Weather Extremes

Wild Week of Weather for the U.S.

By: weatherhistorian, 7:50 PM GMT on April 29, 2014

Wild Week of Weather for the U.S.

After a relatively quiet first three weeks of April weather-wise, the past five days have made up for lost time. Top of the list, of course, has been the deadly tornado outbreaks on April 27-28. In addition, heavy snow in the Rockies and Black Hills has also occurred as well as some extreme heat and amazing rainfall and hail events.

Tornado Outbreak

As of midday April 29th, the death toll from the tornadoes on April 27th and 28th officially stands at 34. There were at least 97 tornado reports over the two-day period but some of these may have been reports of the same storm so the actual number of tornadoes that formed was probably less than this. Jeff Masters has posted a detailed blog about the tornado events today (April 29th) already so I will not go into further details about the event (other than to note that since he posted his blog the two-day death toll has now increased from 29 to 34).



An aerial view of some of the damage caused by a tornado in Mississippi on April 28th. It is expected that at least one of the tornadoes to hit the state was of EF-4 intensity. NBC News.

Hail

As usual, very large hail accompanied many of the super cells that produced the tornadoes, with 1”-2.5” diameter hailstone reports being common. However, it was a storm in Mississippi last Friday (April 25th) that was particularly noteworthy. Observers in the town of West in Holmes County, Mississippi reported hail up to 4.25” in diameter. Although Mississippi does not officially keep track of record hailstone size events (as a handful of other states do, (see this blog for a list of such), the 4.25” figure would be the largest hail ever observed in Mississippi if the estimate was accurate. The previous largest hailstone report from the state was a 4.0” monster that fell on Batesville during the catastrophic tornado outbreak of April 27, 2011.



A map of the hail streak that hit Holmes County, Mississippi on April 25th and the accompanying hail report. From hailtrends.com

Heat

Corpus Christi, Texas recorded their hottest temperatures ever measured during the month of April on the 27th and 28th with 103°F (39.4°C) readings both days. The previous April heat record was 102°F (38.9°C) set on April 23, 1955 and also on April 26, 1984. Laredo, Texas reached a scorching 109°F (42.8°C) on April 27th which, though amazing, fell well short of their April heat record of 112°F (44.4°C) also set on April 27th back in 1937.

Snow

Heavy late April snowfall is not uncommon to the Rocky Mountain States or the Black Hills of South Dakota but is worthy of mention since it occurred simultaneously with the heat and tornado events of the past several days. Some sites in the Black Hills, like Lead, have measured up to 24” of snow since Sunday (and 15" in Deadwood) and it is still snowing where an additional 4-8” is expected today (April 29th). Heavy snow accumulated in the Colorado Rocky Mountains over the past weekend with one to two-foot depths common. Red Mountain Pass reported 30”. Snow flurries and showers also invaded portions of central Nebraska and Kansas on Monday April 28th on the backside of the powerful low pressure system that was responsible for the severe weather outbreaks to its east. Places that reached near 90°F (32.2°C) on Saturday (April 26th) in Kansas saw some snowflakes just a few days later, as was the case in Goodland, Kansas that went from 86°F (30°C) on Saturday to light snow and temperatures in the mid-30°s this Tuesday morning (April 29th).

Rainfall

Some of the severe storms that plagued the south-central and southeast portions of the country also brought torrential rainfalls and local flooding problems. Locations in northeastern Arkansas and southern Missouri saw 5”-6” of rain fall in a 24-hour period Sunday-Monday. The most impressive report, however, was the 4.00” of rain that deluged Mobile, Alabama in one hour Tuesday (April 29th) morning between 2 a.m. and 3 a.m. The storm total so far for the day has been 8.99”. Late reports now indicate 5.68" in one hour at Pensacola, Florida between 8:53 p.m-9:53 p.m. on April 29th with an estimated 15.50" daily total although the gauge only actually only measured 11.13" prior to failing around 10:30 p.m. April 29th. The data from Pensacola Airport ceased to report after this hour. At least one fatality has been reported due to flooding in the area. According to the estimated 15.50” at Pensacola on April that NWS-Mobile now has published, the Pensacola April 2014 monthly rainfall stands at  24.61” (this does not include any precip that fell on April 30th). Nevertheless, 24.61” would surpass the previous all-time monthly record (for any month) for Pensacola which was 24.46” in April 2005.

Also, depending on how much rain fell between the 5:53 a.m. April 29 and 5:53 a.m. April 30th the all-time 24-hour record of 17.07” on October 4-5, 1934 may have been broken, assuming that at least an additional 1.57” fell between midnight April 29 and 5:53 a.m. April 30th.



A photograph of street flooding in downtown Mobile during the intense rain event early morning on April 29th. Image tweeted to NWS-Mobile.

More severe weather is expected today and Wednesday, April 29th-30th in the Southeast.

