Knowing the forecast beyond a week out would be awesome, but it’s also not reliable. While some models go beyond a week, the forecast tends to flip flop a lot beyond even a few days. There are some instances when models will be consistent in the long term, but that doesn’t happen very often. Trends are more realistic for long term forecasts. For example, will it be cooler, wetter, or warmer than average next week? Will it be cooler or wetter than normal?
A flip-flopping forecast between model runs lowers confidence levels, but usually grows as the event gets closer. Models start with initializing, so if their current readings are off then that affects the whole model run. This is like the butterfly effect. Sometimes a model will show a low developing ten days out, and you can’t see it on satellite at the time being. Meteorologists like to see how the model is performing by comparing current analysis with model output.
On occasion, the models can be in alignment two weeks out and consistent too. This rarely happens, and if it does, confidence levels are much higher. This is also why the National Weather Service will usually issue a watch before a warning. The difference between the two has to do with confidence level. According to NOAA forecasts are only 50% accurate after 5 days.
Looking at Halloween, the forecast does include a chance for rain, beginning in the afternoon. Where the rain sets up is a close call, but for now it looks to be mainly just east of the Truckee Meadows, but the line between staying dry and getting rain is very close. Yes, the models have been flip flopping a lot, but are starting to come together more. It is too far out to nail down any specifics, but plan on Trick or treating being cold, with a chance for rain, especially just east of Reno. I would plan for some light rain in Reno just in case. Stay tuned, as we are still four days out.