798
FXUS66 KPDT 061101
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
401 AM PDT WED MAY 6 2026
KEY MESSAGES
- ABOVE-NORMAL TEMPERATURES AND MOSTLY DRY CONDITIONS THROUGH
THIS WEEK INTO NEXT WEEK
- WIND ADVISORY IN EFFECT THIS AFTERNOON AND EVENING
- PERIODS OF LOW RELATIVE HUMIDITY (10-20 PERCENT) COUPLED WITH
BREEZY TO WINDY WESTERLY WINDS THURSDAY AND FRIDAY THROUGH
THE CASCADE GAPS AND ACROSS THE COLUMBIA BASIN AND BLUE
MOUNTAIN FOOTHILLS
DISCUSSION
SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES EARLY THIS MORNING
UNDER AN UPPER-LEVEL RIDGE OF HIGH PRESSURE. WATER VAPOR
IMAGERY REVEALS THE RIDGE OF HIGH PRESSURE EXTENDS FROM OFFSHORE
NORTHEAST THROUGH THE CANADIAN ROCKIES.
LATER TODAY, A WEAK SHORTWAVE WILL RIDE OVER THE TOP OF THE
RIDGE ACROSS BRITISH COLUMBIA AND THE NORTHERN ROCKIES. COUPLED
WITH A CROSS-CASCADE THERMAL GRADIENT (WARMER ON THE EAST SIDE,
COOLER ON THE WEST SIDE) DUE TO AN ESTABLISHED MARINE LAYER
(EVIDENT IN NIGHTTIME MICROPHYSICS RGB IMAGERY AS WELL AS 00Z
OBSERVED SOUNDINGS AT SLE AND UIL) ON THE WEST SIDE OF THE
CASCADES, THIS WILL INDUCE A DECENTLY STRONG CROSS-CASCADE
PRESSURE GRADIENT (8-12 MB BETWEEN PDX AND GEG PER LATEST
GUIDANCE) AND RESULT IN BREEZY TO LOCALLY WINDY WESTERLY WINDS
THROUGH THE CASCADE GAPS AND ACROSS THE COLUMBIA BASIN AND BLUE
MOUNTAIN FOOTHILLS. NBM PROBABILITIES OF EXCEEDANCE SHOW A
MEDIUM-HIGH (50-95 PERCENT) CHANCE OF REACHING ADVISORY-LEVEL
WIND GUSTS FOR CLIMATOLOGICALLY WIND-PRONE LOCATIONS WITHIN THE
AFOREMENTIONED REGION, WITH SIGNIFICANTLY LOWER CHANCES
ELSEWHERE. CONFIDENCE WAS HIGH ENOUGH (70-90 PERCENT) THAT
PERIODS OF ADVISORY-LEVEL SUSTAINED WINDS AND/OR WIND GUSTS WILL
BE MET TODAY, SO WENT AHEAD AND ISSUED A WIND ADVISORY FOR
MULTIPLE ZONES FOR THIS AFTERNOON AND EVENING.
ANOTHER ROUND OF BREEZY CONDITIONS IS FORECAST THURSDAY AS THE
SHORTWAVE EXITS TO THE EAST OVER THE ROCKIES AND UPPER-LEVEL
RIDGING REBUILDS OVER THE PACIFIC NORTHWEST. THAT SAID, A DRIER
AIR MASS IS FORECAST TO BE PRESENT THURSDAY IN THE WAKE OF THE
SHORTWAVE, AND LOCALLY LOW RELATIVE HUMIDITY (10-20 PERCENT) IS
FORECAST. FUELS ARE NOT YET READY FOR RED FLAG WARNINGS, SO NO
FIRE WEATHER HEADLINES HAVE BEEN ISSUED.
BY FRIDAY, ENSEMBLE MEAN 500-HPA HEIGHTS AND VORTICITY SHOW
ANOTHER SHORTWAVE FROM THE PACIFIC ENTERING THE PACIFIC
NORTHWEST LATE MORNING THROUGH AFTERNOON. CONFIDENCE IS VERY
HIGH (90 PERCENT) IN ANOTHER ROUND OF WIDESPREAD BREEZY TO WINDY
WESTERLY WINDS THROUGH THE CASCADE GAPS AND ACROSS THE COLUMBIA
BASIN AND BLUE MOUNTAIN FOOTHILLS. NBM PROBABILITIES OF
REACHING OR EXCEEDING ADVISORY-LEVEL WIND GUSTS ARE MEDIUM-
HIGH (40-80 PERCENT) FOR WIND-PRONE AREAS WITHIN THE REGION
OUTLINED ABOVE. SIMILAR TO THURSDAY, THE DRY AIR MASS (ENSEMBLE-
ADVERTISED PWATS OF 0.25-0.50") COUPLED WITH SUFFICIENT
DOWNWARD MIXING DURING THE DAYTIME SHOULD FACILITATE SOME LOW
RELATIVE HUMIDITY (10-20 PERCENT) PRIOR TO THE ARRIVAL OF A
MORE HUMID AIR MASS BY LATER FRIDAY.
