Now that summer has officially arrived, both meteorologically and astronomically speaking… I think it’s a good time to remember we’re now in warm-season mode when it comes to rain chances in the forecast.
Later last week was a good example of what I mean by this. Showers and t-storms were in the forecast for Thursday and Friday. But if you paid close attention to the forecast, you would have heard that the chances were for Thursday morning… then again late Thursday into Thursday night… and then the Friday rain chances were mainly with the prime heating of the afternoon, with the best chances south and east of La Crosse.
Where I’m going with this is we will rarely see rain and t-storms all day long in June, July and August. It’s not like Winter where it might snow for 18-24 hours straight… or like Fall or early Spring where we might get a chilly rain falling steadily all day.
I had several people ask me where the rain was last Thursday when the sun was out during the afternoon. One person here at Channel 8 (who will remain nameless) even called me a “liar”, although I think (and hope) he was joking. This is why we get 3 minutes to give the weather forecast during our newscasts… to further explain these fine details that you need to listen for. If you don’t, then you might miss when the rain chances are highest during the day or night… or if we’re expecting better rain chances to our north or south, whatever the case may be.
Make sure you pay attention to the percentage numbers (or POPs - probability of precipitation) we associate with our rain chances. Of course, an 80% chance of rain is a much better chance of rain than only a 20% of rain. Sometimes we’ll even put “AM” or “PM” on certain days to help illustrate when we think the rain chances will occur.
I think what happens is sometimes people just watch a small part of the forecast, or the forecast gets “watered down” or “generalized” as it is put out over various media outlets… or even just as it spreads via word of mouth. Not to pick on any one medium, but last week I heard “rain today, rain tonight and rain tomorrow” on a radio station. Now I know they are trying to give a forecast in a short amount of time… but that might make many of you think it’s going to be raining all that time. Yes, there might indeed be a chance of rain today, a chance of rain tonight and a chance of rain tomorrow… but try to dig deeper. How likely or how small are the chances, what are the time frames we’re looking at and are there better chances for a certain part of the viewing area?
My best advice is just remember it’s summer. Chances for rain and t-storms are usually caused by mesoscale features this time of year, meaning everything is on a smaller scale than during the cold months. This usually means we’ll get rain and t-storms rolling through in about 3-6 hour windows. Now there will always be exceptions where we could get storms roll through in an hour or less… or a line of storms might park themselves or “train” over one area and dump lots of rain for a good 12-18 hours. But, more often than not… the rain moves in and out relatively fast.
Not only that, but the storms will often times be scattered in nature. The last week or so has illustrated this well with parts of the viewing area getting 2″-4″ of rain from a certain front or disturbance… while other parts of the viewing area barely get 0.10″. Last night and this morning, Medford, WI picked up 3.5″ of rain while the La Crosse airport got 0.09″. Last Thursday night, the airport barely got anything… while southern and eastern parts of our viewing area picked up 1″-3″ of rain.
Now with these weather systems functioning on a smaller scale during the warm months… we’re most likely going to miss a forecast here and there. We might call for a chance of rain and nobody in our entire viewing area gets rain. Or we might call for a dry day, and a few spots see some rain. I’m always the first to admit that meteorology is an “in-exact” science and we are just doing are best to predict Mother Natures next move.
All I ask is just to try to make sure you get the full forecast and any details that might help you understand what the rain chances are and when. Then you’ll be prepared as possible for these hit & miss showers and t-storms we’ll be dealing with over the next several weeks.
Until next time, see you in the morning!
on Aug 5th, 2009 at 7:39 am
I always learn something about meteorology from the weather segments. I appreciate the thoroughness of each forcast. As meteorology is an inexact science and attempting to predict the weather is difficult, I am grateful for the detail given to each forcast by Bill, Cory and Josh.