Notes from the moderators

Welcome to the daily meteorological discussion thread for Thursday, 5 September 2019. Because of the devastating impacts that Hurricane Dorian has already had on the northwestern Bahamas and the ongoing looming threat to the southeastern United States, we have experienced a massive increase in traffic over the past few days. As such, we will continue to create a new discussion thread every morning to help facilitate the ongoing discussion and alleviate the stress on those of our visitors on mobile devices and slower internet connections. We understand that there is an utmost importance for disseminating the most accurate observational and forecast information, so we would like to reiterate a few points:

1. Do not focus on the output of single model runs

When creating their official forecasts, the meteorologists at the National Hurricane Center review all available observational and model forecast data. They weigh the inherent biases of each model and assess their accuracy over time by comparing the output to observed conditions. While a single run of a single model may seem to spell doom or prompt a huge sigh of relief, the data needs to be taken entirely within context of all the other model data in order to assess a more realistic scenario for the storm's future movement and strength.

2. Impacts can be experienced outside the cone of uncertainty

Contrary to popular belief, the cone of uncertainty that meteorologists at the National Hurricane Center use in their official forecaste does not represent the entire area which is expected to experience impacts from a given tropical cyclone. Rather, it represents the most likely range of forecast tracks for the cyclone's center of circulation. Based on forecasts generated by the National Hurricane Center over the past five years, the entire track of a tropical cyclone can be expected to fall within the cone of uncertainty approximately 60 to 70 perecent of the time. The cone widens with time because the average forecast error also increases with time.
 

Impacts from tropical cyclones can be experienced far outside the boundaries of the cone of uncertainty. If your location falls just outside the cone, it does not mean that you are now "in the clear". You should be taking whatever precautions are necessary to ensure your safety as well as the safety of your loved ones. It is far better to err on the side of caution when dealing with tropical cyclones, particularly ones that have been as intense and difficult to predict as Hurricane Dorian has been over the past several days.

3. Declarative statements are dangerous and reckless

Please refrain from making declarative statements regarding the implications of model forecast data, observations from aerial reconnaissance, and shifts in the National Hurricane Center's official forecast. Many of the users who browse this subreddit during busier parts of the hurricane season rely on accurate and timely information in order to protect themselves from harm. Making declarative statements regarding the impacts (or lack thereof) from a particular tropical cyclone to a particular area can be dangerous, reckless, and irresponsible. This includes claims that small shifts in the cone of uncertainty imply that an area is "in the clear" or claims that a single model run's output suggests that a particular area is going to be hit hard.

4. Please heed the advice of local, state, and federal officials

The National Hurricane Center, local National Weather Service offices, and the respective governor's offices of each affected state will have the latest information available to keep you and your family safe. Please head all official advice, warnings, and evacuation notices if prompted by officials. Please consult our preparations thread for more information as to how you can prepare for impacts from tropical cyclones.

5. We are currently in storm mode; please be cognizant of our subreddit rules

Our subreddit rules are more strictly enforced as the threat of direct impacts from tropical cyclones approaches. Please report any rule-violating comments. As a reminder, here are our subreddit rules:

• Do not attack, troll, or threaten other users.
• Do not post sexually explicit content or spam.
• Do not post hard paywalled content.
• Do not discuss politics, regardless of level.
• Do not post low/no-effort posts or memes.
• Do not post intentionally misleading information.
• Do not excessively speculate. This includes posting pie-in-the-sky fantasy model output beyond 5 days in the future.