The 2023 Heat Wave

Every year before summer starts people ask me if it is going to be a hot summer. I usually tell them that it is Columbia, South Carolina, of course it is going to be hot. However, this summer has been a little different and not what I expected. Let me give you a couple of examples. 
 
Columbia, South Carolina had its 13th coldest May on record (Avg. T=68.9˚F) this year. That was followed by the 17th coldest June on record (Avg. T=76.2˚F). So maybe it will not be so hot this summer. Then came July. The first 8 days have put the month on track for the 8th warmest July even though the highest temperature has been 95˚F. It has been the low temperature pushing the average up as it has put the month on track for the 3rd warmest low temperature. 
 
When you see the reports for Texas and the Southwest about the current heat wave this does not seem so bad. I was amazed how far north the heat has been driven. Take the example of the weather station at Norman Wells in the Northwest Territories in Canada. It is at about latitude 65˚N and yesterday it reported a high temperature of 100˚F. This beat its previous all-time high temperature record by 5˚F. On top of that it had visibilities of about a mile in smoke from wildfires. Truly epic. A cold front passed late in the day and winds shifted blowing up to 40 mph. This blew the smoke away and lowered the temperature. 
 
I have been following the media reports of the heat wave this year. As meteorologists we often do not know how the pattern will evolve until we get into the season. The models have not always given us a clear picture, but now we have a better sense of what lies ahead. 
 
High pressure in the middle of the atmosphere was centered over Texas early in the summer which was responsible for the start of the heat wave there. Over time it expanded and now stretches from Florida to Texas to the Southwest. The high pressure is centered over New Mexico and by the end of the week it will be over Arizona. This will push the heat wave into California and north to Washington state. 
 

The atmospheric pattern at 500 mb (~18,000 ft.). This is the forecast for next Sunday July 16, 2023 from the European model. The H represents the center of the high pressure system and the L the low pressure system. These will not move much over the next week.

Temperatures will be hotter than normal across much of the southern U.S. by next weekend. Readings in Death Valley, California may approach 130˚F. Even in the central valley of California temperatures will be above 110˚F. (The lowest relative humidity I ever experienced was in Fresno, CA at 4%. It was drier than Death Valley.) Parts of South Carolina may approach 100˚F with heat indices in the range of 105-108˚F. No doubt the heat will continue to be news. 
 

Projected high temperatures for Sunday July 16, 2023 from the European model. Actual temperatures may differ slightly, but the overall pattern has higher confidence. It will be hot from the intermountain region, the Southwest, Texas into the Southeast.

 Notice the low-pressure system in Canada. The combined flow around it and the high over Arizona will push cooler air into the Midwest. The 6 to 10 day forecast reflects the evolving pattern. 

 

From the National Weather Service. This is the 6 to 10 day outlook for July 15-19 made on July 9. The cool weather in the central U.S. will be short-lived. The heat wave will begin to expand northward after this time.

 However, this will be temporary. The computer models suggest that the heat will begin to build north and east during the third week of July. The area that may escape much of the heat will likely be around the Great Lakes to the Northeast. 
 
Don’t think that this is the end of the story. I have only looked at the temperature here. There will be areas struck by severe thunderstorms and floods mainly in areas outside the heat wave. We have already seen examples of this over the past few weeks. Thus, the summer of extremes is likely to continue. 
 
I wonder what August will look like. 

Time to Plant

I have been advising gardeners to delay planting tender plants this year due to a weather pattern that has been in place since late October, 2013.  The pattern made it more likely for a late freeze.  Normally the last freeze would occur in the Midlands by late March.  Most would simply wait until Easter, but Easter is quite late this year.  The latest freeze was on March 27^th and it was a hard freeze with a low of 28° F.  It was very close to freezing on March 31^st with a low of 33° F, but there was frost that morning.

