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712
FXUS66 KPQR 232120
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 PM PDT WED APR 23 2014

.SYNOPSIS...A WARM FRONTAL BOUNDARY REMAINED DRAPED ACROSS SOUTHWEST
WASHINGTON AND NORTHWEST OREGON THIS AFTERNOON AS MOISTURE FROM THE
PACIFIC RIDES ALONG THE FRONT. THE ASSOCIATED COLD FRONT WILL MOVE
INTO SOUTHWEST WASHINGTON AND NORTHWEST OREGON TONIGHT AND MOVE EAST
OF THE AREA THURSDAY MORNING FOR CONTINUED FAIRLY HEAVY RAIN AND
HIGHER ELEVATION SNOW. THE ASSOCIATED STRONG SURFACE LOW WILL
APPROACH VANCOUVER ISLAND TODAY THEN STALL NEAR VANCOUVER ISLAND AND
WEAKEN THURSDAY AND FRIDAY. THE PARENT UPPER LOW OR TROUGH WILL DIG
SOUTH TOWARD CALIFORNIA THURSDAY AFTERNOON AND THURSDAY NIGHT BEFORE
MOVING ONSHORE AND THROUGH THE AREA FRIDAY AND FRIDAY EVENING FOR
MORE SHOWERS. ANOTHER SIGNIFICANT FRONTAL SYSTEM IS EXPECTED LATE
SATURDAY AND SATURDAY NIGHT.
&&

.SHORT TERM...A FRONTAL BOUNDARY THAT HAS TRANSITIONED TO A WARM
FRONT REMAINED DRAPED OVER SOUTHWEST WASHINGTON AND A GOOD PART OF
NORTHWEST OREGON THIS AFTERNOON. THIS FEATURE IS NOW MERGING THIS
AFTERNOON WITH THE CLOUD SHIELD FROM THE MAIN COLD FRONT WITH THE
NEXT APPROACHING STRONG LOW.

THIS NEXT STRONGER COLD FRONT WILL BE MOVING INTO OUR AREA
TONIGHT...AND THE MODELS HAVE SOME PRETTY DECENT PRECIPITATION
AMOUNTS WITH IT. IT WILL NOT BE ENOUGH TO CAUSE FLOODING...BUT IT
WILL BE QUITE WET. RAINFALL AMOUNTS THROUGH THURSDAY MORNING OF 1 TO
2 INCHES ARE EXPECTED ALONG THE COAST AND IN THE MOUNTAINS...WITH
0.5 TO 1 INCH IN THE VALLEYS.

SNOW LEVELS ARE SLOW TO RISE IN THE CASCADES AHEAD OF AND WITH THE
WARM FRONT...SO HAVE CONTINUED THE SNOW ADVISORY THROUGH TONIGHT BUT
WITH A BIT HIGHER SNOW LEVEL...CLOSER TO 5000 FEET. THUS IT WILL
BEGIN RAINING TONIGHT AT THE PASSES...BUT SKI RESORT ELEVATIONS
COULD STILL GET SOME DECENT AMOUNTS AGAIN TONIGHT.

THE ASSOCIATED 995 MB LOW WILL APPROACH VANCOUVER ISLAND LATE TODAY
AND TONIGHT...THEN STALL NEAR VANCOUVER ISLAND AND SLOWLY WEAKEN
THROUGH THURSDAY AND FRIDAY. THIS WILL PRODUCE ENOUGH GRADIENT ALONG
OUR COAST FOR GALES IN THE COASTAL WATERS AND FAIRLY STRONG WINDS
ALONG THE COASTAL STRIP. IT LOOKS LIKE IT WILL STAY BELOW WARNING
CRITERIA ALONG THE COASTAL STRIP...BUT SOME HEADLANDS MAY GET CLOSE.

WE SHOULD SEE PLENTY OF SHOWERS THURSDAY BEHIND THE COLD FRONT.
MODEL LIFTED INDEX VALUES LOOK A LITTLE WEAK FOR THUNDER BUT WE
SHOULD AT LEAST SEE SOME SMALL HAIL...WITH MODEL SOUNDINGS SHOWING A
BIT OF A CAP AT 700 MB AS THE MAIN COLDER AIR ALOFT IS STILL
OFFSHORE. ON FRIDAY THE MAIN UPPER TROUGH WILL BE MOVING THROUGH
SOUTHWEST WASHINGTON AND NORTHWEST OREGON AND THUNDER CHANCES LOOK A
BIT BETTER AS TEMPS AT 500 MB FALL TO MINUS 28 DEG C.

