836
FXUS66 KPQR 130950
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
250 AM PDT TUE APR 13 2021
SYNOPSIS
HIGH PRESSURE OVER THE REGION WILL MAINTAIN CLEAR SKIES
AND DRY WEATHER THROUGH THE COMING WEEKEND, WITH GRADUAL WARMING
TREND. COMBINATION OF HIGH PRESSURE EAST OF THE CASCADES, AND THERMAL
TROUGH WEST OF THE CASCADES WILL MAINTAIN LIGHT TO MODERATE OFFSHORE
FLOW. THIS WILL BRING BREEZY EAST TO NORTHEAST WINDS TODAY INTO
TONIGHT, ALONG WITH RATHER LOW HUMIDITY.
SHORT TERM...TODAY THROUGH THURSDAY
HIGH PRESSURE OVER THE REGION
WILL MAINTAIN MOSTLY CLEAR SKIES UNDER A DRY AIR MASS. SURFACE HIGH
PRESSURE EAST OF THE CASCADES WILL INTERACT WITH THE THERMAL TROUGH
ALONG THE OREGON/WASHINGTON COAST TO BRING BREEZY EAST TO NORTHEAST
WINDS TO THE REGION TODAY INTO TONIGHT. PRESSURE GRADIENTS WILL
GENERALLY BE THE TIGHTEST THIS AFTERNOON INTO THIS EVENING. WOULD
EXPECT TO SEE STRONGEST WINDS IN THE AFTERNOON INTO TONIGHT, WITH
GUSTS 25 TO 40 MPH OVER THE HIGHER TERRAIN, AS WELL AS AREAS OF THE
PORTLAND/VANCOUVER METRO AS MOVE CLOSER TO THE COLUMBIA GORGE.
THERMAL TROUGH WILL GRADUALLY SHIFT BACK INLAND ON WED, WEAKENING
PRESSURE GRADIENTS AND RESULTING LESS WIND.
STILL HAVE SOMEWHAT COOLER TEMPERATURES ALOFT, WHICH WILL COUNTERACT
THE DOWNSLOPE COMPRESSION WARMING DUE TO OFFSHORE FLOW. SO, WILL
GENERALLY SEE 60S ACROSS REGION, RATHER THAN THE FULL POTENTIAL OF
REACHING THE 70S. BUT, THAT SAID, A FEW SPOTS ALONG THE COAST COULD
GET CLOSER TO OR EVEN CRACK 70 DEG TODAY. BUT, WILL DEFINITELY BE A
DRY DAY, WITH UNSEASONABLY LOW HUMIDITY ACROSS REGION. LIKELY TO SEE
MINIMUM HUMIDITY OF 15 TO 25 PERCENT TODAY AND LIKELY AGAIN WED.
NOW, ON THURSDAY, THE OFFSHORE GRADIENTS ARE STILL IN PLAY, BUT NOT
ALL THAT STRONG. AIR MASS ALOFT WILL BE WARMER, THANKS TO RIDGE
WORKING FURTHER INTO THE PAC NW. ALL AND ALL, WILL SEE TEMPERATURES
INLAND PUSHING INTO THE 70S, AND WELL INTO THE 60S ALONG THE COAST.
GIVEN THE WARM AFTERNOON TEMPERATURES, BREEZY OFFSHORE WINDS, AND
VERY DRY AIR MASS, FIRE DANGER WILL BE UNSEASONABLY HIGH AS FINE
FUELS CONTINUE TO DRY OUT IN WHAT HAS BEEN A VERY DRY APRIL.
FORTUNATELY, HEAVIER FUELS REMAIN SEASONALLY MOIST AND THERE IS
PLENTY OF SNOWPACK AT ELEVATIONS ABOVE 2500-3000 FEET. BUT ANYONE
PLANNING TO BURN SLASH PILES OR YARD DEBRIS SHOULD BE ESPECIALLY
CAREFUL THROUGH AT LEAST MIDWEEK, AS THESE CONDITIONS DO MAKE IT
POSSIBLE FOR FINER FUELS TO CARRY FIRE DESPITE IT BEING WELL BEFORE
OUR TYPICAL FIRE SEASON.
