JUST WHAT IS INDIAN SUMMER AND DID INDIANS REALLY HAVE ANYTHING TO DO WITH IT?

Hope all have been enjoying these beautiful stretches of Indian Summer-like weather ("like" since some areas have yet to receive a frost/freeze). These gradual engulfing and expanding frost/freezes with every surge of cold air masses are more common across the Great Lakes states.  These days remind me of one of my very first articles on the orientations of the term "Indian Summer"

JUST WHAT IS INDIAN SUMMER AND DID INDIANS REALLY HAVE ANYTHING TO DO WITH IT?

Written by: William R. Deedler, Weather Historian
(originally written in the Autumn of 1996)

An early American writer described Indian Summer well when he wrote, "The air is perfectly quiescent and all is stillness, as if Nature, after her exertions during the Summer, were now at rest." This passage belongs to the writer John Bradbury and was written nearly an "eternity" ago, back in 1817. But this passage is as relevant today as it was way back then. The term "Indian Summer" dates back to the 18th century in the United States. It can be defined as "any spell of warm, quiet, hazy weather that may occur in October or even early November." Basically, autumn is a transition season as the thunderstorms and severe weather of the summer give way to a tamer, calmer weather period before the turbulence of the winter commences.

The term "Indian Summer" is generally associated with a period of considerably above normal temperatures, accompanied by dry and hazy conditions ushered in on a south or southwesterly breeze. Several references make note of the fact that a true Indian Summer can not occur until there has been a killing frost/freeze. Since frost and freezing temperatures generally work their way south through the fall, this would give credence to the possibility of several Indian Summers occurring in a fall, especially across the northern areas where frost/freezes usually come early.

While almost exclusively thought of as an autumnal event, I was surprised to read that Indian Summers have been given credit for warm spells as late as December and January (but then, just where does that leave the "January Thaw" phenomenon?). Another topic of debate about Indian Summer has been "location, location". Evidently, some writers have made reference to it as native only to New England, while others have stated it happens over most of the United States, even along the Pacific coast. Probably the most common or accepted view on location for an Indian Summer would be from the Mid-Atlantic states north into New England, and then west across the Ohio Valley, Great Lakes, Midwest and Great Plains States. In other words, locations that generally have a winter on the horizon! But then, what about the king of winter weather in the United States, Alaska? Do they have an "Indian Summer", or something similar? Some places in Alaska are lucky to have a "summer", let alone an Indian Summer! One would certainly have to throw out the notion of it usually happening in October or November, when, winter generally has already taken an aggressive foothold on much of the state. What about other locations that come to mind, The Rocky Mountain States and parts of Canada, particularity in the east and south? Note: If anyone reading this has any information on Indian Summers in those areas questioned, or just thoughts on Indian Summers drop me a note or comment. (Editors note: Over the years while at the NWS and after, I received several fascinating notes from all over the world on how common and widespread "Indian Summers" were with each having it's own specific local or regional definition).

A typical weather map that reflects Indian Summer weather involves a large area of high pressure along or just off the East Coast. Occasionally, it will be this same high pressure that produced the frost/freeze conditions only a few nights before, as it moved out of Canada across the Plains, Midwest and Great Lakes and then finally, to the East Coast. Much warmer temperatures, from the deep South and Southwest, are then pulled north on southerly breezes resulting from the clockwise rotation of wind around the high pressure. It is characteristic for these conditions to last for at least a few days to well over a week and there may be several cases before winter sets in. Such a mild spell is usually broken when a strong low pressure system and attending cold front pushes across the region. This dramatic change results from a sharp shift in the upper winds or "jet stream" from the south or southwest to northwest or north. Of course, there can be some modifications to the above weather map scenario, but for simplicity and common occurrence sake, this is the general weather map.

