434
FXUS66 KPDT 131159 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED AVIATION.
NATIONAL WEATHER SERVICE PENDLETON OR
459 AM PDT MON JUL 13 2026
KEY MESSAGES
- HIGHS TODAY FORECAST LARGELY 10-15 DEGREES WARMER THAN
YESTERDAY WITH ABOVE AVERAGE HIGHS BY GENERALLY 5-10 DEGREES
PREVAILING INTO MID-WEEK.
- CHANCES FOR ISOLATED TO WIDELY SCATTERED THUNDERSTORMS
ANTICIPATED TOMORROW ACROSS CENTRAL OR TO THE EASTERN
MOUNTAINS THEN INCLUDING NORTH CENTRAL OR AND SOUTH CENTRAL WA
WEDNESDAY.
- TYPICAL JULY DRYNESS WITH LOW AFTERNOON HUMIDITY TODAY AND
TOMORROW WITH LIGHT BREEZES PROMOTING LOCALLY ELEVATED FIRE
WEATHER CONDITIONS IN THE GORGE SPILLING INTO NORTH CENTRAL
OR.
- WARMER THAN AVERAGE TEMPERATURES MORE LIKELY THAN NOT THIS
UPCOMING WEEKEND INTO EARLY NEXT WEEK WITH LOW-END POTENTIAL
(5-20%) FOR THUNDERSTORMS ACROSS PORTIONS OF SOUTH CENTRAL WA
THURSDAY.
DISCUSSION
AMPLIFIED LARGE-SCALE PATTERN IN PLACE ACROSS THE
CONUS WITH YESTERDAY'S 00Z UPPER AIR PLOT SHOWING BROAD HIGH
PRESSURE CENTERED ACROSS THE NORTHERN HIGH PLAINS AND TROUGHING
ACROSS BC AND SOUTHEAST AK TO WELL OFFSHORE THE WEST COAST.
LATEST WATER VAPOR IMAGERY SHOWS A MID-LEVEL LOW OFFSHORE BAJA
CALIFORNIA NEAR 30 N -135 W AND A SHORTWAVE TROUGH WELL OFFSHORE
THE WA/OR BORDER THAT IS ROTATING EASTWARD. CONTINUED SOUTHERLY
FLOW PREVAILS WITH MONSOONAL MOISTURE BEING TAPPED INTO AS ITS
TRANSPORTED ACROSS CA INTO EASTERN OR. THIS IS CONTRIBUTING TO
HIGH CLOUDS STREAMING ACROSS EASTERN OR WITH LARGELY CLEAR
SKIES ACROSS MUCH OF CENTRAL OR AND SOUTH CENTRAL WA. LIMITED
SENSIBLE WEATHER CONCERNS TODAY WITH HIGHS REBOUNDING 10-15
DEGREES FROM YESTERDAY. MODEST CROSS-CASCADE SURFACE PRESSURE
GRADIENT WILL PROMOTE WESTERLY BREEZES SPILLING OUT OF THE
EASTERN GORGE AND CASCADE GAPS. LIMITED FIRE CONCERNS OWING TO
LIGHT WINDS THOUGH THEY WILL BE PAIRED WITH TYPICAL SEASONAL
DRYNESS FOR THIS TIME OF YEAR. WHILE VERY LOW-END CHANCES FOR
LIGHTNING/STORMS EXIST ACROSS THE CENTRAL OR MOUNTAINS TODAY
AND WALLOWA (5-15%), ACTIVITY IS EXPECTED TO BE WELL SOUTH OF
THE FORECAST AREA AND MORE TOWARDS THE OR/CA BORDER IF IT
MATERIALIZES.
