Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
789 FXUS66 KPDT 032309 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 409 PM PDT Sun Aug 3 2025 .UPDATED AVIATION. .AVIATION...00Z TAFs...Kept thunderstorms PROB30 groups for BDN/RDM with radar showing some cells just south of the area. Strongest storms could lower visibility to MVFR levels briefly. Winds breezy across the Gorge and DLS and will remain so for the remainder of the period. Precip for tomorrow is possible around the Basin sites but not sure in confidence for a widespread event, so went ahead and put PROB30 for light showers for the late morning/early afternoon hours. && .PREV DISCUSSION... /issued 1247 PM PDT Sun Aug 3 2025/ DISCUSSION...Thunderstorm activity will persist in the region through Monday afternoon, with the next round of precipitation chances developing Wednesday into Thursday. More benign weather conditions will develop across the region starting Wednesday, while locally breezy conditions will develop each afternoon through Thursday in the Cascade Gaps into the Columbia Basin. Today through Monday: Satellite and radar imagery shows convective activity is already starting to kick off across southeast and central OR this afternoon. This activity is associated with a shortwave impulse moving across the region ahead of the shortwave trough located offshore the PacNW. Scattered showers and thunderstorms will continue to develop across central OR to the eastern mountains through this evening, with most thunderstorms capable of producing abundant lightning, gusty outflow winds, small hail, and heavy rainfall. Forecast CAPE of 500-1000 J/kg, effective shear of 25-35 kts, and inverted-v soundings should facilitate a marginal threat of severe (58 mph or greater) outflow winds, while hail will generally remain small and sub severe through this evening(though a strong storm could produce hail near 1 inch). Convective activity will become more isolated overnight with mainly showers persisting across the eastern mountains. Shower and isolated thunderstorm activity will push to far northeast OR and southeast WA Monday as the shortwave trough swings inland. Most of the storm activity will continue to be focused ahead of the shortwave trough axis, and will lift out of the region by Monday evening as the shortwave exits into ID. Tuesday through Thursday: Dry conditions will develop Tuesday as broad troughing begins to build across the PacNW and northeast Pacific. Ensemble cluster guidance is in good agreement that by Wednesday the axis of the broad trough will move inland while a surface cold front pushes across western WA and northwest OR. Shower activity will develop along the Cascade crest by Wednesday afternoon, with shower chances (15-30%) expanding to the Blue Mountains Wednesday night through Thursday (confidence 60-80%). During this period, temperatures will also cool to below seasonal normals, with mainly 80s across the region. Friday through next weekend: great agreement amongst ensemble cluster members that upper level ridging will develop over the northeast Pacific, with the ridge axis nudging closer to the PacNW through Sunday. This will leave the region under dry conditions with a slight warming trend back into the 90s across the lower elevations (confidence 50-70%). Lawhorn/82 AVIATION...18Z TAFs...Mostly VFR conditions to prevail through the period. Exceptions will be sites RDM/BDN, where scattered thunderstorms are expected to impact these sites between 21Z-02Z today. These storms may produce MVFR or less conditions under heavy rainfall (50-60% confidence). Winds will be mostly light, 12kts or less, at sites PDT/RDM/BDN/YKM/ALW/PSC through the period. However, sites RDM/BDN could also see gusty erratic winds from thunderstorm outflows between 21Z-02Z. Winds at site DLS will be 12-20kts with gusts up to 30kts through the period. Lawhorn/82 && .PRELIMINARY POINT TEMPS/POPS... PDT 58 82 56 86 / 20 20 0 0 ALW 63 82 60 86 / 20 30 10 0 PSC 59 86 57 88 / 10 20 0 0 YKM 60 86 58 88 / 10 0 0 0 HRI 61 85 58 88 / 20 20 0 0 ELN 58 80 57 84 / 0 0 0 0 RDM 49 80 47 84 / 30 10 0 0 LGD 55 79 51 86 / 50 40 10 0 GCD 53 79 51 85 / 60 30 10 0 DLS 60 79 59 85 / 10 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 8 PM PDT this evening for ORZ698. WA...None. && $$ SHORT TERM...82 LONG TERM....82 AVIATION...95