High Wind Warning 15, NWS Portland, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
943 AM PST MON DEC 9 2014

.SYNOPSIS...A BUSY WEATHER PATTERN WILL PREVAIL THIS WEEK FOR
SOUTHWEST WASHINGTON AND NORTHWEST OREGON WITH WET AND WINDY WEATHER
AT TIMES. THE POTENTIALLY STROGNEST SURFACE LOW RUNS NORTH ALONG THE
COAST THURSDAY BUT WITH CONSIDERABLE UNCERTAINTY AS TOLOCATION AND
TIMING. BROAD LOW PRESSURE OVER THE GULF OF ALASKA AND A STRONG
PACIFIC JET STREAM WILL ROTATE A SERIES OF STORMS ACROSS THE E
PACIFIC AND INTO THE PACIFIC NORTHWEST PAST MIDWEEK. THE MAIN UPPER
LOW WILL OPEN UP AND MOVE ACROSS THE PACIFIC NORTHWEST LATE IN THE
WEEK BRINGING COOLER AND SHOWERY WEATHER THURSDAY NIGHT AND FRIDAY.

&&

.UPDATE...THE COLD FRONT IS SHOWING SLOW BUT FORWARD PROGESS TOWARD
THE COAST WITH PEAK WINDS EXPEXCTED OVER THE NEXT COUPLE HOURS.
STILL LOOKING LIKE IT WILL BE A LOW END EVENT OVERALL. ALTHOUGH WITH
THE FRONT HAVING STALLED OFF THE COAST A BIT...WARM ADVECTION
OVERNIGHT PLUS CLOUDS KEPT TEMPERATURES WARM. SEVERAL LOCATIONS MAY
END UP SETTING RECORD MAXIMUM LOW TEMPERATURES AS CONDITIONS MAY NOT
COOL ALL THAT MUCH BEHIND THE FRONT TODAY. HAVE SEEN SOME LIGHTNING
APPEARING OFFSHORE UNDER JET ENHANCED CONVECTION. CELLS ARE TOO FAR
OUT FOR RADAR INTERROGATION BUT DID DECIDED TO CONVERT THE
THUNDERSTORMS TO ISOLATED COVERAGE. BEST CHANCE FOR THEM TO OCCUR
NOW SEEMS LIKE IT WILL BE FOR THE AFTERNOON HOURS AND PERHAPS
CARRYING A BIT IN THE EVENING. EARLY LOOKS AT 12Z MODELS SHOW GOOD
POTENTIAL FOR ANOTHER COASTAL HIGH WIND EVENT FOR LATE TONIGHT AND
WEDNESDAY. THURSDAY IS SETTUNG UP TO BE THE MOST SIGNIFICANT WIND
EVENT OF THIS SERIES. MODELS FINALLY ARE COMING TO CONSENSUS
REGARDING CLOSING OFF THE SURFACE LOW AND HAVING IT PEAK OFF THE SW
OREGON COAST. IT WILL THEM MOVE NORTH AND FILL AS IT CROSSES INTO
OUR AREA. WHILE THERE IS DECENT AGREEMENT ABOUT THE CENTRAL LOW
PRESSURE MINIMUM...THERE IS STILL CONSIDERABLE UNCERTAINTY REGARDING
THE TRACK AND MORE SO IN THE TIMING. HAVING DECENT CONFIDENCE THE
COAST AND COAST RANGE WILL RECEIVE VERY STRONG WINDS BUT STILL SEE
SOME POTENTIAL FOR THE SURFACE LOW TO PUSH FURTHER INLAND BRINGING
STRONG WINDS TO THE VALLEY AND PERHAPS METRO AREA. WILL CONTINUE TO
ASSESS AS MORE DATA BECOMES AVAILABLE. /JBONK