Christopher C. Burt
Weather Historian

Extreme Weather

Updated: 7:51 AM GMT on May 01, 2014

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Snowiest Season on Record for Some U.S. Cities

By: weatherhistorian, 8:20 PM GMT on April 25, 2014

Snowiest Season on Record for Some U.S. Cities

A late season snowstorm deposited up to 13.5” in northeastern Minnesota (near Gunflint Lake) yesterday April 24th, with 4.3” accumulating at the official NWS site in Duluth. This brings Duluth’s seasonal snowfall total up to 129.6”, 3rd greatest total on record and just shy of the 135.4” measured during the winter of 1995-1996. However, several cities have already broken their seasonal snowfall records. Here’s a brief recap.



Many cities in the Upper Midwest and Northeast ‘broke the bank’ so far as their snow removal budgets were concerned this past winter season. A late-season blizzard pounded Cape Cod on March 26th as this scene from Hyannis illustrates. Photo by Darren McCollester/Getty Images.

Although the snowfall season of 2013-2014 doesn’t officially end until June 30th, it is unlikely that any additional snowfall will accumulate in any cities east of the Great Plains except, perhaps, in the far northern portions of the Great Lakes and the Northeast.

Duluth, Minnesota is perhaps one of those places that may yet see some additional snowfall. Its normal May snowfall total is 0.4” but, in May 1954, 8.1” fell and a 24-hour-May-snowstorm record of 5.5” occurred on May 10, 1902. With the 4.3” that fell on April 24th (yesterday), the city needs an additional 5.8” to tie its all-time seasonal record of 135.4” set in 1995-1996:

TOP FIVE SNOWIEST WINTER SEASONS IN DULUTH

1. 135.4” 1995-1996
2. 131.8” 1949-1950
3. 129.6” 2013-2014 (as of April 24th)
4. 129.4” 2012-2013
5. 128.2” 1996-1997



Just another snowy winter for the hardy souls of Duluth, Minnesota. Photo by Bob King/The Duluth News-Tribune.

Another city that is likely to see additional snowfall in May is Billings, Montana, which has already experienced its snowiest season on record with 101.4” so far. Their May average snowfall is 2.0” and they once saw 15.0” in a single day on May 11, 1981!

Here is a list of sites that have already experienced their snowiest winter on record (totals are as of April 24th):

Billings, Montana 101.4” (previous record 98.7” 1996-1997)

Detroit, Michigan 94.9” (previous record 93.6” 1880-1881)

Flint, Michigan 83.9” (previous record 82.9” 1974-1975)

Petoskey, Michigan 184.4” (previous record 183.9” 1970-1971)

Toledo, Ohio 86.3” (previous record 74.9” 1977-1978)

Rhinelander, Wisconsin 107.8” (previous record 107.0” 1938-1939)

Spooner, Wisconsin 109.4” (previous record 95.5” 1898-1899)

Jeff Masters reported that Ann Arbor, Michigan (his home town) has already broken its seasonal record with 97.0” (prior record 89.8” in 2007-2008). Of course, Detroit is the most significant site among those listed above, being one of America’s major cities and having a POR (period of record) dating back to 1880. Detroit also broke its record for single-snowiest-month when 39.1” fell this past January, surpassing the previous record for such of 38.4” in February, 1908.

Other major cities that came very close to experiencing their snowiest season, include Chicago with 88.4”, just shy of their all-time record 89.7” set in 1978-1979 (with a POR dating back to 1894) and Indianapolis with 55.4” shy of their record 58.2” in 1981-1982. Fort Wayne, Indiana had its 2nd snowiest season on record with a 74.7” accumulation (the record being 81.2” in 1981-1982). However, Fort Wayne did experience its single-snowiest-month (any month) ever observed with 30.3” this past January, previous record was 29.5” in January 1982.

Meanwhile, in the West it has been a schizophrenic winter season with near record low seasonal snowfall in California, Arizona, southern Oregon, and much of Nevada, while much above normal snowfall has fallen in the central and northern Rocky Mountains. Jackson, Wyoming is being threatened by a slow moving landslide caused, in part, by winter precipitation (mostly snowfall) running 150% of normal.



Map of percent of normal snow water content as of April 23rd in the West. Map from the WRCC.

I’m sure that once all the facts are in (so far as seasonal snowfall totals) we will see additional all-time winter snowfall records for some other sites in the Rocky Mountain States and Upper Midwest.

Christopher C. Burt
Weather Historian

Extreme Weather Snow

Updated: 3:59 AM GMT on April 30, 2014

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March 2014 4th Warmest Globally

By: weatherhistorian, 6:59 PM GMT on April 22, 2014

March 2014 4th Warmest Globally

NOAA released its global March 2014 summary today (April 22nd) which stated that it was the 4th warmest March on record over global land and ocean surfaces since 1880. The global average temperature for the month was 12.3°C (54.1°F) which was 0.71°C (1.28°F) above the 20th century average.



March 2014 land and sea surface temperature anomalies in degrees Celsius. NOAA



March 2014 land and sea surface temperature deciles. NOAA

As can be seen in the above maps, March was much warmer than normal across all of Europe and Asia aside from the sub-continent of India and surrounding areas. The month was the warmest March on record for South Korea and Slovakia and ranked in the top three such for Austria, Norway, Latvia, and Germany. Other sources claim it was actually the warmest March on record for Germany. On the other hand, it was one of the coldest March’s on record for portions of eastern Canada and the Upper Midwest and Northeast of the U.S.A. In spite of this, the Arctic Sea Ice Extent was 4.7% below the 1981-2010 average and the 5th smallest for March since satellite records of such began in 1979. However, in Antarctica the ice extent was 20% above the 1981-2010 average and 3rd largest March extent on record.



