Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
334 PM PDT FRI AUG 28 2015

.SYNOPSIS...THE FORECAST CONTINUES TO BE ON TRACK COMPARED TO THE
MODELS AND SATELLITE TRENDS AS A VERY SIGNIFICANT PATTERN CHANGE IS
ALREADY UNDERWAY FOR THE NEXT WEEK OR SO. AN UNSEASONABLY STRONG LOW
PRESSURE SYSTEM OFF THE SOUTH OREGON AND NORTHERN CALIFORNIA COAST
CONTINUES TO GAIN STRENGTH AND WILL LIFT NORTH ALONG THE COAST LATE
TONIGHT AND SATURDAY MORNING. THIS SYSTEM WILL PRODUCE HIGH WIND
ALONG THE COASTAL STRIP AND THE HIGHER ELEVATIONS AND EXPOSED AREAS
OF THE COAST RANGE...AS WELL AS WINDY CONDITIONS IN THE INLAND
VALLEYS AND OVER THE CASCADES. A FEW THUNDERSTORMS ARE ALSO POSSIBLE
NEAR THE COAST AND IN THE NORTH INTERIOR LATE TONIGHT AND SATURDAY
MORNING. THIS LOW MOVES NORTH OF THE FORECAST AREA SATURDAY AFTERNOON
BUT ANOTHER FRONT WILL APPROACH THE COAST WITH ANOTHER GOOD SHOT OF
RAIN AND BREEZY CONDITIONS LATE SATURDAY AND MOVE THROUGH SOUTHWEST
WASHINGTON AND NORTHWEST OREGON SATURDAY NIGHT. THE PATTERN WILL
REMAIN COOLER AND UNSETTLED THROUGH MUCH OF THE COMING WEEK...WITH
ANOTHER DECENT SHOT OF RAIN AROUND THE MIDDLE OF NEXT WEEK. 


&&


.SHORT TERM...AS EXPECTED...MODEL FORECASTS AND SATELLITE TRENDS
CONTINUE TO SUPPORT THE CURRENT FORECAST STILL SEEMS WELL ON TRACK
WITH OUR VERY SIGNIFICANT CHANGE IN THE WEATHER. 

THE STRONGEST SYSTEM OF THE EXPECTED SERIES IS A LOW THAT CONTINUES
TO GAIN STRENGTH OFF THE SOUTH OREGON AND NORTHERN CALIFORNIA COASTS.
SATELLITE TRENDS OF A STRONGLY DEVELOPING BAROCLINIC LEAF CLOUD AND
THE COLD AIR CUMULUS NEAR ITS CENTER TESTIFY TO THE UNSEASONABLY
DYNAMIC AND BAROCLINIC CHARACTER OF THIS SYSTEM. THIS SYSTEM HAS
ENTRAINED MOISTURE FROM TROPICAL SYSTEMS THAT HAD BEEN OUT AROUND THE
HAWAIIAN ISLANDS. THE MODELS CONTINUE TO LIFT THIS SYSTEM NORTH
THROUGH OUR FORECAST AREA AFTER MIDNIGHT TONIGHT AND ON SATURDAY
MORNING. THE STRONG SURFACE LOW WILL TRACK NORTHWARD JUST OFF THE
COAST...POSSIBLY DEEPENING AS LOW AS 990 MB OR PERHAPS A BIT LOWER.
THE WINDS MAY START NEAR THE CENTRAL COAST AROUND 12Z SATURDAY THEN
MOVE NORTHWARD ALONG THE COAST THROUGH THE MORNING... WITH THE
GRADIENT FINALLY EASING BETWEEN 18Z AND 21Z ON SATURDAY... THAT IS 11
AM TO 2 PM. HIGH WIND WATCHES ALONG THE COAST AND OVER THE COASTAL
MOUNTAINS HAVE BEEN UPGRADED TO WARNINGS. ALSO ISSUED WIND ADVISORIES
IN THE INLAND VALLEYS FOR SATURDAY MORNING AND EARLY AFTERNOON. WINDS
MIGHT NOT QUITE MAKE ADVISORY CRITERIA BUT MANY TREES ARE STRESSED
FROM THE DRY SUMMER...THEY ARE FULL OF LEAVES... AND THERE ARE MANY
OUTDOOR EVENTS THAT HAVE TENTS AND THE LIKE THAT WILL BE SUSCEPTIBLE
TO THE WINDS. THERE WILL BE A SURGE IN RAIN AS WELL...BUT OFTEN THE
RAIN IS NOT QUITE AS HEAVY AS YOU MIGHT EXPECT WITH THESE WIND
STORMS.  

