Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 220406
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
906 PM PDT TUE OCT 21 2014

.SYNOPSIS...A STRONG FRONTAL SYSTEM CONTINUED TO INTENSIFY OFF THE
COAST THIS EVENING AND WAS MOVING INTO WESTERN WASHINGTON AND
BEGINNING TO MOVE INTO NORTHWEST OREGON THIS EVENING. THIS FRONT WILL
BRING STRONG WINDS TO THE COAST TONIGHT AND WEDNESDAY MORNING...WITH
BREEZY CONDITIONS. THIS SYSTEM WILL BE A SLOW MOVER...PRODUCING HEAVY
RAIN ALONG THE NORTH COASTAL AREAS LATER TONIGHT...SPREADING INLAND
MAINLY ON WEDNESDAY...AND LINGERING IN THE SOUTHERN AREAS SUCH AS
LANE COUNTY WEDNESDAY NIGHT. ANOTHER WET AND POTENTIALLY QUITE WINDY
FRONT NOT ONLY FOR THE COAST BUT POSSIBLY INLAND IS EXPECTED BY THE
WEEKEND.
&&

.SHORT TERM...TONIGHT THROUGH FRIDAY...A STRONG FRONTAL SYSTEM WAS
INTENSIFYING OFF THE WASHINGTON AND OREGON COASTS THIS EVENING...
WITH SATELLITE IMAGERY INDICATING A DECENT SURFACE LOW DEVELOPING
ALONG THE FRONT. THE OCCLUDED OR WARM FRONT IS MOVING ONTO THE
COAST...WITH THE STRONGEST WINDS ALONG THE COAST IN THE NORTH ALONG
BEACHES AND HEADLANDS. WINDS HAVE BRIEFLY LIGHTENED ALONG THE CENTRAL
OREGON COAST...BUT SHOULD PICK UP LATER TONIGHT THROUGH WEDNESDAY
MORNING AS THE DEVELOPING LOW MOVES NORTHEAST AND ONSHORE AND THE
ASSOCIATED COLD FRONT SLOWLY SAGS SOUTH. THE CURRENT HIGH WIND
WARNING FOR THE COAST LOOKS GOOD AND WILL BE CONTINUED. LOOK FOR SOME
BREEZY CONDITIONS AS WELL TONIGHT AND WEDNESDAY MORNING ALONG THE
INTERSTATE 5 CORRIDOR ESPECIALLY FROM ABOUT PORTLAND NORTHWARD.

THE MAIN IMPACT FROM THIS FRONTAL SYSTEM WILL BE THE HEAVY RAIN. THE
INITIAL FOCUS WILL BE INTO WESTERN WASHINGTON...BUT BEGIN TO SPREAD
INTO OUR NORTH COASTAL AREAS LATE TONIGHT AND WEDNESDAY MORNING...
AND EXTEND FROM THE SOUTH WASHINGTON CASCADES TO THE CENTRAL OREGON
COAST WEDNESDAY AFTERNOON. THE MAIN BAND OF PRECIPITATION WILL
CONTINUE TO MOVE SLOWLY SOUTH THROUGH LANE COUNTY WEDNESDAY NIGHT
INTO EARLY THURSDAY AS PRECIPITATION RATES EAST IN THE NORTH. AT THIS
POINT WE THINK THE RIVERS WILL HAVE SHARP RISES BUT PROBABLY NOT
FLOOD...BUT IF THE FRONT STALLS A BIT OR RAINFALL RATES ARE A BIT
HEAVIER THAN FORECAST THAN WE MAY GET A COUPLE OF RIVER CLOSE TO
FLOOD STAGE. HOWEVER...THE HEAVY RAIN WILL LIKELY LEAD TO AREAS OF
URBAN AND SMALL STREAM FLOODING AS SMALLER CREEKS HAVE TROUBLE
CONTAINING THE RUNOFF AND STORM DRAINS GET BLOCKED BY LEAVES AND
CAUSE SOME LOCAL FLOODING.

THURSDAY STILL LOOKS SOMEWHAT WET UNDER SOUTHWEST FLOW ALOFT BUT THE
MAIN FRONT WILL BE SOUTH OF OUR AREA AND RAINFALL ACCUMULATIONS WILL
BE CONSIDERABLY LESS THAN WEDNESDAY AS THE PRECIPITATION IS MORE
SHOWERY.

THERE IS ANOTHER STRONG AND WET STORM EXPECTED TO LIFT NORTH ALONG
THE COAST AND IMPACT NORTHWEST OREGON AND SOUTHWEST WASHINGTON
SIGNIFICANTLY ON FRIDAY INTO THE EARLY PART OF THE WEEKEND. WHILE
THERE ARE SOME DIFFERENCES AMONGST THE MODELS...THIS SYSTEM IS
LOOKING QUITE WET AGAIN...WITH A SURFACE LOW THAT WILL PROBABLY BRING
MORE WIDESPREAD HIGH WINDS TO THE COAST AND A SIGNIFICANT NUMBER OF
TRACKS SUGGEST POSSIBLY VERY WINDY CONDITIONS INLAND AS WELL. AUTUMN
IS KICKING INTO FULL GEAR WITH A BANG. TOLLESON