Global and hemispheric land and ocean surface mean temperature anomalies for the entire POR of 1880-present. NOAA et al.

NASA concluded in their analysis that March 2014 globally was also the fourth warmest such on record. The warmest March was that of 2002 followed by 2010 and 1990. The NASA statistics can be found here.

I posted last week a blog titled ‘March 2014 Global Weather Extremes Summary’ with some details about specific extreme weather events that occurred during the month.

For the complete NOAA March 2014 Global Analysis report see this posting here.

Christopher C. Burt
Weather Historian

Updated: 11:42 PM GMT on April 22, 2014

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A Warm Winter in Alaska

By: weatherhistorian, 7:27 PM GMT on April 18, 2014

A Warm Winter in Alaska

In contrast to much of the contiguous U.S., the National Weather Service (NWS) in Alaska noted in a post this week that Alaska has enjoyed its third warmest ‘winter’ on record for 2013-2014. The period of time they are calling ‘winter’ is for the six months of October 2013 through March 2014. Here are a few details.

According to the NWS statement, statewide it was the 3rd warmest October-March period for Alaska surpassed only by the October-March periods of 2000-2001 and 2002-2003. For some sites it was actually the warmest such period on record. This was the case for Barrow, Kotzebue, McGrath, and Cold Bay. All of the state was much milder than normal except for the Southeastern Panhandle where temperatures were normal to slightly below normal.



Map of various sites in Alaska and how each ranked in terms of being the mildest October-March period for their respective POR’s. Southeastern Alaska (which was not included on the map) experienced normal to slightly below normal temperatures. Map from NWS-Alaska.

For the four sites that recorded their warmest October-March period on record (Barrow, Kotzebue, McGrath, and Cold Bay) here are the statistics:





For Cold Bay, the last month with a below normal than average temperature was May 2013. For Barrow, Kotzebue, and McGrath, September 2013 was the last such.

The mild winter in Alaska is in sharp contrast to that in the eastern portions of the contiguous U.S. where Marquette, Michigan just observed a -5°F temperature on April 16th: its coldest such reading for so late in the season and also the latest date for a zero or below temperature ever observed. As of April 17th some 28” of snow still lies on the ground (18.3” of which fell in the past four days). Additionally, Lake Superior is clogged by the most ice (34% coverage) for this time so late in the season since accurate measurements of such began in 1973.

KUDOS: Thanks to Rick Thoman of NWS-Fairbanks for bringing this to my attention.


Christopher C. Burt
Weather Historian

Updated: 5:26 AM GMT on April 19, 2014

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March 2014 Global Weather Extremes Summary

By: weatherhistorian, 8:45 PM GMT on April 15, 2014

March 2014 Global Weather Extremes Summary

March featured a number of anomalous extreme weather events such as the floods in portions of Egypt and New Zealand, a freak hailstorm in Asmara, Eritrea, record warmth in much of Europe, severe cold and snow in the eastern half of the U.S. and heavy rainfall in the Pacific Northwest that culminated in a deadly landslide in Washington. Preliminary data from NASA indicates that globally (land-ocean temperature index), it was the 4th warmest March on record (since 1880).

Below are some of the month’s highlights.

NORTH AMERICA

It was a long cold month for the eastern and midwestern U.S. with temperatures averaging 7°-10°F (4°-7°C) below normal. In fact, it was the coldest March on record for Vermont and 2nd coldest for Maine and New Hampshire. A blizzard pounded Cape Cod and Nantucket on March 26th where wind gusts reached 83 mph and 10” (25 cm) of snow fell. Ice coverage on Lakes Michigan and Superior reached their 2nd greatest extent since comprehensive records for such began in 1973. In the West a series of wet storms pounded Washington State resulting in a tragic landslide in the town of Oso where at least 39-45 people died.



An aerial view of the tragic landslide at Oso, Washington that resulted in at least 39 fatalities. Photo by Washington State Patrol.

The airport in Seattle (Sea-Tac) measured 9.44” (240 mm) of precipitation; a March record for the site and Portland, Oregon measured 7.52” (191 mm) for its 2nd wettest March. On the other hand, no precipitation was measured in Las Vegas, Nevada tying with six other March’s for the driest such. Drought conditions worsened in the southern Plains and Southwest.





Temperature (top map) and precipitation (bottom map) rankings by state for March. It was Vermont’s coldest on record and Montana’s 3rd wettest. NCDC.

Alaska has gotten off to its 3rd warmest start to the year and in Barrow it was the 3rd warmest March since records began there in 1921.

The coldest temperature observed in the northern hemisphere during March was -63.3°C (-81.9°F) at Summit GEO site, Greenland on March 23rd.

SOUTH AMERICA and CENTRAL AMERICA

Following the extreme rainfall in Asuncion, Paraguay on February 27th, more extreme rainfall deluged the country between March 14-18.

