910
FXUS66 KPQR 290900
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
200 AM PDT SAT MAR 29 2025
SYNOPSIS
ACTIVE WEATHER WILL CONTINUE TODAY, WITH COOL, NEAR
NORMAL TEMPERATURES AND PERSISTENT SHOWERS. SATURDAY NIGHT INTO
SUNDAY A BRIEF BREAK IN THE PRECIPITATION AS WELL AS A SLIGHT
WARMING TREND IS EXPECTED AS A SHORTWAVE RIDGE QUICKLY MOVES
ACROSS THE FORECAST AREA. BY THEE START OF THE UPCOMING WEEK,
A BROAD AREA OF LOW PRESSURE WILL BRING A RETURN OF COOLER
TEMPERATURES, RAIN AND CASCADE SNOW BY LATE SUNDAY NIGHT/MONDAY
AND THESE CONDITIONS LOOK TO PERSIST THROUGH THE UPCOMING WEEK.
DISCUSSION...TODAY THROUGH FRIDAY
THE TRAILING END OF THE
LOW PRESSURE SYSTEM WILL FINALLY BE PUSHED OUT THROUGH THIS
AFTERNOON. THE LOW WILL BE REPLACED BY A SHORTWAVE RIDGE WHICH
WILL QUICKLY BE REPLACED BY ANOTHER LOW PRESSURE SYSTEM BY
SUNDAY EVENING/MONDAY. WHAT THIS MEANS IS THAT LIGHT SHOWERS
WILL CONTINUE TO DISSIPATE THROUGH THE AFTERNOON, WITH DRY AND
WARMER WEATHER IS EXPECTED BY TONIGHT. SUNDAY WILL START OFF AS
SLIGHTLY WARMER AND DRIER THAN THE PREVIOUS FEW DAYS, BUT THIS
WILL BE SHORT LIVED AS THE NEXT MAJOR LOW WILL BRING ANOTHER
ROUND OF COOLER TEMPERATURES AND WIDESPREAD SHOWERS ACROSS THE
FORECAST AREA THROUGH ALL OF NEXT WEEK.
THE SYSTEM ON SUNDAY NIGHT/MONDAY IS A RATHER BROAD, VERTICALLY
STACKED LOW, WITH THE SURFACE LOW EXPECTED TO BE AROUND 985 MB
AND CENTERED AROUND 45.75N/136.40W ON MONDAY. THIS LOW WILL
SLOWLY WEAKEN AND TRAVEL SOUTHEASTWARD THROUGH THE UPCOMING
WEEK, WITH MODELS SHOWING LANDFALL IN-BETWEEN FLORENCE, OR AND
THE OR/CA BORDER. AS THIS LOW MOVES SOUTHEASTWARD, IT WILL SEND
MULTIPLE FRONTS ACROSS THE REGION. THIS WILL RESULT IN
SOUTH/SOUTHEASTERLY FLOW, THAT ALONG WITH MODERATE WARMING AND A
MOISTURE LATENT ATMOSPHERE WILL RESULT IN AROUND A 10-20%
PROBABILITY FOR THUNDERSTORMS COME MONDAY AFTERNOON AND
CONTINUE THROUGH THE LATE MONDAY EVENING. COOL AND MOIST
CONDITIONS WILL CONTINUE AS THE LOW CONTINUES TO TRUDGE
SOUTHEASTWARD AND WILL BRING WIDESPREAD PRECIPITATION ALONG
WITH 850 MB TEMPERATURES DIPPING DOWN TOWARDS -1C TO -4C. THIS
WILL RESULT IN A LOWERING OF SNOW LEVELS AND THE COMBINATION OF
LOWERING SNOW LEVELS AND PRECIPITATION COULD EASILY BRING 6-11
INCHES OF NEW SNOW TO THE CASCADES. CURRENT GUIDANCE IS SHOWING
6-11 INCHES OR SO, EVERY 24 HOURS STATING ON MONDAY AND
CONTINUING THROUGH THURSDAY FOR ELEVATIONS ABOVE 2500-3000 FT.
THE CURRENT TRACK OF THE LOW THE FOCUS OF THE SNOW WILL BE MORE
TOWARDS THE LANE AND LINN COUNTY CASCADES. THERE IS ALSO A
10-20% PROBABILITY OF ELEVATIONS ABOVE 5000 FT SEEING SNOW
ACCUMULATION AROUND 10-12 INCHES FOR THE SAME REGION.