.LONG TERM...FRIDAY NIGHT THROUGH MONDAY...FORECAST MODELS CONTINUE
TO KEEP THE REGION IN AN ACTIVE WEATHER PATTERN THROUGH THE WEEKEND
AS FRONTAL SYSTEMS MOVE THROUGH EVERY OTHER. WHILE SOME SUBTLE
DIFFERENCES REMAIN...MODELS REMAIN IN REASONABLE AGREEMENT THAT
ANOTHER POTENT LOW PRESSURE SYSTEM WILL DEVELOP OFFSHORE BRINGING A
ROUND OF GUSTY WINDS AND POTENTIAL HEAVY RAINFALL FOR LATE FRIDAY
INTO SATURDAY. SHOWERS LIKELY LINGER FOR SUNDAY BEFORE ANOTHER
FRONTAL SYSTEM APPROACHES ON MONDAY INTO TUESDAY FOR MORE RAINFALL.
WHILE SOME QUESTION REMAINS AS TO HOW THE LOW PRESSURE SYSTEMS WILL
EVOLVE AND TRACK...AND JUST HOW STRONG THEY WILL BE...IT SEEMS
LIKELY THAT WE WILL REMAIN IN AN ACTIVE PATTERN WITH WET WEATHER AT
TIMES THROUGH EARLY NEXT WEEK.CULLEN

&&

.AVIATION...WARM FRONT OFFSHORE WILL MOVE INLAND OVERNIGHT WITH
FOLLOWING COLD FRONT TO THE COAST LATE TONIGHT AND INLAND WED. VFR
SHOULD PREVAIL INLAND THROUGH 15Z-20Z WED WITH INCREASING CHANCES FOR
MVFR AS HEAVIER RAIN MOVES IN WITH THE FRONT. MVFR WILL PROBABLY BE
WIDESPREAD AFTER 00Z THU. FOR COASTAL AREAS...A MIX OF VFR AND MVFR
TO START BUT AS THE WARM FRONT NEARS THE CONDITIONS WILL DETERIORATE
WITH MVFR AND IFR LIKELY. STRONG LOW LEVEL WINDS WILL ALSO BE A
CONCERN WITH MODEL SOUNDING SHOWING SOUTH WIND 45 TO 50 KT AS LOW AS
1000 FT.

KPDX AND APPROACHES...VFR PREVAILING THROUGH 18Z WED AND PERHAPS
UNTIL 00Z THU. BUT AFTER 18Z WED GUIDANCE INDICATING INCREASING
CHANCES FOR MVFR CONDITIONS TO DEVELOP AS THE COLD FRONT NEARS THEN
MOVES THROUGH IN THE EVENING. SOUTHEAST WINDS ARE EXPECTED TO SWITCH
TO SOUTHERLY WINDS TO INCREASE OVERNIGHT. LOW LEVEL WINDSHEAR NOT A
HIGH CONCERN AT THIS POINT BUT SHOULD THE EAST TO SOUTHEAST SURFACE
WIND HOLD...AREAS TOWARD THE COLUMBIA RIVER GORGE COULD EXPERIENCE
LLWS WED MORNING.
&&

.MARINE...A WARM FRONT WORKING ITS WAY TO THE COAST. WINDS HAVE
TURNED A LITTLE MORE TO THE SE THIS EVENING BUT WILL RETURN TO SOUTH
ONCE THE WARM FRONT LIFTS NORTH OVERNIGHT.

HIGH END GALE FORCE GUSTS NEAR 45 KT AT TIMES TONIGHT...WITH STORM
FORCE GUSTS OF 50 TO 55 KT POSSIBLE OVER THE NEAR SHORE WATERS DUE TO
COASTAL JET ENHANCEMENT. WINDS WILL BEGIN TO DIMINISH BY MID TO LATE
MORNING TOMORROW AFTER THE COLD FRONT PUSHES ONSHORE. UPDATE WITH 00Z
MODEL RUN APPEARS PEAK WIND AT THE COAST SHOULD BE BETWEEN 3 AND 5 AM
WED.

SEAS ARE CURRENTLY SITTING IN THE 13 TO 15 FT RANGE...BUT EXPECT THEM
TO INCREASE SIGNIFICANTLY TONIGHT IN RESPONSE TO THE STRENGTHENING
SOUTHERLY WINDS. SEAS MAY APPROACH 20 FT OVERNIGHT DURING THE PERIOD
OF HIGHEST WINDS. SEAS WILL GRADUALLY DECREASE DURING THE DAY
TOMORROW AS THE WINDS DIE DOWN...BUT EXPECT THEY WILL REMAIN IN THE
MID TEENS THROUGH MUCH OF THE DAY.

THERE WILL BE A BIT OF A BREAK THU AND PART OF FRIDAY AS WEAKER
TROUGHS MOVE THROUGH. BUT ANOTHER POTENTIALLY STRONG FRONT IS BEING
MODELED FOR LATER FRI INTO SAT. THERE IS QUITE A BIT OF UNCERTAINTY
IN THIS SYSTEM AT THIS TIME..SO WILL KEEP PREVIOUS FORECAST AS IS AND
WAIT FOR REMAINDER OF 00Z MODEL RUNS TO ARRIVE. BUT IT APPEARS THAT
ANOTHER SOLID GALE WITH SEAS INTO THE MID TO UPPER TEENS IS A STRONG
POSSIBILITY. PYLE/MH
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING UNTIL 9 AM PDT WEDNESDAY FOR NORTH OREGON
     COAST.

     HIGH WIND WARNING UNTIL NOON PDT WEDNESDAY FOR CENTRAL OREGON
     COAST.

WA...HIGH WIND WARNING UNTIL 9 AM PDT WEDNESDAY FOR SOUTH WASHINGTON
     COAST.

PZ...GALE WARNING UNTIL 11 AM PDT WEDNESDAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 9 AM
     PDT WEDNESDAY.

&&

$$

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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