Now we come to the origin of the term itself, "Indian Summer". Over the years, there has been a considerable amount of interest given to this topic in literature. Probably one of the most intensive studies occurred way back around the turn of the century. A paper by Albert Matthews, written in 1902, made an exhaustive study of the historical usage of the term. Evidently, the credit for the first usage of the term was mistakenly given to a man by the name of Major Ebenezer Denny, who used it in his "Journal", dated October 13th, 1794. The journal was kept at a town called Le Boeuf, which was near the present day city of Erie, Pennsylvania. Matthews however, uncovered an earlier usage of the term in 1778 by a frenchman called St. John de Crevecoeur. It appeared in a letter Crevecoeur wrote dated "German-flats, 17 Janvier, 1778." The following is a translation of a portion of the letter:

"Sometimes the rain is followed by an interval of calm and warmth which is called the Indian Summer; its characteristics are a tranquil atmosphere and general smokiness. Up to this epoch the approaches of winter are doubtful; it arrives about the middle of November, although snows and brief freezes often occur long before that date."

Since the writer says, "it is called the Indian Summer", obviously one could argue that term would have had to been used before him and became popular, but by whom, an earlier explorer or possibly an Indian tribe?

Now, after looking at all of this, the question you might ask yourself is, "Does the term 'Indian Summer' really have anything to do with Indians?" Again, there is host of possibilities, read on...

One explanation of the term "Indian Summer" might be that the early native Indians chose that time of year as their hunting season. This seems reasonable seeing the fall months are still considered the main hunting season for several animals. Also, the mild and hazy weather encourages the animals out, and the haziness of the air gives the hunter the advantage to sneak up on its prey without being detected. Taking this idea one step further, Indians at that time were known to have set fires to prairie grass, underbrush and woods to accentuate the hazy, smokey conditions. But Albert Matthews pointed out that the Indians also did this at other times of the year. Other possibilities include; the Indians made use of the dry, hazy weather to attack the whites before the hard winter set in; that this was the season of the Indian harvest; or, that the predominant southwest winds that accompanied the Indian Summer period were regarded by the Indians as a favor or "blessing" from a "god" in the desert Southwest. Another idea, of a more prejudicial origin, was that possibly the earliest English immigrants equated Indian Summer to "fools" Summer, given the reliability of the resulting weather. Finally, another hypothesis, not at all in the American Indian "camp" of theories, was put forward by an author by the name of H. E. Ware, who noted that ships at that time traversing the Indian Ocean loaded up their cargo the most during the "Indian Summer", or fair weather season. Several ships actually had an "I.S." on their hull at the load level thought safe during the Indian Summer.

In any event, there are several theories or possibilities of the explanation and origin of the term "Indian Summer", yet no one theory has actually been proven. Given the fact it has been centuries since the term first appeared, it will probably rest with its originators. All in all, even with the variety of opinions on this weather (or seasonal) phenomenon, the most popular belief of Indian Summer is as follows...It is an abnormally warm and dry weather period, varying in length, that comes in the autumn time of the year, usually in October or November, and only after the first killing frost/freeze. There may be several occurrences of Indian Summer in a fall season or none at all.

Since Indian Summers are fairly common, it would be interesting to find out if there is any correlation between the years that had no Indian Summer (in a particular area) and the type of winter weather that followed. Oh well, possibly another time and another article but enjoy the Indian Summer while its around, because one thing is for certain, it never lasts!

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian

 

Posted by WeatherHistorian_SeMI at 4:26 PM

Hurricanes in Michigan??? Along with...Hurroncane! - /With Tropical Storm Beryl Expected Mid-week; Reflecting Back on Tropical Storms Affecting Michigan; last Updated 2017/

 Hurricanes in Michigan??? Along with...Hurroncane!

Originally written September 1999 & Updated September 2004/2012/2013 and with more the latest reanalysis information - 2016. And in 2017; all tropical remnants listed in Table-1 have links to the paths of the storms along with attending narratives back nearly a century to 1923!

