Weather Forcast

[DavidHouston]

I have a question about the weather forecast. Take a typical daily forecast, this one for today for the Andaman area of Thailand:

"ภาคใต้ (ฝั่งตะวันตก)มีฝนฟ้าคะนองกระจาย ร้อยละ 40 ของพื้นที่ ส่วนมากบริเวณจังหวัดภูเก็ต กระบี่ ตรัง และสตูล อุณหภูมิต่ำสุด 23 องศา สูงสุด 32 องศา ลมแปรปรวน ความเร็ว 15-35 กม./ชม. ทะเลมีคลื่นสูง 1-2 เมตร"

"The South (West Coast)

"Scattered thunder showers in 40% of the [forecast area], mostly in the provinces of Phuket, Krabi, Trang, and Satul. Lowest temperature 23 degrees [Celsius]; Highest temperature 32 degrees [Celsius]. Variable winds; speed from 15 - 35 km/hour. Wave height 1-2 meters."

My question concerns the meaning of the phrase "ร้อยละ 40 ของพื้นที่". Does this mean, "40% of the area will have rain today" or "there is a 40% chance of rain somewhere in the defined area today?"

I believe that the U.S. National Weather Service defines probabilities as follows:

"To summarize, the probability of precipitation is simply a statistical probability of 0.01" inch of more of precipitation at a given area in the given forecast area in the time period specified. Using a 40% probability of rain as an example, it does not mean (1) that 40% of the area will be covered by precipitation at given time in the given forecast area or (2) that you will be seeing precipitation 40% of the time in the given forecast area for the given forecast time period.

Let's look at an example of what the probability does mean. If a forecast for a given county says that there is a 40% chance of rain this afternoon, then there is a 40% chance of rain at any point in the county from noon to 6 p.m. local time." See http://www.utexas.edu/depts/grg/kimmel/nwsforecasts.html

Does the Thai method of forecasting mean the same thing as the above explanation? This is very important to me as I need to know whether we need to take our umbrella with us today.

[taxexile]

i would guess that it means that there is a 40% chance of rain somewhere in the defined area today

คะนอง

this word is interesting in itself.

it means wild and high spirited .

when combined with ฟ้า it means thunder.

as คะนองปาก it means to say things one shouldnt

as วัยคะนอง it means teenaged

and as คะนองมือ it means to fool around with ones hand or to have an "itchy" hand

[yoot]

มีฝนฟ้าคะนองกระจาย ร้อยละ 40 ของพื้นที่ does mean exactly what it's written.

มี(have)ฝน(rain)ฟ้าคะนอง(thunder)กระจาย(spread over) ร้อยละ 40 (40%)ของ(of)พื้นที่ (area)

This sentence shows rain as the subject which means there is rain for sure but about 40% of the area.

"there is a 40% chance of rain somewhere in the defined area today"

- มีโอกาสที่ฝนจะตกในพื้นที่พยากรณ์ราว 40 เปอร์เซ็นต์

This sentence shows the chance as the subject, so, 40% is the probability of the chance.