&&

.PREV DISC... /ISSUED 312 AM PST TUE DEC 9 2014/

SHORT TERM...IT WILL BE A BUSY WEATHER PATTERN FOR THE FEW DAYS...
COMPLICATED BY MODELS WHICH HAVE BEEN STRUGGLING TO AGREE ON SOME
KEY FEATURES. SATELLITE SHOWED A VERY STRONG LOW ON THE ORDER OF 965
MB NEAR 49N 136W EARLY THIS MORNING...EXPECTED TO CONTINUE TO LIFT
NNE TODAY. STRONG PRESSURE GRADIENTS ASSOCIATED WITH THE LOW
EXTENDED ALL THE WAY DOWN TO THE OREGON COAST. A COLD FRONT
EXTENDING S OF THE LOW WAS APPROACHING 130W. PEAK WIND ALONG THE
COAST OVERNIGHT WERE LIMITED BY A SOUTHERLY ORIENTATION TO THE
GEOSTROPHIC WIND FIELD...WITH HIGHEST OBSERVED WINDS ON THE ORDER OF
50 TO 60 MPH. WITH MODEL LOW LEVEL WINDS STILL SHOWING 50 TO 60 KT
BETWEEN 975 AMD 950MB THIS MORNING AS THE FRONT PUSHES IN...EXPECT
TO SEE WINDS PICK UP SOME WITH THE FRONTAL PASSAGE...MOST LIKELY
BETWEEN 15Z AND 18Z. AIR MASS AHEAD OF THE FRONT THIS MORNING
POSSESSES PRECIPITABLE WATER VALUES BETWEEN ONE AND ONE AND A
QUARTER INCHES. SATELLITE AND RADAR IMAGARY INDICATES LIKELY A
COUPLE OF MAIN BANDS OF PRECIPITATION EXPECTED TO MOVE THROUGH THIS
MORNING FOR HIGH POPS...BUT NOT LIKELY TO BE PROLONGED ENOUGH TO
CAUSE ANY SERIOUS ISSUES. WITH REGION IN THE WARM SECTOR EARLY
TODAY...HIGHS WILL BE ABOVE NORMAL.

A VERY SIMILAR SITUATION WILL FOLLOW TONIGHT AND WED. UPPER PATTERN
THROUGH WED KEEPS THE MAIN UPPER TROUGH WELL OFFSHORE THROUGH WED
WITH ANOTHER WAVE LIFTING NE OUT OF THE UPPER LOW. ANOTHER INTENSE
SURFACE LOW IS GENERALLY AGREED UPON BY MODELS TO FOLLOW A SIMILAR
TRACK N OFF THE BC COAST W OF 130W. AS A WARM FRONT LIFTS BACK N
OVERNIGHT MODELS SHOWING DECENT MOST ISENTROPIC LIFT ALONG THE 300K
INSETROPE SO WILL KEEP POPS GENERALLY CATEGORICAL OVENRIGHT. STRONG
PRESSURE GRADIENTS AGAIN EXPECTED TO EXTEND SE INTO WESTERN OREGON
WITH A SOUTHERLY ORIENTATION TO THE SURFACE GEOSTROPHIC WIND FIELD.
THIS WILL BRING ANOTHER THREAT OF WINDS TO THE COAST...AND PERHAPS
THE COAST RANGE...TONIGHT INTO WED WITH THE BEST CHANCES FOR HIGH
WINDS COMING WITH THE ARRIVAL OF ANOTHER COLD FRONT WED. TROPICAL
MOISTURE IS EXPECTED TO AGAIN BE PULLED UP AHEAD OF THIS
SYSTEM...WHICH IS LIKELY TO RESULT IN A PERIOD OF SUBSTANTIAL RAIN
ALONG AND AHEAD OF THE WED FRONT. AGAIN...REGION WILL SPEND GOOD BIT
OF TIME IN THE WARM SECTOR TONIGHT AND WED WHICH WILL KEEP TEMPS
ABOVE NORMNAL THROUGH WED.

