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When will it start cooling again during the HOT Alabama summer?

Most of you who know me, know of my great disdain of summer. I think it’s one of those things that must be endured for years for one to truly develop a contempt for sweating every time you go outside, or if you are visually impaired and wear glasses, having your glasses fog up, going from indoors to outdoors.

As I write this, May 2015 is about to begin. When speaking to a co-worker about the pending summer arrival, I wondered at what point do we in central Alabama begin to cool off again. And since I’ve done some research about temperature dips in summer in Alabama, I thought I would venture down the road of figuring out what day of the year is kind of an average, when central Alabama reaches it’s hottest average day. When could we expect it to start cooling again?

Knowing this day would give me something to look forward to since I would know that about this day, we would start the decline in temperatures and HUMIDITY towards a more comfortable and reasonable environment. The bottomline is we will have to endure this unpleasantness each summer.

How did I get there from here?

Basically, I had the information from my analysis about various cooler periods during our normally hot summers. During this analysis, I had collected an 11 year mean average temperature on my weather station at home and gathered the same 11 year mean average from the National Weather Service.

Top 31 warmest days in BHM

Combining and averaging the two gives me a good solid average temperature for each day for the past 11 years. One of the things I noticed in looking at this information was every date was after the summer solstice, also known as the longest day of the year. BUT, I also noticed there were several dates from July and August.

If you look at the spreadsheet there are dates Aug 3, July 4, Aug 7, Aug 5…and in the top 10 is a June 24 as well as a smattering of July’s, etc. If there is one thing we notice it is H-O-T and around here, humid as well. Yes, I know it is hotter and more humid in other places.

The next step was for me to figure out an average date based on the data provided. Since the data is sorted by hottest days based on temperature, it seemed reasonable to take the top, hottest 31 days and use the average Excel function for these dates and see what date we should start cooling down.

All that glitters is not gold…it may have melted.

After doing the math, that average date appears to be JULY 20. This appears to be about right, at least in my mind. For example we know the longest day of the year in the northern hemisphere is about June 20-21 depending on location. Incoming solar radiation will continue to heat the earth days after that longest day and while the daylight times get shorter, it is still a relatively long period of time of the sun’s exposure.

We also know there are significant variations in daily temperatures based on a variety of factors including latitude, longitude, geography and weather, like hurricanes, etc. For example, in the top 31 hottest average days annually, there are 12 in July and August respectively and only 7 days in June making the top 31. Only one of the days, June 16 comes before the summer solstice. For some reason this date is warmer than most June days.

The downside to all of this is even though on July 20 it SHOULD start getting cooler in Birmingham, as all of us know, it does not in reality. The absolute hottest day of our year based on the data is AUGUST 3 with an average temperature of 92.9.

And for some strange reason for the past 11 years, July 9th has been exceptionally warm with an average temperature of 92.1. This July 9th date and the other two July dates make the average for the top 10 hottest days come on July 31.

The top 10 average hottest days in BHM

What do we think we know?

It will be HOT and HUMID in Alabama.
The truth is our summers vary based on a variety factors. Like we learned the past few years, some summers will be more moderate than others while a few years before that it was exceptionally warm.
Based on the information we have experienced for the past 10+ years, we should reach our peak heating about August 1 and then start cooling from there, even though it won’t FEEL like it until probably late September.
But as all of us know, your experience may vary. Summer is subject to change with or without our consent. STAY COOL!

I hope you enjoyed this article. If you have any questions or comments about it, please contact me at http://www.facebook.com/weatherwalrus

Another ‘cool’ July 4th

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I noticed the al.com this morning about our record low temps in BHM for July 5. If you recall, I posted a few months ago about ‘temp dips‘ and how we should be looking for this to occur periodically throughout the summer. SO FAR WE ARE RIGHT ON TRACK.

Our July 5th low this morning at work was 63, and at home was 61…very nice. And for those visiting Texas now, it sure is nice here in Alabama, for the next 10 minutes.

But I got to doing some over analysis, and what started as doing a few weeks worth of analysis to determining what the temperatures have done on average for the past 113-ish years. I’ve done the analysis for my theory on Heliocentric Climate Seasons, and had all of this data sitting there, why not see what our ‘low temperatures’ in BHM look like for the past century plus.