Monday, September 25th is the 76th anniversary of one of the most unusual and intense wind storms ever to hit Southeast Lower Michigan. Well over seven decades ago on September 25th, 1941; the remnants of a tropical storm hit the region. This storm was not that usual being in that the remnants of tropical systems do occasionally make it up to the Great Lakes region. But, the coming together of all the meteorological components made for this Astonishing Storm of September 25th, 1941

At first glance, when one reads that headline, one might say, "What? Hurricanes here in the Great Lakes?? No way!" Of course you'd be right, no actual hurricane has ever been observed in Michigan under the true definition of a hurricane. The definition of a hurricane, according to the Glossary of Weather and Climate edited by Ira W. Geer, is as follows: "A severe tropical cyclone with maximum 1-minute sustained surface wind speed greater than 64 knots (74 mph) in the North Atlantic Ocean, Caribbean Sea, Gulf of Mexico and the Eastern North Pacific off the west coast of Mexico to the International Dateline. West of the Dateline they are known as typhoons." Furthermore, the definition of a tropical cyclone is as follows: "A generic term for a non-frontal synoptic-scale cyclone originating over the tropical or subtropical waters with organized convection and a definite cyclonic surface wind circulation." Clearly, neither definition applies in the Great Lakes area, although remnants of hurricanes that have become extra-tropical (loses its tropical characteristics) occasionally do make their way into the Great Lakes region.

Scanning a century's (since 1917) worth of hurricane track data suggests that remnants of a hurricane or tropical storm make their way into the Great Lakes region on an average of nearly twice a decade, especially the southern Great Lakes area (see Table-1). Also, in the majority of instances, by the time they visited this region they diminished to an area of rain with maybe some squally winds with many of the rainfalls/winds on the tail-end of their "lives".. There have been a few instances, along the way, however, that do bear mentioning, and ONE STORM in particular that screams for attention!

TABLE - 1

REMNANTS OF HURRICANES/TROPICAL STORMS THAT HAVE AFFECTED THE GREAT LAKES AND SOUTHEAST LOWER MICHIGAN (SINCE 1921)
DATE (Storm's life cycle)		DETROIT RAINFALL/DATES (Inches)	MAXIMUM WIND (mph)
	10/16-19 1923	.55 - 10/18	SE - 22
	7/22-8/2 1926	1.11 - 8/1	E - 25
	8/27-9/3 1932	2.95 - 9/3-4	NE - 21
	9/10-22 1938 $	.23 - 9/21-22	SW - 20
	9/16-25 1941	Trace - 9/25	SW - 52 *
	9/1-6 1948	.82 - 9/6-8	N - 25
	9/27-10/6 1949	1.30 - 10/6-7	SW - 21
Connie -	8/1-8/14 1955	.69 - 8/13-14	W - 20
TD ** -	6/22-6/28 1960	.31 - 6/28	SW - 23
Carla -	9/3-9/15 1961	.13 - 6/14	W - 29
Candy -	6/22-26 1968	2.55 - 6/24-26	NE - 30
Hugo -	9/10-24 1989	Trace - 9/22-23	NW - 38
Opal -	9/27-10/6 1995	1.41 - 10/5-6	N - 38
Fran -	8/23-9/8 1996	.99 - 9/7	NW - 25
Isabel -	9/6-9/19 2003	0.25 - 9/18-19 #	W - 33
Ike - 9/1-9/15 2008                                                        3.78 - 9/13-14                                                                 N - 43 * denotes officially at Detroit City Airport, but gusts were clocked up to 75 mph across the Metro      Detroit area. ** TD - Tropical Storm # Up to 2.50" reported along the St. Clair River

$ 1938 New England Hurricane: Fast forward speed reached 70 mph on September 20th, making it the fastest-moving Atlantic tropical cyclone on record.