EUROPE

March was the warmest such on record for Germany and many other locations in Europe. In Germany the March average temperature was 7.0°C (12.6°F) above normal beating out the March’s of 2012 and 1989, the POR going back to 1881. The temperature peaked at 24.1°C (75.4°F) at Sachsenheim on March 20th and the coldest temperature observed in the country during the entire month was a relatively mild -8.6°C (16.5°F) at Oberstdorf on March 26th. Record March heat was observed at many locations across the continent including 19.8°C (67.6°F) in Moscow. For more details on the European March warmth see my blog of March 19th and also on March 12th.

In the U.K. it was also warmer than normal (1.2°C/2.2°F above average) but not on the scale observed in other parts of Europe. Precipitation ran at 85% of the long-term average. The warmest temperature measured during the month was 20.9°C (69.6°F) at St. James Park (London) and Santon Downham, Suffolk on March 30th and the coldest -6.8°C (19.8°F) at Redesdale Camp, Northumberland on March 24th. The greatest 24-hour precipitation measured was 78.8 mm (3.10”) at Cluanie Inn, Highland on March 19-20.

AFRICA

A freak hailstorm battered Asmara, Eritrea on March 12th. See my blog of March 17th for details. Photo from TesfaNews, Asmara.



Hail drifts some one meter thick accumulated in downtown Asmara, Eritrea on March 12th.

Also of note was the exceptional rainstorm that deluged portions of the Upper Nile in Egypt on March 9-10. Luxor picked up 30 mm (1.18”) during the event. It’s average annual rainfall is just a little over 1 mm (.04”).

The hottest temperature measured in the northern hemisphere and on earth during March was 45.5°C (113.9°F) at N’guigmi, Niger on March 30th. The Comoros Islands came within 0.1°C of setting its all-time national heat record on March 23rd when a temperature of 35.5°C (95.9°F) was observed at Grande Comore Airport.

ASIA

Torrential rainfall pounded southern China and Hong Kong on March 30th with 174 mm (6.85”) measured in 24 hours at Guangzhou (Canton).

The Kashmir of India and Pakistan experienced a tremendous snowfall on March 10-12 with Srinagar, India picking up 211 mm (8.31”) of melted precipitation and the snowfall ranging from 25-60 cm (10-25”) in and around the city. Avalanches resulted in the deaths of at least 16 and injured 30 in the region.



Trucks stranded along the Srinagar-Jammu National Highway near Qazigund during the heavy snowfall of March 10-12. Photo from The Hindu newspaper.

AUSTRALIA

March was warmer than average overall and the 7th warmest on record for Western Australia. Precipitation was 34% below the long-term average nation-wide although some extreme rain events resulted in flash floods in parts of Queensland and New South Wales. A two-day rainfall of 557 mm (21.93”) was measured at Pacific Heights in Yeppoon, Queensland on March 27-28.






Temperature deciles (top map) and precipitation deciles (bottom map) for Australia during the month of March Maps courtesy of the Australian Bureau of Meteorology.

The highest temperature observed in Australia and the southern hemisphere during March was 44.6°C (112.3°F) at Roebourne Aero, Western Australia on March 7th and the coldest -0.7°C (30.7°F) at Mount Hotham, Victoria on March 17th. The greatest calendar day rainfall was 324.6 mm (12.78”) at Pacific Heights, Queensland on March 27.

NEW ZEALAND

A terrific storm, said to be the worst in 40 years, battered Christchurch, South Island on March 3-5. For details see my blog of March 7.



Flooding in Christchurch following the storm of March 3-5 which dropped 100-150 mm (4”-6”) of rain on the city in just 24 hours. Photo by Joseph Johnson.

Precipitation was low again (50% of normal) for most of the North Island following a dry February. Many locations ranked in their top three for driest March on record. Hamilton experienced its second driest March on record with only 6 mm (0.24”) of rain (POR 1935, 7%), and Palmerston North had 9 mm (0.35”), driest on record for March (POR 1928, 14%). The South Island was drier on the western side and wetter in the east and south. Christchurch had its wettest March on record, 200mm (7.87”) (POR 1863, 467%) as a result of the big March 3-5 storm. On the west coast of the South Island Westport had just 25mm (0.98”), its driest ever March (POR 1944, 18%).

The highest temperature measured during the month was 30.8°C (87.4°F) at Wallaceville, North Island on March 16th and the coldest -3.3°C (26.1F) at Pukaki Airport, South Island on March 25th. The greatest calendar day rainfall was 153 mm (6.02”) at Lyttelton, South Island on March 4th.

ANTARCTICA

The coldest temperature in the southern hemisphere and the world during March was –74.5C (-102.1°F) recorded at Dome A on March 22nd. This was close to the coldest March temperature ever measured in Antarctica during a March which was -76.1°C (-104.1°) at Ago 4 site some years ago (this site is now closed).

KUDOS Thanks to Maximiliano Herrera for global temperature extremes data, Jeremy Budd and NIWA for New Zealand data, and Michael Theusner of Klimahaus for the German statistics.

