Just as precipitation forecasts may be misinterpreted by the users, forecasts which describe cloud conditions also seem to invoke confusion. The NWS uses many terms to describe the sky condition and/or weather for any given time period, and we chose to test a few that are used often in Juneau. The authors also wanted to take this opportunity to test public understanding of wind forecasts.
The terms respondents were asked to define were fair and partly cloudy. Of the two, fair drew the widest range of responses. The possible answer choices were clear, a few scattered puffy clouds, high, thin clouds, or cloudy but without rain or snow. NWS guidelines are rather ambiguous concerning use of the word fair. The Operations Manual defines fair as "less than four tenths [of the celestial dome] opaque, no precipitation, no extreme conditions of visibility, wind or temperature, and generally pleasant weather." Almost 50% of the respondents chose the answer, a few scattered puffy clouds, and 31% selected high, thin clouds . Of the remaining answers, 13% chose clear . At the Juneau forecast office, meteorologists tend to use fair to describe a high, thin cloud condition; although, a few scattered puffy clouds may also be correct under the NWS guidelines. Therefore, the use of the word fair in Juneau is being correctly interpreted by less than one-third of our users. Because the term fair is considered to be vague, the NWS operations manual (Chapter C-11, 8.6) recommends using other words if possible.
The phrase partly cloudy was better understood by the respondents. Nearly two-thirds of the respondents chose the answer phrase, the same as partly sunny, which does match the NWS definition (Chapter C-11, 8.6). The response which received the lowest response to this question was, the same as mostly sunny, while nearly 20% of those surveyed thought that partly cloudy implied cloudy conditions for part of the day. This being the case, it could explain why some people will perceive a partly cloudy forecast as inaccurate because they could see blue sky the entire day. To lessen the confusion, it might be better to use partly sunny during the daytime forecast. If fact, one respondent commented on his questionnaire, "You guys never say partly sunny, it's always partly cloudy. If you could just mention the sun more!"
Another question asked respondents if they felt there is a difference between "rain" and "showers" and if so, what these differences are. The four possible answers were: A) no real difference B) rain is steady and continuous, showers start and stop abruptly and can vary in intensity C) rain is light, and showers are heavier D) rain is heavier, while showers are light and periodic. Of the total responses, only 6% felt that there was no real difference. The most common response (46%) was the correct NWS definition, rain is steady and continuous, showers start and stop abruptly and can vary in intensity. The remaining 48% felt that intensity determined the difference (answers C and D), with more people thinking that rain was heavier than showers. Also, 77% did correctly assume that showers were periodic (answers B and D).
Based on the results of this question, when a "rain" or "showers" forecast is written, over half of the general public does not understand the precise meaning of the forecast; but since more than three-quarters of the respondents knew (or guessed) that showers imply precipitation that start and stops, use of the term "showers" does seem to convey more detail to the user. On the other hand, a forecast that says, "rain changing to showers," may be unnecessarily detailed considering the exact difference between rain and showers is not widely understood. We did receive comments on this particular wording; one of which stated, "Rain changing to showers...to me either it's going to rain or not. Rain is rain. What's the difference?"
As mentioned before, the authors also wanted to test the community's understanding of the wind forecast. This is of particular interest to the Juneau office because forecasters write an extensive marine forecast twice a day. It is also significant because the wind observations given over NOAA Weather Radio and telephone recordings are read in knots. The goal was to determine whether the public had a clear understanding of the difference between miles per hour and knots, as well as what direction the wind was coming from. The question simply asked which wind speed was faster, 20 knots or 20 miles per hour. Nearly 80% of the respondents answered this question correctly, the answer being 20 knots. Those respondents who were polled at the boat show scored nearly 100% correctly on this question, probably because the marine forecasts are done in knots, and marine navigation is almost exclusively done in knots and nautical miles. This does leave 20% of the public who got the question backwards. Respondents who missed the question probably have less exposure to the marine environment, but the concept is significant nevertheless, as these people will likely underestimate the winds that are reported regularly on NWS weather broadcasts. Further public education on this subject may be necessary in the Juneau area.
One of the things that all meteorologists know is that the wind direction always refers to where the wind is blowing "from"; however, this may not be obvious to the general public. For example, those with an oceanography background know that sea currents and tide directions are given in the direction the flow is going "to." Thus a question asked, The forecast reads, "North winds to 20 mph." This means that the winds are... A) blowing from the north; B) Blowing to the north. The results were very encouraging with 87% of the respondents choosing from the north. One possible way to alleviate any confusion over what is meant might be to occasionally say, "Winds out of the north to 20 mph."