WE MAY SEE A FEW THUNDERSTORMS OVER THE WATERS AND ALONG THE COAST AS
THE LOW MOVES NORTHWARD LATE TONIGHT AND SATURDAY MORNING... POSSIBLY
EXTENDING INLAND INTO THE NORTH INTERIOR SATURDAY MORNING AS THE COLD
FRONT MOVES THROUGH.

THE PRECIPITATION WILL TURN TO SHOWERS AND DECREASE BY AFTERNOON...
BUT THE NEXT FRONT CURRENTLY ALONG 50N/135W WILL REACH THE COAST LATE
SATURDAY AND SWING THROUGH THE AREA SATURDAY NIGHT. THE MODELS ARE
FORECASTING A DECENT RAIN WITH THIS SYSTEM AS WELL AS PRETTY BREEZY
CONDITIONS...POSSIBLY CLOSE TO GALES AGAIN AT THE COAST. THIS SYSTEM
HAS SOME TROPICAL MOISTURE FROM ONE OF THE WESTERN PACIFIC TYPHOONS
IN IT.

THE PRECIPITATION WILL TURN TO SHOWERS ON SUNDAY WITH DECENT ONSHORE
FLOW. AN UPPER TROUGH REMAINS OFF THE COAST ESPECIALLY TO OUR NORTH
WITH CYCLONIC WESTERLY FLOW ALOFT ON MONDAY. THE BEST CHANCE OF
SHOWERS WILL BE NORTH OVER THE HIGHER TERRAIN. TOLLESON
 
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY. THE FALL-LIKE WEATHER
PATTERN WILL CONTINUE NEXT WEEK WITH PRIMARILY COOLER THAN NORMAL
TEMPERATURES...CLOUDY CONDITIONS...AND CHANCES FOR ADDITIONAL RAIN. A
TROUGH WILL REMAIN NEAR THE PACIFIC NORTHWEST COAST THROUGH MOST OF
THE PERIOD WITH SOME RAIN AT TIMES...ESPECIALLY DURING THE EARLY AND
MIDDLE PARTS OF NEXT WEEK. LITTLE CHANGE MADE TO THE CURRENT
FORECAST. TOLLESON


&&


.AVIATION...VFR CONDITIONS ACROSS THE AREA WITH CIGS PRIMARILY UP
ABOVE 10KFT. CIGS ALONG THE COAST WILL LOWER TO MVFR THIS EVENING
AROUND 03Z AS MORE SUBSTANTIAL SHOWERS MAKE THERE WAY ONTO THE
COAST. EXPECT MVFR CIGS TO CONTINUE OVERNIGHT WITH OCCASIONAL
DROPS IN VIS WITH HEAVIER SHOWERS. SHOWERS MOVES INLAND AROUND
08Z WHICH WILL LOWER CIGS AT INLAND TAF SITES TO LOW VFR...
OCCASIONALLY DROPPING TO MVFR THROUGH SATURDAY MORNING. SOUTHERLY
WINDS
ALONG THE COAST WILL INCREASE AROUND 09Z-12Z ALONG THE CENTRAL
OREGON COAST AND 12Z TO 15Z ALONG THE NORTH OREGON COAST...WITH
GUSTS UP TO 35 TO 45 KT. SOUTHERLY WINDS AT INLAND SITES START TO
INCREASE AROUND 11 TO 13Z WITH GUSTS TO 25 TO 35 KT AND
OCCASIONALLY TO 40 KT. 