Christopher C. Burt
Weather Historian

Extreme Weather

Updated: 1:08 AM GMT on April 17, 2014

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Persistent Drought Still Reigns in Much of Texas

By: weatherhistorian, 8:32 PM GMT on April 11, 2014

Persistent Drought Still Reigns in Much of Texas: The case Of Lubbock

Although much attention has (rightly) been focused on the extreme drought in California, it seems that we’ve almost forgotten about how intense and long-lasting the drought has been for much of central and northwestern Texas. This drought developed a long three and half years ago and, in some localities, it is far and away the worst drought on record. That’s the case in Lubbock.



The latest (April 8th) drought monitor for Texas. While the drought situation has improved for far western Texas it remains extreme to exceptional for 27.6% of the state, with the Panhandle and central regions worst affected including Lubbock. NOAA et al.

Since January 1st Lubbock has received just 0.47” of precipitation versus a normal to-date (April 10) of 2.91”. More astonishing is the 32.91” total since October 1, 2010 (normal would be 63.81”). This is not only the driest 3 and a half-year period on record but surpasses the previous record for such by the amazing margin of 8.28”. The average annual precipitation for Lubbock (POR 1981-2010) is 19.12”.



Driest 42-month periods on record for Lubbock, Texas (since 1911). The previous driest such period (aside from this year) was that ending on April 30, 1955 when a total of 41.19” was measured versus the current 32.91”. Note that the great Dust Bowl drought of the 1930s ranks in third place with a 42-month total of 42.41” ending on April 30, 1936. Table from NWS-Lubbock.



The persistence of the drought in Lubbock can be seen in this monthly drought monitor graphic (it chart begins in January 2000) which shows that the city has been in a severe to exceptional drought situation since early 2011, more than three years. Graphic from NWS-Lubbock.

As a consequence of the prolonged drought, dust storms have become regular occurences for Lubbock and other drought-stricken regions of western and central Texas. There have been nine significant such events in Lubbock since the beginning of this year.



A massive dust storm looms over Lubbock’s Texas Tech’s football stadium at Jones AT&T Stadium. This event occurred last October. Photo by Scott Lacefield.

Christopher C. Burt
Weather Historian

Extreme Weather Drought Mini Blog

Updated: 6:18 AM GMT on April 18, 2014

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Slow Start to Tornado ‘Season’ but Watch out for April

By: weatherhistorian, 8:33 PM GMT on April 09, 2014

Slow Start to Tornado ‘Season’ but Watch out for April

So far it has been a relatively quiet tornado year across the U.S. with no EF-3 or stronger tornadoes yet reported, the latest in the year for such since at least 1950. However there are almost three weeks left to go in what historically has been one of the deadliest months for tornado outbreaks.



Satellite image of the Southeast on the afternoon of April 27, 2011 during the peak of one of the worst tornado outbreaks in U.S. history. It was the 2nd (or tied for 2nd) deadliest April tornado outbreak on record and the 4th deadliest such for any month of the year. Image from Wikicommons.

The ‘modern’ era of tornado observations is generally accepted as beginning in 1950 when the U.S. government-funded ‘Tornado Project’ was implemented with the establishment of an observational network of 134 stations and 34 cooperative stations across Oklahoma and Kansas. These sites were devoted to reporting, analyzing, and forecasting tornadoes. In 1953 the Severe Local Storms Center (SLSC) was established as part of the U.S. Weather Bureau and also in that year the first popular yet scholarly book about tornadoes was published by the University of Oklahoma Press, Tornadoes of the United States by Snowden Flora. Tornado research and forecasting efforts continued in earnest throughout the 1950s and 1960s and, in 1971, the eponymously named Fujita Tornado scale (after Univ. of Chicago physicist Tetsuya Theodore Fujita) the official ranking of tornado intensities began. The Fujita Scale was modified in 2007 to fine-tune tornado damage assessments and re-named the Enhanced Fujita Scale, or the EF ranking now in use. Although 1950 is used as the baseline for compiling modern tornado statistics there are good records of tornado events going back to 1680. Virtually every single one of these has been exhaustively researched by a modern-day ‘Tornado Project’ organization founded by Thomas P. Grazulis who compiled a list of all known ‘significant’ (F-2 or EF-2) tornadoes ever reported and published the data in his book Significant Tornadoes: 1680-1991. The information has been continuously updated on the Tornado Project web site linked to above.

Although (as of April 9th) there have been no reports of EF-3 or stronger tornadoes so far this year, and this is the latest such since 1950:



Graphic courtesy of The Weather Channel.

…looking at the Grazulis data we see a number of years with later dates for a first F-3 tornado occurrence. To wit:

1. June 6, 1874
2. May 6, 1910
3. May 1, 1915
4. April 28, 1902
5. April 23, 1926
6. April 18, 1877
7. April 15, 1900
7. April 15, 1887
9. April 13, 1883
10. April 12, 1941
10. April 12, 1881
(today = April 9, 2014 – would be 12th 1871-2014)
12 (13). April 8, 1896
13 (14). April 7, 1903
14 (15). April 6, 1872

Of course, in the 19th century there were large areas of tornado country (in the Plains) that were not as densely populated as today and many EF-3 or stronger tornadoes may have occurred in unpopulated areas or simply were never reported because they did no damage. Also, obviously, the advent of tornado radar detection and other modern weather observation systems did not exist until at least 1950, so this also has to be taken into account.

