284
FXUS66 KPDT 030524
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
924 PM PST MON FEB 2 2026
KEY MESSAGES
- WEAK WARM FRONT TODAY
- HIGH PRESSURE RETURNS TUESDAY THROUGH FRIDAY
- LIKELY PATTERN CHANGE BY THE WEEKEND
DISCUSSION
A WEAK AR/WARM FRONT OVER WESTERN WA WAS CREATING WARM AND
MOIST ADVECTION INTO CENTRAL WA THIS MORNING WITH NUMEROUS
NETWORK OBS REPORTING WETTING RAINS (AROUND ONE TENTH OF ONE
INCH) IN THE FOOTHILLS/LOWER SLOPES OF THE WA CASCADES. LESSER
AMOUNTS (0.01 - 0.05) WERE OBSERVED ACROSS THE COLUMBIA BASIN
AND INTO SE WA BY EARLY AFTERNOON. WITH A STAGNANT PATTERN OF HIGH
PRESSURE RETURNING AND INFLUENCING THE BOUNDARY LAYER, EXPECT
PATCHY FOG TO DEVELOP IN SOME OF THE VALLEYS AND BASINS
OVERNIGHT. THE CONFIDENCE IN DEVELOPMENT ANY ONE LOCATION
HOWEVER IS LOW, WITH NOT A LOT OF SUPPORT FROM THE GFS LAMP
GUIDANCE OR HREF ENSEMBLE AT LEAST FOR THIS FIRST NIGHT. STILL
THIS MIGHT BE THE MOST SIGNIFICANT SENSIBLE WEATHER IMPACT OVER
THE NEXT SEVERAL DAYS. WEDNESDAY NIGHT AND THURSDAY NIGHT SHOULD
BE A COUPLE OF DEGREES COOLER, COMPRESSING THE DEW POINT
DEPRESSIONS AND FAVORING SATURATION AND THUS FOG DEVELOPMENT.
THE OTHER RISK TO KEEP ON EYE ON THIS WEEK WILL, BE POTENTIAL
FOR AN AIR STAGNATION EPISODE. WE WILL DEFINITELY (100%) HAVE
SUB 10 MPH TRANSPORT WINDS THROUGH THE WEEK, HOWEVER THE
QUESTIONS IS THE UNCERTAINTY IN MAINTAINING LOW (SUB 1500 FT
AGL) MIXING HEIGHTS THROUGH THURSDAY AFTERNOON WHEN THE NBM
BRINGS DEEPER MIXING, IF ONLY SLIGHTLY.
THE UPPER RIDGE WILL ALSO ACT TO KEEP THE REGION PRECIPITATION
FREE AT LEAST THROUGH THE END OF THE WEEK. LIKELY PROBABILITIES
FOR PRECIPITATION (80-90%) RETURN SATURDAY ACROSS THE WA
CASCADES WHILE STILL SPREADING LOWER END LIKELY VALUES, (55-65%)
ACROSS THE EASTERN MOUNTAINS ON SATURDAY NIGHT THROUGH SUNDAY.
ENSEMBLE CLUSTERS ALL SHOW THIS GENERAL PRECIPITATION PATTERN
AND COLD AIR ADVECTION BY SUNDAY AS THE NBM REFLECTS THIS WITH
DECREASING SNOW LEVEL VALUES THROUGH THE LATTER HALF OF THE
WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
CONDITIONS WILL
INITIALLY START AT VFR, BUT PATCHY FOG COULD DEVELOP AT SOME
SITES OVERNIGHT. CONFIDENCE IN FOG AND LOW STRATUS IN GENERAL
HAS A LOWER CONFIDENCE LEVEL TONIGHT AS THE RIDGE ENTERS THE
REGION. WHILE FOG MAY NOT BE WIDESPREAD, IT COULD DEVELOP IN
AREAS ACROSS THE BASIN AND SHELTERED AREAS OVERNIGHT. FOR
TONIGHT, THERE WASN'T ENOUGH CONFIDENCE TO PUT IN FOG AT <1SM.
SUB-VFR CONDITIONS WERE PUT IN FOR DLS/YKM/ALW/PSC FOR LOW
STRATUS AT IFR LEVELS AND VISIBILITIES AT MVFR LEVELS. THERE IS
A SMALL CHANCE (5 TO 15 PERCENT CHANCE) THAT LIFR CONDITIONS OF
LESS THAN A HALF MILE OF FOG DEVELOPS OVER THESE SITES THROUGH
THE EARLY MORNING HOURS. FOR NOW, THEY ARE FORECASTED TO HOVER
BETWEEN 3 AND 5 MILES THROUGH THE OVERNIGHT HOURS.
PRELIMINARY POINT TEMPS/POPS
PDT 35 50 32 50 / 10 0 0 0
ALW 38 49 36 51 / 20 0 0 0
PSC 33 49 34 49 / 10 0 0 0
YKM 33 49 35 50 / 10 0 0 0
HRI 33 50 34 49 / 10 0 0 0
ELN 33 44 33 45 / 20 0 0 0
RDM 29 58 28 59 / 0 0 0 0
LGD 34 54 35 55 / 20 0 0 0
GCD 32 57 33 58 / 0 0 0 0
DLS 38 52 37 52 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...71
AVIATION...95
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