478
FXUS66 KPDT 190543
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
943 PM PST TUE FEB 18 2025
UPDATED FOR AVIATION
AVIATION
06Z TAFS...FLIGHT CATEGORIES RANGE FROM LIFR AT PDT AND ALW TO
VFR AT BDN AND RDM TO EVERYTHING IN BETWEEN. FOR THE MOST PART
EXPECT STEADY STATE OR SOME DETERIORATION AS PRECIPITATION MOVES
IN OVERNIGHT OR TOWARDS MORNING AND REMAINS OVER THE AREA FOR MOST
OF WEDNESDAY. AT YKM, IT WILL BE MOSTLY SN. AT DLS, BDN AND RDM,
MAINLY RA. FOR THE OTHER SITES, TEMPERATURES WILL BE MARGINAL BUT
THERE COULD BE SOME FREEZING OR FROZEN PRECIP AT THE ONSET BEFORE
A CHANGEOVER TO RA DURING THE LATE MORNING HOURS ON WEDNESDAY,
THOUGH CONFIDENCE IS BELOW AVERAGE ON EXACTLY WHAT TYPES OF
PRECIPITATION PDT, ALW AND PSC WILL RECEIVE DUE TO THE MARGINAL
TEMPERATURES.
WINDS WILL MAINLY BE 10 KTS OR LESS EXCEPT AT BDN AND RDM WHERE
GUSTS TO AROUND 25 KTS ARE EXPECTED WEDNESDAY AFTERNOON THROUGH
EARLY EVENING.
PREV DISCUSSION
/ISSUED 813 PM PST TUE FEB 18 2025/
EVENING UPDATE...MADE SOME ADJUSTMENTS TO THE FORECAST BASED ON
LATEST OBS AND LATEST RUN OF THE HREF. DENSE FOG HAS ROLLED BACK
IN ACROSS THE FOOTHILLS OF THE BLUES, SO HAVE ISSUED A DENSE FOG
ADVISORY THROUGH TOMORROW MORNING. PATCHY FOG HAS BEEN OBSERVED IN
NORTH CENTRAL OREGON ALONG US97, BUT FOG DOESN'T APPEAR TO BE
WIDESPREAD ENOUGH TO WARRANT ANY ADVISORIES.
AS FAR AS THE WINTER WEATHER ADVISORY FOR TONIGHT INTO TOMORROW IS
CONCERNED, MOUNTAIN SNOW HEADLINES WILL REMAIN UNCHANGED. LATEST
CAMS HAVE SCALED BACK THE FREEZING RAIN THREAT IN THE LOWLANDS,
WHICH MAKES SENSE AS UNDER LOW CLOUD COVER, MUCH OF THE BASIN IS
RECORDING TEMPS IN THE MID 30S, WITH LITTLE ROOM FOR FURTHER
COOLING GIVEN THE WARM AIR MOVING IN WITH THIS ONCOMING SYSTEM.
MODELS SEEM TO PIN BETTER CHANCES FOR FREEZING RAIN ACROSS THE
BASE OF THE BLUES AND POCKETS OF THE GORGE AND NORTH CENTRAL
OREGON. HAVE STILL LEFT MENTION OF FREEZING RAIN ACROSS THE BASIN,
BUT WOULD NOT BE SURPRISED IF THE THREAT SHIFTS MORE TOWARD THE
MOUNTAINS WHERE COLDER AIR IS PILING IN. WILL LEAVE WORDING OF THE
ADVISORY UNCHANGED ACROSS THE LOWLANDS, BUT USERS SHOULD BE AWARE
OF THE BUST POTENTIAL IN THIS FORECAST. FREEZING RAIN IS QUITE THE
FICKLE BEAST, AFTER ALL. EVANS/74
PREV DISCUSSION... /ISSUED 305 PM PST TUE FEB 18 2025/
SHORT TERM...TODAY THROUGH THURSDAY...
