550
FXUS66 KPQR 181034
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
334 AM PDT FRI JUL 18 2025
SYNOPSIS
EXPECT ONSHORE FLOW TO CONTINUE TO INCREASE IN THE
COMING DAYS FACILITATING A COOLING TREND THROUGH THE WEEKEND
INTO EARLY NEXT - WIDESPREAD NEAR TO BELOW NORMAL TEMPERATURES
RETURN BY SUNDAY/MONDAY. AN UPPER- LEVEL TROUGH MAY PROVIDE THE
BEST RAINFALL CHANCES SO FAR THIS MONTH ON MONDAY, ALTHOUGH ODDS
REMAIN LOW FOR ACCUMULATING PRECIPITATION. FORECAST CONFIDENCE
STILL REMAINS FAIRLY LOW THROUGH THE COMING WORKWEEK BEYOND A
GENERAL WARMING TREND INTO TUESDAY/WEDNESDAY.
SHORT TERM...NOW THROUGH SUNDAY NIGHT
SATELLITE IMAGERY
EARLY THIS MORNING DEPICTS A MARINE STRATUS/FOG LAYER CURRENTLY
IN PLACE ACROSS THE COASTLINE STRETCHING EASTWARD INTO SEVERAL
OF THE ATTENDANT COAST RANGE RIVER VALLEYS INCLUDING THE I-5
CORRIDOR NEAR LONGVIEW/KELSO. THIS STRATUS WILL ATTEMPT TO SURGE
INTO THE WILLAMETTE VALLEY COME SUNRISE BUT THE MAJORITY OF
HIGH RESOLUTION GUIDANCE KEEPS IT PINNED FURTHER WESTWARD.
MOSTLY SUNNY SKIES FAVORED ACROSS THE INLAND VALLEYS THIS
MORNING. COME THE AFTERNOON HOURS, AN UPPER-LEVEL SHORTWAVE
RIDING DOWN THE B.C. COASTLINE WILL PUSHING INTO THE REGION
USHERING IN FURTHER ONSHORE FLOW IN ADDITION TO SLIGHTLY
CLOUDIER AND BREEZIER CONDITIONS THIS AFTERNOON - THE LATTER OF
THE THREE FEATURES MOST EVIDENT THROUGH THE CENTRAL COLUMBIA
GORGE WHERE GUSTS LIKELY REACH 30-35 MPH. ANTICIPATE 850MB
TEMPERATURES TO FALL FROM AROUND 15-16C TODAY TO 9-11C ON
SATURDAY/SUNDAY HELPING TO PUSH SURFACE TEMPERATURES TO BELOW-
NORMAL VALUES. AFTERNOON HIGHS THROUGH THE WEEKEND ARE EXPECTED
IN THE LOW 60S ALONG THE COAST AND MID 70S TO LOW 80S WITHIN
INLAND VALLEYS. INCREASED MARINE STRATUS COVERAGE MAY SEE AREAS
COASTAL FOG AND MIST, MOST LIKELY OVERNIGHT AND INTO THE MORNING
BOTH DAYS THIS WEEKEND AND WHERE THE STRATUS INTERSECTS THE
TERRAIN IN THE COAST RANGE. ALL IN ALL, A PATTERN NOT OUT OF THE
ORDINARY FOR THIS TIME OF YEAR. -SCHULDT
LONG TERM...MONDAY THROUGH THURSDAY
GOING FORWARD THROUGH THE
LONG TERM PERIOD SOMEWHAT LOWER CONFIDENCE PERSISTS AS
NUMERICAL GUIDANCE DIVERGES BEGINNING MONDAY ONWARD THROUGH THE
WEEK. TROUGHING INITIALLY PRESENT OVER THE PACIFIC NORTHWEST
LOOKS TO BECOME MORE ELONGATED AS A SHORTWAVE DIVES SOUTH ON ITS
WESTERN FLANK ON MONDAY. WHILE THIS WAVE MAY SUPPORT LIGHT RAIN
REACHING INTO THE REGION TO START THE WORK WEEK, CHANCES REMAIN
