768
FXUS66 KPDT 012113
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
213 PM PDT TUE SEP 1 2026
KEY MESSAGES
- ISOLATED SHOWERS AND THUNDERSTORMS IN THE EASTERN MOUNTAINS
TODAY, WITH GREATER & MORE WIDESPREAD CHANCES WEDNESDAY AND
THURSDAY.
- BREEZY WINDS ACROSS THE REGION DEVELOP WITH THE PASSING
SYSTEM.
- TEMPERATURES COOL TOMORROW TO FALL LIKE LEVELS AND LAST
THROUGH AT LEAST THIS WEEK.
DISCUSSION
RADAR AND SATELLITE DEPICTS PRECIP AND CLOUD COVER SECLUDED TO
THE EASTERN MOUNTAIN REGIONS WITH LOW TO MODERATE SHOWERS
APPROACHING AT/NEAR THE JOSEPH AND ENTERPRISE AREA. A SLIGHT
CHANCE (UP TO 15%) OF A THUNDERSTORM OR TWO WILL DEVELOP WITH
LOW CAPE VALUES (100-150 J/KG) AND WEAK WIND SHEAR VALUES. AS
THE SHORTWAVE CONTINUES TO MOVE THROUGH THE AREA, POP'S WILL
INCREASE AS WE HEAD INTO THE EARLY MORNING HOURS THROUGH
THURSDAY.
WEDNESDAY: THE SHORTWAVE CONTINUES TO MOVE TOWARDS ONSHORE WITH
INCREASING SOUTH/SOUTHWESTERN FLOW THAT WILL CONTINUE MOISTURE
TRANSPORTATION. NBM CONTINUES TO ADVERTISE A MAXIMA AREA OF CAPE
DEVELOPING NEAR CROOK AND GRANT COUNTIES IN THE EARLY MORNING
HOURS AROUND SUNRISE. HIGHEST VALUES DEVELOP UP TO 100-150 J/KG
WITH WEAK WIND SHEAR, SO ANY STORMS ARE EXPECTED TO PULSING AND
NOT LAST A LONG TIME. WEATHER PATTERN APPEARS TO BE MORE
STRATIFORM THAN CONVECTIVE IN NATURE DUE TO THE LACK OF DAYTIME
HEATING AND IT BEING THE TIME OF THE YEAR WITH CONVECTION
SEASON DYING DOWN. ISOLATED THUNDERSTORM DEVELOPMENT IS MOSTLY
SITUATED ACROSS PARTS OF THE BLUE AND EASTERN MOUNTAINS (UP TO
15% CHANCES). POP'S ACROSS THE ENTIRE AREA INCREASE UP TO 70-90%
BY THE AFTERNOON HOURS, WITH IT BEING MOSTLY STRATIFORM WITH AN
OCCASIONAL THUNDERSTORM POSSIBLE NEAR THE SLOPES AND FOOTHILLS
OF MOUNTAINS (UP TO A 10% CHANCE). BREEZY WINDS WITH GUSTS UP TO
20 TO 30 MPH IS EXPECTED THROUGHOUT THE COLUMBIA BASIN AND
KITTITAS VALLEY, ESPECIALLY NEAR THE CASCADE GAPS WITH THIS
SYSTEM.
THURSDAY: THE PATTERN ON THURSDAY IS SIMILAR TO WEDNESDAY WET,
BREEZY PATTERN WITH PRECIPITATION CHANCES CONTINUING IN THE
40-70% PERCENT RANGE WITH HIGHER VALUES IN SOME OF THE MOUNTAIN
REGIONS. THE ONCOMING SHORTWAVE CONTINUES TO PUSH AT/NEAR THE
COAST. CAPE VALUES CONTINUE TO BE UNIMPRESSIVE WITH GUIDANCE
DEVELOPING UP TO 100-150 J/KG WITH WEAK WIND SHEAR. THIS
SUGGESTS AGAIN THAT ANY STORM DEVELOPMENT WILL NOT BE LONG LIVED
AND PULSATE THROUGHOUT THE DAY (70-90% CHANCE). THE COLUMBIA
BASIN COULD SEE QPF AMOUNTS UP TO A QUARTER OF AN INCH WITH
AMOUNTS UP TO .75 TO 1.0 INCHES IN THE MOUNTAIN REGIONS (60-80%
CHANCE). PARTS OF THE CASCADE AND WALLOWA CRESTS CAN SEE LOCALLY
HIGHER AMOUNTS OF UP TO 1.5" (50-70% CHANCE).
FRIDAY AND BEYOND: THINGS BECOME UNCERTAIN GOING INTO FRIDAY AND
BEYOND, AS CLUSTERS AND GUIDANCE START TO DIVERGE ON STRENGTH
AND TIMING OF THE WEATHER SYSTEM. BY FRIDAY, ABOUT 60% OF
SOLUTIONS KEEPS THE LOW CLOSED AND CONTINUE ON THE WETTER
PATTERN, WHILE THE OTHER 40% OPENS UP THE WAVE AND BRING DRIER
CONDITIONS ACROSS THE AREA. MODELS ARE STILL ALMOST EVENLY SPLIT
GOING THROUGH THE REST OF THE WEEKEND WITH 57% (CLUSTERS 1 AND
3) STILL SHOWING THE WETTER SOLUTION, WITH SOME TIMING ISSUES
BETWEEN CLUSTERS 1 AND 3. REGARDLESS, NO SIGNIFICANT IMPACTS ARE
CURRENTLY EXPECTED THROUGH SUNDAY (70-90% CHANCE) AND WE WILL
CONTINUE TO MONITOR THIS EVOLVING SYSTEM.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
VFR CONDITIONS CONTINUE THROUGH THE TAF PERIOD, BUT CONFIDENCE
IN STAYING VFR GOES DOWN AS WE HEAD INTO TOMORROW MORNING, AS A
WEATHER SYSTEM CONTINUES TO PUSH INTO THE AREA. BREEZY WINDS
THROUGH MOST OF THE SITES WITH PEAKS OCCURRING SOMETIME THIS
AFTERNOON INTO THE EVENING HOURS. RAIN CHANCES OF 15-30% START
ENTERING THE PICTURE AT 15Z AT ALW/PDT/PSC WITH NO ANTICIPATED
THUNDERSTORMS EXPECTED. WE'LL SEE THE SYSTEM START TO IMPACT
MOST/ALL TAF SITES WITH MODERATE TO HEAVY RAIN STARTING WITH THE
00Z TAFS, BUT FOR NOW WE CAPTURED THE TAIL END OF THE DRY
PERIOD WITH THE 18Z TAFS.
PRELIMINARY POINT TEMPS/POPS
PDT 48 75 45 68 / 10 50 80 40
ALW 54 76 50 69 / 10 50 90 50
PSC 56 79 50 73 / 0 30 60 30
YKM 55 75 50 70 / 0 30 50 30
HRI 55 77 50 71 / 10 40 60 30
ELN 49 71 44 66 / 10 30 60 40
RDM 43 65 40 63 / 10 80 90 40
LGD 48 73 47 66 / 30 70 90 80
GCD 48 73 46 65 / 10 60 100 70
DLS 57 72 53 69 / 0 80 90 60
PDT WATCHES/WARNINGS/ADVISORIES
WA...AIR QUALITY ALERT UNTIL 10 AM PDT WEDNESDAY FOR WAZ026-522-523.
OR...AIR QUALITY ALERT UNTIL NOON PDT WEDNESDAY FOR ORZ041-505-506-
509>511.
DISCUSSION...95
AVIATION...95
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page