BOTTOM LINE UP FRONT
1) WINTER WEATHER ADVISORIES
2) WARMER TEMPERATURES ON THE WAY
WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 10 PM THIS EVENING TO
NOON PST WEDNESDAY FOR THE FOOTHILLS OF THE SOUTHERN BLUE MOUNTAINS
OF OREGON-NORTH CENTRAL OREGON-SIMCOE HIGHLANDS.
WINTER WEATHER ADVISORY IN EFFECT FROM 4 AM WEDNESDAY TO 4 AM PST
THURSDAY FOR THE NORTHERN BLUE MOUNTAINS OF OREGON-NORTHWEST BLUE
MOUNTAINS, UPPER SLOPES OF THE EASTERN WASHINGTON CASCADES CREST-
LOWER SLOPES OF THE EASTERN WASHINGTON CASCADES CREST.
WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 10 PM THIS EVENING TO
4 AM PST THURSDAY FOR THE EAST SLOPES OF THE OREGON CASCADES.
WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 2 AM TO NOON PST
WEDNESDAY FOR THE LOWER COLUMBIA BASIN OF OREGON-FOOTHILLS OF THE
NORTHERN BLUE MOUNTAINS OF OREGON-YAKIMA VALLEY-LOWER COLUMBIA BASIN
OF WASHINGTON-FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON.
CURRENT SATELLITE IS SHOWING THE LEADING EDGE OF THE UPPER
LEVEL RIDGE IS SITTING OVER THE REGION BRINGING IN CLOUDY
CONDITIONS. UPPER LEVEL WATER VAPOR SHOWS A RELATIVELY MOIST LAYER
MOVING IN ALONG THE RIDGE WHICH HAS ASSISTED WITH THE PATCHY DENSE
FOG THIS MORNING THAT HAS PERSISTED ACROSS A FEW ISOLATED AREAS
THROUGH THIS AFTERNOON. THE UPPER LEVEL RIDGE WILL GIVE WAY TO AN
UPPER LEVEL TROUGH THE AT WILL BRING WITH IT INCREASED PRECIPITATION
STARTING THIS EVENING AND PERSISTING THROUGH THURSDAY MORNING.
MODELS ARE IN FORM AGREEMENT WITH AN UPPER LEVEL TROUGH MOVING
TOWARDS THE REGION SHIFTING THE WINDS FROM THE NORTHWEST TO THE
SOUTHWEST. THIS WILL BRING WITH IT PLENTY OF MOISTURE AS AN
ATMOSPHERIC RIVER WILL GET SUCKED UP INTO THE TROUGH AND BROUGHT
ACROSS THE REGION. WARM AIR ADVECTION WILL ACCOMPANY THE SYSTEM
BRINGING THE SNOW LEVELS TO ABOVE 3000-3500 FEET. THERE IS HIGH
CONFIDENCE (70-90%) IN THE FORECAST FOR THE FOLLOWING AREAS WHEN IT
COMES TO SNOW AND MODERATE-HIGH CONFIDENCE IN FREEZING RAIN,
HOWEVER, ICE ACCUMULATION AMOUNTS CONFIDENCE IS LOW-MODERATE. SNOW
AMOUNTS ARE 5 TO 8 INCHES ALONG THE EASTERN AND UPPER AND LOWER
SLOPES OF THE WA CASCADES, 5 TO 8 INCHES AND ICE ACCUMULATIONS
AROUND A LIGHT GLAZE AND WINDS GUSTING AS HIGH AS 45 MPH FOR THE
EAST SLOPES OF THE OR CASCADES, SNOW ACCUMULATIONS OF 8-10 INCHES
ABOVE 4000 FEET AND ICE ACCUMULATIONS FOR THE NORTHERN BLUES OF OR &
WA AS WELL AS A LIGHT GLAZE OF ICE, EXCEPT NEAR MEACHAM WHERE ICE
ACCUMULATIONS WILL NEAR 0.02-0.04 INCHES IN THE EARLY MORNING
WEDNESDAY, SNOW ACCUMULATIONS UP TO ONE INCH AND ICE ACCUMULATIONS
AROUND ONE TENTH OF AN INCH FOR THE FOOTHILLS OF THE SOUTHERN BLUE
MOUNTAIN FOOTHILLS, NORTH CENTRAL OR AND SIMCOE HIGHLANDS, LOWER
COLUMBIA BASIN OF OR & WA, FOOTHILLS OF THE NORTHERN BLUES AND THE
YAKIMA VALLEY.
