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. 

A Cold End to January 2014

A weather pattern we have seen many times since late October, 2013, has reappeared in its amplified form.  The ridge of high pressure in the upper atmosphere has been building since late last week along the Pacific Coast, stretching from northwest Mexico to Alaska.  This has pushed the jet stream far to the north into Alaska and the Yukon. 

The 500 mb pattern for North American at 00z January 21, 2014.  Click on the image for a larger view.  Image Credit: WLTX-TV.

The result has been unseasonably warm temperatures for this time of year.  It is still cold, but in Fairbanks the temperature averaged 24° F above normal on Monday.  There have been wild swings in Fairbanks, AK, this month with its coldest temperature of -41° F on January 12^th & 13^th, and its warmest temperature at 34° F on January 17^th.  On that day the temperature averaged 32° F above normal.

Alaskan temperatures at midnight January 21, 2014.  These are warm readings for central Alaska in January.  Click on the image for a larger view.  Image Credit: WLTX-TV.

The Polar Vortex & More

The first major North American weather event of 2014 was the cold Arctic outbreak in the first week of January.  The term polar vortex became the buzz word (in the media) for the cold outbreak, though it was much more.  As a previous post notes this was a pattern extending back to late October of 2013.

The term polar vortex has been around since the 1940s.  From the American Meteorological Society Glossary of Meteorology:

Polar vortex - (Also called polar cyclone, polar low, circumpolar whirl.) The planetary-scale cyclonic circulation, centered generally in the polar regions, extending from the middle troposphere to the stratosphere.

The westerly airflow is largely a manifestation of the thermal wind above the polar frontal zone of middle and subpolar latitudes. The vortex is strongest in winter when the pole-to-equator temperature gradient is strongest. In the Northern Hemisphere, the vortex has two centers in the mean, one near Baffin Island and the other over northeast Siberia.

I prefer to use the term Arctic outbreak to describe what happened in early January.  The polar vortex was involved, but the overall pattern was much more than the polar vortex.  The winds in the upper atmosphere plunged from northwestern Canada into the southeastern U.S. due to an amplification of the ridge of high pressure off the West coast and the deep trough over the eastern part of North America.

NASA put together a movie of temperature observations from NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft.  The Atmospheric Infrared Sounder, AIRS, in conjunction with the Advanced Microwave Sounding Unit, AMSU, sense emitted infrared and microwave radiation from the Earth to provide a three-dimensional look at Earth's weather and climate. Working in tandem, the two instruments make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, three-dimensional map of atmospheric temperature and humidity, cloud amounts and heights, greenhouse gas concentrations, and many other atmospheric phenomena. The AIRS and AMSU fly onboard NASA's Aqua spacecraft and are managed by the Jet Propulsion Laboratory, Pasadena, California, under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

The temperatures shown are at a pressure of 850 hectopascals (hPa, also known as 850 mbs) which is at an altitude of 4500 to 5000 feet over much of the U.S. It begins on December 1, 2013 and runs through January 7, 2014.  The most obvious feature of the movie is the tongue of cold air moving out of Canada and southward to cover much of the eastern United States during early January 2014.

This is a picture of the last day of the movie, Tuesday, January 7, 2014.  The dark blue areas start at -12° C and become purple at -24° C.  This was the farthest extent south and the surface temperature dropped to 13° F in Columbia, SC, with a wind chill temperature of 3° F.  Click on the image for a larger view.  Image Credit: NASA.

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.

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.

Spring 2013: DELAYED

It’s spring!

The vernal equinox on March 20, 2013.  It is that time of year again (it happens twice) when the relative angle of Earth is perpendicular to the Sun, causing equal incoming solar energy to the Northern and Southern hemispheres - as well as equal day and nighttime. At 7:02 ET on March 20, 2013, Earth was at its equinox. At 7:45 ET, the GOES-13 satellite captured this full disk image of Earth.  Click on the image for a larger view.  Image Credit: NOAA.

Both meteorological and astronomical springs have arrived.  The vernal equinox marks the beginning of spring in the Northern Hemisphere.  This is when the vertical rays of the sun are directly over the earth’s equator and crosses the equator on its northward journey.

Funny, it doesn’t feel like spring.  Let me check the forecast:

The 5-day forecast for March 20, 2013 for Columbia, SC.  Image Credit: WLTX-TV.

Remember those groundhog forecasts from six weeks ago.  A couple of them got it right, but most got is wrong.  Not only did spring not come early, it does not appear to be in sight.

A Change In The March 2013 Outlook

The Climate Prediction Center (CPC) issues outlooks for the next month in the middle of the current month.  They will often issue an updated outlook near the last day of the current month.  Usually these projections do not vary much, but this month saw a substantial revision.

Computer models designed to forecast daily weather are run out to 15 days, four times each day.  Most are familiar with the 7-day forecast.  The CPC also issues 8-14 day outlooks for the second week of the forecast in additions to the monthly and seasonal outlooks that they make each month.

Beginning with the 8-14 day temperature outlook on February 21 and the one issued on February 28, it seems that the first half of March would be colder than normal for South Carolina as seen in the outlooks below.

The 8-14 day temperature outlooks.  The first one made February 21 and the second one (right) made February 28.  Click on the image for a larger view.  Image Credit: NOAA/CPC.

