The Most Anomalous Weather Events in U.S. History (Part 1)

This past July a wildfire near Redding, California, produced what was determined to be a fire tornado with winds on par with those of an EF3 tornado. This event astonished the nation’s meteorologists and prompted me to consider what some of the most unusual or anomalous weather events in U.S. history might have been. The list is, of course, purely subjective, and it is difficult to narrow the list of such down to just a dozen. This will be a two-part blog post arranged chronologically from most recent to earliest. I present the first six in this post and the next six in a post planned for late October.

2018: The Fire Tornado near Redding, California

As mentioned above, the fire tornado near Redding on July 26 during what was called the Carr Fire Event was unprecedented in terms of its size and ferocity. Intense wildfires almost always produce fire devils and/or fire whirls, and very occasionally stronger vortexes that resemble the tornadoes produced by severe thunderstorms. Although these are not typically classified as tornadoes by the NOAA/NWS Storm Prediction Center (SPC), the center will be examining the Redding event to see if it qualifies, as it was associated with a pyrocumulus cloud (a fire-spawned thunderstorm). As far back as 1978, the National Weather Service recognized such phenomena in a technical memorandum:

FIRE TORNADOES - These systems begin to dominate the large-scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 mph.

Below is a video clip of the fire tornado in progress during the Carr Fire event west of Redding, Calif., on July 26, 2018, provided by CAL FIRE.

Video evidence and storm damage assessments made following the fire tornado near Redding seem to have expanded what was previously considered the ‘upper limits’ of fire-tornado intensity, with the wind associated with the tornado estimated at 143 mph (thus in EF3 territory). Sadly, one fireman lost his life when he was caught in the tornado’s path.

California experiences, on average, several weak tornadoes every year (in the EF0 to EF1 range), usually during the winter storm season of October to April. However, there have only been two EF3-strength tornadoes documented in California (tornado historian Thomas Grazulis lists 25 F2 tornados in California between 1898 and 1986). Prior to the Carr Fire event, there had never been a tornado-caused fatality in the state’s modern history except for one caused by another fire-related twister in 1926 (see this Category 6 discussion). Therefore, the 2018 fire tornado ranks as one of the most anomalous weather-related events in modern U.S. history.

Figure 1. A satellite image of Hurricane Sandy as it approached the shoreline of New Jersey on October 29,, 2012, as the largest Atlantic hurricane on record. Note how Sandy’s cloud shield extends from Canada in the north to South Carolina in the south and from Lake Michigan in the west to well east over the Atlantic Ocean. Image credit: NASA MODIS/LANCE, via Wikimedia Commons.

2012: Hurricane Sandy

The year of 2012 was one of exceptional weather extremes in the U.S.—so much so that two of the top 12 anomalous weather events that are featured in this post occurred during that year. One of those is Hurricane/Superstorm Sandy, which came ashore in New Jersey as a strong extratropical storm on October 29.

Sandy was a unique event for several reasons: it was the most powerful (in terms of integrated kinetic energy along the storm’s track) and third most destructive Atlantic hurricane in recorded history.

Ten hours before landfall, at 9:30 am EDT October 29, the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules—the highest value for any Atlantic hurricane in data going back to 1969. After taking a freakishly rare west-northwesterly track into New Jersey, Sandy's tropical-storm-force winds at landfall spanned 943 miles of the U.S. coast. No hurricane on record has been larger.

Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee—an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lakeshore, and toppled power lines in Nova Scotia, Canada—locations 1200 miles apart!

Sandy made landfall near Atlantic City, NJ, on October 29, with sustained winds of 80 mph and a central minimum pressure of 946 mb—the lowest pressure on record along the Northeast U.S. coast. The Battery, in New York City Harbor, had an observed water level of 13.88 feet, besting the previous record storm surge set by Hurricane Donna in 1960 by 3 feet. This catastrophic storm surge was responsible for the majority of the 131 deaths and $62 billion in damage in the U.S. Sandy also brought torrential rainfall in excess of 12 inches to the mid-Atlantic (the maximum amount being 12.83” in Bellevue, Maryland), and blizzard conditions to the central and southern Appalachians: 36” of snow fell in Richwood, West Virginia and also on Wolf Laurel Mountain, North Carolina. Such was Sandy’s massive circulation that at one point it was snowing in the mountains of Virginia and West Virginia while at the same time temperatures were in the low 70s in Vermont.

2012: The Freak March Heat Wave in the Midwest

What was probably the most extraordinarily anomalous heat event in U.S./Canadian history unfolded in the Upper Midwest on March 14 and continued across the rest of the Great Lakes region, the northeastern U.S., and southeastern Canada until March 22. Never before has such an extended period of temperatures so far above normal been recorded. In some instances average daily temperatures were 40°F above normal, and even the daily low temperatures in some locations were higher than the record for their daily high temperature!