OVERALL, EXPECT DAYTIME HIGHS TO BE NEAR NORMAL (50S AND 60S)
FOR THE FORECAST AREA, WITH SUNDAY EXPECTED TO BE THE WARMEST
THROUGH THE UPCOMING WEEK. SATURDAY INTO SUNDAY EVENING WILL BE
DRY, BUT PRECIPITATION RETURNS BY THE START OF NEXT WEEK. ALSO,
COOLER TEMPERATURES ARE ON DECK FOR THE START OF NEXT WEEK AND
THAT COULD BRING ADVISORY LEVEL SNOWFALL (6-11 INCHES) TO THE
OREGON CASCADES MONDAY THROUGH THURSDAY. EARLY ENSEMBLE GUIDANCE
SHOWS SNOW LEVELS FALLING TO AROUND 2000-3500 FT, AND MOUNTAIN
SNOW CAN BE EXPECTED AT TIMES THROUGHOUT NEXT WEEK. CURRENTLY
EVALUATING POTENTIAL FOR WINTER WEATHER ADVISORY-LEVEL SNOW IN
THE MOUNTAINS WITH THE INITIAL FRONT, PARTICULARLY IN THE LANE
COUNTY CASCADES. WE WILL CONTINUE TO MONITOR MODEL OUTPUT AS
THIS IS STILL 3 TO 5 DAYS OUT AND COULD EASILY CHANGE. /42
AVIATION
NORTHWEST FLOW ALOFT WITH LIGHT SOUTHERLY SURFACE
WINDS ON SATURDAY, WITH BOTH SHIFTING NORTHERLY AFTER 21Z
SATURDAY - 00Z SUNDAY. SCATTERED SHOWERS CONTINUE ACROSS THE
REGION THROUGH SATURDAY, DISSIPATING OVER THE INTERIOR LOWLANDS BY
18-21Z SATURDAY AND ACROSS THE COAST AND HIGH TERRAIN BY 00-03Z
SUNDAY. EXPECTING MAINLY VFR CONDITIONS THROUGH THE TAF PERIOD FOR
MOST TERMINALS EXCEPT FOR A 70-90% CHANCE OF MVFR CIGS AND VSBYS
ALONG THE COAST THROUGH AROUND 18Z SATURDAY. HEAVIER SHOWERS
COULD TEMPORARILY LOWER CIGS AND VSBYS TO MVFR. ADDITIONALLY,
THERE IS AROUND A 20-40% CHANCE OF MVFR CIGS WITHIN THE WILLAMETTE
VALLEY AND AROUND A 50-70% CHANCE FROM KPDX NORTHWARD FROM 10-18Z
SATURDAY. HOWEVER, IF THE BKN/OVC MID TO HIGH LEVEL CLOUD DECK
CLEARS BY 10-14Z INLAND, THEN PROBABILITIES WILL INCREASE FOR MVFR
CONDITIONS. -HEC
PDX AND APPROACHES...SCATTERED RAIN SHOWERS THROUGH 00Z SUNDAY
WITH CONDITIONS PREDOMINATELY VFR THROUGH THE PERIOD. THERE IS
AROUND A 40-60% CHANCE OF MVFR CIGS 11-18Z SATURDAY. SOUTH TO
SOUTHWEST WINDS LESS THAN 10 KTS SHIFTING NORTHERLY AFTER 00Z
SUNDAY. -HEC
MARINE
THE SURFACE TROUGH PUSHED INLAND LATE FRIDAY NIGHT, AND
WINDS AND WAVES ARE WEAKENING ON THE BACK SIDE OF THIS TROUGH.
SOUTHWEST WINDS WILL CONTINUE WEAKENING THROUGH SATURDAY AS WEAK
HIGH PRESSURE MOVES OVER THE WATERS. WINDS TURN OFFSHORE LATE
SATURDAY INTO SUNDAY MORNING WITH LOCALLY BREEZY WINDS THROUGH
COASTAL GAPS. WINDS THEN TURN SOUTHERLY BY SUNDAY AFTERNOON AND
INCREASE THROUGH SUNDAY NIGHT AS ANOTHER FRONTAL SYSTEM
APPROACHES. THERE IS ABOUT A 40-60% CHANCE OF LOW- END GALE FORCE
WIND GUSTS FOR SUNDAY NIGHT INTO MONDAY MORNING. MORE UNCERTAINTY
INTO EARLY NEXT WEEK AS TO WHERE THE SURFACE LOW TRACKS, BUT
CONFIDENCE IS HIGH FOR AT LEAST SMALL CRAFT WIND GUSTS OVER 21
KTS.
SEAS HAVE FALLEN TO AROUND 9 TO 11 FEET AT 10 TO 11 SECONDS, AND
WILL REMAIN HERE THROUGH SATURDAY MORNING. A SMALL CRAFT ADVISORY
IS IN EFFECT THROUGH 11 AM SATURDAY. SEAS SHOULD CONTINUE TO
SUBSIDE THROUGH THE WEEKEND, FALLING TO AROUND 5 TO 6 FT ON
SUNDAY. SEAS WILL BUILD AGAIN INTO THE LOW TEENS LATE SUNDAY
NIGHT INTO EARLY NEXT WEEK IN RESPONSE TO THE APPROACHING WEATHER
SYSTEM AND INCREASING SOUTHWESTERLY WINDS. -DH/HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PDT THIS MORNING FOR
PZZ210.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS MORNING FOR
PZZ251>253- 271>273.
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