526
FXUS66 KPDT 072050
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
150 PM PDT THU AUG 7 2025
DISCUSSION
SATELLITE AND RADAR IMAGERY THIS AFTERNOON SHOWS
SCATTERED SHOWERS/THUNDERSTORMS DEVELOPING ACROSS THE WA COLUMBIA
BASIN AND ISOLATED CELLS DEVELOPING OVER THE HIGHER TERRAIN OF
THE NORTH EAST OR, INCLUDING THE GRANDE RONDE VALLEY. THESE STORMS
ARE THE RESULT OF AN UPPER TROUGH PASSING OVER THE PACNW TODAY,
WITH THUNDERSTORMS DEVELOPING UNDER FAVORABLE CONDITIONS, AS THE
EXIT REGION OF AN UPPER JET WRAPPING AROUND THE TROUGH IS
CURRENTLY CO-LOCATED OVER THESE STORMS.
THROUGH TONIGHT: THE UPPER TROUGH WILL CONTINUE TO MOVE ACROSS THE
PACNW TODAY, RESULTING IN SHOWERS AND THUNDERSTORMS TO CONTINUE TO
DEVELOP INTO THE EARLY EVENING HOURS. THUNDERSTORMS WILL BE AIDED
BY MODERATE TO STRONG LOW/MID LEVEL LAPSE RATES (LOW: ~10C/KM
MID: ~7C/KM), THE EXIT REGION OF AN UPPER LEVEL JET ALOFT, AND
MODEST INSTABILITY (500-750J/KG), WITH STORMS CAPABLE OF PRODUCING
GUSTY OUTFLOW WINDS AND SMALL HAIL. THIS ACTIVITY WILL MOSTLY BE
FOCUSED NORTH AND EAST OF THE FORECAST AREA, HOWEVER AREAS OF THE
NORTHERN BLUES, UNION/WALLOWA COUNTIES, AND PORTIONS OF THE WA
COLUMBIA BASIN. OTHERWISE, THE UPPER TROUGH PASSAGE WILL RESULT IN
BREEZY CONDITIONS THROUGH THE CASCADE GAPS INTO THE COLUMBIA BASIN
THROUGH THIS EVENING.
TOMORROW THROUGH MONDAY: GROWING CONFIDENCE (70-90%) THAT UPPER
LEVEL RIDGING WILL BUILD ACROSS THE NORTHEAST PACIFIC AND THE
PACNW THROUGH MONDAY. WHILE THE UPPER RIDGE WILL BE CENTERED WELL
OFFSHORE THE REGION, 500MB HEIGHTS WILL BE INCREASING THROUGH
THIS PERIOD, RESULTING IN WARMING TEMPERATURES AND DRIER
CONDITIONS OVERALL. THERE IS HIGH CONFIDENCE (70-85%) THAT THE
LOWER ELEVATIONS WILL SEE TEMPERATURES IN THE MID TO UPPER 90S,
WHILE THERE IS A 60-80% CHANCE THAT TEMPERATURES IN PORTIONS OF
THE COLUMBIA BASIN AROUND TRI-CITIES/HERMISTON, PORTIONS OF NORTH
CENTRAL OR, AND THE JOHN DAY BASIN REACH THE 100 DEGREE MARK
MONDAY AFTERNOON.
TUESDAY THROUGH THURSDAY: MODERATE CONFIDENCE (50-70%) THAT UPPER
LEVEL TROUGHING WILL DEVELOP ACROSS THE PACNW TUESDAY AS THE
OFFSHORE UPPER RIDGE RETROGRADES. HOWEVER, CONFIDENCE IN
STRENGTH/TIMING OF THE UPPER TROUGH ARE LOW-MOD (30-50%) THROUGH
THIS PERIOD, AS ENSEMBLE CLUSTER GUIDANCE SOLUTIONS DIFFER IN THE
TROUGH AXIS POSITION AND THE DEPTH OF THE TROUGH AS WELL.
REGARDLESS, EXPECTATION IS FOR TEMPERATURES TO COOL SLIGHTLY
DURING THIS PERIOD TO NEAR NORMAL VALUES, WHILE BREEZY WINDS
DEVELOP THROUGH THE CASCADE GAPS INTO THE COLUMBIA BASIN AND
CENTRAL OR (CONFIDENCE LOW, 30%, IN STRENGTH OF WINDS). LAWHORN/82
AVIATION...PREVIOUS DISCUSSION...18Z TAFS
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. SCT-BKN CIGS AROUND 4KFT AGL WILL
CONTINUE TO IMPACT SITES RDM/BDN INTO THE EARLY AFTERNOON, WITH
CIGS OTHERWISE ABOVE 10KFT AGL THROUGH THE REST OF THE PERIOD FOR
ALL SITES. BREEZY WEST TO NORTHWEST WINDS 12-20KTS WITH GUSTS UP
TO 30KTS WILL IMPACT SITES DLS/PDT THROUGH 7Z, BECOMING 12KTS OR
LESS OVERNIGHT AND THROUGH THE REMAINDER OF THE PERIOD. WINDS
10-15KTS WITH GUSTS UP TO 25KTS WILL IMPACT SITE YKM THROUGH 4Z,
AND SITE ALW THROUGH 00Z, AND RDM/BDN THROUGH 3Z, BECOMING LIGHT
THROUGH THE REST OF THE PERIOD. WINDS WILL BE 12KTS OR LESS AT
SITE PSC THROUGH THE PERIOD. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 51 83 55 89 / 0 0 0 0
ALW 55 83 61 89 / 0 0 0 0
PSC 52 86 56 91 / 0 0 0 0
YKM 52 86 58 90 / 0 0 0 0
HRI 54 86 57 91 / 0 0 0 0
ELN 52 85 58 89 / 0 0 0 0
RDM 40 84 46 89 / 0 0 0 0
LGD 46 82 51 86 / 0 0 0 0
GCD 44 83 51 87 / 0 0 0 0
DLS 56 87 61 92 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...82
AVIATION...82
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