WHILE THE UPPER TROUGH MOVES EAST OF THE AREA FRIDAY NIGHT...SOME
SHOWERS WILL CONTINUE FRIDAY NIGHT AND SATURDAY AS ONSHORE FLOW
CONTINUES AND THERE IS NOT MUCH UPPER RIDGING IN BETWEEN SYSTEMS.
THE NEXT STRONGER FRONT IS EXPECTED SATURDAY NIGHT. TOLLESON

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...
THE LATEST MEDIUM RANGE FCST MODELS CONTINUE TO ADVERTISE A FRONTAL
SYSTEM MOVING ONSHORE SAT NIGHT AND EARLY SUN. KEPT CATEGORICAL POPS
FOR THIS TIME PERIOD...WITH A TRANSITION TO SHOWERS LATER IN THE DAY
SUNDAY BEHIND THE TRAILING COLD FRONT. A WEAK WARM FRONT MAY BRUSH
THE FCST AREA WITH SOME LIGHT PRECIPITATION ON MON...BUT THE TREND
WILL BE TOWARD DRIER WEATHER AS UPPER LEVEL RIDGING BUILDS OVER THE
PAC NW. RIGHT NOW...CONFIDENCE IS PRETTY HIGH THAT TUE WILL BE WARM
AND DRY WITH THE RIDGE DIRECTLY OVERHEAD...AND HIGH TEMPS WERE RAISED
SIGNIFICANTLY WITH THE LATEST FCST PACKAGE. MODEL UNCERTAINTY BEGINS
TO INCREASE WED...AS THE 12Z GFS AND SOME OF ITS ENSEMBLES INDICATE
THAT A TROF OVER THE NE PAC WILL SPLIT...WITH THE NORTHERN ENERGY
PUSHING INTO THE PAC NW WED AS AN OPEN TROF. THE 12Z ECMWF MAINTAINS
A NE PAC CLOSED LOW THAT HARDLY MOVES THROUGH THE END OF THE
WEEK...ALLOWING RIDGING TO REMAIN IN PLACE OVER THE PAC NW FOR
SEVERAL DAYS. HAVE KEPT SOME LOW CHANCE POPS ON WED DUE TO THIS
UNCERTAINTY. PYLE
&&

.AVIATION...GRADUALLY DETERIORATING CONDITIONS AS WARM FRONT LIFTS
ACROSS THE REGION THROUGH THIS EVENING. MVFR CONDITIONS CONTINUE.
BEST CONDITIONS ARE S OF KSLE...WHERE AREAS OF VFR WILL CONTINUE
UNTIL 00Z...THEN MVFR SPREADING INTO THOSE AREAS. MTNS/PASSES REMAIN
OBSCURED. SOUTH WINDS WILL GRADUALLY INCREASE TONIGHT...WITH GUST 35
TO 45 KT ALONG COAST/OVER COAST RANGE AFTER 02Z. WILL SEE BREEZY
CONDITIONS INLAND AS WELL...BUT NOT AS STRONG. COLD FRONT LOOKS TO
PUSH TO COAST AROUND 12Z TO 14Z THU...AND THEN TO CASCADES BY 17Z.
CONDITIONS SLOWLY IMPROVING AT THAT TIME. ROCKEY.

KPDX AND APPROACHES...MVFR WITH BRIEF BOUTS OF VFR CIGS FOR NEXT
SEVERAL HOURS...BUT GENERALLY MVFR AFTER 00Z AS RAIN INCREASES. MVFR
CONDITIONS TO PERSIST THROUGH TONIGHT. COLD FRONT WITH TURN TO SW TO
W WINDS AROUND 15Z THU. ROCKEY.
&&

.MARINE...A DEVELOPING 990 MB LOW PRES WILL SLOWLY MOVE TOWARDS
VANCOUVER ISL OVER THE NEXT 36 HOURS. WARM FRONT NOW LIFTING ACROSS
THE N ORE/S WASH COASTAL WATERS THIS EVENING...WITH SOUTH WINDS GUSTY
30 TO 40 KT THIS EVENING.

THE TRAILING COLD FRONT WILL THEN PUSH TOWARDS THE COAST LATER
TONIGHT. WILL HAVE SOLID S WIND 25 TO 35 KT...WITH 35 TO 45 KT WIND
GUSTS LIKELY...PRIMARILY WITHIN 20 NM OF COAST. GALE FORCE WINDS
SHOULD END AROUND DAYBREAK THU...BUT WILL KEEP THE KEEP THE CURRENT
TIMING ASSOCIATED WITH THE GALE HEADLINE AS IS...IN CASE THIS SYSTEM
SLOWS DOWN A FEW HOURS. ANOTHER APPROACHING FRONT LATE AFTERNOON AND
EVENING WILL LIKELY CAUSE SOUTH WIND GUSTS TO INCREASE INTO THE 30 TO
35 KT RANGE.

SEAS RUNNING 10 TO 13 FT TODAY...BUT WITH INCREASING WINDS LATER
TONIGHT...CHOPPY WIND DRIVEN SEAS WILL BUILD. WILL SEE SEAS PEAK AT
15 TO 17 FT TONIGHT INTO THU AM. SEAS WILL GRADUALLY SUBSIDE ON THU
AND THU EVENING.ROCKEY.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 6 AM PDT THURSDAY MORNING FOR
     NORTHERN OREGON CASCADES.

WA...WINTER WEATHER ADVISORY UNTIL 6 AM PDT THURSDAY MORNING FOR
     SOUTH WASHINGTON CASCADES.

PZ...GALE WARNING NOW THROUGH 11 AM THU ON ALL COASTAL WATERS.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
  TONIGHT AND THU.

&&

$$

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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