LOOKING AHEAD, A DISTURBANCE ROTATING NORTHWARD FROM THE
AFOREMENTIONED MID-LEVEL LOW IN TANDEM WITH THIS STREAM OF
MONSOONAL MOISTURE WILL PROMOTE BETTER CHANCES FOR THUNDERSTORMS
ACROSS CENTRAL OR INTO THE EASTERN MOUNTAINS. DECENT SIGNAL
CAPTURED IN BOTH HREF AND REFS ENSEMBLE SYSTEMS THAT INCREASES
CONFIDENCE IN THIS THREAT. BOTH SYSTEMS SHOW A SIGNAL WITH
CHANCES EXCEEDING 30% FOR NEIGHBORHOOD PROBS FOR DBZ GREATER
THAN 40 DBZ WITH THE LATTER SHOWING HIGHER CHANCES ACROSS THE
EASTERN MOUNTAINS. BETTER SURFACE AND LOW-LEVEL MOISTURE
TUESDAY SHOULD SUPPORT MARGINAL INSTABILITY WITH MUCAPES
500-1000 J/KG AND MLCAPES 200-500 J/KG BASED ON DETERMINISTIC
GUIDANCE. LARGE SCALE FORCING FOR ASCENT WITH OROGRAPHIC LIFT
WILL PROMOTE ISOLATED-WIDELY SCATTERED COVERAGE. CHARACTER OF
STORMS SHOULD LEAN WET TO A WET/DRY MIX GIVEN PRECIPITABLE
WATERS 0.75-1.10” WITH ANOMALIES ~150-200% OF NORMAL BASED ON
THE EPS. HOWEVER, HIGH-BASES AND INVERTED-V PROFILES WILL
PROMOTE SOME DRY STORM RISK, ESPECIALLY AREAS OUTSIDE THE MAIN
RAIN CORES. A SIMILAR THREAT THEN PRESENTS ITSELF ON WEDNESDAY
WITH THE LIGHTNING CHANCES/THUNDERSTORM POTENTIAL SPREADING TO
ALSO INCLUDE NORTH CENTRAL OR AND SOUTH CENTRAL WA WEDNESDAY.
THERE IS INCREASED UNCERTAINTY IN THE LARGE-SCALE PATTERN
THURSDAY-FRIDAY AS IT RELATES TO THE EVOLUTION OF THE UPPER
TROUGH OFF THE WEST COAST. CLUSTERING GUIDANCE SHOW A SCENARIO
WITH AN EJECTING DISTURBANCE TRACKING ACROSS THE PACNW REGION
BRINGING MORE UNSETTLED WEATHER AND HIGHS MORE TYPICAL TO
SLIGHTLY ABOVE AVERAGE. THE OTHER LEADING SOLUTION IS A SCENARIO
WITH MEAN TROUGHING THAT IS MORE OFFSHORE AND OVER THE EASTERN
NORTH PACIFIC. THE EPS ENSEMBLE SYSTEM LEANS STRONGLY (70% OF
ITS ENSEMBLE MEMBERS) TOWARD THE FORMER OUTCOME WITH 50% OF THE
GRAND ENSEMBLE (EPS, GEFS, GEPS) ENCOMPASSING IT OVERALL. THE
LATTER SOLUTION WOULD LEAD TO A WARMER OUTCOME WITH THIS BEING
CAPTURED BY PROBABILISTIC HEATRISK. OF WHICH, THE BEST CHANCES
FOR MAJOR HEATRISK SEEN OVER THE NEXT 5 DAYS IS THURSDAY AND
FRIDAY WITH CHANCES 15-40%. THIS SITUATION WILL BEAR MONITORING
CONSIDERING THE LATTER OUTCOME WITH ITS HIGH-END POTENTIAL
WOULD SUPPORT MORE HEAT IMPACTS. FURTHER AHEAD, HIGHS ARE
CONTINUE TO BE FORECAST ABOVE NORMAL THIS WEEKEND INTO EARLY
NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
VFR CONDITIONS AREA-WIDE
WITH HIGH CLOUDS STREAMING ACROSS EASTERN OR INTO SOUTHEAST WA, SOME
SMOKE ALOFT IS AFFECTING CENTRAL OR TERMINALS. LARGELY LOW AVIATION
CONCERNS BEYOND SMOKE LAYERS ALOFT AFFECTING TERMINALS IN CENTRAL OR
AND AREAS NEAR WILDFIRES IN EASTERN OR. HIGH CLOUDS WILL CONTINUE TO
STREAM ACROSS THE AREA. MEANTIME, LIGHT BREEZES WITH OCCASIONAL
GUSTS IN CENTRAL OR AND IN THE EASTERN GORGE WITH GUSTS GREATER THAN
17 KTS, MAINLY AFTER 22 UTC. HIGHEST PEAK GUSTS THERE TODAY LIKELY
IN THE RANGE OF 20-25 KTS (CONFIDENCE >80%).
PRELIMINARY POINT TEMPS/POPS
PDT 92 61 93 63 / 0 0 10 20
ALW 94 66 95 66 / 0 0 10 10
PSC 95 62 97 64 / 0 0 0 10
YKM 95 60 98 64 / 0 0 0 10
HRI 95 64 96 67 / 0 0 0 10
ELN 90 58 94 62 / 0 0 0 0
RDM 93 55 92 56 / 0 0 10 20
LGD 94 62 92 62 / 0 0 10 40
GCD 94 61 92 59 / 0 10 20 40
DLS 94 62 96 66 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...80
AVIATION...80
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