INDIANA, USA — We have a long stretch of warm, sunny weather ahead of us across Indiana thanks to a weather pattern called an "omega block."
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September is typically one of our quieter months, however the weather has been extremely calm. So far we have only picked up 0.05" in Indianapolis.
The dry, sunny, warm weather is set to continue for at least another week (most likely until around Sept. 22). This long stretch of heat is due to a blocking pattern. The weather is clogged and can't change for a bit.
What is an "omega block"?
You may have see the omega symbol Ω. It is the 24th letter of the modern Greek alphabet. It's also used on Christianity as a title for Christ in the Book of Revelation (the alpha and omega). In engineering it's used to symbolize ohms (units of electrical resistance).
In meteorology, or the study of weather, it is used to depict a blocking pattern, only because the jet stream resembles the shape of Ω.
In this setup, you have a dome high pressure in the middle, usually pretty strong. On both sides, to the west and to the east, you have deeper low pressure. In between the lower and high pressure, you see the jet stream snaking around.
This is very inefficient for wind flows. Essentially the atmosphere gets clogged up and can't move very well or quickly. Whatever weather you currently have, you will generally keep. Many times it can take a week or two to break this pattern.
We won't see much change until Sept. 21-23.
Lots of heat for Indiana
We aren't quite at records, but we will be close. Expect lots of 80s and a few 90s day-after-day for the next week. The good news is that the humidity will not be sky high. Expect drier heat for the next week. Lots of sunshine will also continue with limited clouds.
Long duration heat drying out the ground
Sunny, warm days evaporate water out of the ground, streams, and lakes. When you don't get days of rain to interrupt the evaporation, you can quickly dry out the ground. If the temperatures are hot, especially over 80 degrees, you can accelerate this process.
Rapid drought is taking place across Indiana. Dry conditions are quickly expanding.
The "levels" indicate degrees of severity of drought. Level 1 is the lowest and Level 4 is the highest — or worst — drought. The yellow color indicates dry ground that is not necessarily in drought conditions yet.
We are watching drought conditions quickly.
We could use 1-3" of rain across the state.