Figure 2. A graphic illustrating the persistent weather pattern that resulted in the anomalous heat event in the Upper Midwest and southern Canada March 14-22, 2012. Image credit: National Weather Service/Milwaukee.

Monthly record high temperatures for March were set in many locations, including Bismarck, North Dakota (81° on March 16), International Falls, Minnesota (79° on March 18), Milwaukee, Wisconsin (84° on March 21), Detroit, Michigan (86° on March 22), Cleveland, Ohio (83° on March 21), Bangor, Maine (84° on March 22), Ottawa, Canada (81° on March 21), and Montreal, Quebec (79° on March 21). The temperature reached 90° in Lapeer, Michigan on March 21! This is just a small sampling of the extremes. Keep in mind that this occurred in what is still the winter season. Subzero temperatures have occurred in many of these same locations at this time of the year, when snowpack is sometimes at its deepest.

Impressive as all the specific temperature records broken were, it was the persistence of the record warmth and the amazing departures from normal seasonal temperatures that were the most notable aspect of the event. International Falls broke or tied its daily record maximum temperatures for an amazing 10 consecutive days from March 13 to 22. This is the longest such stretch of which I am aware at a site with 100+ years of records. Chicago, Illinois, saw daily high records broken or tied for nine consecutive days March 14-22.

Perhaps the most anomalous temperature departures were those observed on Michigan’s Upper Peninsula. In Marquette (where the snow would normally still be several feet deep at this time of the year) the temperature reached 81° on March 21—crushing the previous March monthly record high of 71° set on March 8, 2000. The previous record high for the date of March 21 was 50°—yes, the old daily record high was beaten by 31°! In fact, the low temperature on March 21 was 50° (i.e. even the low temperature would have been a daily record high!). The average temperature for March 21 in Marquette is 27.5°. Prior to this event there had never been a daily low temperature warmer than 44° in March. Every day from March 18 to 22 surpassed this. A blog I posted on WU at the time delves into more detail concerning this event.

1974: Two F5 Tornadoes Strike the Same Place on the Same Day

F5 or EF5 tornadoes are exceedingly rare. Only a handful of tornadoes of this intensity have been documented outside of the United States. Since 1900 there have only been 104 of these monsters recorded anywhere on Earth. The United States averages roughly one EF5 per year, but there is great variation from year to year.

The Super Tornado outbreak on April 3, 1974, accounted for seven of the 104 known EF5 occurrences, an anomaly in its own right. Even more amazing, one location in Alabama, near the town of Tanner about 20 miles west of Huntsville, was actually struck twice that day by F5 twisters within 30 minutes of each other. The odds of that occurring are astronomically small. It should be noted that some scientists, including tornado guru Thomas Grazulis, rated the second Tanner tornado as F4, although the NWS rated it F5 in a reanalysis performed in 2012. Regardless of whether or not the second tornado was an F4 or F5, it is still an astonishing feat to have an area scoured twice within an hour by such mighty storms.

Figure 3. An aerial photograph of the F4 or F5 damage that the second tornado on April 3, 1974 caused near the town of Hazel Green, Alabama, which is 25 miles northeast of Tanner. Image credit: Wikimedia Commons.

The first tornado formed at 6:30 pm CDT in Lawrence County and tracked northeast for a full 90 minutes, killing 28 people along the way. Tanner took a direct hit when the twister was at its most powerful, around 7:15 pm. At 7:30 pm the second tornado formed and followed a path almost identical to the first tornado (just 500-1000 yards to the south). Tanner was the first community to be struck by this second tornado, around 7:45 pm. This tornado was on the ground for 50 miles and killed 22. One victim injured near Tanner during the first tornado was transported to a nearby church that was struck by the second tornado, killing him. The Alabama communities of Capshaw and Harvest were also struck by both tornadoes.

1972: A 103° Temperature Rise in 24 Hours at Loma, Montana

The greatest temperature change in a 24-hour period ever measured in the U.S.—and perhaps the world—occurred at Loma, Montana, on January 14-15, 1972. NWS COOP observer Jim Wood measured a temperature of –54°F in his Stevenson Shelter at 9 am on the morning of January 14. By that evening a powerful chinook wind enveloped the area with downsloping winds blowing a sustained 30-40 mph.

Figure 4. Rancher and NWS COOP Observer Jim Wood with his Stevenson-screen instrument shelter in the background near Loma, Montana. Image credit: Weather Forecast Office-Great Falls.

In a paper entitled “A National Temperature Record at Loma, Montana” (see PDF file), Mr. Wood is quoted as follows:

“Shortly after midnight I woke to the sound of a howling wind. I dressed and read the temperature and could not believe it read 34° above [zero]. The severe southwest wind continued and by 6:00 am the temperature was in the mid-40°s. By 8 am it had reached 49° and never raised higher the rest of the day."

