Weather percentages for rain.
 

I was just wondering about the 5 day extended weather forcasts in The Daily Sun and I hope someone will come up with a good answer for my question.

I know that when you flip a coin the chance of getting heads or tails is always 50%. So even if you flip ten heads in a row, the eleventh flip will still represent a 50% chance for heads or tails.

But is the weather the same? I know it seems like a dumb question, but hear me out.

Suppose you have a five day extended forcast that predicts a 50% chance of rain on Monday but a 0% chance for (each day) the rest of the week.

Then compare it with this forcast: A 50% chance of rain for each day for Monday through Friday. This means there could be no rain at all for the whole week or it could rain every day. Both scenarios are possible.

What is the percentage chance of rain for each week as a whole?

I'll give it a try.

Scenario 1 ... 50% chance of rain on Monday only ... 50% chance of rain during the week.

Scenario 2 ... 50% chance MTWTF ... 96.875% chance of ANY rain during the week.

Which also means a 3.125% chance of NO rain during the week.

Oh my! I feel a headache coming on. :-)

If a train leaves LA on Thursday morning traveling at 50 mph and a train leaves NYC on Wednesday evening traveling at 60 mph, when will your bathtub get a ring?

Seniors have a LOT of time on their hands.

I once had a meteorologist explain to me that an 80% chance of rain means that there is an 80% chance of it raining somewhere in a specific area. The are could be Sumter County for example. It may rain in Wildwood, but not in Lake Sumter landing. The people up on 466 will be talking about how the weather man doesn't know what he's talking about. Of course there would still be a 20% chance that it will not rain at all anywhere in that area.

50% times 7 equals 50%.

Same with the forecast. 50% chance of rain for each day means that the chance for rain that week is 50%. If it rains one day then the chance of rain that day is 100% but the chance of it raining again for the balance of the days is still 50% each day and 50% for the rest of the days.

Think of it this way. If you went into a store and bought ten items each selling at 10% off, you wouldn't be getting 100% off because you bought ten items.

Since weather moves from point A to point B over several days I would think that the forecast on any given day depends on the prior couple of days so it does not have to be a 50/50 chance.

All I know is I hear the "sun will come up tomorrow, tomorrow bet your bottom dollar tomorrow there will be sun"after all "tomorrow is only a day away"

According to Google:

Using a 50% probability of rain as an example, it does not mean (1) that 50% of the area will be covered by precipitation at given time in the given forecast area or (2) that you will be seeing precipitation 50% 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 50% chance of rain this afternoon, then there is a 50% chance of rain at any point in the county from noon to 6 p.m. local time.

Now , back to my discussion of how many angels dance on the head of a pin. :smiley:

:2excited:The answer is......12!!! :D

Actually, the weather here is pretty interesting to a girl who came from a nice, fairly predictable climate. The weatherman has quite a boring job most days in San Diego County....forecast for Monday - Nice; forecast for Tuesday - Nice; forecast for Wednesday - Nice......:laugh::laugh::laugh:

Weather reporter here says chance of rain and I also wonder just where this liquid will fall.

The answer is actually never. There are no bathtubs on the trains, only showers. However, if one can fit into the sink or the toil...... :a20:

I knew I could count on you Skyguy to think I was a little bit funny.

But is that funny ha ha? or funny strange................?

Yup, I definitely feel a headache coming on!

Whenever somebody decides to call it. :shocked:

:pepper2:

Bill :wave:

Or when it becomes engaged? :duck: