591
FXUS66 KPDT 130946
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
246 AM PDT THU AUG 13 2026
KEY MESSAGES
- RED FLAG WARNINGS IN EFFECT FOR ABUNDANT LIGHTNING TODAY INTO
FRIDAY MORNING.
- A CONVECTIVE WEATHER PATTERN WILL CONTINUE THROUGH AT LEAST
SATURDAY WITH DAILY SHOWER AND THUNDERSTORM CHANCES. MORE
UNCERTAINTY IN PATTERN DETAILS SUNDAY INTO NEXT WEEK.
- NEAR-SEASONAL TEMPERATURES THROUGH THE WEEK.
DISCUSSION
WATER VAPOR IMAGERY REVEALS A SHORTWAVE TROUGH OVER THE PACIFIC
NORTHWEST, WITH AN EMBEDDED CIRCULATION NOTED OVER NORTHEAST
WASHINGTON. FORCING ASSOCIATED WITH THE AFOREMENTIONED
CIRCULATION HAS LIKELY BEEN THE CATALYST FOR CONVECTION THAT
DEVELOPED YESTERDAY AFTERNOON ACROSS THE WASHINGTON CASCADES AND
REMAINS ONGOING NORTHEAST OF OUR FORECAST AREA. MEANWHILE, THE
BLUE MOUNTAINS REMAIN BENEATH THE ENTRANCE REGION TO A SUBTLE
MID/UPPER JET. COUPLED WITH MODEST VORTICITY ADVECTION AND MID-
LEVEL MOISTURE, SOME WEAK SHOWERS ARE DEVELOPING EARLY THIS
MORNING. NOT ANTICIPATING ANY ROBUST CONVECTION, BUT
OBSERVATIONS ARE CONSISTENT WITH WHAT NWP GUIDANCE HAS BEEN
ADVERTISING: MODEST SYNOPTIC-SCALE FORCING COUPLED WITH
SUFFICIENT MID-LEVEL (700-500 HPA) MOISTURE AND NEGATIVE MID-
LEVEL (700-500 HPA) THETA-E LAPSE RATES TYPICALLY FACILITATE
SOME WEAK NOCTURNAL CONVECTION (PREDOMINANTLY SHOWERS WITH
ISOLATED EMBEDDED THUNDERSTORMS).
THE CIRCULATION MENTIONED ABOVE WILL THEN EXIT TO THE NORTHEAST
INTO THE NORTHERN ROCKIES THROUGH THE DAY, BUT A SECOND
VORTICITY LOBE IS EXPECTED TO DIVE SOUTHEAST INTO THE PACIFIC
NORTHWEST TODAY, REINFORCING THE SHORTWAVE TROUGH. ADDITIONAL
CONVECTION IS EXPECTED (95 PERCENT CONFIDENCE) TO DEVELOP THIS
AFTERNOON ACROSS THE MOUNTAINS, AND THE PREVIOUS DAY SHIFT
ISSUED RED FLAG WARNINGS FOR MULTIPLE FIRE WEATHER ZONES IN
OREGON DUE TO FORECAST SCATTERED THUNDERSTORMS AND ABUNDANT
LIGHTNING. NOTE THAT THE WARNINGS FOR MUCH OF THE BLUE MOUNTAINS
CONTINUE THURSDAY NIGHT FOR NOCTURNAL CONVECTION.
LOOKING AHEAD, ENSEMBLE NWP GUIDANCE SUGGESTS CONTINUED
SOUTHWEST FLOW ALOFT AND ADDITIONAL REINFORCING SHORTWAVES
THROUGH AT LEAST SATURDAY. THIS WILL KEEP A CONVECTIVE PATTERN
IN PLACE RESULTING IN DAILY SHOWER AND THUNDERSTORM CHANCES,
MAINLY OVER THE MOUNTAINS. ADDITIONAL FIRE WEATHER WATCHES OR
RED FLAG WARNINGS MAY BE NEEDED IF CONFIDENCE IN ABUNDANT
LIGHTNING INCREASES FOR FRIDAY AFTERNOON OR OVER THE WEEKEND.
SUNDAY INTO NEXT WEEK, UNCERTAINTY IN PATTERN DETAILS BURGEONS
DUE TO MODEL DIFFERENCES IN THE DEVELOPMENT AND EVOLUTION OF A
DEEP CLOSED LOW IN THE PACIFIC. ENSEMBLE CLUSTER ANALYSIS
INDICATES CONCENSUS THAT THE LOW WILL DEVELOP, BUT ROUGHLY EQUAL
CHANCES (40-60 PERCENT) OF EITHER THE DEEP CLOSED LOW REMAINING
WELL OFFSHORE INTO THE MIDDLE OF NEXT WEEK OR A SOMEWHAT MORE
PROGRESSIVE PATTERN WITH A WEAKER OPEN WAVE TROUGH OVER THE
PACIFIC NORTHWEST IN ADDITION TO A WEAKER OFFSHORE LOW. EITHER
SOLUTION PUTS THE FORECAST AREA UNDER A PATTERN THAT IS
FAVORABLE FOR SOME PERIODS OF CONVECTION, BUT CHANCES OF
CONVECTION HAVE TRENDED DOWNWARD SINCE YESTERDAY'S DISCUSSION
FOR SUNDAY INTO EARLY NEXT WEEK. BROADLY, STILL HAVE 10-25%
CHANCES OF PRECIPITATION FOR THE MOUNTAINS WITH LOWER CHANCES
FOR NON-MOUNTAIN AREAS.
LASTLY, AIR QUALITY ALERTS/ADVISORIES ISSUED BY AIR QUALITY
AGENCIES REMAIN IN EFFECT FOR THE MAJORITY OF OUR FORECAST AREA
DUE TO WILDFIRE SMOKE FROM ONGOING REGIONAL WILDFIRES.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
VFR CONDITIONS PREVAIL WITH MORE ELEVATED SMOKE IN SOME AREAS.
COUPLE OF TAF SITES ARE ON THE BORDERLINE WITH VISIBILITIES DOWN
TO 6 MILES. MAY SEE SOME MVFR CONDITIONS DEVELOP BUT NOT IN A
PROLONGED WAY. MAY SEE SOME SMOKE SETTLE DOWN TO THE SURFACE
OVERNIGHT, BUT CHANCES OF THAT HAPPENING ARE SMALL AT 5 TO 15
PERCENT. NO BREEZY WINDS ANTICIPATED WITH MOST SUSTAINED WINDS
AT LESS THAN 12 KNOTS WITH MOST GUSTS NOT EXCEEDING 20 KNOTS.
PRELIMINARY POINT TEMPS/POPS
PDT 85 54 87 57 / 0 0 0 0
ALW 87 59 88 62 / 0 0 0 0
PSC 89 58 90 58 / 0 0 0 0
YKM 88 61 88 59 / 0 10 10 0
HRI 88 59 90 60 / 0 0 0 0
ELN 83 57 82 56 / 10 20 30 0
RDM 84 49 85 49 / 0 10 10 10
LGD 86 55 86 55 / 0 30 30 10
GCD 87 54 86 54 / 10 60 40 20
DLS 90 63 91 63 / 0 0 10 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...AIR QUALITY ALERT UNTIL 3 PM PDT FRIDAY FOR WAZ026>030-521>523.
OR...AIR QUALITY ALERT UNTIL 3 PM PDT FRIDAY FOR ORZ041-049-050-502-
503-505-506-509>511.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 5 AM PDT FRIDAY
FOR ORZ696>699.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR ORZ700-705.
DISCUSSION...86
AVIATION...95
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