390
FXUS66 KPDT 032117
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
217 PM PDT FRI JUL 3 2026
KEY MESSAGES
- CRITICAL FIRE WEATHER CONDITIONS IN THE OR COLUMBIA BASIN,
LOCALLY ELSEWHERE, SATURDAY AFTERNOON
- WARM TEMPERATURES AND DRY CONDITIONS IN THE LOWER ELEVATIONS,
ISOLATED THUNDERSTORMS IN THE EASTERN MOUNTAINS SUNDAY THROUGH
TUESDAY
- ANOTHER ROUND OF ELEVATED FIRE WEATHER CONDITIONS TUESDAY AND
WEDNESDAY WITH RETURN OF BREEZY WESTERLY WINDS
DISCUSSION
TODAY THROUGH SATURDAY: SATELLITE IMAGERY THIS
AFTERNOON SHOWS VERY LITTLE IN ACTIVITY ACROSS THE FORECAST
AREA. CURRENTLY, BROAD TROUGHING ACROSS WESTERN CANADA IS
PLACING THE PACNW UNDER A DRY ZONAL FLOW ALOFT. WHILE CONDITIONS
ARE MOSTLY QUIET, BREEZY WINDS HAVE DEVELOPED THROUGHOUT THE
MORNING AND AFTERNOON THROUGH THE CASCADE GAPS, OWING TO A
MARINE LAYER ACROSS WESTERN WA AND NORTHWEST OR.
BY TOMORROW AFTERNOON, A SHORTWAVE TROUGH PASSING THROUGH
SOUTHERN BC WILL CLIP THE PACNW, PRODUCING BREEZY WINDS THROUGH
THE CASCADE GAPS AND INTO THE OR COLUMBIA BASIN, WITH LOCALLY
BREEZY WINDS ELSEWHERE. MEANWHILE, WITH LACK OF PRECIPITATION,
AND ANY MOISTURE FOR THAT MATTER, AFTERNOON RELATIVE HUMIDITIES
HAVE BEEN ON A DOWNWARD TREND THE LAST SEVERAL DAYS. THIS TREND
WILL RESULT IN WIDESPREAD RHS INTO THE TEENS AND LOW 20S
TOMORROW AFTERNOON. THE BREEZY WEST WINDS AND LOW RHS WILL
OVERLAP IN THE OR COLUMBIA BASIN TOMORROW, RESULTING IN CRITICAL
FIRE WEATHER CONDITIONS THROUGHOUT THE DAY. LOCALIZED AREAS OF
THE YAKIMA/KITTITAS VALLEY, WARM SPRINGS RESERVATION, AND
HANFORD WILL ALSO SEE A CHANCE (20-45%) OF CRITICAL FIRE
WEATHER CONDITIONS SATURDAY AFTERNOON.
SUNDAY THROUGH TUESDAY: GOOD AGREEMENT AMONGST ENSEMBLE CLUSTER
SOLUTIONS THAT THE FOUR CORNERS HIGH WILL DEVELOP WITH BROADER
UPPER LEVEL RIDGING DEVELOPING ALONG THE ROCKIES. MEANWHILE, A
CLOSED LOW IN THE GULF OF ALASKA WILL SLOWLY PUSH SOUTH, WITH
SHORTWAVES ROUNDING THE LOW AND REINFORCING AN UPPER TROUGH
OFFSHORE THE PACNW. THE PACNW WILL SIT UNDERNEATH A SOUTHWEST
FLOW ALOFT THAT WILL DEVELOP BETWEEN THOSE TWO FEATURES,
RESULTING IN A WARMING TREND THAT WILL BRING BACK WIDESPREAD 90
DEGREE TEMPERATURES IN THE LOWER ELEVATIONS, LIGHT WINDS THROUGH
THE CASCADE GAPS AND LOWER ELEVATIONS, AND MOSTLY DRY
CONDITIONS (CONFIDENCE 60-75%).
