Sort of Interesting Weather DayFebruary 7th, 2013 at 6:39 pm by Chad Evans under Chad's WLFI Weather Blog
Its been sort of an interesting weather day. Rain is almost immediately coinciding with the arrival of clouds after a mostly sunny day for much of the area.
We saw the process of adiabatic warming today. This is air starting at a high elevation & then downsloping & compressing. This heats the air up, dries it out & acts as a cloud eater. This said, you often gets this on the western & northwestern edge of a hurricane where you have such rising motion inside it, the outflow spreading out from it, or its “lungs” creates a corridor of sinking area on it top & left outer edges.
Today, intense low pressure is developing south of the Appalachians with wind pivoting around this & up & over the Appalachians. The air then downslopes into the Ohio Valley & eastern Corn Belt with south-southeast wind component. This actually is a more common phenomenon than you think in places like Louisville, Kentucky where wind downsloping of the “knobs” frequently warms the city & metro area in the Ohio Valley bowl there, compared to areas nearby. This can occur there with a southeast wind even without rapidly-intensifying surface low pressure nearby.
You also can get some sinking air out ahead of a cold front, as rising air accompanies the front with rain. The air is being pulled toward it sinks.
Also, a tongue of warm air originating down in Texas was pulled northward too, all pointing to a relatively warm day ahead of our cold & northwest of intense storm developing in the southeast U.S.
Our relatively humidity dropped from 85% at 9 a.m. to 41% by 3:45 p.m.
With adiabatic warming processes gone, we have cooled off to 43 as of 6:37 p.m. at WLFI after a high of 53. Logansport is already down to 37. After a high of 58, Crawfordsville is down to 46, even without rainfall.