136
FXUS66 KPDT 282135
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
235 PM PDT MON SEP 28 2026
KEY MESSAGES
- LIGHT TO MODERATE RAIN SHOWERS (70-90% CHANCE) ALONG THE
CASCADE MOUNTAINS ON THE WASHINGTON SIDE, WITH LIGHTER AMOUNTS
ALONG THE NORTHERN BLUE MOUNTAINS.
- BREEZY WINDS DEVELOP ACROSS THE CASCADE GAPS AND OTHER PARTS
OF THE BASIN.
- TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGHOUT
THE WEEK.
DISCUSSION
VERY LITTLE ACTIVITY WITH SATELLITE AND RADAR CURRENTLY AS ZONAL
FLOW CURRENTLY DOMINANTS ALOFT. OVERNIGHT FREEZING WAS PRESENT
IN PARTS OF CENTRAL OREGON AND THE WALLOWA'S, WE MAY SEE A
SECOND ROUND OF SOME FREEZING ALTHOUGH CONFIDENCE IS LOWER THIS
TIME AROUND (10-20% CHANCE) AS WINDS ARE STRONGER TONIGHT
COMPARED TO LAST NIGHT. GIVEN THAT, I'M NOT EXPECTING FREEZING
TEMPERATURES, IF ANY, WILL LAST ENOUGH TO WARRANT FREEZE
WARNINGS TONIGHT.
OUR NEXT WEATHER MAKER AND COLD FRONTAL SYSTEM IS AROUND THE
CORNER, BUT WILL MOSTLY IMPACT THE MOUNTAIN REGIONS AND PARTS OF
THE FOOTHILLS OF THE BLUES TO A LESSER EXTENT. A
TROUGH/SHORTWAVE LOCATED IN THE PACIFIC AND BRITISH COLOMBIA
WILL MOVE ALONG THE AREA, BRINGING LIGHT TO MODERATE RAIN
SHOWERS IN THE WASHINGTON CASCADES (70-90% CHANCE), NORTHERN
BLUE MOUNTAINS (20-40% CHANCE), AND PARTS OF THE FOOTHILLS OF
THE BLUES (UP TO 20% CHANCE). GUIDANCE MAKES IT PRETTY CLEAR
THAT PARTS OF THE CASCADE REGION NEAR SNOQUALMIE (AND THE THREE
QUEENS FIRE) WILL SEE WETTING RAINS DEVELOP OVER THE 24-48
HOURS. IT'S KEYED IN THAT REGION WILL SEE AT LEAST A TENTH OF AN
INCH OF RAIN (>90% CHANCE), WHILE SEEING A QUARTER OF AN INCH IS
ALSO VERY LIKELY (75-85% CHANCE). CURRENT NBM GUIDANCE
ADVERTISES NEARLY AN INCH CLOSE TO SNOQUALMIE PASS WHILE IT
QUICKLY DROPS OFF THE FURTHER AWAY FROM THE PEAKS YOU ARE. THE
SECONDARY MAXIMUM OF QPF IS LOCATED IN THE NORTHERN BLUE
MOUNTAINS WITH ONLY UP TO A TENTH OF AN INCH ADVERTISED (50-70%
CHANCE). WHILE SNOQUALMIE COULD GET UP TO AN INCH, IT'S
UNLIKELY WE'LL SEE ANY WIDESPREAD FLOODING (EVEN ON BURN SCARS)
HAPPENING, ALTHOUGH THE CHANCE FOR LOCALIZED FLOODING IN FLOOD
PRONE AREAS IS NOT OUT OF THE QUESTION. THE FRONT WILL ALSO
INCREASE PG'S ACROSS THE AREA, DEVELOPING BREEZY TO LOCALLY
WINDY CONDITIONS ACROSS THE AREA (ESPECIALLY NEAR THE GAPS AND
PARTS OF THE BASIN). WIND GUSTS IN THE STRONGEST AREAS COULD
REACH 30-40 MPH (50-70% CHANCE).
CLUSTERS STRUGGLE A BIT TRYING TO HANDLE THE STRENGTH OF ZONAL
FLOW AHEAD OF A RIDGE PUSHING ONSHORE. ABOUT 29% OF CLUSTERS
WANT TO KEEP THE ZONAL FLOW ABOVE THE AREA, BRINGING ADDITIONAL
LIGHT TO MODERATE MOUNTAIN SHOWERS. SOMETHING TO MONITOR, BUT
NO BIG IMPACTS ARE EXPECTED FROM THIS SET-UP WITH ANY QPF'S
FALLING SHOULD BE LIGHT TO MODERATE (80-90% CHANCE). GUIDANCE
PAINTS THE END OF THIS WEEK THROUGH NEXT WEEK AS A RIDGE
AMPLIFYING OVER THE PACNW, BRINGING DRY AND WARM CONDITIONS.
SOMETHING TO KEEP AN EYE OUT FIRE WEATHER WISE, BUT ANY IMPACTS
ON RH'S AND/OR WINDS IS A BIT TOO FAR OUT TO MAKE ANY
CONCLUSIONS.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
VFR CONDITIONS PREVAIL WITH DRY AND MOSTLY CLEAR CONDITIONS
THROUGH THE FORECAST PERIOD. WINDS WILL BE A BIT ELEVATED IN THE
7 TO 12 KNOT RANGE, WITH BREEZIER CONDITIONS DEVELOPING IN THE
DLS BY THE AFTERNOON. OTHERWISE, NO CIG OR VIS ISSUES EXPECTED.
PRELIMINARY POINT TEMPS/POPS
PDT 45 75 49 72 / 0 0 0 0
ALW 52 75 54 73 / 0 0 10 0
PSC 47 78 50 75 / 0 0 0 0
YKM 48 74 49 71 / 0 10 0 0
HRI 49 77 51 75 / 0 0 0 0
ELN 45 66 46 66 / 0 20 20 0
RDM 37 75 39 74 / 0 0 0 0
LGD 41 75 46 71 / 0 0 10 10
GCD 40 75 43 74 / 0 0 0 0
DLS 50 73 54 76 / 0 0 10 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...95
AVIATION...95
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