And like we see in the HCS analysis, we get this real pretty sinusoidal wave, based on the influence of the sun. As elementary as it sounds, the sun goes up and the temperatures rise in our day and year. As the sun goes down, our temperatures lower in our day and year.

all broad mean low temp average 113 year

click for a larger image- average min. low temps next to months at the bottom

When looking at this, much of the detail is lost because this is a very large data set. Remember this shows low temps in Fahrenheit for every day since from 1900 to 2013. Doing some quick math, 365 x 113 = 41,245 total. Then we have to average these for each day of the year and it was A LOT of manipulation and massaging.

One thing I noticed with the low temps, as the year progresses and we get into the ‘hotter’ months, the average low temps are not making such a drastic swing. That is, as it warms, the average low temp doesn’t fluctuate as much as it does during the cooler months. But, our ‘zoom’ is way out.

And if you are wondering why I started in late-December, that’s when the winter solstice occurs. It is the lowest point the sun makes in our trip around the sun. It should be near the lowest temp of the year, and sure enough it is.

My next graph, I wanted to ‘zoom in’ and show more detail of our warmest months. Perhaps this will give us a better idea of any patterns in BHM as it relates to temperature. Let’s take a look…

As we zoom in, we get a better idea of any patterns that may exist…

Frankly, it looks like a jagged line. But remember this is an average low temperature view for BHM for the past 113 years, FOR EACH DAY of the year. We can really see there are some drops in the temps, but the dates don’t necessarily line up. The idea is though that we get natural weather influences that make our temps drop noticeably on average about every year. And I’ll bet as we study this for a longer period of time, there will be a longer term pattern too.

Then I narrowed the zoom a little more to June 15 – Sept 7. Using the bigger chart, you can see our average daily temp rises about June 15, above 67 and lowers below 67 on or about Sept. 7. That is show in this chart…

june 15 thru sep 7 - 67d threshold mean low temp average 113 year

I added a polynomial trend line to this as well as plotted the actual average temps…

Looking at this during our warmer months in Birmingham, Alabama, we can see there are various average drops in temperature. These may come a few days earlier or later, but they happen. And with the trend line in place you can get an idea of how the trend of our temp will behave for the next coming months…which is no real surprise because we are past the summer solstice and the days are already getting shorter.

But perhaps worse yet, as I write this on July 5, I have had the realization again that we haven’t hit the real peak of our summer heating and will not for a few more weeks…which is very unfortunate. I DO NOT LIKE SUMMER. But that has nothing to do with this analysis.

STAY COOL and let’s hope we have another cool summer like we did in 2013.

If you would like to comment, post it either here or on https://www.facebook.com/weatherwalrus

Quadcopters and change of temperatures with height

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A friend of mine posted this on FB recently. I know very little about ‘drones.’ But this is pretty awesome. It’s a video of his new quadcopter with telemetry including altitude and temperature on screen.

click me to watch the video

I also only know a little about ‘soundings’ performed by the NWS daily. As I understand, a balloon is sent up from the local weather station, twice a day. This balloon has a package of sensors attached to it, recording a ‘slice’ of the atmosphere including temp, wind direction, and other information. Basically it’s a tool for atmosphere analysis. More info about upper are sounding can be found here or here.

And basically, this is what’s happening here, except this is quad copter doing the ‘measuring.’ As we’re watching Michael’s video, we notice as the copter elevates, the temperature drops. And one of the things I learned from meteorology school about 14 years ago, as well as experienced personally when flying (no I’m not a pilot), on average per 1000ft in elevation, the temp drops about 5 degrees, but is not always the case.

So knowing a little about the weather and seeing the telemetry data on screen, I thought it would be neat to graph this.

Warning! I’m doing math and graphs

altitude along bottom – temp on left side

So we start at 72ish at the surface and as we rise, while the temp moderates a bit, around 1000′, by the time we reach ~4000′, the temp is about 10 degrees cooler.

In this instance, our average rate of the decrease in temp is about ~2.5 degrees per 1000′. There are much smarter folks out there that can explain much greater detail about ‘warm noses’ and varying temperatures with height and why all of this happens. But I just had to share.

