Funnel Cloud in Oregon, October 15, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
947 AM PDT WED OCT 15 2014

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL MOVE ACROSS THE PACIFIC NW
TODAY. HIGH PRESSURE WILL BUILD THURSDAY AND BRING A BREAK IN
PRECIPITATION BEFORE ANOTHER FRONT BRINGS ADDITIONAL RAIN AND GUSTY
WINDS FRIDAY. SHOWERS WILL LINGER SATURDAY BEFORE HIGH PRESSURE
BRINGS ANOTHER DRY PERIOD FOR SUNDAY. UNSETTLED WEATHER WILL
CONTINUE EARLY NEXT WEEK.

&&
.SHORT TERM...SURFACE ANALYSIS SHOWED A 999 MB LOW MOVING INLAND
OVER THE OLYMPIC PENINSULA...WITH THE TROUGH EXTENDING S ALONG THE
COAST. SHOWERS WERE WIDESPREAD...AND LIGHTNING NETWORKS INDICATED
SOME RECENT STRIKES ALONG THE CENTRAL OREGON COAST. SURFACE PRES
GRADIENTS WERE ROUGHLY 10 MB ALONG THE OREGON COAST...AND 4 MB
THROUGH THE WILLAMETTE VALLEY. AS THE LOW MOVES NE AND INLAND EXPECT
GRADIENTS TO BE NEAR THEIR PEAK...AND TO DROP OFF IN THE NEXT FEW
HOURS. OBSERVED WINDS THEMSELVES WERE MARGINAL FOR ADVISORY...SO
WILL DROP ADVISORY A LITTLE EARLY AS THE PEAK GRADIENTS HAVE PASSED
BY. SHOWERS WITH THE TROUGH PASSING THIS MORNING ARE LIKELY TO
BECOME MORE OROGRAPHICALLY DRIVEN THIS AFTERNOON AS A SW LOW LEVEL
ONSHORE LOW PERSISTS BEHIND THE UPPER TROUGH. SNOW LEVELS AROUND
5500 FEET MAY BRING A DUSTING OF SNOW FOR THE HIGHER CASCADES TODAY.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...AN UPPER RIDGE WILL
BUILD OVER THE WESTERN CONUS THURSDAY AS ANOTHER UPPER TROUGH DIGS
OFFSHORE...RESULTING IN A BREAK IN RAIN THROUGH THURSDAY NIGHT. THE
NEXT MOIST FRONT WILL STALL OFFSHORE THURSDAY NIGHT BEFORE PUSHING
ONSHORE EITHER FRIDAY MORNING OR FRIDAY AFTERNOON. WARM AIR
ADVECTION AHEAD OF THIS FRONT WILL BRING SNOW LEVELS ABOVE 8000 FEET
BEFORE THE ONSET OF RAIN. GUSTY WINDS WILL ALSO ACCOMPANY THIS
FRONT. THE NAM MODEL HINTS OF A COASTAL JET POSSIBLY DEVELOPING JUST
OFFSHORE FRIDAY EVENING WHICH COULD BRING A BRIEF PERIOD OF STRONG
GUSTS TO THE COAST.

THE 00Z GFS FORECASTS 1.25 INCH OF TROPICAL PRECIPITABLE WATER AND
DECENT ISENTROPIC LIFT ON THE 300K SURFACE...HINTING AT THE POTENTIAL
FOR HEAVY RAIN. HOWEVER...SOME OF THE MODELS ARE SHOWING THE TROUGH
SPLIT AS IT NEARS WHICH WOULD BRING THIS HEAVIER RAIN NORTH OR SOUTH
OF THE PORTLAND FORECAST AREA. THEREFORE...FORECAST CONFIDENCE IS
HIGH ON THE PROBABILITY OF RAIN BUT LOW ON RAIN AMOUNTS WITH THE
FRIDAY FRONT. RAIN WILL DECREASE OVERNIGHT FRIDAY...BUT SHOWERS WILL
LIKELY CONTINUE OVER THE HIGHER TERRAIN THROUGH SATURDAY MORNING. TJ