FAIRLY LOW OVERALL, ONLY 10-24% ALONG THE COAST AND IN THE
HIGHER TERRAIN OF THE CASCADES AND COAST RANGE WHILE THE
LOWLANDS SEE LESS THAN A 10% CHANCE. ECMWF BASED DETERMINISTIC
AND ENSEMBLE SOLUTIONS, INCLUDING THE ECMWF AIFS, REMAIN THE
MOST BULLISH ON LIGHT PRECIPITATION ACROSS THE AREA ON MONDAY
COMPARED TO OTHER MODELING SOLUTIONS WHICH KEEP THE UPPER-LEVEL
WAVE LESS DEVELOPED AND FURTHER EAST. ENSEMBLE MEMBERS THEN SHOW
A WIDE VARIETY OF POSSIBLE SCENARIOS INCLUDING A CUTOFF LOW
DEVELOPING OVER THE FAR EASTERN PACIFIC OR A DEAMPLIFICATION OF
THE TROUGH WITH AN ASSOCIATED WARMING TREND AS COOLER AIR IN THE
MID-LEVELS MODERATES. SHOULD THE FORMER CUTOFF LOW SOLUTION
MATERIALIZE MID TO LATE WEEK (ROUGHLY 40-50% OF THE ENSEMBLE
SPACE) WE'LL HAVE TO KEEP AN EYE OUT FOR CASCADES THUNDERSTORM
CHANCES. AT LEAST AT THIS POINT THE MAJORITY OF MEMBERS FAVOR
THE TREND BACK TOWARD A MORE ZONAL FLOW ALOFT AND THE FORECAST
THEREFORE WARMS BACK ABOVE SEASONAL NORMS COME THE MIDDLE OF THE
WEEK. -SCHULDT/PICARD
AVIATION
LIFR/IFR MARINE STRATUS CONTINUES ALONG THE COAST
THROUGH 19-21Z FRI. AFTERWARDS, THERE IS A 50-60% CHANCE THAT
LIFR/IFR STRATUS ALONG THE COAST CONTINUES THROUGH THE AFTERNOON.
HIGH PRESSURE WILL MAINTAIN VFR CONDITIONS INLAND WITH INCREASING
HIGH CLOUDS IN THE AFTERNOON. WINDS GENERALLY WEST-NORTHWESTERLY
ACROSS THE AREA TODAY AROUND 5-10 KT.
PDX AND APPROACHES...VFR UNDER MOSTLY CLEAR SKIES. INCREASING HIGH
CLOUDS THIS AFTERNOON. EXPECT NORTHWESTERLY WINDS AROUND 5-10 KT,
STRONGEST IN THE AFTERNOON. -ALVIZ
MARINE
A DENSE FOG ADVISORY REMAINS IN EFFECT ACROSS THE WATERS
THROUGH 1400 FRIDAY FOR VISIBILITIES OF 1 NM OR LESS. WEAK WINDS
AND SUBSIDING SEAS ACROSS THE INNER WATERS (OUT 10 NM) HAS LEAD TO
THE CANCELLATION OF THE SMALL CRAFT ADVISORY. WHILE WINDS ALSO
REMAIN WEAK ACROSS THE OUTER WATERS (10-60 NM OUT), THE SMALL
CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1100 FRIDAY DUE TO CHOPPY
SEAS. SEAS SHOULD GRADUALLY FALL TO AROUND 5-7 FT AT 8-9 SECONDS
TODAY. HIGH PRESSURE WILL MAINTAIN NORTHERLY TO NORTHWESTERLY
WINDS THROUGH NEXT WEEK. SEAS CONTINUE TO SUBSIDE THIS WEEKEND
WITH MINIMAL IMPACTS EXPECTED. -ALVIZ
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...DENSE FOG ADVISORY UNTIL 2 PM PDT THIS AFTERNOON FOR
PZZ251>253-271>273.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS MORNING FOR
PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page