Given the above caveats we can say with some confidence that the 2014 tornado season is off to an unusually and temperate start.

The key word above is “start”. Historically, April is one of the deadliest months of the year for tornadoes and 7 of the top 20 deadliest tornado outbreaks in U.S. history have occurred during April. Below is a list below of April’s top ten deadliest tornado outbreaks on record:



The death statistics in the above table are from Grazulis ‘Significant Tornadoes: 1680-1991’ and may vary according to other sources. For the April 2011 event the death toll includes storm-related but not tornado-related fatalities. The number of deaths caused directly by tornadoes stands at 324. It is not entirely clear if the fatalities for the other events include storm-related deaths or tornado only such.

KUDOS: Thanks to Jon Erdman, Stu Ostro, and Nick Wiltgen at The Weather Channel.

Christopher C. Burt
Weather Historian

Extreme Weather Tornadoes

Updated: 1:10 AM GMT on April 10, 2014

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World Rainfall Records for 24- and 48-Hour Periods

By: weatherhistorian, 9:02 PM GMT on April 07, 2014

World Rainfall Records for 24- and 48-Hour Periods

The U.N. WMO (World Meteorological Organization) recently announced that a ‘new’ world record for a 48-hour (or two day) period has been confirmed following an investigation by a group of climatologists from around the world. The figure is said to be an amazing 2,493 mm (98.15”) at Cherrapunji, India that fell on June 15-16, 1995. However, this may not be what was truly the greatest 48-hour precipitation record.

48-hour World Precipitation Records

Previous to the now officially recognized Cherrapunji 48-hour record mentioned above, the previous record was thought to be 2,467 mm (97.13”) set on March 15-17, 1952 at Cilaos, Reunion Island, a French territory in the Indian Ocean. However, the WMO committee does not appear to have been aware of (or dismissed) an even greater 48-hour total that also occurred on Reunion Island on February 27-March 1, 1993 when a site identified as Baril 1600 (the 1600 refers to the site’s elevation of 1,600 m/6,300’) measured 3,000.5 mm (118.13”) during an intense generalized rainfall event associated with Tropical Depression Hutelle that affected the island from February 27 to March 5 that year. This rainfall event was the subject of a scholarly article in the December 1997 issue of Monthly Weather Review, Vol. 125, pp. 3341-3346. The article states that the rain gauge at Baril 1600 was part of a 5-year investigation of water resources on the Piton de la Fournaise massif on Reunion Island undertaken by the University of Reunion Island. This may be the reason that the WMO has not accepted the Baril 1600 reading, since the gauge was not part of the official Meteo France (French Meteorological Organization) rain gauge network on the island. Nevertheless, the equipment used in the research project was of exacting standards and the measurement at Baril 1600 was in line with other measurements made in the region during the event.



Geographic location of rain gauges on the Piton de la Fournaise massif used in the study. The Baril transect is where the heaviest rainfall apparently occurs on a regular basis on the island. The back circles indicate the location of official Meteo France rain gauges and the numbered squares the gauges used in the research project. Map from ‘Monthly Weather Review’ article by Alain Barcelo et al.



Above is a table of the 7 a.m. to 7 a.m. local time 24-hour precipitation totals (in millimeters) for the sites listed on the map above during the period of February 27-March 4, 1993. The 3000.5 mm 48-hour total for the Baril1600 location occurred between 8.33 p.m. on February 27 and 8:33 p.m. on March 1st. Table from ‘Monthly Weather Review’ article.



A table comparing the Baril 1600 rainfall event of February 27-March 5, 1993 to the Reunion Island and world all-time precipitation records for various periods of time. World records are in bold. Table from ‘Monthly Weather Review’ article.



24-hour World Precipitation Records

It is generally acknowledged (and officially accepted by the WMO) that the greatest 24-hour rainfall record also occurred on Reunion Island at the site of Foc-Foc on January 7-8, 1966 when 1,825 mm (71.85”) on rainfall was measured during Tropical Storm Denise. There is also an unofficial 24-hour total of 1,870 mm (73.62”) at Cilaos on March 15-16, 1952 that is cited by J.L.H. Paulhus in a Monthly Weather Review article published in 1965 (Vol. 93 No. 5, pp. 331-335). This record has been discounted by Meteo France.

Outside of Reunion Island the world record for a 24-hour rainfall is the 1,637 mm (64.45”) that fell on Isla Mujeres (an island of the coast of the Yucatan Peninsula), Mexico on October 21-22, 2005 during the passage of Hurricane Wilma, the most intense tropical storm ever observed in the Western Hemisphere. There is a mention of a 1,672 mm (65.83”) 24-hour precipitation figure at Xinliao, Taiwan on October 17-18, 1967 in some Chinese publications, but this figure is unofficial and dubious.

A very close second to the Isla Mujeres figure is a little reported event that took place in central Vietnam on November 2-3, 1999 when 1,630 mm (64.17”) of rainfall fell on Truoi. Nearby, the city of Hue was inundated with 1,422 mm (55.98”) in the same 24-hour period resulting in floods that killed at least 622 and destroyed 42,000 homes. The streets of downtown Hue were swamped under 3 meters (10’) of floodwater.