NOAA verified the observation with an investigation of the event undertaken in 2012 by its National Climate Extremes Committee (NCEC). Note that 88° of the temperature rise actually occurred in just a 15-hour period between 9 am and midnight on January 14. Another way to picture just how extreme this was: imagine the 103° spread (–54° to 49°) spanning the range from 0° to 103°, or 17° to 120°, in just a 24-hour period!

This chinook event occurred over a wide area in the leeside of the Rocky Mountains of western Montana. Great Falls, 40 miles southwest of Loma, observed a 62° temperature rise (from –29° to 33°) during the same time period. Havre, 50 miles northeast of Loma, saw its temperature rise 79° from –36° to 43°. Numerous COOP sites in the region saw temperatures rises of 80° or more, including a 92° rise at the hamlet of Iliad (–42° to 50°).

Figures 5 and 6. These 1972 daily weather maps for January 14, 1972 (top), and January 15 (bottom) illustrate the surface weather pattern that facilitated the occurrence of the strong chinook event that affected much of central Montana, resulting in the record-breaking 103° temperature rise in Loma. Image credit: NOAA/NWS Daily Weather Maps.

Montana is no stranger to extreme temperature fluctuations. The state also holds the U.S. (and perhaps world) record for the greatest drop in temperature for a 24-hour period, when the temperature fell from 44° to –56° at Browning on January 23-24, 1916.

1942: Deluge at Smethport, Pennsylvania on July 18

One of the most extraordinary rain events in U.S.—and world—history unfolded at the unlikely location of McKean County, Pennsylvania, located in the north-central portion of the state near the New York border. The rainfall, as observed by Mr. E. Hultz, who was located between Smethport and Port Alleghany, began at midnight July 17–18. Six inches of rain fell between then and about 9 am on July 18, ordinarily a flooding rainfall in its own right. Then (according to the mass rainfall curve—see below) between 9 am and noon another 28.50” fell. All told, 34.50” of rain fell in an 18-hour period, of which 34.30” fell in 12 hours and 30.80” in just 4.75 hours. Short-period rainfall rates were estimated to have been as high as 40” per hour!

Figure 7. A section of the daily weather map at 7 am ET July 18, 1942, that shows the surface conditions in the region surrounding Smethport when the intense rain event was underway, leading to flooding in north-central Pennsylvania. Image credit: USWB Daily Weather Maps. https://library.noaa.gov/Collections/Digital-Collections/US-Daily-Weather-Maps.

These interval rainfall amounts are interpolated from the mass rainfall curves provided in the U.S. Army Corps of Engineers storm study report of the event (see Figure 9 below, as well as the discussion starting on p. 62 of this PDF file). If accurate, no such rain intensity has ever been recorded anywhere in the world.

Other stations in the area also measured extreme rainfall values, including 20.40” near Emporium over a 12-hour period and 18.50” at Mt. Jewett (also in Pennsylvania) over 18 hours. An observer in Wellsville, just across the state border in New York, measured 14.00” in a span of just six hours. Hillsides in the Smethport area were reported stripped of vegetation and, of course, mudslides were common. River stages in the area broke all records, thousands of people were forced from their homes, numerous bridges washed out, and landslides and high water blocked all railroads. At least 15 people died (11 in Pennsylvania and four in New York) as a result of the storm, including two lightning-related deaths.

Figure 9. The first page of the Army Corps of Engineers’ Storm Study Report for the Smethport rain event. It shows the mass rainfall curves for several of the sites noted in the text above. Image credit: Army Corps of Engineers, Storm Studies, War Department, Washington D.C., 1887-1955 (from the author’s personal collection)

The town of Smethport itself had a USWB COOP observer who measured only 6.68” during the storm (which was still enough to set a new 24-hour record for the site), and other official USWB reports included 8.48” in Coudersport and 7.53” in Emporium (before a flood covered the gauge). However, in the July 1942 Climatological Data by Sections report for Pennsylvania, the general summary said the following: “Unofficial records, now being investigated, indicate much heavier rain occurred in the ungaged [sic] area within the periphery formed by the stations mentioned above.”

Residents who were interviewed following the storm reported the following, “…many people said the rain did not come down in drops and they had the visual impression, at least, that the rain came down in streams which they likened to strings and ropes...there were people who had not been able to reach shelter and were afraid they would drown during the downpour through lack of oxygen. One man expressed the effect by saying it was just like breaking water after a long dive, lungs bursting, with water pouring down over his head”. For more incredible stories and details (including photographs) concerning this event, see this technical report (PDF file) about extreme rainfall events prepared by engineer John Harrison some years ago.

In October, I will follow up on my (rather arbitrary) choices to round out my list of the dozen most anomalous weather events in U.S. history. See if you can guess what the next six will be!

Christopher C. Burt
Weather Historian