Excessive Heat in Oregon, June 26 to 28, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
135 PM PDT FRI JUN 26 2015

.SYNOPSIS...A STRONG UPPER LEVEL RIDGE WILL CONTINUE THE HOT WEATHER
THROUGH SAT. ONSHORE FLOW IS EXPECTED TO BRING A PUSH OF MARINE AIR
SUNDAY FOR A SHORT BREAK FROM THE HEAT. A SOUTHERLY FLOW ALOFT OVER
THE WEEKEND WILL BRING A CHANCE FOR THUNDERSTORMS TO THE REGION SAT
AND SUN...THEN A SLIGHT CHANCE FOR SHOWERS AS AN UPPER LEVEL
DISTURBANCE PASSES. MORE HOT WEATHER IS EXPECTED NEXT WEEK AS AN
UPPER LEVEL RIDGE REBUILDS OVER THE INTERIOR PACIFIC NW. &&

.SHORT TERM...MARINE CLOUDS HAD RECEDED BACK TO THE COASTLINE BY
EARLY AFTERNOON AS INLAND TEMPS WARMED. THROUGH EARLY AFTERNOON HAVE
NOT SEEN MUCH IN THE WAY OF CONVECTIVE CLOUDS ANY CLOSER THAN
NORTHERN CA. SPC MESOANALYSIS DID INDICATE SOME INSTABILITY
DEVELOPING OVER THE CASCADES...BUT OVERALL SUSPECT THE DRY AND WARM
LOW TO MID LEVELS ARE LIKELY TO SUPRESS CONVECTION THIS EVENING.
WILL HOWEVER INCLUDE A SLIGHT CHANCE FOR CONVECTIVE REMNANTS TO MOVE
UP FROM THE S TONIGHT ACROSS THE S AS THE UPPER LEVEL FLOW BEGINS TO
OPEN UP FROM THE S.

SAT LOOKS LIKE A SIMILAR SITUATION FOR CONVECTIVE PROSPECTS...EXCEPT
FLOW IS MORE OPEN TO THE S AND MODELS HINTING A LITTLE MORE AT WEAK
SHORTWAVES MOVING UP. IT IS NOT CLEAR HOWEVER THAT THE CAP CAN BE
BROKEN DESPITE PROMISING INSTABILITY HIGHER UP. WILL CONTINUE TO
INDICATE LOW END CHANCES FOR THUNDERSTORMS SAT...FIRST TO THE
MOUNTAINS IN THE EVENING...THEN IN GENERAL OVERNIGHT SAT NIGHT AS AN
UPPER JET DEVELOPS OFF THE COAST AND MODELS SUGGEST A LITTLE BETTER
PROSPECTS FOR SOME DIVERGENCE ALOFT TO DEVELOP. UPPER RIDGE AXIS
BEGINS TO INCH E SAT...BUT WITH H8 TEMPS STILL ON THE ORDER OF 24
DEG C EXOECT MOST OF THE INTERIOR TO BE ABOUT AS WARM SAT AS THEY
WERE FRI. ONE EXCEPT MAY BE THE S WILLAMETTE VALLEY AS A W ONSHORE
FLOW BEGINS TO KICK IN.

MODELS CONTINUE TO SHOW AIR MASS STABILIZING SUN AS OSHORE FLOW
PICKS UP. THIS WILL LEAD TO TEMPS COMING DOWN SOME INLAND AREAS SUN.
WILL ALSO DROP THE MENTION OF THUNDER W OF THE CASCADES AFTER THE
MORNING SUN AS MODEL SOUNDINGS SHOW ONLY REMAINING INSTABILITY OVER
THE CASCADES. WILL HOWEVER KEEP A SLIGHT CHANCE FOR SHOWERS THROUGH
SUN NIGHT AND INTO MON MORNING UNTIL THE MAIN SHORTWAVE LIFTS OUT.
TEMPS MON A LITTLE TRICKY...STILL SOME ONSHORE FLOW BUT WITH H8
TEMPS STILL AROUND 18 DEG C EXPECT TO SEE INLAND VALLEY TEMPS BOUNCE
BACK CLOSE TO 90.

