663
FXUS66 KPDT 301726
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1026 AM PDT MON JUN 30 2025
UPDATED AVIATION DISCUSSION
AVIATION...18Z TAFS
VFR CONDITIONS EXPECTED. SKIES WILL REMAIN
CLEAR DURING THE DAY WITH LIGHT, TERRAIN-DRIVEN WINDS LESS THAN 12
KTS, EXCEPT FOR SOME GUSTS UP TO 20 KTS FOR BDN AND RDM. MID
CLOUDS SCT-BKN WILL THEN BUILD IN LATE THIS EVENING AND OVERNIGHT
FOR BDN AND RDM, SPREADING TO ALL OTHER SITES BY DAYBREAK
TUESDAY. EVANS/74
PREV DISCUSSION... /ISSUED 146 PM PDT SUN JUN 29 2025/
SHORT TERM...TODAY THROUGH TUESDAY NIGHT...QUIET WEATHER IS
FORECAST FOR THE REMAINDER OF TODAY, TONIGHT, AND MUCH OF MONDAY
AS AN UPPER-LEVEL RIDGE OF HIGH PRESSURE BUILDS INTO THE PACIFIC
NORTHWEST. THE RIDGE WILL FACILITATE LIGHT OFFSHORE FLOW INTO
MONDAY, AND MORE NOTABLY, WARMING TEMPERATURES.
ENSEMBLE NWP IS VERY CONFIDENT (95% OR GREATER) THAT THE
AFOREMENTIONED UPPER-LEVEL RIDGE WILL AMPLIFY THROUGH MONDAY AND
REMAIN IN PLACE THROUGH TUESDAY, LEADING TO HOT CONDITIONS.
MEANWHILE, AN UPPER-LEVEL CLOSED LOW WILL CONTINUE TO DEVELOP OFF
THE CENTRAL CALIFORNIA COAST, SETTING THE STAGE FOR CONVECTION IN
SOUTHERN/EASTERN OREGON MONDAY AND TUESDAY.
CAMS SUGGEST THE BULK OF THE CONVECTIVE ACTIVITY MONDAY WILL BE
ACROSS SOUTH-CENTRAL OREGON WITH LIMITED EXTENSION NORTHWARD INTO
CENTRAL OREGON, PERHAPS DUE TO WEAK FORCING ALOFT. THAT SAID,
HAVE MAINTAINED A SLIGHT CHANCE (15%) OF THUNDERSTORMS IN THE
FORECAST FOR THE EAST SLOPES OF THE OREGON CASCADES IN DESCHUTES
COUNTY AND ALSO FOR AREAS EAST INTO THE OCHOCOS-JOHN DAY
HIGHLANDS. CONFIDENCE IS LOW (<50%) THAT THUNDER WILL ACCOMPANY
ISOLATED TO SCATTERED SHOWERS IN CENTRAL AND EASTERN OREGON
MONDAY NIGHT, SO HAVE OMITTED MENTION IN THE FORECAST. SHOULD
MENTION THAT, DUE TO AMPLE FORECAST DCAPE OF 1000-1500 J/KG PER
HREF AND REFS SOUNDINGS, CONVECTIVE OUTFLOW HAS THE POTENTIAL TO
GENERATE GUSTS IN EXCESS OF 50 MPH IN CENTRAL OREGON MONDAY
AFTERNOON, AND THE SPC HAS A MARGINAL (LEVEL 1 OF 5) RISK OF
SEVERE THUNDERSTORMS PLACED JUST SOUTH OF DESCHUTES COUNTY.
CONVECTIVE POTENTIAL LOOKS BETTER TUESDAY ACROSS THE BLUE
MOUNTAINS REGION WHERE A SLIGHT CHANCE (15-24%) TO CHANCE
(25-30%) OF SHOWERS AND THUNDERSTORMS HAS BEEN INCLUDED DUE TO THE
COMBINATION OF SUFFICIENT MID-LEVEL MOISTURE, INSTABILITY, AND
MODEST UPPER-LEVEL FORCING.
ANTICIPATED WARMING UNDER THE UPPER-LEVEL RIDGE HAS PROMPTED THE
ISSUANCE OF HEAT ADVISORIES FOR MOST OF OUR LOWER-ELEVATION AREAS
ACROSS NORTHERN OREGON AND SOUTH-CENTRAL WASHINGTON FOR MONDAY
THROUGH TUESDAY. WIDESPREAD MODERATE (LEVEL 2 OF 4) TO MAJOR
(LEVEL 3 OF 4) HEATRISK IS ON TAP DUE TO FORECAST HIGH
TEMPERATURES OF 91-103 DEGREES AND OVERNIGHT LOW TEMPERATURES OF
61-73 DEGREES. WILL NOTE THERE IS SOME UNCERTAINTY IN HIGH AND LOW
TEMPERATURES TUESDAY AND WEDNESDAY DUE TO POTENTIAL CLOUD COVER
-- CONVECTIVE DEBRIS OR OTHERWISE. PLUNKETT/86
LONG TERM...WEDNESDAY THROUGH SATURDAY...WEDNESDAY THROUGH
FRIDAY, ANALYSIS OF ENSEMBLE CLUSTERS INDICATES THERE IS MORE
UNCERTAINTY (TIMING AND AMPLITUDE OF 500-HPA HEIGHTS) IN PATTERN
DETAILS, BUT GUIDANCE IS STRONGLY SUGGESTING ONE OR MORE
SHORTWAVES EMBEDDED WITHIN BROADLY SOUTHWESTERLY FLOW ALOFT. THIS
PATTERN FAVORS SHOWERS AND THUNDERSTORMS FOR THE BLUE MOUNTAINS
REGION, SO HAVE ADDED A SLIGHT CHANCE (15%) OF THUNDER EACH
AFTERNOON.
OTHERWISE, BREEZY TO WINDY WESTERLY WINDS ARE FAVORED THROUGH THE
CASCADE GAPS WEDNESDAY THROUGH THURSDAY. CONFIDENCE IN SURFACE
MOISTURE (DEW POINT AND RELATIVE HUMIDITY) IS STILL LOW (<30%) DUE
TO AFOREMENTIONED UNCERTAINTY IN PATTERN DETAILS SO WILL HOLD OFF
ON MENTIONING POTENTIAL FOR ANY FIRE WEATHER HIGHLIGHTS.
PLUNKETT/86
PRELIMINARY POINT TEMPS/POPS
PDT 98 64 100 67 / 0 0 0 20
ALW 97 68 99 70 / 0 0 0 10
PSC 99 64 102 66 / 0 0 0 10
YKM 97 65 100 65 / 0 0 0 0
HRI 99 64 102 68 / 0 0 0 10
ELN 95 63 96 65 / 0 0 0 0
RDM 95 60 94 54 / 0 20 10 20
LGD 94 59 96 64 / 0 0 0 20
GCD 97 61 96 61 / 0 10 10 30
DLS 101 68 96 66 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...HEAT ADVISORY UNTIL 9 PM PDT TUESDAY FOR ORZ041-044-507-508-510.
WA...HEAT ADVISORY UNTIL 9 PM PDT TUESDAY FOR WAZ024-026>029-521.
SHORT TERM...86
LONG TERM....86
AVIATION...74
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