>>Note; Hurricane Sandy's path /2012/ did not pass over/near Southeast Lower Michigan<<

First off, under the "mention" category in 1932 (well before hurricanes were named), a hurricane that developed in the Caribbean on August 27th, tracked northwest into the Gulf of Mexico, then generally north, across Alabama, eastern Arkansas, southeast Missouri, into southern Illinois and then from there, headed northeast across Indiana into Southeast Lower Michigan. The storm approached Southeast Lower Michigan late on September 3rd. A light to moderate northeast wind proceeded the storm on the 2nd and 3rd averaging around 11 mph with gusts into the lower 20s, hardly anything noteworthy wind-wise. The storm did however, pass right over Detroit, causing the barometric pressure to fall from around 30.20 inches early on the 2nd to around 29.60 late on the 3rd. Rain began to fall lightly but steadily early in the morning on the 3rd, but from mid afternoon into the evening, moderate to heavy rain fell and by midnight, over two and a half (2.55) inches was dumped on the Detroit area. Close to an additional half inch or so of rain was added to that on the 4th for a total of nearly three inches.

Another mentionable was odd from the start because of its timing; occurring very early in the season during late June of 1968 (only one other June system was found since 1921 to have affected the Great Lakes: the weak remnants of a tropical storm that moved from the Gulf of Mexico to near Chicago, June 22-28th, 1960). On June 22, 1968, Tropical Storm Candy formed off the coast of eastern Mexico and then headed north into southeast Texas, just north of Corpus Christi. She then weakened, headed north-northeast through eastern Texas and Oklahoma, central Missouri and Illinois, then she pivoted on a more easterly track across northern Indiana into extreme northwest Ohio, over Toledo. Candy began to influence Southeast Lower Michigan's weather on the morning of the 25th. A nearly steady rain, interspersed with a few thunderstorms, continued through the day and evening, depositing nearly two and a quarter (2.17) inches. More scattered, lighter showers fell on the 26th, adding another .38 to give a grand total of 2.55. Through it all, an east to northeast wind blew averaging 10 to 14 mph with gusts into the 20 to 30 mph range.

During the busy mid 1990s; a fairly impressive tropical system wound its way north out of the Gulf of Mexico, through Alabama, Tennessee, Kentucky and into Northern Ohio. She was known as Hurricane Opal and had a 10-day life span from September 27th to October 6th, 1995. On the evening of Oct 5th at 8pm, the remnants of Opal were located over the eastern Great Lakes. What was left of the "eye", or center of the storm, was well indicated on the NWS Doppler radar in White Lake (DTX). The radar showed the "eye" over Sandusky, Ohio moving north out over western Lake Erie. Light to moderate rain, with isolated areas of heavy rain, extended from Southeast Lower Michigan east across Southwest Ontario and Northeast Ohio. Spotty light rain first made an appearance in Southeast Lower Michigan earlier in the day, during the forenoon hours. During the afternoon, steadier rainfall developed with the heaviest rain (.54) falling between 5pm and 7pm. The rain ended just after midnight with a total of 1.41 inches falling from the storm. With the approach of the storm on the 5th, a generally north wind picked up and averaged over 15 mph with gusts up into the 30s (peak wind gust was 38 mph)

One of the more recent Hurricane remnants to affect Southeast Lower Michigan was Isabel, which moved quickly through the Eastern Great Lakes on September 18-19th, 2003. Rainfall from the system was quite variable ranging from just a trace over far western areas of Southeast Michigan, to as much as 2 1/2 inches at local spots along the St. Clair River. In 2008, remnants of Hurricane Ike September 13-14th brought very heavy rains to the region along with strong winds and a brief EF2 over western Wayne County on the 13th. The EF2 tornado struck Plymouth Township and damaged an apartment complex, flipped over cars and knocked out power to several hundred residents.

The Astonishing Storm of September 25th, 1941

Earlier, I mentioned "one storm that screams for attention", but maybe "howls" would be more appropriate. Before researching this project, I expected to find the above case scenarios, but not the following...