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. SATURDAY NIGHT
THROUGH TUESDAY NIGHT...BUILDING HIGH PRESSURE WILL BRING A BRIEF
PERIOD OF WARMER AND DRIER CONDITIONS SUNDAY BEFORE ANOTHER FRONT
MOVES ACROSS THE REGION LATE SUNDAY NIGHT THROUGH MONDAY. AN UPPER
LEVEL TROUGH WILL CONTINUE RAIN AND COOLER WEATHER THROUGH AT LEAST
TUESDAY NIGHT. SNOW LEVELS MAY DIP BACK DOWN TO AROUND 6000 FEET
TUESDAY. TJ

&&

.AVIATION...MIX OF VFR AND MVFR WITH RAIN...WITH OCCASIONAL IFR
FROM HEAVIER SHOWERS. THUNDERSTORMS HAVE BEEN OBSERVED OFF CENTRAL
COAST. SHOWERS TO CONTINUE ON AND OFF THROUGH THE DAY. STRONG
SOUTHERLY WINDS THIS MORNING ARE BEING OBSERVED CURRENTLY...WITH
GUSTS OF 20 TO 30 KTS. INLAND WINDS SHOULD BEGIN TO WEAKEN BY
18Z...BUT SUSTAIN SPEEDS OF 10 TO 15 KTS THROUGH THIS EVENING WITH
GUSTS UP TO 20 KTS. STRONGEST WINDS WILL BE AROUND SLE WITH GUSTS
TO 25 KTS. COASTAL SITES WILL CONTINUE TO SEE WINDS SUSTAINED 15
TO 20 KTS...WITH GUSTS TO 30 THROUGH TODAY.

KPDX AND APPROACHES...MIX OF VFR AND MVFR CIGS AT TERMINAL...BUT
SHOULD REMAIN ABOVE 2000 FT. SOUTHERLY SUSTAINED WINDS CLOSE TO
CROSSWIND THRESHOLD OF 20 KTS...GUSTING TO 25 KTS AND SHOULD START
WEAKENING BY 18Z. SOUTHERLY WINDS TO REMAIN AROUND 10 KTS GUSTING
TO 15 KTS THROUGH THIS EVENING.

&&

.MARINE...LOW PRESSURE SYSTEM MOVING ONSHORE CURRENTLY...STEMMING
FROM STATIONARY LOW PRESSURE CENTER LOCATED OVER THE GULF OF
ALASKA. ADVISORY WINDS LOOK TO REMAIN OVER THE SOUTHERN WATERS
THROUGH TONIGHT...WHILE WINDS OVER NORTHERN WATERS LOOK TO DROP
BELOW ADVISORY CRITERIA AFTER 5PM TONIGHT. SEAS LOOK TO BUILD TO
14 TO 15 FT LATE THIS AFTERNOON...BEFORE SUBSIDING TO 11 FT
TOMORROW MORNING. NEAR-SHORE WATERS MAY SEE WAVES SUBSIDING TO
BELOW SMALL CRAFT CRITERIA DURING THE DAY TOMORROW...WHILE OUTER
WATERS REMAIN WELL ABOVE 10 FT.

A STRONGER SYSTEM LOOKS TO MOVE THROUGH LATE THIS WEEK. MODELS
ARE IN FAIRLY GOOD AGREEMENT THAT THIS SYSTEM WILL START TO IMPACT
OUR WATERS THURSDAY AS WINDS INCREASE AHEAD OF THE LOW. GALE GUSTS
LOOK POSSIBLE LATE THURSDAY...SO WILL BE ASSESSING THE NEED FOR A
GALE WATCH THIS AFTERNOON.

SEAS...W-NW SWELL WILL BE INCREASING FROM A WELL-ENTRENCHED BROAD
PARENT LOW DOMINATING THE GULF OF ALASKA AND NE PACIFIC. W-NW
SWELL 12-15 FT WILL BE POSSIBLE AT TIMES THROUGH THE WEEKEND DUE
TO OCCASIONALLY STRONG LOW PRESSURE SYSTEMS ROTATING AROUND THIS
BROADER UPPER LOW.

MCCOY/BOWEN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 PM PDT THIS AFTERNOON
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT
     THURSDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 AM PDT THURSDAY FOR
     COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     5 AM PDT THURSDAY.
&&

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.

&&