Another cold, dry air mass is making its way south and computer models have been suggesting that a frost or freeze might occur on Thursday, April 10^th.  High pressure will settle over the area with clear skies, light winds, and dry air for Thursday morning.  The forecast for Columbia is for a low near 40° F that morning, but outlying areas may drop into the mid 30s.  This would be enough for a light frost in low-lying protected areas due to radiational cooling at night.

This will likely be the last chance of a frost or freeze.  If it does not happen then the previous dates will be the last freeze or frost.  The chance of a frost or freeze on April 10^th was strong enough to advise gardeners to wait.  The seven-day forecast reveals that it will be time to plant this weekend.

The 7-day forecast made Wednesday, April 9, 2014 for Columbia, SC.  Click on the image for a larger view.  Image Credit: WLTX-TV.

Weather? Climate? Confused?

Have you noticed the attention the weather has been getting in the media?  The cold blast for much of the U.S. & Canada, the trapped ship in the Antarctic, and the storms hitting Europe around Christmas are just a few examples.  Other news reports that you may not have been aware were the floods in southern Brazil and in the Caribbean, the heat wave in Argentina, the usually cold weather in the Middle East.  These are all weather events.

Some media outlets are reporting the cold events indicate that we have little to fear from global warming.  Yet global warming does not cancel the seasons.  In fact what we know about our changing climate is to expect more weather extremes worldwide.   Not just heat waves, but more floods, droughts, and even energized storm systems.  This is how a changing climate translates into daily weather.

Often many in the media confuse the difference between weather and climate.  Don’t worry, because some meteorologists do too.  The weather is basically composed the events that unfold in the present.  Meanwhile climate looks at the long term average of weather.  By definition this is a 30-year period.  We can look at shorter term trends to look at how changes are progressing, but we still have to look at the climate period of 30 years.

The Cool, Wet Summer of 2013

This past summer (June 1-August 31) was a great relief from the past three scorching summers.  Remember that the summer of 2010 and 2011 were back to back the warmest summers on record.  Last summer wasn’t quite as hot, but we did see the all-time record high temperature for South Carolina broken when it reached 113 F in Columbia.

It was during this time that much of the region was also battling drought.  There was some rainfall during the normal wet season of summer, but there were few wet months beginning in 2010.  In fact there were only 8 wet months out of 36 ending in 2012.  It looked like it would never change.

However, the weather pattern began to change in February of this year.  Rains began to increase, but it also got colder.  There were shifting patterns throughout the spring, but it too was cool and wet.  Then summer began with a very sluggish pattern that dominated June and July.  It was not as dominate in August, but it was still enough to keep the month on the cool side.

This weather pattern persisted for much of June and July.  Click on image for a larger view.  Image Credit: WLTX-TV.

From One Extreme To Another

June was a month of extremes across the U.S. Record heat dominated the West, where all time record June temperatures were being set in multiple states. Meanwhile, the same weather pattern that supported the prolonged, intense heat across the West locked in an extremely wet set up across the East. Not only were numerous daily rainfall records set, but both Philadelphia, PA and Macon, GA, ended up with their wettest June ever.

Some of the extreme weather across the U.S. in June 2013.  Click on image for a larger view. Image Credit: Climate Central.

You can also add Augusta, GA, to the wettest June on record.  Bush Field in Augusta received 10.83 inches of rain which was 6.11 inches above normal. An observer near Martinez, northwest of August, received 16.02 inches for June.  This is remarkable since that area of Georgia and South Carolina had been suffering from nearly 3 years of drought until recently.

A Cool Start To May 2013

Just as we were getting used to hotter springs, Mother Nature pulls a fast one.  It has been unusual to say the least for South Carolina weather since April 26^th.  Cloudy, cool conditions have been the rule with plenty of rain.  The griping has begun as many are tied of conditions we normally attribute to Seattle.

My favorite tweet during the past week has been “Breaking news: This just in – Cleveland wants its weather back.”  I’m sure those in Cleveland might think this an improvement over what they normally get in early May.