 Recently /2013 changes/ the Hurricane Research Division /HRD/ did a reanalysis of the hurricane and its associated track and wind speeds. *Note the asterisks in the following storm account are adjusted for those changes. (Thanks to Hoosier, moderator of American Weather for the heads up on the reanalysis)
   
* The storm made landfall in Texas as a category 3

* After moving onshore and through its entire remaining path, the storm was upgraded by maintaining tropical force winds as she evolved from a tropical storm to extra-tropical.. Also note the shifted, slightly westward track depicted over upper Ohio Valley and Lower Great Lakes in Indiana and Michigan.

Comparing the two tracks;

Original

  Reanalyzed

A tropical storm (#2 on original analysis map & #17-under 19-21, unseen on reanalyzed) formed in mid September over the Gulf of Mexico on September 17th, 1941. As it formed it meandered over the Gulf, making a loop in its track, well south of New Orleans. By this time it was a hurricane, intensifying briefly to a category #3 storm (111-130 mph wind) offshore as it took aim on eastern Texas. The hurricane made landfall late on the 23rd near Freeport, Texas with an estimated wind of a category #3* (111-130 mph), extremely high tides of nearly 11 feet and a barometer reading of 28.31 inches (959 MB). Further to the northeast, a ship just offshore of Texas City recorded a lowest pressure of 28.66 inches and winds of 83 mph. Other wind gusts were estimated near 100 mph at several locations near the hurricane's center along the Texas Gulf Coast. The hurricane quickly weakened to a category #1 (74-95 mph) as it made landfall and by the time the storm pushed on north to Houston, wind gusts had already dropped to 75 mph. Four lives were lost from the storm in Texas and property damage was estimated at $6.5 million (1941 dollars).

The storm continued to roar on its northward path through Texas and by 7 am on the 24th, it was located near the city of Tyler, over extreme northeast Texas. From this point on, the storm's last 36 hours or so really grabs ones interest for peculiarity as it tracked through the Mississippi Valley and on into the Great Lakes. From 7AM on the 24th to 7am the 25th, the storm shot northeast from Tyler to near Battle Creek, Michigan, covering close to 1000 miles in 24 hours! Thus, the forward movement of the remnants of the hurricane averaged 40 to 45 mph as it approached Southern Lower Michigan. As the storm tracked into the Great Lakes, it merged with a fairly strong cold front that pushed across the upper Midwest into the Lakes. The combination of the strong push of cool fall air, strong upper level dynamics and the remnants of the hurricane created quite a storm (not unlike the more common intense late fall cyclones that are seen in the Great Lakes). In addition, the track and speed of our "hurricane" brings to mind that of the "Panhandle Low" type of low pressure system in the winter (more information). While the speed of the system was fairly quick, it's not uncommon for hurricanes to accelerate northeast as they become extra-tropical and get "picked up" by the mid-latitude upper winds or jet stream. Yet, what was really unusual and noteworthy was the surface wind that accompanied the storm as it moved through the Great Lakes. By the time hurricanes make it this far north, they usually have blown themselves out, at least to the extent that surface winds are only gusting to, at best, 30 or 40 mph. Note the following, taken from the Detroit weather records on September 25th, 1941:

Windstorm: An intense tropical cyclone moving up from the Gulf thru eastern Texas (causing great damage in Texas), along the Missip. Valley and thence Newd across Ill & Mich, passing W & NW of Detroit with gale force winds and gusts to 65 mph from 10:18 AM - 2:30 PM & gusts to 75 mph 12:30 PM - 2:00 PM (see envelope back of book for newspaper clippings).

