Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 061642 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
937 AM PDT FRI MAY 6 2016

.SYNOPSIS...HIGH PRESSURE BUILDING ACROSS THE REGION WILL BRING
WARMER TEMPERATURES AND PLENTY OF SUNSHINE FRIDAY AND SATURDAY. A
WEAK FRONT WILL BRING MARINE CLOUDS AND AREAS OF DRIZZLE AND LIGHT
SHOWERS SATURDAY NIGHT AND SUNDAY MORNING. EXPECT TEMPERATURES TO
DROP MUCH CLOSER TO AVERAGE SUNDAY AND MONDAY. HIGH PRESSURE PUSHING
BACK OVER THE REGION NEXT WEEK WILL BRING ANOTHER ROUND OF
UNSEASONABLY WARM WEATHER.

&&

.SHORT TERM...MINOR ADJUSTMENTS THIS MORNING TO CLOUD COVER IN THE
SOUTHERN WILLAMETTE VALLEY. OTHERWISE...ADDED GUSTY WIND WORDING TO
FOR THIS AFTERNOON AND EVENING.

SATELLITE PICTURES SHOWED A LARGE UPPER LOW OFF THE S CA COAST...WITH
THE NORTHWARD EXTENDING TROUGH AXIS RUNNING ROUGHLY
UP THE PACIFIC NW COAST. MODELS CONTINUE THE PREVIOUS TREND OF
INDICATING THE LOW MOVING SLOWLY E AND THEN NE THROUGH THE WEEKEND
ACROSS THE DESERT SW. WHILE SURFACE PRES GRADIENTS REMAINED ONSHORE
OVER THE FORECAST AREA EARLY FRI MORNING...THE LOW LEVEL FLOW ABOVE
THE SURFACE WAS OFFSHORE OUT OF THE NE. THIS HAS RESULTED IN DRYING
OVER THE AIR MASS AT LOW LEVELS...WITH LITTLE INDICATION IN SURFACE
OBSERVATIONS THROUGH THE EARLY MORNING HOURS OF ANY MARINE CLOUDS
REDEVELOPING. THE MOST LIKELY AREA IN THIS PATTERN FOR ANY LOW
CLOUDS OR FOG TO DEVELOP IN THE MORNING WOULD BE ALONG THE CENTRAL
OREGON COAST...SO WILL LEAVE A MENTION FOR CLOUDS AND FOG IN THIS
MORNING.

MODEL SOUNDINGS AGAIN HINTING AT SOME CONDITIONAL INSTABILITY OVER
THE CASCADES THIS AFTERNOON...ALTHOUGH MOST MODEL QPF FIELDS
GENERALLY INDICATE ANY THREAT OF PRECIPITATION WILL BE SUPPRESSED SE
OF THE FORECAST AREA. WITH THE INCREASINGLY EASTERLY MID AND UPPER
LEVEL FLOW TODAY WILL HANG ON TO A CHANCE FOR AFTERNOON AND EVENING
THUNDERSTORMS OVER THE S PART OF THE CASCADES. WILL CONTINUE WITH A
DRY AND MOSTLY SUNNY FORECAST INTO SAT AS THE UPPER LOW CONTINUES TO
MOVE E AND A SW TO NE ORIENTED UPPER RIDGE SINKS DOWN OVER THE
REGION SAT. SUBSIDENCE WILL RESULT IN WARMING TEMPS AGAIN FRI AND
SAT.

SAT NIGHT INTO SUN MODELS CONTINUE TO AGREE ON A EITHER A WEAK COLD
FRONT OR A STRONG NW MARINE PUSH...YOU DECIDE. EITHER WAY DEEP
MARINE MOISTURE MOVES IN SAT NIGHT AS THE UPPER FLOW TURNS NW BEHIND
A SHORTWAVE CUTTING ACROSS WA. WITH SOME DYNAMICS AND LOW LEVEL
MOISTURE WILL KEEP IN CHANCES FOR DRIZZLE MOVING IN SAT NIGHT...THEN
SOME DRIZZLE OR LIGHT SHOWERS MAINLY IN THE MORNING SUN. COOLER
TEMPS ALSO IN STORE...AND MORE IN LINE WITH CLIMATOLOGY WITH THE
MARINE AIR MASS.
&&