So what has been happening?  Why has it been so cloudy and cool for so long?  When will this go away so that we can get on with summer?

The first half of spring was influenced by a weather pattern associated with a negative phase of the Arctic Oscillation.  This was described in the previous post.  However, that has not driving the weather pattern recently.  Instead the jet stream has retreated to the north leaving upper-level low pressure systems isolated from the main flow.  This has resulted in a blocking pattern where weather systems slow to a crawl and can persist for days.

The weather pattern at 500 mb (~18,000 ft) on Saturday, May 4, 2013 at 12z UT.  The jet stream had retreated farther to the north leaving isolated pockets of low pressure over the mid-latitudes.  Click on the image for a larger version.  Image Credit: WLTX-TV.

A Dramatic Change This Spring

It is amazing how fast the weather pattern can change.  Temperatures were much below normal at the end of March.  There was a brief warm up at the beginning of April, but a brief cool snap followed.  Finally the cold air retreated leaving much of South Carolina with above normal temperatures.  In a matter of five days high temperatures in Columbia went from 55 degrees F on April 4^th to 87 degrees F on April 9^th & 10^th.

A previous post talked about the delay of spring this year.  High pressure centered near Greenland continued to pump cold Arctic air south into North America.  This was part of the negative phase of the Arctic Oscillation which became extreme in March.  This led to colder temperatures in March than in January.

This image shows the sea level pressure anomaly calculated from NCEP climate reanalysis data from February 25 through March 25, 2013. The area of anomalous high pressure over Greenland illustrates the negative phase of the Arctic Oscillation, by which persistent high pressure blocks Arctic air from moving eastward, causing it to drop down into the middle latitudes and is a contributing factor in keeping temperatures unseasonably cool in Canada and the US.  Click on the image for a larger view.  Image Credit: NOAA.

When Weather Becomes Climate

Note: It has been a busy three weeks which included a week of much needed vacation.  Much has happened in the interim.  I am working on a number of posts which will be rolled out in May.

Meanwhile, many people often confuse weather with climate.  You have heard the refrains like it is so cold, how could the earth be warming?  Or how can we be in a drought when we’re having a flood?  Just when does weather become climate?  Good question!  Meteorologists at the European Space Agency have produced an answer to that question.

The following video is about 12 minutes long, but it is well produced and worth the time to view it.  They have a wealth of information with which to determine climate change and it is interesting comparing weather in the early 1800’s to weather today.  I hope you enjoy this production.

Click here: When Weather Becomes Climate

The Rise Of Extreme Weather

Extreme weather has always been with us, but the trend over the past few decades has been for it to increase in number.  The Climate Extremes Index (CEI) was developed by the National Climatic Data Center (NCDC) and goes back to 1910.  It looks at the number of events that occur.  The graph below compares the period of January through October so that data from this year can be included.

The CEI for the period of January - October 1910 - 2012.  Image Credit: NOAA/NCDC.

The CEI with the experimental tropical cyclone indicator included.  Image Credit: NOAA/NCDC.

A new report recently released (before Hurricane Sandy) by Munich Re, the world’s largest reinsurance company, re-enforces this observation.  The report is about the increase in extreme weather over North America.  The report states:

The Growing Season Ends For 2012

Frosts and freezes were common across the midlands of South Carolina this morning.  A few areas saw temperatures drop to freezing on the first of November, but most of those readings were in low-lying protected areas.  However, much of the area saw temperatures to freezing this morning.  A few areas like the city of Columbia still have not reached freezing, but most of the area saw enough frost to end the growing season for the Midlands.

Low temperatures for the first-order stations in South Carolina for Friday, November 9.  Image Credit: WLTX-TV.

Coastal Storm Followed By Cold Weather?