Map of the region in central Vietnam affected by the tremendous rainfall of November 2-3, 1999. From ‘Monthly Weather Review’ Vol. 136, No. 9, September 2008 article by S. Yokoi about heavy rainfall events in central Vietnam.



The flood in Hue in early November 1999 damaged many of the city’s famous historical sites. Photograph from a Vietnamese climate science journal.



Table of 24 and 48-hour precipitation totals at Hue and Truoi on November 2-3, 1999. Note the near world-record (excluding Reunion Island) amounts not just for 24 hours but also 48 hours for which Truoi picked up 2,200 mm (86.61”). Table from Vietnamese climate journal.

For the U.S., the record 24-hour rainfall was the 43.00” (1,092 mm) reported from Alvin, Texas on July 25-26, 1979 during Tropical Storm Claudette. More about this storm and other great 24-hour rainfalls from around the world can be found in this blog I posted last October. However, since I wrote the October blog new information, like the rainstorm in Vietnam, has dated some of the material and the list of locations with 40”+ rain events is questionable. For instance, the Australian 24-hour record should be 960 mm (37.80”) not the 1142 mm (44.92”) listed, which was an estimated amount. Also, the Amini Devi, India figure is not reliable, a result of a typographical error in the Indian records. I will re-publish a more accurate accounting of this in a future blog.

KUDOS: Thanks to Maximiliano Hererra for bringing the Vietnamese rain event to my attention.

Christopher C. Burt
Weather Historian

Extreme Weather Precipitation Records

Updated: 12:54 AM GMT on April 08, 2014

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California Drought Update

By: weatherhistorian, 7:39 PM GMT on April 03, 2014

California Drought Update

March precipitation was near normal for most of central and northern California following a couple of big rain/snow events between March 29-April 1 that helped boost the ground moisture and Sierra snowpack (at least in the northern two thirds of the state). Unfortunately, it was too little too late as the most recent, and last, important snow survey for the season conducted on April 1st has shown. Here are the details.



The lack of progress against the drought, in spite of the recent rains, can be seen in the latest California Drought Monitor report issued today (April 3rd). The areal coverage of D4 (Exceptional drought) has increased slightly from last week’s report although some improvement in the DF3-4 (Extreme drought) has been seen, this improvement taking place in the northern Sierra region. Drought Monitor maps created by NOAA et al.

The latest Sierra snow pack water content report (issued on April 1st) shows that statewide the snowpack is at 33% of normal. Although this is a slight improvement to the 29% of normal on March 1st, it is a dire situation, since normally the snow pack will be melting down from now on to the end of the water season on June 30th. The April 1st survey is considered the most significant of all the monthly snow surveys since statewide agricultural water allocations are be based upon the April 1st surveys. This is the 3rd consecutive year with the April 1 snowpack well below normal. On April 1, 2013 it was 46% of normal, and on April 1, 2012 54% of normal. Below are the maps and data for ALL three of the April 1 surveys 2012-2014:







Snow pack surveys for April 1, 2014 (top), April 1, 2013 (middle) and April 1, 2012 (bottom). Of course, this is why the drought has reached such a critical phase this year even though the water year has not been close to record territory. California Department of Water Resources.

As one can see from the above maps, the reason the drought has become so critical is that this is the third consecutive season with much below normal precipitation and snowfall. This season has been the driest of all three but will not go down in the record books as one of the driest single seasons on record, thanks to the normal precipitation of February and March. In fact, San Francisco’s current 11.92” seasonal total no longer ranks even in the top dozen of such (since 1849-1850). If not a drop of rain falls for the rest of the water season (until June 30th) only Bakersfield and Fresno would have a chance of establishing their all-time driest water year on record (Bakersfield’s driest such was 2.26” in 1933-1934 and Fresno’s 4.43” also in 1933-1934).

Below is a chart of how the precipitation totals stand now compared to one month ago. As one can see, slight improvements have occurred at all sites except in the far south where Los Angeles and San Diego did not receive any significant rainfall during March.



Seasonal (July 1-to date) precipitation totals for select California cities and the % of normal for such as of March 2nd (top table) and April 2nd (bottom table).

At this point in the season about 85%-90% of the total normal seasonal precipitation would normally have already fallen. No significant storms are forecast until at least April 10th and so, barring a miracle, the state must now resign itself to an extreme drought situation through at least next November.

Christopher C. Burt
Weather Historian

Extreme Weather Drought

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Record and Average Dates of Late Season Snowfall in the U.S.

By: weatherhistorian, 7:21 PM GMT on April 01, 2014

Record and Average Dates of Late Season Snowfall in the U.S.

A late season blizzard has pounded the northern Plains with snowfall of up to 20” in North Dakota. How unusual is this and when can the last measurable snowfall be expected across the country? Here are some interesting maps on the subject created by climate scientist Brian Brettschneider and some examples of incredible late season snowfalls from the pre-USWB era.



