Many years we talk about the latest 100 degree day occurring in October: well forget about that. The highest temperature we’ve recorded this month has been a “cool” 89 degrees.
Don’t look now but warmer weather is in the forecast, but even highs on the warmest days look to only be a degree or two above average.
With two weeks still remaining of the month, it would take a major heat wave to put the entire month of October above average…and that isn’t in the forecast. This means October 2018 will be the first below average month we’ve seen since September of 2016.
TUCSON – Rain overspread much of metro Tucson – AGAIN – tonight and more rain is in the forecast tonight through Tuesday. And oh, don’t look now, but more rain is possible this weekend and even into next week if we can tap into Tropical Storm Tara.
Okay back to the big chill: the first 15 days of October have been colder than the first 15 days of November last year. (How is that even possible?)
So halfway through the month, we now rank as the 19th coldest October since records have been kept (1894). What’s more staggering is if you take out most of the colder October’s which occurred at the beginning of the 20th century, this October ranks as the 4th coldest since 1959! Only the first 15 days of October in 1966, 1970, and 1982 were colder!
And by the way, it’s currently snowing on top of Mt. Graham. See the image below.
In addition, for the first time since the early 1980s, Tucson has picked up over 7.00″ of rain in three consecutive years.
Drought conditions remain across much of the State of Arizona and according to chief Meteorologist Matt Brode, this is in part due to fewer Winter storms over the past several years.
Drought conditions still remain for much of the State if Arizona despite abundant monsoon rain. Here's to hoping for more late Fall and Winter storms with good snow pack in the mountains. #AZwx#KVOAwxpic.twitter.com/V4UFwIlv9q
Abundant monsoon rain has the City of Tucson in a small yearly surplus, but we’ll need to pick up about another 3″ of rain through the end of the year to match our annual average of almost 12″ of rain.
We’re off to a good start this year when it comes to our monsoon rain. Nearly 1″ of rain fell at TIA on Friday, and way more out toward Vail.
We have two positive factors for the potential of heavy rain this week and one potentially negative.
I’ll address the ‘good’ first, good if you were hoping for rain.
1) Tropical Storm Erick
A very favorable factor is on our side if you like rain. Tropical Storm Erick is churning to the West off Baja in Mexico. Often times we get what’s called a ‘gulf surge’ from tropical storms – even when they’re well to our south. Essentially, mid level moisture travels up the Sea of Cortez and helps us in the rain category. We still need a ‘trigger” or a mechanism to lift this tropical moisture to create rain. Enter factor #2.
2) A disturbance moving from East to West.
Remember the definition of monsoon? A seasonal shift of the wind. While most of the year we look to the West for our weather, disturbances this time of year come from the East and can help lift our moist air to create the rain. A disturbance is moving our way and should help lift our moist air for good rain chances. In the following picture you can see an area of lower pressure to our Southeast- this would be our trigger.
I’ve seen this too many times during the summer months. Often times despite a ‘trigger’ and good moisture, we do NOT get good rain in the Desert. This can be a function of too much of a good thing.
Ample storms may fire-up, many miles away from Tucson, but they can weaken sending us only clouds. If we are left with leftover clouds, we do not get warm enough at the surface to destabilize the atmosphere for convection (aka storms).
So as of now, I think the two ‘good’ factors outweigh the one ‘bad’ one and parts of Southern Arizona get abundant rain this week. But keep in mind, as contrary as it may sound, waking up with sunshine is a good thing if you are hoping for rain!