The South Carolina State Fair was lucky and enjoyed great weather for its entire run which ended today.  Dry weather is expected to continue over the Midlands most of the coming week and it will be delightful fall weather.  However, the weather pattern will begin changing this week and the Midlands, as well as much of the East coast, will be challenged by the changing conditions next weekend.

All of the computer models, used for medium-range weather forecasts, are converging on a solution that changes the weather for much of North America.  The change is already underway.  It is happening in the middle troposphere (500 mb) over western Canada where a double-barrel low pressure system is pushing the polar jet stream south from Alaska to California.

The 500 mb chart for 00z, 22 Oct 2012.  Winds generally blow parallel to the contours lines.  Click on the image for a larger view.  Image Credit: WSI.

This will bring colder air south into the western U.S.  The low pressure system will slowly swing east and become an elongated trough of low pressure.  It will extend through the Plains states on Saturday intensifying a surface low pressure system and moving it north toward the Arctic.  At the same time a tropical system will be headed north from the Caribbean Sea into the Bahamas.

Flood & Drought: Part 1

This is the first of a three parts examining changes in the hydrologic cycle, also known as the water cycle.  Our changing climate is changing the water cycle and the weather patterns that deliver precipitation.

Part 1 is a rewrite of a blog post that I published in 2009.  It is as important today as it was then.  Part 2 will be an update of the observed rainfall extremes in the Southeast and U.S.  Part 3 will look at drought and new research as to why drought is becoming more common across the southern U.S.

From 2009:

The idea for this blog came from two sources. The first source was a comment on an earlier story.

In the comment section, a reader wrote:

“By the way, the article above does not inform you that global warming does not cause droughts or dry weather. Global warming would mean MORE RAIN.
I would defer to Mr. Gandy on that though. Am I correct Mr. Gandy, wouldn't global warming mean more evaporation of surface water and snow and more evapotranspiration from plants, causing more rain?”

This seemed intuitive, more water vapor, more rain.  Just over a year ago I was at a panel discussion in Denver, Colorado, where Dr. Kevin Trenberth mentioned that water vapor had increased about 7% globally.  Dr. Trenberth was a lead author of the 2001 and 2007 IPCC Scientific Assessment of Climate Change and serves on the Scientific Steering Group for the Climate Variability and Predictability program.  He currently heads the Climate Analysis Section at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.  This information has since been confirmed in several papers.

The top 10 daily rainfall totals for Columbia, SC.  Click on the image for a larger version.  Image Credit: Climate Central.

The second source came from a recent study (citation below) published 5 September 2009, in the Geophysical Research Letters (GRL).  It has changed my thinking after a careful review of the paper.

Scientists to Study Impacts of Thunderstorms on the Upper Atmosphere

Our thunderstorm season is about to get underway.  Spring is known for severe weather, but summer is known for its afternoon and evening thunderstorms.  These storms build up in the heat and humidity of the day and provide most of the rain during the summer.  A study will be conducted from May 15 to June 30 to measure the impact of thunderstorms on the upper atmosphere.  The following is a press release from the National Center for Atmospheric Research in Boulder, Colorado.

Press Release:

Scientists at the National Center for Atmospheric Research (NCAR) and other organizations are targeting thunderstorms in Alabama, Colorado, and Oklahoma this spring to discover what happens when clouds suck air up from Earth’s surface many miles into the atmosphere.

Thunderstorm in eastern Colorado. (Photo by Bob Henson.)

The Deep Convective Clouds and Chemistry (DC3) experiment, which begins the middle of this month, will explore the influence of thunderstorms on air just beneath the stratosphere, a little-explored region that influences Earth’s climate and weather patterns. Scientists will use three research aircraft, mobile radars, lightning mapping arrays, and other tools to pull together a comprehensive picture.

“We tend to associate thunderstorms with heavy rain and lightning, but they also shake things up at the top of cloud level,” says NCAR scientist Chris Cantrell, a DC3 principal investigator. “Their impacts high in the atmosphere have effects on climate that last long after the storm dissipates.”

