073
FXUS66 KPDT 292126
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
226 PM PDT SAT MAR 29 2025
SHORT TERM
TONIGHT THROUGH MONDAY NIGHT...AN UPPER LEVEL TROUGH OVER FAR
EASTERN PORTIONS OF THE AREA WILL CONTINUE MOVING EAST AND OUT OF
THE REGION THROUGH TONIGHT. BEHIND THIS TROUGH A RIDGE WILL BUILD
IN FOR TONIGHT THROUGH THE EARLY PART OF SUNDAY.
THIS HIGH PRESSURE RIDGE WILL ALSO MOVE EAST AS SOUTH TO SOUTHWEST
FLOW MOVES IN BEHIND IT FOR LATER SUNDAY IN ADVANCE OF A LARGE
LOW PRESSURE SYSTEM OFF THE COAST. AS THIS LOW APPROACHES ON SUNDAY,
PRECIPITATION WILL DEVELOP FROM SOUTHWEST TO NORTHEAST, IN ADVANCE
OF THE LOW. THE LOW ITSELF WILL MOVE ONSHORE IN THE MONDAY NIGHT
TIME FRAME AND KEEP THE WEATHER UNSETTLED UNTIL IT PASSES.
ANY PRECIPITATION FOR THE REMAINDER OF TODAY SHOULD BE LIGHT AND
CONFINED TO THE CASCADES AND FAR EASTERN OREGON MOUNTAINS. BY THIS
EVENING, EVEN THAT PRECIPITATION SHOULD BE OVER. TONIGHT AND
SUNDAY MORNING IS EXPECTED TO BE DRY, THEN PRECIPITATION IS
EXPECTED TO DEVELOP AGAIN BY SUNDAY AFTERNOON, FIRST OVER CENTRAL
OREGON AND THEN MOVE NORTHEAST, AFFECTING ALL OF SOUTHEAST
WASHINGTON AND NORTHEAST OREGON BY EVENING. PROBABILITIES ARE HIGH
(60-80 PERCENT) THAT ALL LOCATIONS WILL SEE PRECIPITATION SUNDAY
EVENING/NIGHT. QPF AMOUNTS ARE HIGHEST FOR THE REST OF THE OREGON
CASCADES WHERE AMOUNTS LOOK TO EXCEED 0.50 INCHES. FOR THE REST OF
THE HIGHER TERRAIN, MOST LIKELY AMOUNTS WILL BE 0.25 TO 0.50
INCHES. ELSEWHERE, AMOUNTS WILL MAINLY BE LESS THAN 0.10 INCHES.
SNOW LEVELS WILL START OFF GENERALLY BETWEEN 3000 AND 3500 FEET
SUNDAY MORNING, BUT RISE TO BETWEEN 4500-5500 FEET SUNDAY
AFTERNOON. SNOW LEVELS WILL DECREASE AGAIN TO 3500-5000 FEET
SUNDAY NIGHT. SNOW AMOUNTS LOOK TO BE MINIMAL EXCEPT AT THE
HIGHEST TERRAIN, GIVEN THE FAIRLY HIGH SNOW LEVELS AND MARGINAL
TEMPERATURES.
PRECIPITATION WILL LIKELY DECREASE AGAIN FOR A TIME ON MONDAY
BEFORE INCREASING AGAIN MONDAY AFTERNOON AND EVENING AS THE LOW
MOVES ONSHORE. QPF AMOUNTS WITH THIS SYSTEM LOOKS SIMILAR IN THE
OREGON CASCADES, PROBABLY A BIT LESS IN THE WASHINGTON CASCADES,
BUT MORE IN THE BLUES AND EASTERN OREGON MOUNTAINS, WHERE QPF
SHOULD BE AROUND 0.50 INCHES ALONG THE CREST. MOST LOWER ELEVATION
LOCATIONS SHOULD RECEIVE LESS THAN 0.10 INCHES ONCE AGAIN.
WITH A LOW MOVING ACROSS THE REGION, BY TUESDAY MORNING, SNOW
LEVELS WILL BE BELOW 3000 FEET EVERYWHERE. IT IS POSSIBLE THAT
THERE COULD BE A FEW INCHES OF SNOW ALONG THE CRESTS OF THE OREGON
CASCADES AND EVEN THE BLUES BY TUESDAY MORNING.
IT WILL BE BREEZY ON MONDAY WITH MANY AREAS HAVING WIND GUSTS IN
THE 25 MPH RANGE. NBM WIND GUSTS PROBABILITIES >=25 MPH ARE 70-90
PERCENT ACROSS MUCH OF THE REGION. HOWEVER, NBM PROBABILITIES OF
WIND GUSTS >=39 MPH ARE GENERALLY 30 PERCENT OR LESS.
LONG TERM
TUESDAY THROUGH SATURDAY...
KEY MESSAGES:
1) LIGHT TO MODERATE MOUNTAIN SNOW IN CASCADES.
2) LIGHT RAIN IN LOWER ELEVATIONS.
3) DRYING TOWARDS THE SECOND HALF OF THE EXTENDED.