A late season blizzard, designated winter storm Xenia by The Weather Channel plastered South Dakota, North Dakota, and portions of Minnesota on March 31st and April 1st. A similar storm, named Xerxes, struck the same area last April depositing similar amounts of snow, as was the case in Dalton, Minnesota pictured above. Photo by Debbie Kaminski.

For some locations in the Upper Midwest and western Great Plains, the 2013-2014 season has been the snowiest on record (details will follow in a future blog). Climatology suggests winter is yet not over for these regions. In fact, for some locations in the Rocky Mountains and western Plains, April is normally the snowiest month of the year. Places like, Casper, Wyoming; Lander Wyoming; Deadwood, South Dakota; and Leadville, Colorado; all experience their snowiest month in April. For those who might be interested in some examples of heavy April snowstorms see my blog ‘Record April Snowstorms published last April (2013).



Sites in the U.S. where, on average, April is the snowiest month of the year. These include the Black Hills of South Dakota and a number of sites in Colorado, Wyoming, and Montana. Of the 4,214 stations in the U.S. for which the National Climate Data Center (NCDC) calculates normal snowfall, and that receive greater than 2” of snow per year, 34 have their snowiest month in April. Brian Brettschneider of Borealis Scientific, LLC.



The map above illustrates which month of the year is normally the snowiest across the entire United States. The data is compiled from the above mentioned 4,214 NCDC sites. The shading on the map is based on the value of up to six nearby points so in a few cases the color may not correspond exactly to the snowiest month. Brian Brettschneider of Borealis Scientific, LLC.

So far as when (during which month) the last measurable snowfall normally occurs we can see in the map below that, for much of New England, the Upper Midwest and Plains, as well as the Rocky Mountain States and higher elevations of other western states, some April snowfall is a norm.



Map of average date of last measurable snowfall across the U.S. In much of Alaska and the Rocky Mountains this doesn’t occur until well into May. The data for the map is derived from the GHCN (v. 3) database and only utilizes primary USW stations with at least 15 years of records since 1980. Brian Brettschneider of Borealis Scientific, LLC.

Of course, there are some years when measurable snowfall occurs well after the ‘normal’ dates as outlined in the map below. This is a map of when the latest measurable snowfalls on record have occurred. As can be seen, June snowfall has occurred at some time in the past in much of the higher elevations of the West and Alaska.



Map above roughly illustrates the dates of occurrence of the latest measurable snowfall on record and uses the same database as the ‘Average Last Measurable Snow Date’ map. For this map, all primary stations were utilized independent of their period of record. Brian Brettschneider of Borealis Scientific, LLC.

Below is a table of latest measurable snowfalls on record for a handful of select cities across the contiguous U.S.:





Some Historic Pre-USWB Late Season Snowstorms

The May 4th Snowstorm of 1774

A general snowfall of around 4” occurred from northern Virginia to southern New England. Both Philadelphia and New York City reported “a considerable quantity of snow”. Thomas Jefferson and George Washington both noted the event in their diaries.

The Great April Fools Day Snow of 1807

Probably the deepest April snowfall in the history of the Ohio Valley and Mid-Atlantic occurred on April 1, 1807 from Illinois to the Northeast. The track of the storm was not the usual coastal nor’easter variety (that normally produces great snowstorms) but rather a low that moved northeast from the lower Tennessee Valley and across the mid-Atlantic states and offshore around New York City. To the north of the storm path incredible snowfalls were reported. The westernmost report we have came from Vincennes on the Illinois-Indiana border with an 11” accumulation but it was in Pennsylvania, New York and New England that astonishing snowfall was reported including: 52” at Montrose, Pennsylvania near Scranton; 54” at Utica, New York, 52” at Lunenburg, Vermont; 60” at Danville, Vermont; 48” at Montpelier, Vermont; and 42-48” at Norfolk, Connecticut.

The June 1816 Snows of the ‘Year without Summer’

Most famous of all cold and snowy late season events would have to be the infamous 1816 ‘Year without Summer’ with snowfall in June that occurred in the eastern U.S. and Canada. On June 6th accumulating snow was observed as far south as the Catskills in New York (where one inch was reported) and highlands of central and northwest Pennsylvania. Snowflakes were seen at sea level as far south as ten miles north of tidewater on the Hudson River, just north of New York City. The deepest accumulations were reported in the mountains of Vermont where drifts of 12”-18” were measured. Quebec City in Canada reported 12” on level with drifts up to two feet deep.

The even Greater Snow of June 1842

It should be noted that June snowfall in the Northeast is not a unique event to 1816. On June 11, 1842 widespread snow fell over northern New York and New England and snowflakes were observed in Cleveland, Ohio; Boston, Massachusetts; and even Harrisburg, Pennsylvania. Accumulations of 10-12” were common in Vermont, so this event may actually have been more extreme than the famous snow of June 1816.

REFERENCES FOR PRE-USWB SNOWFALLS: Early American Winters: Vol 1: 1604-1820 and Vol 2: 1821-1870 by David M. Ludlum, American Meteorological Society, 1966, 1968.

KUDOS: Thanks to Brian Brettschneider of Borealis Scientific, LLC for the maps reproduced above.

Christopher C. Burt
Weather Historian

Extreme Weather Snow

Updated: 11:05 PM GMT on April 01, 2014

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About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.