Past field projects have focused on either the details of thunderstorms but with limited data on the atmospheric chemistry behind them, or on the chemistry but with little detail about the storms themselves. DC3 is the first to take a comprehensive look at the chemistry and thunderstorm details, including air movement, cloud physics, and electrical activity.

Winter Was Warm, But March Is %#!@^

Winter was the fourth warmest on record for the U.S. according to the National Climatic Data Center (NCDC).  Here winter is defined as the months of December through February, also known as meteorological winter.  The map below shows that most of the warm weather was east of the Rockies with near normal conditions in the West.

Statewide rank of winter temperatures for 2011-2012.  Image Credit: NOAA/NCDC.

Enter March.  This supposed to be a time of change, a transition from winter to spring.  However, this month has simply been a continuation of the trends in winter and more so.  It has been unseasonably warm over all, but the west coast of the U.S.  In fact, temperatures have been averaging more than 10 degrees F above normal in the Midwest.

Mean temperature anomalies for the U.S. for March 1-16, 2012.  Image Credit: NOAA/CPC.

Goodbye Mr. Snowman

Image Credit: Climate Central.

Not a snowflake to be had this winter.  Even Jack Frost didn't show much over the winter.  There were cold snaps and hard freezes, but little precipitation.  In mid-February there was some sleet mixed with light rain, but this was the closest we came to wintry precipitation.

This was the 10th warmest winter on record and the 12th driest for the Columbia area.  It was the warmest winter in 40 years with records dating back to 1887.

Some Drought Relief

The winter has been warm and dry for much of the Southeast.  Weather patterns have been quite dry and much of the area has been slipping farther into drought.  The worst stage drought (exceptional drought) first showed up across southern Georgia about a month ago.

The exceptional drought as of last week stretched from southeast Alabama across southern Georgia into the low country of South Carolina.  Almost all of the low country of South Carolina was in extreme or exceptional drought and that extended along the Savannah River to north of Augusta.  Farmers in South Carolina were being hurt by the weather and high fuel prices as seen here.

What’s Causing the Deadly Cold in Europe?

The weather pattern responsible for bringing frigid air to Europe, like this heavy snow fall on the Colosseum in Rome, is driven in part by a naturally-occurring pattern known as the Arctic Oscillation. 

This is a repost from Climate Central 

By Andrew Friedman 

While the U.S. cruises through winter with a snow drought and above-average temperatures, much of Europe and Eurasia are locked in the grips of a deadly cold air outbreak, with more than 300 people reported dead so far. According to news reports, entire communities in Italy, Bosnia, and Romania have become inaccessible due to heavy snowfall and power outages. According to Sky News, a dam in Bulgaria burst due to the combination of snowmelt and heavy rains, killing four people in a village downstream, and other dams in Southeastern Europe are also being threatened. Bosnia, Serbia, Macedonia and Turkey are at risk for heavy snows during the next few days.

According to U.S. News and World Report, the wintry blitz presents a poorly-timed challenge to European economies, which already are struggling to contain a debt crisis:

"In more robust economic times, the economic effects of bad weather might be nothing more than bump in the road, but in a place already teetering on the brink of recession, the stakes are higher."

"[E]ven relatively limited disruption from snow and freezing conditions could very well be enough to tip the balance towards the economy suffering further contraction in the first quarter of this year, which would put it officially back into recession," writes Howard Archer, chief European and UK economist of IHS Global Insight, in a commentary on the cold snap.

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According to Bloomberg News, 93 stations from the Czech Hydrometeorological Institute reported the lowest-ever temperatures for February 5, with one station bottoming out near -38°F. In Ukraine, the cold has killed at least 131 people, and nearly 2,000 were hospitalized due to hypothermia.

Ice has forced Austria to close the Danube river to navigation, shutting down access to part of the second-longest river in Europe. In addition, the iconic canals of Venice were reported to be frozen as well.

What's Going On?