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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR 
853 PM PDT WED JUL 23 2014

.SYNOPSIS...AN UNSEASONABLY STRONG AND COOL LOW PRESSURE SYSTEM  WILL
MOVE OVER SOUTHWEST WASHINGTON AND NORTHEAST OREGON TONIGHT AND EARLY
THURSDAY FOR CONTINUED SHOWERS. ISOLATED THUNDERSTORMS ...PRODUCING
HEAVY RAIN...LIGHTNING...AND SMALL HAIL...WILL CONTINUE THROUGH THE
EVENING. A FEW SHOWERS WILL LINGER THURSDAY...BEFORE
HIGHER PRESSURE BUILDS FRIDAY...BRINGING DRYER AND WARMER CONDITIONS
THROUGH THE WEEKEND AND INTO NEXT WEEK.
&&

.SHORT TERM...AN UNSEASONABLY COOL UPPER LOW IS CENTERED AROUND 100
MILES OFFSHORE THE WASHINGTON/OREGON BORDER. RADAR IMAGERY SHOWS RAIN
ASSOCIATED WITH THIS CENTER MOVING OVER THE SW WASHINGTON. THERE ARE
ALSO SHOWERS EMBEDDED IN BANDS ROTATING AROUND THE LOW MOVING ACROSS
NW OREGON. ISOLATED THUNDERSTORMS HAVE BEEN PRODUCING SMALL
HAIL...HEAVY RAIN...AND LIGHTNING. THE THREAT FOR THUNDERSTORMS IS
MAINLY IN THE NORTHERN PORTION OF THE FORECAST AREA...IN SOUTHERN
WASHINGTON...ALTHOUGH WOULD NOT BE SURPRISED IF AN ISOLATED STORM
POPS UP ALONG THE NORTHER OREGON COAST OR COAST RANGE THIS EVENING. 

THE UPPER LOW WILL PUSH INLAND ACROSS WASHINGTON STATE TONIGHT WITH
SHOWERS LINGERING OVER THE PORTLAND FORECAST AREA THROUGH THURSDAY
MORNING...BUT THE THREAT FOR THUNDERSTORMS WILL END AROUND SUNSET
THIS EVENING. THERE WILL BE JUST A FEW SHOWERS LINGERING OVER THE SW
WASHINGTON CASCADES THURSDAY AFTERNOON. CLEARING SKIES WILL RESULT IN
SOME WARMING THURSDAY AFTERNOON WITH VALLEY TEMPERATURES EXPECTED TO
PEAK IN THE MID TO UPPER 70S AND COASTAL TEMPERATURES IN THE MID TO
UPPER 60S.    

AN UPPER RIDGE...THOUGH INITIALLY QUITE FLAT...WILL SLOWLY START TO
MOVE IN FRIDAY FOR A RETURN TO MORE SEASONABLE DRY WEATHER WITH SOME
MORNING CLOUDS AND AFTERNOON SUNSHINE. TEMPS WILL FINALLY APPROACH 80
AGAIN INLAND. THE WARMING WILL CONTINUE IN EARNEST ON SATURDAY AS 500
MB HEIGHTS BUILD INTO AT LEAST THE MID 580S...WITH PLENTY OF SUNSHINE
PRETTY MUCH ACROSS THE ENTIRE FORECAST AREA AFTER SOME BRIEF MORNING
CLOUDS MAINLY IN THE NORTH. LOOK FOR INLAND HIGHS WELL UP IN THE 80S
SATURDAY...POSSIBLY GETTING CLOSE TO 90 IN SOME AREAS. TJ/TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...HIGH PRESSURE
WILL CONTINUE TO BUILD OVER THE PACIFIC NORTHWEST AHEAD OF A
SHORTWAVE TROUGH...FORECAST TO COME ONSHORE SOMETIME LATE SUNDAY
NIGHT OR MONDAY MORNING. THERE IS STILL UNCERTAINTY ON THE TIME THIS
SYSTEM WILL MOVE INTO OUR AREA AND THE LOCATION OF ANY ASSOCIATED
PRECIPITATION.THE WAVE IS UNRESOLVED IN THE MEAN 500-MB HEIGHT
FIELD FROM GEFS AND NAEFS...BUT THE GFS AND ECMWF BOTH HAVE IT MOVING
THROUGH SUNDAY NIGHT OR EARLY MONDAY MORNING. BEHIND THIS
SYSTEM...THE LARGE UPPER-LEVEL RIDGE IS FORECAST TO CONTINUE TO BUILD
IN AMPLITUDE AND WESTWARD AND WILL BECOME CENTERED OVER THE ROCKIES
BY MID-WEEK.  SOUTHWESTERLY UPPER-LEVEL FLOW AND CLEAR SKIES INLAND
WILL KEEP TEMPERATURES FAIRLY WARM OVER OUR AREA TUESDAY AND
WEDNESDAY. -MCCOY
&&