.LONG TERM...AN UPPER TROUGH OVER THE INTERIOR PACIFIC NW MON IS
EXPECTED TO KEEP THE COOLER AIR AND MARINE CLOUDS IN PLACE THROUGH
MON MORNING. GENERAL TREND WITH MODELS OVER THE NEXT SEVERAL DAYS
HAS HEIGHTS BUILDING OVER THE REGION AS AN OFFSHORE RIDGE NUDGES
EASTWARD. WITH A THERMALLY INDUCED TROUGH EXPECTED TO BUILD UP ALONG
THE OREGON COAST TUE THE RESULTING LOW LEVEL OFFSHORE FLOW WILL
BRINGING DRY AND MOSTLY SUNNY WEATHER WITH WARMING TEMPS THROUGH THE
WEEK. BY THU GFS AND EC AGREE ON H8 TEMPS REACHING 15 TO 16 DEG
C...WHICH SHOULD BE GOOD FOR HIGHS BACK INTO THE MID 80S IN THE
INLAND VALLEYS. WARMEST TEMPS ON THE COAST HOWEVER APPEAR LIKELY TO
COME ON WED...AS ONSHORE FLOW RETURNS LATER IN THE WEEK WITH THE
SURFACE TROUGH AXIS MOVING INLAND.

&&

.AVIATION...VFR ACROSS THE AREA THIS MORNING WILL PREVAIL THROUGH
THE DAY TODAY AND TONIGHT. NORTH WIND GUSTS 20-30 KT ALONG THE
CENTRAL COAST THIS AFTERNOON THROUGH EARLY EVENING...WEAKENING TO
10 TO 15 KT FOR OVERNIGHT.

KPDX AND APPROACHES...VFR CONDITIONS THROUGH SATURDAY MORNING.
-MCCOY

&&

.MARINE...HIGH PRES OVER THE WATERS WITH A VERY SUMMER-LIKE
PATTERN FOR THE NEXT FEW DAYS OF GUSTY AFTERNOON/EVENING
NORTHERLY WINDS OVER THE WATERS. ADDED A SMALL CRAFT ADVISORY FOR
HAZARDOUS SEAS THIS MORNING FOR THE NORTHERN OUTER WATERS MAINLY
FOR SQUARE SEAS AROUND 8 FT WITH WAVE PERIODS AROUND 8 SECONDS
BEING OBSERVED OUT AROUND BUOY 89. EXPECT THIS TO CONTINUE WITH
WINDS INCREASING THIS AFTERNOON. THERE IS A THREAT FOR A FEW LOW-
END GALE GUSTS THIS AFTERNOON IN THE SOUTHERN OUTER WATERS...BUT
DON`T THINK THEY WILL BE FREQUENT ENOUGH TO WARRANT A GALE WARNING
AT THIS TIME. FOR NOW MAINTAINING AN UPPER-END SMALL CRAFT
ADVISORY FOR WIND SPEEDS. INNER WATERS WITHIN 10 NM FROM THE COAST
WILL SEE SMALL CRAFT ADVISORY WINDS TO 30 KT BY EARLY AFTERNOON
WITH STRONGEST WINDS ALONG OREGON CENTRAL COAST...WEAKENING BELOW
20 KT LATE TONIGHT.

COLD FRONT...OR MORE LIKE A STRONG MARINE SURGE...OCCURS
SUN...WHICH WILL TURN THE WIND MORE OUT OF THE NW. STRONGEST
SPEEDS EXPECTED TO SWITCH TO THE NRN OUTER WATERS SUN. WIND SPEEDS
FINALLY FALL BELOW 20 KT MON...AND SHIFT NORTH TO NORTHEAST MON
NIGHT AS A THERMALLY-INDUCED SURFACE LOW DEVELOPS ALONG THE
COASTLINE.

WIND-DRIVEN SEAS WILL CONTINUE THE CHOPPY CONDITIONS WITH SQUARE
SEAS AT TIMES. HIGHEST SEAS TODAY THROUGH SATURDAY WILL BE IN
PZZ275 WHERE WIND-WAVES UP TO 8 FT ARE LIKELY. -MCCOY/WEISHAAR

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 PM PDT SATURDAY FOR
     WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM 10 TO
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT SATURDAY
     FOR WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM 10
     TO 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS FROM 1 PM THIS AFTERNOON TO 11
     PM PDT THIS EVENING FOR COASTAL WATERS FROM CAPE
     SHOALWATER WA TO CASCADE HEAD OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 2 AM PDT SATURDAY FOR
     COASTAL WATERS FROM CASCADE HEAD TO FLORENCE OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 4 PM
     THIS AFTERNOON TO 7 PM PDT THIS EVENING.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 4 AM TO
     7 AM PDT SATURDAY.

&&

$$

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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