Most of the above noted news clippings show widespread wind damage to trees and power lines that would be commonplace in severe thunderstorms or a derecho. A derecho is a widespread windstorm consisting of a complex of thunderstorms that develop into a long-lived squall line. But there also were some unusual or freakish happenings (as the Detroit Free Press deemed them) as well. The following is taken September 26th, 1941, the day after, from the Detroit Free Press about the storm:

"River goes dry"

There were many freakish effects of the wind, including baring of the Detroit River "middle grounds" off Belle Isle when water was backed into Lake St. Clair. The southwest gale literally blew the water out of The Detroit River, reducing its level by three feet, and leaving hundreds of pleasure craft high and dry on the muddy bottom. Several yachts broke their mooring or were heeled over at the Detroit Yacht Club. Another odd effect was the noticeable swaying of Downtown skyscrapers as the full force of the gale struck. Office employees who left tall downtown skyscrapers, were later reassured by engineers.

The Free Press goes on to say that "shortly after noon, the wind blew steadily at 56 miles an hour, but a times gusts reached hurricane velocity of 75 miles an hour." Dozens of people were injured by falling glass from windows blown out or debris tossed by the wind. One woman was literally blown into a fire hydrant, suffering a possible skull fracture. Other reports of scattered damage to homes and businesses across the region were mentioned in the article. In addition, the fierce wind churned up giant waves on the Lakes, including Lake Huron into the St. Clair River where two barges were blown ashore from of the shipping channel, even after dropping their heaviest anchors. In Southeast Lower Michigan, Storm Warnings were posted on Lakes Huron, Erie and St Clair at 10:30, the morning of the 25th. Downed telephone lines caused a disruption of service and communication across the Great Lakes and elsewhere. The "dying" hurricane left a trail of damage from Texas clear up into the Great Lakes and Canada. The wind of the storm was equated to an intense fall low pressure system that hit the area on November 29th, 1919 in which the wind blew 67 mph in Detroit and to the "Black Friday" storm in November of 1913.

The fact that the remnants of the hurricane, after weakening and becoming extra-tropical, traveled over a thousand miles, while sustaining an impressive amount of wind itself was very noteworthy. This, and the important addition of a relatively strong polar front traveling southeast at the same time across the Midwest, made for quite the enhancement and gave the additional punch and life to the storm's "tropical" characteristics. The surface map for the morning of the 25th is available (first and second map, below) and  depict quite nicely our extra-tropical storm racing northeast. This, combined with a rather potent cold front pushing southeast out of the Midwest, wrapped-up into the storm of tropical origins! This type of strong interaction is more likely observed on the East Coast. I inverted and then, enlarged the shading so the data could be seen better (click on all maps).

Being it was 1941, no upper air data/maps are available from the original time but a reanalysis of the day shows some interesting items (click on all maps). Note the strong (for the time of year) 500H /18kft/ trough digging into the upper Midwest. The 500H anomaly map below that map, depicts this nicely - the potency, depth and generally out of character of the trough for late September- very well. The last two maps are the Meridional (north/south) average wind at 500H and 850H /5kft/. Note the max-cores (depicted in meters/sec) over the eastern Lakes that is shown and the large upper trough over the Midwest at these levels in the 24 hour average (remembering that this is a reanalysis for the entire 24hour period - and thus, the average).

 

As the storm moved into Southern Lower Michigan, its center tracked northeast across Battle Creek, Lansing, Saginaw and then out over Lake Huron and into Ontario. Judging by the lowest pressure readings at Detroit (29.25 inches) and Flint (29.17 inches), where the wind gusted to 69 mph, its central pressure was estimated to around 29.10 inches (about 985 MB). Quite impressive for the remnants of a "dying" hurricane in the Great Lakes in September. In fact, this is the second lowest pressure reading ever recorded in Detroit during the month of September (the first being 29.21 inches on Sep 29th, 1966, during the passage of an intense early fall low pressure system).

One can only make a random guess as to the chances of another hurricane-force wind storm, from remnants of an actual hurricane, hitting the Great Lakes again. Since it was the only one of its kind in the record books at Detroit since records began in 1870, it may take several 100 years before another similar storm affects the region!

Hurroncane

One final, extremely interesting "hurricane" that affected the Great Lakes must be mentioned to make this article complete. While this storm was not from remnants of a tropical system, its development over Lake Huron had many uncanny likenesses to tropical systems...

