283
FXUS66 KPDT 050412
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
912 PM PDT SAT JUL 4 2026
KEY MESSAGES
- CRITICAL FIRE WEATHER CONDITIONS STEMMING FROM LOW HUMIDITY
AND BREEZY WINDS TODAY ACROSS THE KITTITAS VALLEY AND OREGON
LOWER BASIN.
- ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS TUESDAY AND
WEDNESDAY.
- LOW THUNDERSTORM CHANCES IN THE CENTRAL OREGON MOUNTAINS
MONDAY SHIFTING TO THE EASTERN MOUNTAINS TUESDAY.
DISCUSSION
LATEST SATELLITE IMAGERY SHOWS CLEAR SKIES THOUGH SOME CU
APPARENT IN EAST CENTRAL OR WITH ERODING STRATUS WEST OF THE
CASCADES. WATER VAPOR SHOWS CYCLONIC FLOW ALOFT AT MID-LEVELS
WITH A WESTERLY MID-LEVEL JET CENTERED ROUGHLY ACROSS THE WA/BC
BORDER. A SHARPENING THERMAL LOW IS DEVELOPING IN THE COLUMBIA
BASIN/INTERIOR NW TODAY WHEREIN THE DEVELOPING CROSS-CASCADE
PRESSURE GRADIENT AND MODEST LOW-LEVEL WINDS ARE CONTRIBUTING TO
GUSTS COMMONLY 20-30 MPH ALONG GAPS OF THE CASCADES, EASTERN
GORGE SPILLING INTO THE LOWER OR BASIN, AND THE KITTITAS VALLEY.
THE LATTER SEEING THE HIGHEST GUSTS WITH GUSTS REACHING 40 MPH.
WINDS WILL LESSEN TONIGHT WITH LOSS OF SOLAR HEATING AND
COOLING. THE LARGE SCALE PATTERN WILL SEE A SIMILAR ZONAL
PATTERN TOMORROW AS TODAY, AND SIMILAR CONDITIONS WITH RESPECT
TO TEMPERATURES AND HUMIDITY WITH WEAK HEIGHT RISES OWING TO A
SHORTWAVE RIDGE WORKING INTO WA/BC. A LOWER SURFACE PRESSURE
GRADIENT WILL BE IN PLACE THOUGH, THUS LIMITED WEATHER CONCERNS
OVERALL WITH LIGHT WINDS EXPECTED AND HIGHS LARGELY 3-8 DEGREES
ABOVE AVERAGE FOR THIS TIME OF YEAR.
LOOKING AHEAD, AN UPPER-LEVEL CLOSED LOW WILL BE DEVELOPING
SOUTHWARD ACROSS THE GULF OF ALASKA PROMOTING LARGE-SCALE
TROUGHING IN THE NORTHERN EASTERN NORTH PACIFIC WITH ANOTHER
CLOSED LOW DEVELOPING NORTHEAST OF HAWAII. THIS WILL WORK TO
PROMPT A SOUTHWEST FLOW ALOFT WITH INCREASING 850 HPA
TEMPERATURES MOVING IN, AND INCREASING MOISTURE INTO SOUTHERN
AND EASTERN OR. THE LATEST ENSEMBLE GUIDANCE SHOWS PRECIPITABLE
WATERS AROUND 125-175% OF NORMAL IN PLACE BY MONDAY ACROSS THE
SOUTHERN-THIRD OF THE FORECAST AREA. THE COMBINATION OF
OROGRAPHIC LIFT AND LARGE SCALE ASCENT WITH THIS REINFORCING
MOISTURE AND MODERATE INSTABILITY (WITH DETERMINISTIC GUIDANCE
SHOWING 500-800 J/KG OF MUCAPES AND MLCAPES OF 400-600 J/KG)
WILL PROMOTE THUNDER CHANCES ACROSS THE CENTRAL OR MOUNTAINS
AND SOUTHERN EASTERN MOUNTAINS. THE WEAK FORCING REGIME AND
QUANTITY OF MOISTURE LOWERS THE OVERALL CONFIDENCE THOUGH WITH
PRESENT THUNDER CHANCES AROUND 10-20%, HIGHEST ACROSS SOUTHERN
DESCHUTES, CROOK, AND GRANT COUNTIES.
THIS MID-LEVEL TROUGH IS FORECAST TO BECOME MORE AMPLIFIED
TUESDAY WITH HIGHS 6-12 ABOVE AVERAGE UNDER THE SOUTHERLY FLOW
AND THE SHOWER/THUNDERSTORM THREAT SHIFTING MORE TO THE EASTERN
MOUNTAINS/BLUES AND WALLOWAS. HOWEVER, MOISTURE REMAINS A
CONCERN AND THE LACK THEREOF UNDER THE WEAK FORCING PATTERN
AGAIN. MEANTIME, SHARPENING PRESSURE DIFFERENCES WILL PROMPT
BREEZY WINDS UNDER HOT, DRY CONDITIONS ON TUESDAY WITH THE
UPPER-LEVEL TROUGHS MID-LEVEL JET SPREADING INTO THE REGION.
