFICANT CHANGES. PREVIOUS DISCUSSION FOLLOWS... HIGH
PRESSURE CONTINUES OVER THE NORTHEAST PACIFIC AND MAINTAINS THE
TYPICAL SUMMERTIME PATTERN OF NORTHERLY WINDS ALONG THE COAST WITH
OCCASIONAL STEEPER WIND DRIVEN SEAS FROM TIME TO TIME THIS WEEK.

THE FIRST ROUND OF WINDS AND HIGHER SEAS SHOULD ARRIVE THIS AFTERNOON
AND EVENING. SMALL CRAFT ADVISORIES FOR WINDS AND HAZARDOUS SEAS
REMAIN IN EFFECT FOR THE CENTRAL OREGON WATERS. THE NEXT MAJOR UPTICK
IN WINDS AND SEAS WILL LIKELY ARRIVE THURSDAY AFTERNOON AND EVENING
AS THERMAL LOW PRESSURE TEMPORARILY STRENGTHENS OVER CALIFORNIA AND
WE WILL LIKELY NEED ANOTHER ROUND OF SMALL CRAFT ADVISORIES FOR THE
CENTRAL OREGON WATERS.

AN UPPER LEVEL TROUGH SHOULD SETTLE INTO THE PACIFIC NORTHWEST OVER
THE WEEKEND...AND A WEAK FRONT MAY BRIEFLY TURN WINDS SOUTHERLY...
BUT WINDS LOOK TO REMAIN RELATIVELY BENIGN. OTHERWISE...WE MAY SEE
NORTHERLY WINDS STRENGTHEN AS THERMAL LOW PRESSURE OVER CALIFORNIA
RETURNS LATE IN THE WEEKEND INTO EARLY NEXT WEEK.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS AND HAZARDOUS SEAS FROM 2 PM
     THIS AFTERNOON TO 3 AM PDT WEDNESDAY FOR COASTAL WATERS
     FROM CASCADE HEAD TO FLORENCE OR OUT 60 NM.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

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.


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