.AVIATION...A POST FRONTAL AIRMASS WILL LEAD TO PRIMARILY VFR AND
MVFR CONDITIONS FOR MOST TAF SITES THROUGH 06Z MONDAY. A SECOND
ROUND OF MORE CONSOLIDATED SHOWERS BEGINNING TO ARRIVE ON THE
COAST WILL LIKE ALLOW MVFR CONDITIONS TO BECOME MORE DOMINANT AT
KAST. THERE IS A DECENT CHANCE THESE LOWER FLIGHT CONDITIONS WILL
EVENTUALLY IMPACT KONP AND PERHAPS THE PORTLAND METRO TAF SITES
CLOSER TO 12Z THURSDAY. ANY LOWER FLIGHT CONDITIONS THAT DO
DEVELOP SHOULD BECOME VFR TOWARDS 18Z TO 20Z THURSDAY.
HOWEVER...BKN TO OVC CONDITIONS WILL LIKELY BE SLOW TO CLEAR
THURSDAY AFTERNOON...ESPECIALLY ACROSS THE NORTH. 

KPDX AND APPROACHES...AN UNSTABLE AIRMASS WILL LEAD TO MAINLY VFR
CONDITIONS THROUGH 06Z FRIDAY. HOWEVER...A LOW PRESSURE SPINNING
OFF WESTERN WASHINGTON WILL INCH ITS WAY CLOSER OVERNIGHT...AND
SPREAD ADDITIONAL SHOWERS INTO THE AREA. WITH THE LOWER ATMOSPHERE
STABILIZING A BIT AND PERHAPS AN UPTICK IN RAIN SHOWERS...A PERIOD
OF MVFR CONDITIONS WILL BE POSSIBLE BETWEEN PRIMARILY 12Z AND 18Z
THURSDAY. /NEUMAN
&&

.MARINE...A BENT BACK OCCLUSION IS BRINGING SOLID SMALL CRAFT
ADVISORY LEVEL WINDS OF 20 TO 25 KT WITH GUSTS NEAR 30 KT ACROSS
THE WATERS THIS EVENING. THESE WINDS WILL CONTINUE FOR MUCH OF
TONIGHT BEFORE EASING BELOW 20 KT AROUND OR SLIGHTLY AFTER DAWN. 

THESE WINDS ARE ALSO CREATING A FRESH SWELL THAT IS INCREASING
INTO THE 7 TO 9 FT RANGE...AND MAY EVEN BRIEFLY TOUCH 10 FT ACROSS
THE OUTER WATERS. REGARDLESS...DOMINANT PERIODS WILL ALSO HOVER IN
THE 7 TO 9 SECOND RANGE...MEANING SEAS WILL BE ESPECIALLY STEEP
AND POTENTIALLY HAZARDOUS. SEAS SHOULD BEGIN TO LOWER THURSDAY
MORNING. 

A ROUGH BAR FOR HAZARDOUS SEAS WAS ALSO HOISTED FOR THE EBB LATE
TONIGHT. ANOTHER ONE MAY BE NEEDED FOR THURSDAY AFTERNOON...BUT
WILL LET LATER SHIFTS DECIDE BASED ON SEA TRENDS VS MODEL
GUIDANCE. THE SETUP TONIGHT IS SOMEWHAT SIMILAR TO AN EVENT A
COUPLE WEEKS AGO THAT RESULTED IN A FISHING BOAT CAPSIZING ON THE
COLUMBIA RIVER BAR.

HIGH PRESSURE WILL THEN BUILD OVER THE NORTHEAST PACIFIC THURSDAY
INTO FRIDAY...WITH THERMAL LOW PRESSURE BUILDING OVER NORTHERN
CALIFORNIA. THIS WILL BRING A MORE TYPICAL SUMMERTIME PATTERN OF
GUSTY NORTHERLY WINDS...AND POTENTIALLY STEEP SEAS...ESPECIALLY
ACROSS THE CENTRAL OREGON WATERS. /NEUMAN
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 9 AM PDT THURSDAY FOR 
     COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT   
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 AM PDT THURSDAY 
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR   
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 2 AM TO  
     6 AM PDT THURSDAY.
&&

$$

MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND
    
INTERACT WITH US VIA SOCIAL MEDIA    
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV    
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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