TAKING A GLANCE AT THE WEEKEND INTO NEXT WEEK, ENSEMBLE NWP
GUIDANCE SHOWS LITTLE TO NO SIGNAL FOR ORGANIZED PRECIPITATION
UNTIL TUESDAY AS UPPER-LEVEL RIDGING REMAINS THE FAVORED
SCENARIO FOR THE BULK OF THE WEST. PERIODS OF BREEZY WESTERLY
WINDS ARE FAVORED AS THE RIDGE AXIS SHIFTS INLAND SUNDAY THROUGH
EARLY NEXT WEEK AND ENSEMBLE GUIDANCE SHOWS POTENTIAL FOR A
COUPLE ADDITIONAL SHORTWAVES TO RIDE OVER THE TOP OF THE RIDGE.
TO BRIEFLY TOUCH ON FORECAST TEMPERATURES, FOR MOST OF OUR
POPULATION CENTERS HIGH TEMPERATURES IN THE UPPER 70S TO LOWER
90S COUPLED WITH LOWS IN THE UPPER 40S TO LOWER 60S WILL PRESENT
PREDOMINANTLY MINOR (LEVEL 1 OF 4) HEATRISK. THIS LEVEL OF HEAT
PRIMARILY AFFECTS THOSE WHO ARE EXTREMELY SENSITIVE TO HEAT AND
WITHOUT COOLING/HYDRATION.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
VFR CONDITIONS ARE FORECAST FOR THE NEXT 24 HOURS. WINDS WILL BE
BREEZY TO WINDY LATER THIS MORNING THROUGH EVENING AT ALL
TERMINALS, STRONGEST AT DLS/PDT. PREDOMINANTLY MID- TO HIGH-
LEVEL CLOUD IS FORECAST TO INCREASE IN COVERAGE BY EARLY
AFTERNOON.
FIRE WEATHER
BREEZY TO WINDY WESTERLY WINDS ARE FORECAST TODAY, AND WIND
ADVISORIES ARE IN EFFECT FOR MULTIPLE ZONES. LOCALLY LOW (10-20
PERCENT) RELATIVE HUMIDITY IS FORECAST TO ACCOMPANY BREEZY
(THURSDAY) TO WINDY (FRIDAY) WESTERLY WINDS ACROSS THE COLUMBIA
BASIN AND SURROUNDING LOWLANDS. POOR TO MODERATE OVERNIGHT
RELATIVE HUMIDITY RECOVERY IS ANTICIPATED THURSDAY NIGHT FOR
RIDGETOP, MID-SLOPE, AND SOME BASIN LOCATIONS. ABOVE-NORMAL
TEMPERATURES ARE FORECAST THIS WEEK AND INTO NEXT WEEK, AND
SIGNIFICANT PRECIPITATION IS UNLIKELY (90 PERCENT CONFIDENCE).
HYDROLOGY
THE NACHES RIVER IS FORECAST TO REMAIN NEAR (CLIFFDELL) OR
ABOVE (NACHES) ACTION STAGE THROUGH THE REMAINDER OF THE WEEK
AND INTO NEXT WEEK. SIGNIFICANT PRECIPITATION IS UNLIKELY (90
PERCENT CONFIDENCE) FOR THE NEXT WEEK.
PRELIMINARY POINT TEMPS/POPS
PDT 82 54 77 51 / 0 0 0 0
ALW 82 56 77 54 / 0 0 0 0
PSC 89 58 83 57 / 0 0 0 0
YKM 88 53 83 51 / 0 0 0 0
HRI 85 57 80 54 / 0 0 0 0
ELN 80 49 77 49 / 0 0 0 0
RDM 83 44 80 43 / 0 0 0 0
LGD 81 48 75 44 / 0 0 0 0
GCD 81 46 78 45 / 0 0 0 0
DLS 83 55 80 52 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM PDT THURSDAY
FOR WAZ024-026-521.
OR...WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM PDT THURSDAY
FOR ORZ041-044-507-508-510.
DISCUSSION...86
AVIATION...86
FIRE WEATHER...86
HYDROLOGY...86
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