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...ONSHORE FLOW WILL
CONTINUE LATE MONDAY AND INTO TUESDAY MORNING AS ANOTHER WEAK
SHORTWAVE DISTURBANCE SHIFTS OVERHEAD. THIS WILL BRING THE COOLEST
NIGHT OF THE WEEK...WITH OVERNIGHT LOWS DROPPING INTO THE 50S FOR
MONDAY NIGHT. THIS IS SHORT-LIVED AS MODELS QUICKLY HAVE THE UPPER
LEVEL RIDGE REBOUNDING TUESDAY. THIS MEANS HOT SUMMER TEMPERATURES
CONTINUE INTO THE FORESEEABLE FUTURE...WITH HIGH TEMPERATURES
HOLDING STEADY NEAR 70F ON THE COAST AND IN THE LOWER TO MID 90S
INLAND. NOT EXPECTING OVERNIGHT LOWS TO COOL OFF MUCH EITHER...WITH
LOWS IN THE LOWER TO MID 60S TUESDAY NIGHT AND ON. LATEST GUIDANCE
HAS FURTHER BACKED OFF ON THE THREAT FOR MONSOONAL MOISTURE MAKING
ITS WAY TOWARDS THE PACIFIC NORTHWEST...KEEPING US DRY AND HOT. /27

&&

.AVIATION...DRY AND CLEAR OVER REGION WITH LIGHT SOUTHERLY FLOW
ALOFT. WILL HAVE VARIABLE HIGH CLOUDS WHICH WILL BE REMAINS OF
CONVECTION FROM N CALIF AND FAR S OREGON WILL DRIFT OVERHEAD
AFTER 06Z. MARINE IFR STRATUS WITH TOPS 015 ON THE PAC OCEAN WILL
SPREAD BACK ONSHORE AFTER 03Z...AND PERSIST INTO SAT AM.

KPDX AND APPROACHES...CLEAR UNDER LIGHT S FLOW. WILL SEE VARIABLE
HIGH CLOUDS OVER AREA AFTER 08Z.                         ROCKEY.
&&

.MARINE...NOT MUCH CHANGE. HIGH PRES OVER NE PAC...WITH THERMAL
LOW PRES OVER SW OREGON. THIS MAINTAIN GUSTY N WINDS ON THE WATERS
TODAY AND TONIGHT. WINDS WILL EASE CLOSER TO SHORE LATER TONIGHT
AND ACROSS ALL WATERS SAT AM. AS UPPER LEVEL LOW PRES APPROACHES
LATE SAT AND SUN...WINDS WILL BECOMING SOUTHERLY...BUT STILL 15 KT
OR LESS.

SEAS ARE CURRENTLY 6 TO 8 FT MAINLY DUE TO THE BRISK N WINDS. AS
WINDS EASE SAT...SO WILL THE SEAS. LIKELY 5 TO 6 FT ON SAT AND SUN.

HIGH PRES AND GUSTY N WINDS WILL RETURN BY TUE AND WED AS THERMAL
LOW PRES REBUILDS OVER SW OREGON AND NW CALIF.         ROCKEY.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...EXCESSIVE HEAT WARNING THROUGH SATURDAY NIGHT FOR...
          WILLAMETTE VALLEY...
          LOWER COLUMBIA VALLEY...
          HOOD RIVER VALLEY...
          AND COLUMBIA RIVER GORGE.

     HEAT ADVISORY REMAINS IN EFFECT THROUGH SATURDAY NIGHT FOR...
          COAST RANGE...
          FOOTHILLS OF THE NORTH OREGON AND LANE COUNTY CASCADES.

     RED FLAG WARNING UNTIL 11 AM PDT SUNDAY FOR ZONE 602-ZONE 603-
     ZONE 604-ZONE 605-ZONE 606-ZONE 607-ZONE 608.

     FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
     MORNING FOR ZONE 601-ZONE 612.

WA...EXCESSIVE HEAT WARNING THROUGH SATURDAY NIGHT FOR...
          CLARK COUNTY...
          I-5 CORRIDOR IN COWLITZ VALLEY...
          COLUMBIA RIVER GORGE.

     HEAT ADVISORY REMAINS IN EFFECT THROUGH SATURDAY NIGHT FOR...
          WILLAPA HILLS...
          FOOTHILLS OF THE SOUTH WASHINGTON CASCADES.

     RED FLAG WARNING UNTIL 11 AM PDT SUNDAY FOR ZONE 602-ZONE 604-
     ZONE 660.

     FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
     MORNING FOR ZONE 601.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 8 AM SAT FOR THE OUTER
         COASTAL WATERS...OR FROM 10 TO 60 NM OFFSHORE FROM CAPE
         SHOALWATER TO FLORENCE.
     SMALL CRAFT ADVISORY FOR WINDS THIS EVENING FOR THE INNER
         COASTAL WATERS...OR FROM 0 TO 10 NM OFFSHORE FROM CAPE
         SHOALWATER TO FLORENCE.
&&

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.