HOWEVER, ISOLATED THUNDERSTORM CHANCES WILL INCREASE AS
SHORTWAVE IMPULSES RIDE UP THE SOUTHWEST FLOW SUNDAY THROUGH
TUESDAY. THE DEVELOPMENT OF THE FOUR CORNERS HIGH WILL BRING
INCREASED SURFACE MOISTURE INTO PORTIONS OF CENTRAL OR AND THE
EASTERN MOUNTAINS, RESULTING IN AT LEAST LIGHT RAIN CORES (0.05
TO 0.1 INCHES) TO DEVELOP WITHIN ANY DEVELOPING THUNDERSTORM
(CONFIDENCE 45-60%). THAT SAID, WITH DRYING CONDITIONS AND
FUELS, THE THREAT OF THUNDERSTORM DEVELOPMENT WILL STILL RESULT
IN ELEVATED FIRE WEATHER CONDITIONS. THE SOUTHWEST FLOW AND
RIDGING ALOFT WILL ALSO BRING INCREASED SURFACE INSTABILITY WITH
MODEST LOW TO MID LEVEL LAPSE RATES, SUPPORTING INITIAL
DEVELOPMENT OF THUNDERSTORMS. LASTLY, LOW TO MID LEVEL SHEAR
WILL BE ENOUGH (20-30KTS) TO HELP MAINTAIN THUNDERSTORMS THAT DO
DEVELOP DURING THIS PERIOD.
TUESDAY, UPPER LEVEL TROUGHING OFFSHORE WILL BEGIN TO MOVE
INLAND (CONFIDENCE 60-75%), PRODUCING BREEZY WINDS THROUGH THE
CASCADE GAPS AND INTO PORTIONS OF THE COLUMBIA BASIN TUESDAY
AFTERNOON. CONFIDENCE IS MOD-HIGH (60-80%) THAT CRITICAL FIRE
WEATHER CONDITIONS WILL DEVELOP ACROSS THE OR COLUMBIA BASIN,
KITTITAS/YAKIMA VALLEYS, AND PORTIONS OF NORTH CENTRAL OR.
WEDNESDAY AND THURSDAY: BREEZY TO LOCALLY GUSTY WINDS WILL
REMAIN THE CONCERN THROUGH THE MIDDLE OF THE WEEK AS ENSEMBLE
CLUSTER GUIDANCE SHOWS THE SHORTWAVE TROUGH PASSING OVER THE
PACNW WEDNESDAY, WITH ZONAL FLOW DEVELOPING IN IT'S WAKE FOR
THURSDAY. (CONFIDENCE 45-60%) OVERALL, CONDITIONS WILL REMAIN
DRY ACROSS THE FORECAST AREA, WITH TEMPERATURES DROPPING BACK TO
NEAR NORMAL (MID TO UPPER 80S) IN THE LOWER ELEVATIONS
(CONFIDENCE 45-50%). LAWHORN/82
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
VFR CONDITIONS
ACCOMPANIED BY DIURNALLY AND/OR TERRAIN-DRIVEN WINDS ARE
FORECAST THROUGH THE PERIOD. WINDS WILL BE BREEZY DURING THE
AFTERNOON AND EVENING HOURS, STRONGEST AT DLS.
FIRE WEATHER
BREEZY WINDS WILL CONTINUE THROUGH SATURDAY,
WHILE A LOW RH TREND WILL CONTINUE THROUGH THE WEEK. STRONG
WINDS AND LOW RH OVERLAPPING SATURDAY WILL BRING CRITICAL FIRE
WEATHER CONDITIONS IN OR COLUMBIA BASIN AND LOCALIZED AREAS
ALONG THE CASCADE EAST SLOPES AND GAPS. BREEZY DIURNAL WINDS
RETURN TUESDAY, WITH ELEVATED FIRE WEATHER CONDITIONS THROUGH
THE MID WEEK. ISOLATED TO WIDELY SCATTERED THUNDERSTORM CHANCES
INCREASE SUNDAY THROUGH TUESDAY.
PRELIMINARY POINT TEMPS/POPS
PDT 54 88 52 86 / 0 0 0 0
ALW 60 89 58 88 / 0 0 0 0
PSC 57 92 55 90 / 0 0 0 0
YKM 56 91 54 90 / 0 0 0 0
HRI 58 91 56 89 / 0 0 0 0
ELN 53 83 51 86 / 0 0 0 0
RDM 48 88 49 89 / 0 0 0 0
LGD 53 88 53 88 / 0 0 0 0
GCD 51 92 52 92 / 0 0 0 0
DLS 57 87 56 92 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...OR...RED FLAG WARNING FROM NOON TO 10 PM PDT SATURDAY FOR ORZ691.
DISCUSSION...82
AVIATION...86
FIRE WEATHER...82
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