The first likeness was its timing, forming over the Great Lakes right at the height of the typical hurricane season, September 11-15th, 1996. What started as a typical core-cold 500 MB low pressure system evolved into a warm-core system as it settled over the relatively warm waters of the Great Lakes, in particular, Lake Huron. The low pressure system actually had moved past Lake Huron but then retrograded, or was "drawn back", to the relatively warm waters of Lake Huron. (Similar to the tropics, the Great Lakes usually reach their warmest water temperatures late August into mid September.) The storm then deepened and intensified at the lower levels of the atmosphere compared to aloft, typical of a warm-core low. It is believed that the warm waters of Lake Huron and associated low level instability over the lake were, to a large extent, the major contributing factors in this storm's evolution. The storm went on to form a broad cyclonic circulation, including the "spiral bands and eye", typically seen in hurricanes! At one point, the cyclone produced tropical storm force winds (39 - 73 mph) and some of the spiral bands even had rainfall exceeding 10 cm (better than four inches), causing some flooding.

On satellite, the storm looked very much like the classic hurricane picture:

This "Hurroncane" reached its maximum intensity during the day on September 14th, when a central pressure of 29.34 inches (993 MB) was recorded in the late morning by a Lake Huron buoy that fortunately was positioned, at one point, in the "eye". By 2 PM, that "eye" measured close to 20 miles across and had a ring of tall convective clouds surrounding it, strongly resembling that of an "eye wall". The convective showers encircled the "eye" well out over 300 miles. As the "eye" moved to the southwest (retrograded), over the aforementioned buoy, the surface wind backed from west at close to 35 mph to the southeast, and then diminished to near 10 mph. After, the "eye" continued to track to the southwest, away from the buoy, and the surface wind backed further to the northeast, and briefly attained tropical storm force. A similar scenario but with varying wind speeds, would also be expected at the ocean's surface if a tropical system retrograded from northeast to the southwest overhead. In addition, the air temperature rose from 13°C (55°F) in the spiral shower bands, to near 18°C (64°F), which was also the lake temperature, in the clearing above the "eye". The storm weakened overnight as the surface lake temperature dropped 5°C (9°F) back into the mid 50s due to up-welling and mixing. The lower water temperature helped greatly in weakening the storm as a result of the lower latent heat supply. 

For additional information on hurricanes, check in with the National Hurricane Center.

Background on "Hurroncane" was provided by a paper entitled "Hurricane Huron" by Mr. Todd Miner of Pennsylvania State University along with Dr. Peter Sousounis, Mr. James Wallman and Dr. Greg Mann of the University of Michigan.

Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian

 

One of the Warmest Winters & Springs Followed by a Warm or Cool Summer?

Southeast Lower Michigan Summer 2024 Outlook

I look for the Summer Temperatures to average normal to above; while rainfall is also expected to be normal to above. I use the two-tier category for all of Southeast Lower Michigan and reasons mentioned below. Another trend clearly observed is rainfall is even more variable during the summer with convective rains - and sometimes it's feast or famine. 

Abbreviated Review of Winter/Spring Temperatures

Spring of 2024 was an extraordinarily warm spring across Southeast Lower Michigan. And really; not unlike the very mild winter of 2023-24 it followed as far as high ranking for above normal temperatures. See both seasons below:

Top 20 Coldest/Warmest Winters in Southeast Lower Michigan
Rank	Detroit Area*				Flint Bishop**				Saginaw Area***
	Coldest		Warmest		Coldest		Warmest		Coldest		Warmest
	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year
1	18.8	1903-1904	36.9	1881-1882	16.7	1976-1977	34.0	2023-2024	15.7	1962-1963	33.3	1931-1932
2	19.3	1874-1875	35.7	1931-1932	17.0	1962-1963	33.4	1931-1932	16.5	1917-1918	33.2	2023-2024
3	19.7	1976-1977	35.2	1889-1890	17.8	1958-1959	33.0	2015-2016	16.6	1919-1920	31.7	2015-2016
4	19.7	1917-1918	34.8	2023-2024	18.6	1978-1979	32.2	1982-1983	17.5	1978-1979	30.9	1997-1998
5	20.4	1962-1963	33.8	2001-2002	19.0	2013-2014	31.7	2001-2002	18.0	1977-1978	30.6	2011-2012

