Summary:
- August brought a wild mix of weather that was not welcomed by many! However, the month ended largely warmer than average over much of the western US, especially in the PNW and southwest.
- Precipitation in August was dominated by tropical storm Hilary bringing large amounts across much of the west along with the onset of monsoon rains. Dry thunderstorms crossed over the mountains into the west side setting off fires in many regions.
- Drought extent expanded in the PNW while Hilary and the onset of monsoon flow lowered drought most everywhere else.
- Cool start to September north, closer to seasonal south. Temperatures are forecast to warm into mid-month and precipitation is forecast to be lower than average due to what looks like a pause in the monsoon flow.
- The September forecast currently has the month likely ending up pretty much average for temperatures over most of the west coast. For precipitation, the PNW is expected to end the month above average due to early month rain events and the seasonal start of frontal passages (PNW) while the Four Corners region is expected to see a wet month due to early month monsoon rains.
- Heading into the harvest season and fall the forecast is tilting the odds to near average to warmer than average conditions over the majority of the western US. For precipitation, the forecast displays equal chances for a slightly above to slightly below 90 day window for most, except the PNW where, even with the onset of fall frontal passages, amounts are forecast to be below average. The wild card right now rests with El Niño. A strengthening El Niño would mean a greater likelihood of wetter conditions for California and the southwest while the PNW is more likely to be drier.
