525
FXUS66 KPDT 112229
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
329 PM PDT SAT JUL 11 2026
KEY MESSAGES
- ELEVATED FIRE WEATHER CONCERNS DUE TO BREEZY WINDS AND LOW
RELATIVE HUMIDITY ACROSS SOUTHERN PORTIONS OF THE BLUE
MOUNTAINS REGION TODAY
- INCREASING MONSOONAL MOISTURE EARLY AND MID-WEEK WILL LEAD TO
INCREASING (15-40%) CHANCES OF HIGH-BASED SHOWERS AND
PREDOMINANTLY DRY THUNDERSTORMS
- SIGNIFICANT UNCERTAINTY IN WIDESPREAD MODERATE (LEVEL 2 OF 4)
TO LOCALLY MAJOR (LEVEL 3 OF 4) HEATRISK BY MID/LATE WEEK
DISCUSSION
WATER VAPOR IMAGERY REVEALS A BROAD AREA OF HIGH PRESSURE
CENTERED OVER THE FOUR CORNERS REGION. MEANWHILE, A LOW-PRESSURE
SYSTEM IS CHURNING JUST OFFSHORE OF BRITISH COLUMBIA. THIS IS
PLACING THE PACIFIC NORTHWEST UNDER SOUTHWESTERLY FLOW WHICH IS
TRANSPORTING WEAK MONSOONAL MOISTURE INTO THE REGION FROM THE
SOUTHWEST, RESULTING IN INCREASING HIGH CLOUDS. HOT TEMPERATURES
ARE ALSO IN PLACE AT THE SURFACE, ESPECIALLY ACROSS THE EASTERN
HALF OF OUR FORECAST AREA. A HEAT ADVISORY REMAINS IN EFFECT FOR
HELLS CANYON BELOW 3000 FEET THROUGH SUNDAY EVENING WHERE
AFTERNOON HIGH TEMPERATURES OF 95-105 DEGREES ARE FORECAST.
TONIGHT, A SHORTWAVE VISIBLE OFFSHORE WILL ROUND THE BASE OF
THE LOW AND TRACK ACROSS WESTERN WASHINGTON INTO SUNDAY, BUT
LITTLE TO NO PRECIPITATION IS FORECAST TO ACCOMPANY THE WAVE
WITH ONLY A SLIGHT CHANCE (15-20%) OF PRECIPITATION FOR THE
WASHINGTON CASCADE CREST.
LOOKING AHEAD TO MONDAY, ENSEMBLE NWP GUIDANCE IS IN REASONABLY
GOOD AGREEMENT IN PATTERN DETAILS. BROADLY, THE HIGH THAT IS
CENTERED OVER THE FOUR CORNERS IS EXPECTED (95% CONFIDENCE) TO
EXPAND NORTHEASTWARD OVER THE GREAT PLAINS REGION, AND THE
DEVELOPMENT OF ADDITIONAL TROUGHING OFFSHORE IN THE PACIFIC
WILL KEEP SOUTHWESTERLY FLOW OVER THE PACIFIC NORTHWEST. THIS
WILL LEAD TO INCREASING PRECIPITABLE WATER (PWAT) VALUES IN THE
RANGE OF 100-200% OF NORMAL PER ENSEMBLE MEANS THROUGH MID-WEEK.
WHILE PWATS WILL BE HIGH ENOUGH TO SUPPORT WET THUNDERSTORMS,
QUICK STORM MOTIONS OF ROUGHLY 30-40 KTS COUPLED WITH DRY
BOUNDARY LAYER CONDITIONS WILL REDUCE THE CHANCE OF WETTING
RAINS. CURRENT PROBABILITIES OF PRECIPITATION (POP) RANGE FROM
15-40% FOR CENTRAL OREGON AND THE BLUE MOUNTAINS MONDAY
AFTERNOON THROUGH WEDNESDAY, WITH THE BEST CHANCES ON TUESDAY.
CHANCES OF THUNDERSTORMS ARE A BIT LOWER IN THE 10-25% RANGE.
CHANCES OF WETTING RAINS ARE EVEN LOWER.
TUESDAY THROUGH THE REMAINDER OF THE WEEK, CALIBRATED
PROBABILITIES FROM THE NATIONAL BLEND OF MODELS (NBM) INDICATE
LOW (5-40%) CHANCES OF AFTERNOON HIGH TEMPERATURES REACHING OR
EXCEEDING 100 DEGREES ACROSS MUCH OF THE LOWER ELEVATIONS.
MOREOVER, PROBABILITIES OF MAJOR (LEVEL 3 OF 4) HEATRISK ARE
ALSO LOW (5-40%). THIS LEVEL OF HEAT AFFECTS ANYONE WITHOUT
COOLING/HYDRATION.
