178
FXUS66 KPDT 292347
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
447 PM PDT MON JUN 29 2026
KEY MESSAGES
- BREEZY AND BELOW NORMAL TEMPERATURES THROUGH MID-WEEK.
- WARMER AND DRIER TREND THURSDAY, PEAKING OVER THE WEEKEND.
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS VERY LIGHT AND
ISOLATED RETURNS ACROSS PORTIONS OF CENTRAL OREGON UNDER PARTLY
CLOUDY SKIES. THIS IS IN RESPONSE TO AN UPPER LEVEL LOW PRESSURE
CURRENTLY OVER MONTANA, THAT WILL CONTINUE TO DEPART TO THE
NORTHEAST AND INTO SOUTHERN MANITOBA OVER THE NEXT 24 HOURS. A
WEAK, TRANSIENT RIDGE OF HIGH PRESSURE IS BEGINNING TO BREAK UP
EARLIER CLOUD COVER THROUGH THE COLUMBIA BASIN, BUT AN INCOMING
SHORTWAVE WILL RETURN CLOUDS OVERNIGHT INTO TUESDAY. THESE
SYNOPTIC FEATURES HAVE ALSO ALLOWED A PRESSURE GRADIENT TO
DEVELOP ALONG THE CASCADES TO ATTRIBUTE TO BREEZY CONDITIONS
ACROSS THE COLUMBIA GORGE, EAST SLOPE OF THE CASCADES, LOWER
COLUMBIA BASIN, AND THE KITTITAS VALLEY. THE WEAK SHORTWAVE
STALLS ALONG THE COAST OVERNIGHT TONIGHT BEFORE SLOWLY PASSING
THROUGH THE AREA TUESDAY FOLLOWED BY A SECOND SHORTWAVE ON
WEDNESDAY. THE FIRST SHORTWAVE WILL ERODE THE BACKSIDE OF THE
TRANSIENT HIGH PRESSURE RIDGE, WHICH WILL PROVIDE ENOUGH
INSTABILITY FOR ISOLATED THUNDERSTORM DEVELOPMENT ACROSS THE
EAST AND SOUTH EDGES OF GRANT, UNION, AND WALLOWA COUNTIES.
ENOUGH MOISTURE SHOULD BE PRESENT IN ANY DEVELOPING STORM CELLS
TO PROVIDE WETTING RAIN AMOUNTS (>0.10"). WEDNESDAY'S SYSTEM IS
EXPECTED TO BE MUCH DRIER AS THE SHORTWAVE STAYS FURTHER NORTH
AND PASSES ALONG THE CANADIAN BORDER. THIS SHOULD ONLY LEAD TO
AN UPTICK IN CLOUD COVER AND AFTERNOON WINDS.
FLOW ALOFT TURNS FROM THE NORTHWEST TO MORE WESTERLY THURSDAY,
THEN MORE FROM THE SOUTHWEST FRIDAY INTO SATURDAY, WHICH
INITIATES A WARMING AND DRYING TREND THROUGH THE LATTER HALF OF
THE WEEK. BELOW NORMAL HIGH TEMPERATURES WILL BECOME NEAR TO
ABOVE NORMAL VALUES ON SATURDAY, WITH HIGHS BREAKING INTO THE
LOW TO MID-90S ACROSS PORTIONS OF THE LOWER COLUMBIA BASIN ON
SUNDAY. THESE HIGH TEMPERATURES, COUPLED WITH OVERNIGHT LOWS
ONLY DIPPING INTO THE MID-TO UPPER 50S, WILL ATTRIBUTE TO
ISOLATED POCKETS OF MODERATE HEATRISK ACROSS THE LOWER COLUMBIA
BASIN AND NORTHERN BLUE MOUNTAIN FOOTHILLS SUNDAY AND MONDAY.
HOWEVER, GUIDANCE IS NOT IN FULL AGREEMENT REGARDING HOW
ENHANCED THE SOUTHWEST FLOW ALOFT AND UPPER LEVEL RIDGE WILL BE
OVER THE WEEKEND. AT THIS TIME, 80% OF ENSEMBLE MEMBERS
ADVERTISE A SIMILAR OR SLIGHTLY COOLER OUTCOME. THE 20% WARMER
OUTCOME IS RATHER SUBSTANTIAL THOUGH, SUGGESTING SUNDAY'S HIGH
TEMPERATURE BEING 5 DEGREES WARMER THAN THE CURRENT FORECAST.
THIS MAY BE AN OUTLIER AS 27% OF ENSEMBLE MEMBERS WERE
SUGGESTING THIS WARMER OUTCOME JUST 24 HOURS AGO. FURTHER
ANALYSIS OF THIS TREND IS NECESSARY, WHICH MAY LEAD TO MORE
AREAS OF MODERATE HEATRISK SUNDAY. STAY TUNED. 75
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. WITH LACK OF PRECIP MOVING THROUGH
THE AREA, CIGS SHOULD GENERALLY REMAIN ABOVE 8KFT AGL AT ALL
SITES, AND BECOME MOSTLY SKC OR FEW TOMORROW. BREEZY WINDS WILL
CONTINUE TO IMPACT ALL SITES, WITH STRONGEST WINDS AT SITE DLS
(15-25KTS WITH GUSTS UP TO 35KTS). WINDS WILL BECOME LIGHT
OVERNIGHT AT ALL SITES EXCEPT AT DLS. WINDS WILL INCREASE TO
12-17KTS WITH GUSTS UP TO 25KTS AT SITES PDT/RDM/BDN/PSC LATE
TOMORROW MORNING THROUGH THE AFTERNOON. LAWHORN/82
FIRE WEATHER
MINIMAL FIRE WEATHER CONCERNS THIS WEEK AS EARLY WEEK WINDS WILL
BE ACCOMPANIED BY AFTERNOON HUMIDITIES BETWEEN 35-45% WITH
EXCELLENT OVERNIGHT HUMIDITY RECOVERIES OF 70-85%. THERE IS A
SLIGHT THREAT FOR ISOLATED THUNDERSTORMS ACROSS GRANT, UNION,
AND WALLOWA COUNTIES TUESDAY, BUT CHANCES ARE MINIMAL AS
COVERAGE IS CONFINED TO THE SOUTH AND EAST OF OR 693, 694, AND
695. MINIMUM HUMIDITIES TREND LOWER TOWARD THE END OF THE WEEK
AND THROUGH THE WEEKEND, BUT WINDS SHOULD STAY RATHER LIGHT AS
UPPER LEVEL RIDGING DEVELOPS. 75
PRELIMINARY POINT TEMPS/POPS
PDT 52 75 44 75 / 10 10 0 0
ALW 56 77 51 76 / 10 10 0 0
PSC 56 81 49 80 / 0 10 0 0
YKM 55 82 49 81 / 0 0 0 0
HRI 54 78 47 78 / 10 0 0 0
ELN 51 73 45 73 / 0 0 0 0
RDM 40 73 34 74 / 0 0 0 0
LGD 50 75 42 75 / 10 10 0 0
GCD 47 76 39 76 / 10 10 0 0
DLS 54 72 50 73 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL MIDNIGHT PDT TONIGHT FOR WAZ026.
OR...NONE.
DISCUSSION...75
AVIATION...82
FIRE WEATHER...75
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