THIS WILL PROMOTE GUSTS 25-40 MPH ACROSS THE CASCADE GAPS,
KITTITAS VALLEY, AND THE EASTERN GORGE SPILLING INTO THE LOWER
BASIN. CHANCE FOR PEAK DAILY GUSTS EXCEEDING 30 MPH IS 70% OR
HIGHER ACROSS THESE AFOREMENTIONED AREAS; CHANCES FOR 40 MPH OR
HIGHER AROUND 50-90% LOCALIZED ACROSS THE KITTITAS VALLEY AND
PARTS OF THE EASTERN GORGE. THE UPPER TROUGHS ATTENDANT COLD
FRONT WILL THEN MOVE THROUGH EARLY WEDNESDAY PROMOTING WINDY
CONDITIONS AND HIGHS ABOUT 8-15 DEGREES COOLER THAN TUESDAY.
WHILE PRECIPITATION LOOKS LIMITED WITH MOSTLY DRY CONDITIONS
ANTICIPATED, HIGHER GUSTS ARE MORE LIKELY THAN TUESDAY WITH
30-45 MPH GUSTS FORECAST. THERE ARE BETTER CHANCES FOR AREAS
SEEING 40 MPH ACROSS THE LOWER BASIN AND NORTH CENTRAL OR
(50-60%) WEDNESDAY THAN TUESDAY. THE COMBINATION OF WINDY
CONDITIONS AND LOW HUMIDITIES WILL PROMPT POTENTIAL ELEVATED TO
CRITICAL FIRE WEATHER CONDITIONS TUESDAY AND WEDNESDAY.
INCREASING LARGE-SCALE TROUGHING IN THE EASTERN NORTH PACIFIC
LOOKS LIKELY THEN LATE THIS WEEK WITH CHANCES AROUND 70-80% FOR
THIS SCENARIO. THIS WILL PROMPT SIMILAR TO A SLIGHT RISE IN
HIGHS GOING INTO THE EARLY WEEKEND WITH NEAR-AVERAGE HIGHS
FORECAST WEDNESDAY-FRIDAY. OVERALL DRY CONDITIONS LOOK MORE
LIKELY THAN NOT WITH AN INCREASING CROSS-CASCADE GRADIENT
ALONGSIDE DIURNAL BREEZES ON FRIDAY AND SATURDAY.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
VISIBILITY AND CEILINGS ARE GREATER THAN 10 SM AND UNLIMITED
RESPECTIVELY OVER THE TAF PERIOD. LIGHT WINDS OVERNIGHT WILL
PICK UP MARGINALLY BREEZY OUT OF THE NORTH DURING THE AFTERNOON
SUNDAY.
FIRE WEATHER
CRITICAL FIRE WEATHER CONDITIONS ARE IN PLACE WITH LOW RH AND
GUSTY WINDS SEEN ACROSS KITTITAS VALLEY AND THE OR LOWER BASIN.
THE FORMER DIPPING DOWN TO AROUND 15% WITH GUSTS 30-40 MPH EARLY
THIS AFTERNOON WHILE THE LATTER HAS SEEN WINDS 15-20 MPH AND RH
10-15%. CONDITIONS WILL REMAIN FAVORABLE FOR RAPID FIRE SPREAD
INTO THE EVENING WITH A SHARP CROSS- CASCADE PRESSURE GRADIENT
EVOLVING THIS AFTERNOON. LOOKING AHEAD, WEAKER PRESSURE
DIFFERENCES ARE EXPECTED TOMORROW WITH LOW HUMIDITY AGAIN BUT
LIGHTER WINDS. THUS FIRE WEATHER CONCERNS ARE LOWER COMPARED TO
TODAY, AND THIS WILL CONTINUE MONDAY. THAT SAID, THERE ARE LOW
THUNDERSTORM CHANCES MONDAY ACROSS THE CENTRAL OR MOUNTAINS.
TUESDAY AND WEDNESDAY HOLD THE NEXT WEATHER CONCERNS WITH BROAD
TROUGHING IN THE EASTERN NORTH PACIFIC. THIS WILL PROMOTE HOT,
DRY, AND WINDY CONDITIONS WITH A SHARP CROSS-CASCADE GRADIENT
DEVELOPING WITH INCREASING WESTERLY FLOW. MAIN AREAS OF CONCERN
IS ACROSS CASCADE GAPS, EASTERN GORGE INTO NORTH CENTRAL OR,
KITTITAS VALLEY, AND SIMCOE HIGHLANDS. A COLD FRONT WILL CROSS
THE AREA THEN EARLY WEDNESDAY KNOCKING TEMPERATURES DOWN SOME
WITH HUMIDITY INCREASING AS MUCH AS 10% IN THE NORTH. HOWEVER,
MORE WIDESPREAD BREEZY CONDITIONS ARE EXPECTED WITH HIGHER-END
GUSTS MORE LIKELY ON WEDNESDAY.
PRELIMINARY POINT TEMPS/POPS
PDT 53 87 55 90 / 0 0 0 0
ALW 58 88 59 91 / 0 0 0 0
PSC 56 90 56 94 / 0 0 0 0
YKM 55 91 58 95 / 0 0 0 0
HRI 56 90 56 93 / 0 0 0 0
ELN 51 87 55 92 / 0 0 0 0
RDM 49 88 54 89 / 0 0 0 10
LGD 53 88 55 89 / 0 0 0 0
GCD 52 92 55 90 / 0 0 0 20
DLS 57 92 60 96 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...RED FLAG WARNING UNTIL 10 PM PDT THIS EVENING FOR ORZ691.
DISCUSSION...80
AVIATION...71
FIRE WEATHER...80
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