The reason for this projection is that the Arctic Oscillation (AO) has been in a negative phase with the forecast for it to become strongly negative next week.  This usually produces a cold outbreak for parts of the U.S.  Last year the AO was strongly positive and the U.S. saw the warmest March on record.

Bad Place For Science

Two recent editorials in Investor’s Business Daily (IBD) are examples of why you don’t want to get your science from the editorial page.  The paper touts its views as conservative, but these examples are either meant to mislead or are out of ignorance.  They deserve to be put to rest once and for all.  You can read them here and here.

The first editorial attacks the notion that there is no consensus on climate change.  It uses a study published in November and can be read here.  The first red flag in the editorial is that they never mention where the study is published.  However, it did not take long for me to track down the paper.

It seems that the editorial originated with James Taylor, managing editor of The Heartland Institute’s Environment and Climate News, with a post he wrote on the Forbes website.  The original post on Forbes and thus the editorial in IBD have been thoroughly debunked here, here, and here.

Brian Angliss of Scholars and Rogues writes:

“The reality is that, contrary to claims made by Taylor and others at Heartland, every serious attempt to measure the degree of consensus among scientists and climate experts has concluded that the overwhelming majority of experts agree that climate is changing rapidly, that humans are the dominant drivers of the changes, and that model projections indicate that the changes will be highly disruptive if they’re not planned for. And every attempt to disprove the reported consensus has been disproved or shown to be based on distortions. Just like this attempt by Taylor has been.”

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:

Winter Outlook for 2012-13

The Climate Prediction Center released its early outlook for the upcoming winter this morning.  Much of the western U.S. will see warmer than normal temperatures while cooler than normal temperatures are expected for the Florida peninsula.  Equal chances of above or below normal temperatures are forecast for much of the East.

Much of the West will be dry particularly in the Pacific Northwest.  The Central Gulf region is expected to be wetter than normal.  This may help ease the drought in Georgia and South Carolina.

Click on either graphic for a larger version or go here for the temperature map and here for the precipitation map.  Image Credit: NOAA\CPC.

The Effects of Losing Arctic Sea Ice

A dramatic loss of Arctic sea ice occurred this year resulting in a record-shattering minimum in mid-September.  The implications were touched upon in a previous post.  However, it is recognized that the loss of Arctic sea ice is changing the ecology, geology, and meteorology of the region.

I will focus on the meteorology in this post.  The Arctic is warming at a rate that is twice that of the mid-latitudes in a phenomenon known as arctic amplification.  This faster warming is reducing the temperature gradient between the high and mid-latitudes which in turn is changing the dynamics of the jet stream.

Image Credit: NOAA.

The jet stream is a river of high velocity winds in the atmosphere.  It meanders generally from west to east around the globe.  The speed of the wind in the jet stream is usually stronger in the winter than in the summer, because the north-south temperature gradient is much stronger in winter.

A cross-section of the atmosphere shows how the lowest layer of the atmosphere, the troposphere, changes from the equator to the pole.  There are three circulation cells in the northern hemisphere and the jet streams are at the upper boundaries of the cells.  The jet stream helps to drive storm systems across the country so that knowledge of its future helps forecast future weather.

Arctic Sea Ice Matters

A record low in the Arctic sea ice extent occurred on September 16, 2012 and it was the lowest in the satellite record which started in 1979. Even more troubling was that this year also saw a record low in sea ice volume.

Click on the image for a high-resolution version. Image Credit: NSIDC.

The previous record minimum extent occurred in 2007.  What was extraordinary about this year was that weather conditions were not as favorable for melting as in 2007.  That year was noted for long periods of sunshine which allowed the ice to melt over much of the Arctic.  This year came on the heels of a cold winter in which the ice extent came close to normal.  There were more clouds and a powerful storm which hit the Arctic in early August which helped to break up more of the thin ice.

Click on the image for a high-resolution version. Image Credit: Climate Central.

ICE vs STORM: 2012's Great Arctic Cyclone

The Arctic region is warming twice as fast as much of the rest of the globe.  This is transforming the climate and the weather.  A storm earlier this month portents much of what can be expected as the sea ice melts.  In fact this storm may have hastened the melt, but this is still an open question.  The following is a very interesting article posted on NCAR's website.

By Bob Henson

As Shakespeare noted about true love, the course of Arctic sea ice never does run smooth. Even though weather conditions in June and July weren’t especially favorable for melting, the ice vanished at a striking pace. Then came a midsummer tempest—and now 2012 threatens to break 2007’s records for the lowest extent of Arctic sea ice ever observed.

I knew something was afoot when I turned to the indispensible Arctic Sea Ice Blog a few days ago and saw the headline “Cyclone warning!” Computer models were indicating that a vast, powerful area of low pressure would develop over the central Arctic Ocean and stay in place for days. The storm didn’t last quite as long as forecast, but it was indeed a humdinger, one that could stimulate research for years to come.

This mosaic of NASA/MODIS satellite images from August 5 shows a massive low-pressure center spinning across the central Arctic Ocean on August 5, 2012. Canada and Alaska are located to the left, with Europe and Russia to the right. (Image courtesy NASA Earth Observatory.)