BY THE END OF THE DAY WED THE UPPER TROUGH AXIS IS EXPECTED TO BE
AROUND 140W. MODELS AGREE ON A STRONG JET IN EXCESS OF 190KT AT
250MB ON THE BACKSIDE OF THE TROUGH DIGGING THE TROUGH WED NIGHT
THEN PUSHING IT E AS IT ROUNDS THE BASE OF THE TROUGH THU. AS A
JETLET LIFTS UP THE E SIDE OF THE TROUGH THU MODELS HAVE STRUGGLED
WITH HANDLING ANY SORT OF SURFACE LOW THAT DEVELOPS AHEAD OF THE
UPPER TROUGH WED NIGHT AND THU. GFS WHICH HAS BEEN THE MOST
AGRESSIVE IN SHOWING STRONG LOWS LIFTING UP THE OREGON COAST IN
PREVIOUS RUNS... IS A LITTLE TAMER IN THE 00Z RUN WHILE OTHER MODELS
HAVE ALSO COME UP CLOSER TO MIDDLE GROUND WITH THE 00Z GFS. STILL
SOME SUBSTANTIAL DIFFERENCES IN THE MODELS...BUT OVERALL FEEL THEY
ARE A LITTE CLOSER TO COMING TO SOME SORT OF CONSENSUS FOR THU.
BALANCING THE VARIOUS MODEL OUTPUTS...SUSPECT A LOW ON THE ORDER OF
980 MB TO BOTTOM OUT OFF THE S OREGON COAST EARLY THU...THEN LIFT
NNE OFF THE OREGON COAST THU WHILE SLOWLY FILLING BEFORE MOVING
INLAND NEAR THE MOUTH OF THE COLUMBIA THU AFTERNOON. THIS WOULD BE
NOT TOO DISSIMILAR TO THE LOW THAT MOVED UP THE COAST IN LATE
OCTOBER. THE TRACK AND INTENSITY OF THIS STORM WOULD SUGGEST SOME
THREAT OF HIGH WINDS FOR BOTH THE COAST AND TO A LESSER EXTENT THE
INTERIOR.

LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. UPPER LEVEL
TROUGH OVER THE GULF OF ALASKA MOVES ONSHORE ON FRIDAY...BRINGING
HIGH PRESSURE OVER THE PACIFIC NORTHWEST ON SATURDAY. MODELS ARE
INDICATING THAT SATURDAY MAY TURN OUT TO BE A DRY DAY...THOUGH FOG
AND LOW CLOUDS WILL MAKE IT DIFFICULT FOR THE SUN TO COME OUT. THIS
HIGH PRESSURE WILL ALSO BRING COOLER TEMPERATURES FOR THE WEEKEND.
ANOTHER...QUICKER MOVING SYSTEM MOVES THROUGH ON SUNDAY OR
MONDAY...WHICH WILL BRING A ROUND OF RAIN ACROSS OUR AREA. GFS AND
ECMWF DISAGREE ON TIMING OF THIS SYSTEM...AS THE GFS BRINGS IT IN
SUNDAY NIGHT WHILE THE ECMWF BRINGS IT IN ON MONDAY. THIS SYSTEM
SETS UP WHAT LOOKS TO BE ANOTHER ACTIVE WEATHER PATTERN FOR NEXT
WEEK. -MCCOY

&&

.AVIATION...WIDESPREAD VFR CONDITIONS PERSIST TODAY...EXCEPT FOR
OCCASIONAL MVFR VIS AND/OR CIGS IN LIGHT RAIN. EAST WIND IS SLOWLY
DIMINISHING THIS MORNING...BUT STILL EXPECT GUSTS 35-45 KT TO
CONTINUE TO IMPACT THE WEST END OF THE COLUMBIA GORGE. SOUTH WIND
WITH GUSTS 45-55 KT WILL IMPACT THE IMMEDIATE COASTLINE THIS MORNING
WITH PEAK GUSTS 35 TO 45 KT AT TERMINALS. AFTER A BRIEF RESPITE...
WINDS PICK UP AGAIN ALONG THE COAST TONIGHT STARTING AROUND 06Z
WED. LOCAL GUSTS NEAR 55 KT ARE POSSIBLE FOR THE WED SYSTEM.