THE PDT CWA WILL BE UNDER A TROUGH SYSTEM THAT HAS PUSHED THROUGH
FROM THE PACIFIC. MODELS HAVE GOOD AGREEMENT ON TUESDAY AS WINDS
SHIFT FROM WSW TO A MORE NW FLOW WITH THE LOW PRESSURE SYSTEM HEADED
EAST. MOUNTAIN SNOW AND LOWER ELEVATION LIGHT RAIN WILL ACCOMPANY
WITH THE SYSTEM, WITH THE HIGHEST SNOW TOTALS ON THE OR CASCADES.
ALONG THE OR PASSES, EXPECT ANYWHERE BETWEEN 2-5" OF SNOW OF
TUESDAY, FOLLOWED BY 1-4" OF SNOW ALONG THE WA CASCADES. BOTH
AMOUNTS HAVE A 60-80% CONFIDENCE OF OCCURRING.
CLUSTERS BEGIN TO DIVERGE A BIT HEADING INTO WEDNESDAY. A RIDGE IS
EXPECTED TO BUILD JUST OFF THE PACIFIC AND PROGRESS INTO THE PACNW
OVER THE NEXT SEVERAL DAYS. WRAP AROUND FROM THE LOW PRESSURE SYSTEM
MOVING FURTHER FROM THE AREA, WILL KEEP POP CHANCES UP FOR THE NEXT
COUPLE OF DAYS, KEEPING MOUNTAIN SNOW CHANCES AND RAIN CHANCES UP
THROUGH THURSDAY. CONFIDENCE IN QPF IS UNCERTAIN, GIVING THAT
CLUSTERS START TO DIVERGE IN AGREEMENT AS WE HEAD INTO WEDNESDAY. OF
THE CLUSTERS, 19% WANTS TO WEAKEN THE TROUGH, WITH A MORE DRIER
SOLUTION, WITH 18% DEEPENING THE TROUGH FURTHER ENHANCING THE
PRECIPITATION. MODELS DIG FURTHER INTO DISAGREEMENT HEADED INTO THE
LONG TERM, AS CLUSTERS CAN'T AGREE WITH TIMING OR INTENSITY OF THE
SYSTEM AS THE RIDGE BUILDS CLOSER TO THE COAST. CLUSTERS HINT
HEAVILY FOR SNOW IN CENTRAL OR ON THURSDAY, BUT SNOW AMOUNTS
REMAINED TAPERED TO UP TO AN INCH (50-70% CONFIDENCE). OF THE
CLUSTERS, 37% WANT TO DEEPEN A SHORTWAVE INTO THE CWA, ENHANCING
SNOW CHANCES FOR AREAS IN THE MOUNTAINS, CENTRAL OR, AND FOOTHILLS
OF THE BLUES. NOTABLY, 27% OF MEMBERS COMPLETELY DRIES OUT THE
REGION BY THURSDAY AFTERNOON WITH A MORE AMPLIFIED RIDGE OVER THE
REGION. BY LATE THURSDAY NIGHT, 60% OF MEMBERS DRIES OUT THE REGION
WITH A MORE AMPLIFIED RIDGE, BUT 40% KEEPS THE PATTERN FAVORABLE FOR
SOME MORE ADDITIONAL LOW LEVEL RAIN/LIGHT MOUNTAIN SNOW. BY FRIDAY
AFTERNOON, A GENERAL CONSCIOUS IS THAT PRECIP CHANCES WILL DWINDLE
DOWN AND THINGS WILL DRY OUT FOR THE REST OF THE LONG TERM AS THE
RIDGE SETTLES IN OVER THE REGION.
DIURNAL WINDS WILL MATERIALIZE THROUGH THE PERIOD, WITH SOME OF THE
MORE WINDY AREAS SOUTH OF THE BLUE HILLS GUSTING AT 25-35 KNOTS
WEDNESDAY AFTERNOON. NOTHING TO SUGGEST THAT ANY ADVISORIES WILL BE
NECESSARY AT THIS TIME. TEMPERATURES WILL BE AT OR NEAR NORMAL WITH
MOST AREAS RECEIVING HIGH TEMPERATURES 0 TO -10 DEGREES BELOW THE
AVERAGE.
AVIATION
(PREVIOUS DISCUSSION)
12Z TAFS...VFR CONDITIONS PREVAIL AT ALL SITES. SOME CLOUD DECKS
OVER ON THE EASTERN PART OF THE CWA, BUT CIGS REMAIN LIFTED. WINDS
WILL REMAIN AT 10 KNOTS OR LESS AT ALL TERMINALS. /95
PRELIMINARY POINT TEMPS/POPS
PDT 52 35 64 42 / 20 0 10 70
ALW 52 37 62 43 / 20 0 10 80
PSC 58 34 65 42 / 0 0 10 60
YKM 56 35 61 37 / 10 0 10 70
HRI 57 33 65 41 / 10 0 10 70
ELN 52 33 58 36 / 10 0 10 70
RDM 49 31 58 33 / 0 0 30 60
LGD 46 29 54 37 / 50 0 10 80
GCD 44 30 54 36 / 50 0 40 80
DLS 56 37 60 40 / 10 0 50 90
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...77
LONG TERM....95
AVIATION...95
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