LONG TERM...FRIDAY THROUGH SUNDAY
PACIFIC NW WILL REMAIN DRY
THROUGHOUT THE WEEK AND INTO THE WEEKEND. THE LOW THAT MOVED SOUTH
TUESDAY WILL CONTINUE TO MOVE SOUTHEAST INTO THE GREAT BASIN,
MAINTAINING LIGHT TO MODERATE OFFSHORE FLOW THURSDAY. UPPER LEVEL
HIGH PRESSURE WILL BUILD IN BEHIND THE LOW MAINTAINING DRY CONDITIONS
AS WELL AS ALLOWING THE THERMAL LOW TO BUILD TO THE SOUTH CONTINUING
THE OFFSHORE FLOW INTO THE WEEKEND. WITH CONDITIONS REMAINING DRY,
EXPECT COOL NIGHTS AND WARM AFTERNOONS TO CONTINUE. LONGER RANGE NBM
GUIDANCE SUGGESTS WE COULD PUSH 80 DEGREES AS WE HEAD INTO THE
WEEKEND. WEAGLE/BKP
AVIATION
UPPER LEVEL HIGH PRESSURE OFFSHORE AND ACROSS WESTERN
CANADA DRIVING SYNOPTIC OFFSHORE FLOW EVENT ACROSS THE PACIFIC
NORTHWEST. WITH HIGHER PRESSURE WELL INLAND AND A THERMALLY
INDUCED LOWER PRESSURE ALONG THE NORTHERN CALIFORNIA AND SOUTHERN
OREGON COAST. MODEL SOUNDINGS SHOW GOOD POTENTIAL FOR LLWS FOR
AREAS NEAR THE GORGE THROUGH ABOUT MIDDAY, THEN WINDS ARE
EXPECTED TO MIX DOWN TO THE SURFACE. EXPECT NORTH TO
NORTHEASTERLY WIND GUSTS OF 15 TO 25 KT TO DEVELOP IN THE
LATER IN THE MORNING THROUGH THE EARLY EVENING HOURS, PARTICULARLY
ALONG THE COAST AND IN THE WILLAMETTE VALLEY.
FOR DETAILED REGIONAL PAC NW AVIATION WEATHER INFORMATION, GO
ONLINE TO: HTTPS://WEATHER.GOV/ZSE
KPDX AND APPROACHES...VFR EXPECTED NEXT 24 HOURS. MAIN CONCERN IS
EASTERLY WINDS TODAY ALONG WITH LLWS. MODEL SOUNDINGS SHOW GOOD
POTENTIAL FOR LLWS NEAR THE GORGE THROUGH ABOUT MIDDAY, THEN
WINDS ARE EXPECTED TO MIX DOWN TO THE SURFACE. EXPECT EAST TO
NORTHEASTERLY WIND GUSTS OF 15 TO 25 KT TO DEVELOP IN THE LATER
IN THE MORNING THROUGH THE EARLY EVENING HOURS.
MARINE
HIGH PRESSURE CURRENTLY OVER THE NORTHEAST PACIFIC IS
EXPECTED TO REMAIN IN PLACE FOR MUCH OF THE NEXT WEEK. THERMALLY
INDUCED LOWER PRESSURE ALONG THE SOUTHERN OREGON COAST WILL
GRADUALLY SPREAD NORTHWARD RESULTING IN A SUMMER-LIKE GUSTY
NORTHERLY WIND PATTERN ACROSS THE COASTAL WATERS THROUGH TONIGHT.
SMALL CRAFT ADVISORIES ARE OUT TODAY FOR ALL ZONES EXCEPT THE
NEARSHORE ZONE NORTH OF CASCADE HEAD BUT LOCAL GUSTS TO 20-25 KT
ARE POSSIBLE. THE PATTERN WEAKENS ON WEDNESDAY AS THE THERMALLY
INDUCED LOWER PRESSURE ALONG THE COAST SHIFTS INLAND THEREBY
EASING WINDS SOME. HOWEVER, NORTHERLY WINDS CONTINUE THROUGH LATE
IN THE WEEK AS SURFACE HIGH PRESSURE REMAINS OFFSHORE AND THE
THERMALLY INDUCED LOWER PRESSURE REBUILDS ALONG THE COAST. THERE
IS A CHANCE A SOUTHERLY WIND REVERSAL COULD BRING A BRIEF BOUT OF
GUSTY SOUTHERLY WINDS AND FOG TO THE WATERS OVER THE WEEKEND,
BUT PLENTY OF UNCERTAINTY EXISTS AT THIS POINT IF IT WILL OCCUR
AND HOW PRONOUNCED IT WILL BE IF IT DOES.
SEAS ARE CURRENTLY HOVERING AROUND 6 TO 8 FT RANGE ACROSS THE
WATERS, PRIMARILY SHORT PERIOD WIND WAVES/FRESH SWELL. STRENGTHENING
NORTHERLY WINDS TODAY WILL BRING AN INCREASING WIND WAVE
COMPONENT TO THE SEAS. AS A RESULT, SEAS MAY BECOME PARTICULARLY
STEEP AND HAZARDOUS AS DOMINANT WAVE PERIODS FALL INTO THE 6 TO 8
SECOND RANGE ACROSS THE WATERS. SEAS SHOULD GENERALLY BE 5 FT OR
LESS BEGINNING DURING WEDNESDAY AND CONTINUING THROUGH AT LEAST
THE WEEKEND. /MH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 6 AM PDT WEDNESDAY FOR COASTAL
WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM 10 TO
60 NM.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 11 PM PDT THIS
EVENING FOR COASTAL WATERS FROM CASCADE HEAD TO FLORENCE
OR OUT 10 NM.
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
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