KPDX AND APPROACHES...VFR THIS EVENING. MORE WIDESPREAD SHOWERS
MOVE IN AROUND 08Z LOWERING CIGS TO LOW VFR WITH OCCASIONAL DROPS
TO MVFR. SOUTHERLY WINDS INCREASE AROUND 11Z WITH GUSTS TO 25 TO
35 KT AND OCCASIONAL GUST TO 40 KT POSSIBLE. -MCCOY


&&


.MARINE...FALL-LIKE LOW PRESSURE SYSTEM APPROACHES FROM APPROX 400
MI WEST OF NORTHERN CALIFORNIA. AS IT MOVES INTO THE WATERS EARLY
SATURDAY MORNING. WINDS WILL INCREASE OUT OF THE SOUTH TO AT LEAST
HIGH END GALES. MODELS HAVE STARTED TRENDING STRONGER...WHICH MAY
INDICATE AT LEAST A FEW STORM FORCE GUSTS...BUT WOULD LIKE TO SEE
ANOTHER RUN DEPICTING THIS SCENARIO BEFORE CONFIDENCE IMPROVES
ENOUGH TO UPGRADE TO STORM WARNING. AS WINDS INCREASE...SEAS WHICH
WILL BE AROUND 4 TO 5 FT TONIGHT THROUGH EARLY SATURDAY MORNING
WILL RAPIDLY BUILD TO 15 TO 17 FT. SEAS STAY UP AROUND 13 TO 17
FT UNTIL WINDS DECREASE SATURDAY EVENING. WINDS SHIFT MORE TO THE
SOUTH-SOUTHWEST BY SATURDAY EVENING AND FALL BACK DOWN TO 15 KT
GUSTING TO 20 TO 25 KT BY SUNDAY MORNING. SEAS ON SUNDAY WILL BE
AROUND 8 TO 10 FT WITH WINDS WITH WINDS DECREASING FURTHER TO 10
TO 15 KT BY SUNDAY EVENING.

UNSETTLED WEATHER CONTINUES INTO NEXT WEEK WITH SEAS STAYING
AROUND 7 TO 9 FT THROUGH AT LEAST MIDWEEK. -MCCOY


&&


.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 8 AM TO 3 PM PDT SATURDAY FOR GREATER 
     PORTLAND METRO AREA-LOWER COLUMBIA.

     HIGH WIND WARNING FROM 4 AM TO 1 PM PDT SATURDAY FOR CENTRAL 
     OREGON COAST.

     WIND ADVISORY FROM 6 AM TO NOON PDT SATURDAY FOR CENTRAL 
     WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY.

     HIGH WIND WARNING FROM 6 AM TO 2 PM PDT SATURDAY FOR COAST RANGE

     OF NORTHWEST OREGON-NORTH OREGON COAST.

     HIGH WIND WARNING FROM 5 AM TO NOON PDT SATURDAY FOR CENTRAL 
     COAST RANGE OF WESTERN OREGON.

WA...WIND ADVISORY FROM 8 AM TO 3 PM PDT SATURDAY FOR GREATER 
     VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY.

     HIGH WIND WARNING FROM 8 AM TO 3 PM PDT SATURDAY FOR WILLAPA 
     HILLS.

     HIGH WIND WARNING FROM 8 AM TO 2 PM PDT SATURDAY FOR SOUTH 
     WASHINGTON COAST.

PZ...GALE WARNING FROM 3 AM SATURDAY TO MIDNIGHT PDT SATURDAY NIGHT 
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 AM
     SATURDAY TO MIDNIGHT PDT SATURDAY NIGHT.

&&



$$

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.

National Weather Service Glossary of Abbreviations