Drier air settles in, cool and dry for Monday and Tuesday

A cold front swept through the Tennessee Valley Sunday, pushing warm, muggy air out of the region and pulling cool, drier air in.

Dewpoints are falling from the mid-60s into the mid-50s and will continue to fall into the 40s; as a result, Monday morning temperatures will fall into the mid-50s, and Tuesday morning temperatures will fall into the 40s!

Because the air is so dry, temperatures will be quick to cool, but just as quick to warm. This means that afternoon highs will remain in the mid 70s midday Monday and Tuesday. A gradual warm-up will take over for the last half of the week, helping us rise back into the lower 80s Wednesday-Saturday.

What is the “dewpoint”?

The air we breathe consists of a mixture of gases including oxygen, nitrogen, carbon dioxide and water vapor (as well as mix of other trace gases).

Water vapor is simply water in gaseous form, and greater amounts of water vapor can be present in warmer temperatures compared to cooler temperatures.

When air is cooled to a certain point, the water vapor within the air is also cooled to the point that it can no longer remain in a gaseous state — it then condenses into liquid water, which we call “dew”.

So the dewpoint is the temperature at which air needs to cool in order for water vapor to condense into liquid water. The dewpoint is the limit at which air can cool, so on dewy mornings, the coolest air temperatures are close to — if not equal to — the dewpoint.

The dewpoint also impacts stormy weather: If the air has higher amounts of water vapor within it, this water vapor will provide the “fuel” necessary for thunderstorms to develop. In a nutshell, the higher the dewpoint, the more humid the atmosphere — and the more “fuel” available to develop thunderstorms.

Limited Rain Chances: Our rain chances stay low for the week ahead, but we do see a slim chance of rain sneak in Wednesday-Thursday. Dewpoints will rebound back into the low 60s through the second half of the week be fore a weak cold front approaches from the north — this cold front will provide just enough energy to kick off some isolated showers starting Wednesday evening and lasting through Friday morning.

Since we won’t have much moisture in place for the front to work with (dewpoints will only be in the low to mid 60s), rain totals will be low and spotty. Some of us will come away with little-to-nothing, while others get up to .25″ of rain in the next 7-days.

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