KPDX AND APPROACHES...VFR SHOULD PERSIST WITH POTENTIAL FOR MVFR
CONDITIONS AFTER 18Z TUE. EASTERN APPROACHES WILL MAINTAIN WIND
GUSTS UP TO 35 KT...BUT EAST WIND HAS ALREADY STARTED TO DIMINISH
ELSEWHERE WITH LINGERING GUSTS UP TO 25 KT. WILL NEED TO MONITOR
FOR POTENTIAL LLWS THROUGH THE MORNING WITH SURFACE E WIND AND
STRONG S-SW WIND AT/ABOVE FL010. /27

&&

.MARINE...SOUTH WINDS WILL CONTINUE TO GUST BETWEEN 45-55 KT THIS
MORNING AHEAD OF AN APPROACHING COLD FRONT. HAVE HAD A US COAST
GUARD REPORT OF WINDS 45 KT WITH GUSTS TO 55 KT AT THE COLUMBIA
RIVER BAR THIS MORNING...VERIFYING THE CURRENT STORM WARNING FOR
THE COASTAL WATERS. SOUTHERLY GALE FORCE WINDS WITH GUSTS TO 35 KT
ARE EXPECTED BEHIND THE FRONT BY 11 AM OR NOON...AND WILL BE
ISSUING A GALE WARNING FOR THE WATERS FROM THIS AFTERNOON THROUGH
LATE THIS EVENING. CURRENT SEAS AT 20-22 FT THIS MORNING...WILL
LIKELY FALL JUST BELOW 20 FT BY THIS AFTERNOON BUT THIS IS A VERY
BRIEF OCCURRENCE SINCE SEAS BEGIN BUILDING AHEAD OF THE NEXT
FRONTAL SYSTEM LATE TONIGHT.

WILL LIKELY BE UPGRADING THE STORM WATCH TO A STORM WARNING FOR
LATE TONIGHT AND WEDNESDAY. COULD STILL SEE A FEW GUSTS TO LOW
END HURRICANE FORCE...BUT DON'T THINK AT THIS POINT THAT THEY WILL
BE FREQUENT OR WIDESPREAD ENOUGH TO WARRANT THE PRODUCT. WINDS
PEAK AROUND 15Z WEDNESDAY AND THEN DROP TO GALE FORCE BY AROUND
21Z.

AS IF THESE TWO SYSTEMS WERE NOT ENOUGH...THERE IS THE POTENTIAL
FOR A POTENT LOW THU. MODELS REMAIN LARGELY IN DISAGREEMENT
REGARDING BOTH THE TIMING AND STRENGTH OF THE LOW...ALTHOUGH THEY
ALL AT LEAST NOW AGREE THAT A LOW WILL FORM...WHICH IS PROGRESS
FROM LAST NIGHT'S 00Z AND 06Z RUNS. GFS HAS CONSISTENTLY SHOWN
THIS LOW UNDERGOING RAPID CYCLOGENESIS OFF THE S OREGON AND N CAL
COAST LATE WED NIGHT AS IT SWINGS WELL INSIDE 130W. THIS COULD
BRING A FEW HOURS OF SOLID STORM FORCE WIND TO THE WATERS. AS
HAPPENED YESTERDAY...THE 06Z GFS SHOWS A WEAKER LOW COMPARED WITH
THE 00Z RUN (A LA THE ECM) BUT EXPECT TO SEE THE 12Z GFS RETURN
TO THE TREND OF A VERY STRONG LOW. FOR NOW HAVE LEANED TOWARD THE
00Z GFS BUT HEDGED A BIT. BOWEN/27

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING UNTIL NOON PST TODAY FOR CENTRAL OREGON COAST-
     NORTH OREGON COAST.

     HIGH SURF ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR CENTRAL
     OREGON COAST-NORTH OREGON COAST.

     HIGH WIND WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL OREGON COAST-
     COAST RANGE OF NORTHWEST OREGON-NORTH OREGON COAST.

WA...HIGH WIND WARNING UNTIL NOON PST TODAY FOR SOUTH WASHINGTON
     COAST.

     HIGH SURF ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR SOUTH
     WASHINGTON COAST.

     HIGH WIND WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR
     SOUTH WASHINGTON COAST-WILLAPA HILLS.

PZ...STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR
     COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM.

     STORM WARNING UNTIL NOON PST TODAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER TO FLORENCE OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM
     PST 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.