BY THURSDAY MORNING THE UPPER LEVEL TROUGH WILL BROADEN AND MOVE
EAST WHILE THE LEADING EDGE OF THE NEXT UPPER LEVEL RIDGE MAKES ITS
WAY INTO THE REGION. THE WARM AIR ADVECTION FROM THE TROUGH WILL
LINGER ALLOWING THE TEMPERATURES TO STEADILY INCREASE AFTER TODAY.
TEMPERATURES WILL STEADILY INCREASE FROM 5 DEGREES BELOW NORMAL TO
AT OR NEAR NORMAL TEMPERATURES. 60-80% OF THE RAW ENSEMBLES HAVE THE
LOWER ELEVATIONS OF OR IE: CENTRAL OR, NORTH CENTRAL OR THE GORGE
(BOTH PORTIONS), FOOTHILLS OF THE SOUTHERN AND NORTHERN BLUES AND
THE LOWER COLUMBIA BASIN IN THE MID TO UPPER 40S WHILE THE REMAINDER
OF THE AREA BEING IN THE LOW TO MID 40S. BY THURSDAY, TEMPERATURES
WILL IN THE UPPER 40S TO LOW 50S THROUGH THE AFOREMENTIONED AREAS
WITH 70-90% OF THE RAW ENSEMBLES IN AGREEMENT.
WITH THE UPPER LEVEL TROUGH PUSHING ACROSS WEDNESDAY AND THE
EASTERLY FLOW OVER THE BLUES, GUIDANCE SHOWS A TIGHTENING OF THE
SURFACE GRADIENTS ALONG THE GRAND RONDE VALLEY WITH A FEW ISOLATED
LOCATIONS SHOWING GUSTS TO 40 MPH WITH 60% OF THE ENSEMBLES IN
AGREEMENT. 70-80% OF THE RAW ENSEMBLES ALSO SHOW AREAS OF 40 MPH
GUSTS ACROSS THE LOWER EAST SLOPES OF THE OR CASCADES, THE
FOOTHILLS OF THE SOUTHERN BLUE MOUNTAINS AS WELL AS THE RIDGES OF
THE OCHOCO-JOHN DAY HIGHLANDS.
LASTLY, WITH ALL THE SNOW AND ICE FROM THIS NEXT SYSTEM AND THE
WARM UP DIRECTLY AFTERWARDS, WE WILL BE KEEPING AN EYE ON THE
POTENTIAL FOR HYDROLOGIC CONCERNS. BENNESE/90
LONG TERM...FRIDAY THROUGH TUESDAY...
AS WE HAVE A BREAK FROM WEATHER FRIDAY, FRONTAL SYSTEMS WILL RETURN
TO THE PACNW OVER THE WEEKEND INTO MONDAY THUS BRINGING IN MOUNTAIN
SHOWERS. AND WITH MELTING SNOW, THIS COULD BRING SLIGHT HYDROLOGIC
CONCERNS, BUT CAN'T BE RULED OUT JUST YET (20-30% CONFIDENCE). OVER
THE WEEKEND, THE CREST OF THE WA/OR CASCADES AND NORTHERN BLUES WILL
RECEIVE QPF AMOUNTS UP TO 1" OR MORE (>50% CHANCE). AS THE SYSTEM
BEGINS TO WEAKEN MONDAY, LINGERING SHOWERS WILL PERSIST OVER THE
MOUNTAIN AREAS EXCEEDING TO 0.50" OR ABOVE, BUT NO MORE THAN 1" (40-
50% CHANCE). THE LOWLANDS WILL REMAIN UP TO 0.25" OR BELOW. TUESDAY
IS WHEN THE SYSTEMS START TO TAMPER OFF AS DRY CONDITIONS OCCUR AS
THE UPPER RIDGE ARRIVES TO THE PACNW. HOWEVER, THERE COULD BE A
SLIGHT CHANCE (<30%) OF LINGERING MOUNTAIN SHOWERS. WINTERY MIX MAY
POTENTIALLY LINGER MONDAY INTO TUESDAY OVER THE WA CASCADES AS WELL
WITH SNOW ACCUMULATING UP TO 2" AT MOST. CONFIDENCE LOWERS DUE TO
SNOW MELTING FROM WARM TEMPERATURES (20-40%).