SIGNIFICANT UNCERTAINTY IN DETAILS OF THE 500-HPA PATTERN
REMAINS FOR THURSDAY AS ENSEMBLE GUIDANCE IS STRUGGLING TO COME
TO A CONCENSUS ON THE EVOLUTION OF A CLOSED LOW WHICH MAY
(80-85% CHANCE PER 00Z ENSEMBLE CLUSTERS) TRACK INLAND SOMETIME
BETWEEN THURSDAY AND FRIDAY. THE ALTERNATIVE SCENARIO IS THAT
THE AREA OF LOW PRESSURE WILL REMAIN OFFSHORE AND A STRONG RIDGE
OF HIGH PRESSURE WILL BUILD OVER THE PACIFIC NORTHWEST AND
ROCKIES. THE FORMER SCENARIO WOULD PROVIDE SHOWER AND
THUNDERSTORM CHANCES ALONG WITH SOMEWHAT COOLER TEMPERATURES
WHILE THE LATTER SCENARIO WOULD LEAD TO DRY CONDITIONS AND HOT
TEMPERATURES.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
VFR CONDITIONS CONTINUE WITH MID TO HIGH LEVEL CLOUDS MOVING
INTO THE AREA WITH NO LOW CEILING CONCERNS EXPECTED. BREEZY
WINDS INITIATE AT DLS/PDT/RDM/BDN/YKM WITH GUSTS UP TO 20-30
KNOTS EXPECTED TO PERSIST THROUGH THE REST OF THE AFTERNOON
THROUGH THE EARLY EVENING IN SOME SPOTS (WITH THE DLS EXPECTING
TO LINGER LATER INTO THE EVENING AND EARLY MORNING HOURS).
OTHERWISE NO CIG OR VIS ISSUES EXPECTED.
FIRE WEATHER
ELEVATED FIRE WEATHER CONDITIONS WILL CONTINUE TODAY DUE TO
BREEZY WINDS AND LOW RELATIVE HUMIDITY (RH). THE HIGHEST CHANCES
OF OVERLAPPING WIND/LOW RH THRESHOLDS WILL BE CENTERED ACROSS
THE BLUE MOUNTAINS REGION, ESPECIALLY THE SOUTHERN BLUE
MOUNTAINS (OR698), SOUTHEAST PORTIONS OF THE CENTRAL MOUNTAINS
OF OREGON (OR700), AND THE JOHN DAY VALLEY (OR696) WHERE THERE
ARE WIDESPREAD 40-70% CHANCES (LOCALLY HIGHER) OF MEETING LOW-
END RED FLAG CRITERIA. HAVE HELD OFF ON ISSUING ANY HEADLINES
DUE TO MARGINAL CONFIDENCE. CHANCES OF REACHING LOW-END RED
FLAG CRITERIA ARE LOWER (20-40%) FARTHER NORTH IN THE COLUMBIA
BASIN REGION, PARTICULARLY IN AND AROUND THE YAKIMA VALLEY
(PORTIONS OF WA691, WA690, AND THE LOWER ELEVATIONS OF WA694).
LIGHTER WINDS WILL YIELD LIMITED CONCERNS SUNDAY, THOUGH THERE
IS STILL A LOW (10-30%) CHANCE OF MEETING WIND/RH THRESHOLDS
ACROSS PORTIONS OF OR698/OR700 DURING THE AFTERNOON HOURS.
INCREASING MONSOONAL MOISTURE IN THE EARLY TO MID-WEEK TIME
FRAME WILL FACILITATE INCREASING CHANCES OF HIGH-BASED SHOWERS
AND PREDOMINANTLY DRY THUNDERSTORMS. CHANCES OF MEASURABLE
PRECIPITATION PEAK TUESDAY AFTERNOON AT 15-40% ACROSS CENTRAL
OREGON AND THE BLUE MOUNTAINS. CONFIDENCE IS STILL LOW IN
FORECAST DETAILS, ESPECIALLY BY THURSDAY.
PRELIMINARY POINT TEMPS/POPS
PDT 56 83 56 90 / 0 0 0 0
ALW 61 84 60 92 / 0 0 0 0
PSC 60 87 57 93 / 0 0 0 0
YKM 58 87 56 94 / 0 0 0 0
HRI 59 86 58 93 / 0 0 0 0
ELN 53 81 52 90 / 0 0 0 0
RDM 51 86 52 91 / 0 0 0 0
LGD 57 87 57 92 / 0 0 0 0
GCD 56 91 58 92 / 0 0 0 10
DLS 59 87 59 94 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...HEAT ADVISORY UNTIL 7 PM PDT SUNDAY FOR ORZ050.
DISCUSSION...86
AVIATION...95
FIRE WEATHER...86
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