Sunday, June 17, 2012

First mid-90s heat wave of summer 2012

Happy Father's Day to all of you dads out there!  It's been said that being a father is easy, being a dad is something entirely different... I'm grateful and blessed to get to work every day at being a great DAD!

The weather this week is going to cause everyone - dads and all - to want to leave the mower in the garage and find the nearest swimming pool!  Though we've had a taste of summer already this year, this will be the first full week of summer-like conditions for 2012, just in time for the summer solstice, which occurs Wednesday, June 20, at 6:09pm CDT.  The first full day of summer (on Thursday) also happens to coincide with the first day of 2012 that MWN is forecasting mid 90s for high temperatures!

Summer solstice

The summer solstice is the point in time when the Earth's axis is most inclined toward the sun, yielding the longest day of the year for the Northern Hemisphere, thus the beginning of our summer. It is also the day when the apparent position of the sun is the highest in the sky for those in the Northern Hemisphere. The graphic below shows the illumination of the Earth at the summer solstice. Notice that the areas around the Arctic circle get light all day as the Earth rotates, while those areas near the south pole are in darkness all day.

Hot weather this week

The reason for this week's hot temperatures can be traced primarily to the mid and upper levels of the atmosphere, where a massive ridge of high pressure will reside over much of the eastern half of the U.S. with the main jet stream near the U.S./Canadian border. The graphic below shows the jet stream in pinks and reds well to the north and high pressure dominating the eastern U.S. on Tuesday evening.

Jet stream-level picture of the atmosphere on Tuesday evening.
Broad high pressure dominates the eastern half of the nation.
The recent dry conditions won't help the heat either, as the moderate drought will mean the ground, and therefore the air directly above it, can heat even more quickly than if the ground were more moist - perhaps adding a couple of degrees to the high temperatures over what this weather pattern would typically produce given more "normal" rainfall leading up to now.

MWN is expecting highs to be in the lower 90s for the first half of the week, then mid 90s for the end of the week and into the weekend. Rain chances are very isolated until at least next weekend and humidity values will likely mean our first 100-degree heat indices of the summer by next weekend as well!

Heat and drought also tend to build on themselves, meaning once they begin, it takes more rain or a larger "push" of cold air to break the cycle. Hopefully it doesn't mean a long, dry, hot summer ahead!

This heat wave will be felt throughout the eastern U.S. under the influence of the upper level ridge. Check out the nationwide high temperatures forecast for Wednesday below.

High temperatures forecast for Wednesday by the NWS. Heat will dominate the eastern and southern U.S.
How about you? Do you prefer the heat and "dog days" of summer or are you a cool weather fan?

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