WITH THESE SYSTEMS PASSING OVER THE PACNW SATURDAY ONWARDS, BREEZY
WINDS (15-25 MPH) WILL DEVELOP AS THE WESTERLY FLOW INCREASES AT THE
CASCADES, THE FOOTHILLS OF THE BLUES OF OR, AND CENTRAL OR. BUT ON
SUNDAY, WINDS BECOMES GUSTY UP TO 35 MPH MAINLY OVER THE FOOTHILLS
OF THE BLUES, YAKIMA VALLEY, AND THE OR CASCADES (60-80%
CHANCE). FEASTER/97
AVIATION...00Z TAFS...MIX OF FLIGHT CATEGORIES REMAIN FOR
KDLS/KYKM/KALW/KPSC DURING THIS EVENING WHEREAS KPDT/KRDM/KBDN
CURRENTLY IN VFR. KPDT/KPSC COULD POTENTIALLY HAVE FREEZING RAIN
TOMORROW MORNING, BUT CONFIDENCE REMAINS LOW (<20%). KALW CURRENTLY
HAS FOG, THOUGH MAY IMPROVE TOMORROW MORNING AS WELL (40%
CONFIDENCE). WITH THIS NEXT SYSTEM ARRIVING, PRECIP, MIST AND FOG
MAY LOWER CIGS AND VSBYS FOR ALL SITES TO MVFR AND/OR LIFR
CONDITIONS THROUGH THE REST OF THE TAF PERIOD. HOWEVER, KRDM/KBDN
WILL GRADUALLY GO BACK TO VFR OVERNIGHT THROUGH TOMORROW MORNING
WITH GUSTY WINDS UP TO 25KTS. THE REMAINING SITES WILL HAVE WINDS AT
10KTS OR LESS. FEASTER/97
PRELIMINARY POINT TEMPS/POPS
PDT 30 45 34 46 / 20 90 60 20
ALW 31 42 34 44 / 10 90 70 20
PSC 30 41 31 49 / 20 90 40 10
YKM 32 39 29 46 / 80 90 20 0
HRI 31 44 34 51 / 30 90 40 10
ELN 32 39 30 46 / 80 90 20 0
RDM 33 50 26 48 / 50 50 20 10
LGD 29 39 31 43 / 10 90 80 20
GCD 31 44 28 42 / 50 90 60 20
DLS 37 46 37 51 / 80 90 40 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY FROM 2 AM TO NOON PST WEDNESDAY FOR
ORZ044-507.
WINTER WEATHER ADVISORY FROM 4 AM WEDNESDAY TO 4 AM PST THURSDAY
FOR ORZ502.
DENSE FOG ADVISORY UNTIL 8 AM PST WEDNESDAY FOR ORZ507.
WINTER WEATHER ADVISORY UNTIL NOON PST WEDNESDAY FOR ORZ508-510.
WINTER WEATHER ADVISORY UNTIL 4 AM PST THURSDAY FOR ORZ509.
WA...WINTER WEATHER ADVISORY FROM 2 AM TO NOON PST WEDNESDAY FOR
WAZ027>029.
WINTER WEATHER ADVISORY FROM 4 AM WEDNESDAY TO 4 AM PST THURSDAY
FOR WAZ030-522-523.
DENSE FOG ADVISORY UNTIL 8 AM PST WEDNESDAY FOR WAZ029.
WINTER WEATHER ADVISORY UNTIL NOON PST WEDNESDAY FOR WAZ521.
SHORT TERM...74
LONG TERM....97
AVIATION...77
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