And thanks to Michael for providing the info. If you would like to comment on this, visit https://www.facebook.com/weatherwalrus

Tempdips and the summer of 2012 v. 2013 grudge match

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Spaghetti? yes, please…

This chart is a representation of average and realized temperatures from May 1 – Aug 31. It looks pretty busy like a plate of spaghetti. But looking at the detail of it, each line (each noodle) represents the temperature in the BHM/Hoover during the time period.

The chart and data include temperatures I’ve gathered on my weatherwalrus wx station (WXWS). It is a Davis Weather Instruments Wireless Vantage Pro2 weather station located in Hoover, AL.

DWI Vantage Pro2 in Hoover

Other data comes from the State Climatology Office in Huntsville, AL (UAH). The data captured by them is at this website. I then basically created a chart in excel based on the recordings. What is seen is a ten year average of temps recognized in this graph as the gray line for the time period indicated, May 1- Aug 31.

The black line is the average temp and exhibits what was recorded on the WXWS for the same time period. If you look, there are some minor differences based on location, elevation, geography, etc. But for the most part, the lines of black and gray are very similar, but not exact.

The blue line indicates the actual temperatures recorded on the WXWS for 2013. The 2013 summer was considered by many in the area to be a lower or cooler than normal. I tend to agree which was the genesis for this analysis.

The pinkish red line indicate the actual temperatures recorded on the WXWS for 2012. These temps were considered by many in the area to be a higher or hotter than normal.

I should have added 2 additional lines of data to show what the NWS collected and what the differences were between the two, graphically. Maybe in my additional spare time, I’ll do that. For now, looking at this chart, it is fairly self-evident the summer of 2013 was cooler overall than 2012…one rabbit hole at a time please.

What was the difference in temperature between years?

Simply looking at the graph one can see a fairly drastic difference between ’12 and ’13 and the visualized difference above or below the ‘norm.’ For example, some of the highest temps in ’12 were at or above 100, while at the same time the next year in ’13, were about 20-25 degrees cooler. And right in the middle of both were the averages.

The difference in numbers will vary based on the day, but doing a quick look at the graph in 2013, there was one time we hit above 95ƒ. Conversely in 2012, there were several times above 95ƒ including periods above 100ƒ for daily high temps. This would pretty much make me ‘feel like’ 2013 was cooler than 2012…or depending on your point of view, ’12 was hotter than ’13.

a screen shot of some of the numbers…boring

We could drive down into the numbers and come up with specifics, but the charts do it for us. Or you can look at the bottom of this above image and see some of the numbers.

No, I didn’t bother with humidity or dew point or rainfall.

Yes, I probably should have included these as they affect how things ‘feel’ to us. Cloud cover as it relates to rain is a big variable in temp as it helps keep the sun from heating the earth. In my humble opinion, the sun has more influence on the feeling of ‘heat’ than anything. But there is no question, as ‘feel’ is relative, that humidity is a driving force in how temps feel. Right now, I’m pretty stoked with getting something published. We can overanalyze to the point of nausea later.

more numbers…more analysis…

Now this was pretty cool and unexpected…tempdips explained

My journalism professor would admonish me. I buried the lead. One thing i did notice in this analysis were the occasional ‘tempdips’ in temperature that occur periodically in our average and realized temps. We even just had a tempdip in Hoover/BHM, presumably caused by a relative cold front coming through. This is a part of our May 15ish tempdip.

What do I mean by ‘tempdip?’ If we look at the black and gray lines, our temps have a fairly steady rise through the solstice and even a little afterwards as the sun continues to bake the surface of the earth.

But based on the chart, we should have tempdips on the following approximate dates

May 15th-ish– just had this one in 2014
June 10
July 5
August 12 and
August 30

2013 analysis and 10 year average w tempdips

even during ‘hot years’ the tempdips appear…

The tempdips are interesting to see graphically and something that we don’t normally recognize as the temp, humidity, dew point, heat of Alabama summer don’t normally make them that recognizable. But based on the past 10+ years, they happen and are probably just cool/cold fronts occurring. It’s the relative regularity and timeliness of them that are remarkable and seem to create a pattern.

Some of my next posts will get more into my theory on ‘Heliocentric Climate Seasons.’ It’s pretty ‘cool’ stuff and may help explain ‘climate change.’ But in the meantime let’s wait and see what happens this year with our ‘tempdips.’

If you have any questions or comments about this, please reach out to me via Facebook and my weatherwalrus page there…https://www.facebook.com/weatherwalrus