Arizona monsoons: The science of forecasting the storms

Take a look at your screen you guys. We have seen this play out over and over again here in the Valley of the Sun. It starts with those massive towering dust clouds rolling right into town completely swallowing the skyline just like this wall of dust that was captured on Monday. Yeah and it's pretty remarkable. So then the sky just opens up and the wind picks up and most of the time anyways right we hope that the rain starts falling hard and fast because sometimes the dust comes and but that rain if it comes it blinds drivers on the freeway you know you probably dealt with it over the last couple of days with some of the storm activity and it just hits our neighborhoods so hard and many of you have had to be uh you know cleaning up in those morning hours because it all happens in a matter of seconds and then finally all that rain has to go somewhere it leads to exactly what we're seeing here rushing through some of these desert washes spilling onto roads flooding into people's properties as well. So on this weather wisdom Wednesday Crystal is joining us here this morning with what goes into forecasting our monsoon storms it really is remarkable when you look at the science behind it Crystal. Yeah absolutely and I feel like sometimes I'm using phrases or words that maybe we haven't heard we haven't at least heard since last summer so I thought this would be a good time because it's been so active recently and it will continue to be for us to dive into what it takes to forecast during the monsoon what we as your weather experts are looking at each morning or afternoon before we go on air to talk about the forecast so let's pull up our graphics and take a look so there are four key ingredients to forecasting storms for any meteorologist and that includes during the monsoon season for us here in the valley this is what we're looking for first off moisture it's obviously necessary for us to get clouds it's necessary for us to see rain sometimes you'll talk about the fact that maybe we have a good deal of moisture up in the clouds but we're very dry down at the ground and anything that falls is going to evaporate before it can get to us so you need that moisture all the way down to the surface so we track our dew point temperatures as a very clear way to know how much moisture is down at the ground we also look at things like water vapor imagery which I show off on on air sometimes to show where there are those big plumes of moisture starting to move into Arizona which helps us with our storm chances next up you need something called instability which is just the energy in our atmosphere I've been sometimes referencing this as the battery needing to be charged for us daytime heating and sunshine can help to charge us but sometimes there are other factors at play the whole weather pattern across the country and across the globe and how those things may play into the energy our atmosphere contains but we need energy for storms to fire off you also need something known as lift this is just the trigger for those storms to develop I've sometimes referenced it as kind of that match that lights that firestorm of activity so elevation such as our mountains where we typically see storms during the monsoon a cold front or even a nearby storm system can be triggers sometimes you'll hear us talk about outflow boundaries say thunderstorms up in the high country and thunderstorms down in Tucson winds flow out of them and if they collide over the valley you can get storms because of that collision again creating more energy so you have to have these three things for us to even expect there to be storms so in the morning I'm checking these necessary ingredients before I give my chance for storms finally a fourth ingredient is known as wind shear this is the change in wind speed and the direction of those winds at different levels of our atmosphere from the clouds down to the ground this can lead to severe storms when you have a lot of wind shear it creates the spin that can trigger those nastiest most dangerous storms that can lead to things like a microburst or even a tornado so those are the ingredients that we look for each day now when it comes to our chances for rain how do we actually come up with those numbers first off what is pop that's the probability of precipitation it's the number that you see on the map the probability that a within the forecast area will pick up one hundredth of an inch so the percent does not have anything to do with how much rain we're talking guys it is just talking about is there some rain and it's determined not like I said by coverage or intensity but more about my confidence versus the coverage area so this is just the example I want to give you guys if I'm 100 confident it's going to rain but only around 30 of the area that's a 30 chance of rain but if I'm not certain maybe we're missing one of those ingredients that it's going to happen but if it does it's going to hit us all that's still a 30 chance of rain hopefully that helps