Top 20 Coldest/Warmest Springs in Southeast Lower Michigan
Rank	Detroit Area*				Flint Bishop**				Saginaw Area***
	Coldest		Warmest		Coldest		Warmest		Coldest		Warmest
	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year
1	41.7	1875	55.2	2012	40.8	1947	53.3	2012	39.8	1950	52.4	2012
2	42.0	1888	53.1	2010	41.1	1984	51.2	1921	40.1	1926	52.1	1977
3	42.4	1940	52.9	1991	41.5	1960	50.7	1991	40.4	1940	50.8	2010
4	42.5	1877	52.7	1977	41.6	1950	50.5	1977	40.6	1947	50.1	1985
5	42.6	1926	52.5	1921	41.7	1996	50.3	1987	40.9	1923	50.1	1921

As you can see the spring season hasn't been updated yet by the NWS DTX above but looking at the facts and figures for the three-month period /Mar-May 2024/ leaves us with an approximate spring temperature average for all three locations.

City   Spring Ave / Ranking

Detroit          53.4 / 2nd warmest Spring

Flint               51.1 / 3rd warmest Spring

Saginaw       50.6 / 4th warmest Spring

Taking this one step further; it's pretty safe to summarize that the 6th month period winter into spring /Dec - May/ was the warmest period all three cities have had since their perspective record periods started.

ENSO STATUS

https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/

ENSO Forecast

May 2024 Quick Look

Published: May 20, 2024

A monthly summary of the status of El Niño, La Niña, and the Southern Oscillation, or ENSO, based on the NINO3.4 index (120-170W, 5S-5N)

As of mid-May 2024, waning El Niño conditions persist in the central-eastern equatorial Pacific (between 160E to 160W), with important oceanic and atmospheric indicators aligning with ENSO-neutral conditions. All models in the IRI ENSO prediction plume forecast ENSO-neutral for May-Jul, 2024, which then persists during boreal summer seasons of Jun-Aug, and Jul-Sep, 2024. La Niña becomes the most probable category in Aug-Oct, 2024 through Jan-Mar, 2025.

Summer 2024 Analogues

Over a century of similar Neutral ENSO timings (El Nino Spring>Summer Neutral>Autumn La Nina)






The first most striking feature of the analogues is the dominance of cooler (below-normal) summers earlier in the sample, basically before 1973. After; mainly warmer summers tended to hold sway (normal-above) especially from 1988 on. The other notable trend change has been the wetter summers in the same time period as warmer summers but more scattered with still a few months dry. This warmer trend later in my opinion is due to the expanding city and DTW airport heat island affect (mainly overnight lows) and the more recent, general climate warming. That's not to say a cool summer or dry summer can't happen and they will - but less frequent. 

Several warm season analogues were active with storms and subsequent severe weather. Notably; 1973, 1988, 2007 & 2010. It's also worth noting; generally several of the 1970s severe weather seasons were also active (based on analogue data up to 2010 review data). On the flip side; focusing on the latest analogue, 2016 - severe weather tally was one of lowest.

The above summer analogue later year data and trend of the past six months certainly speaks volumes for a normal to above normal temperature summer in 2024. With that said; another contrary indicator has been the predominant upper low and the intermittent strong flow from the northern Canada and even the Arctic into June. This feature is a semi permanent feature -more or less- through the seasons with generally a fading trend into summer and sometimes, even early fall. This is basically what I would expect this summer and fall, being a increasing La Nina ENSO.

Leaning on the preponderance of data; I look for the Summer Temperatures to average normal to above; while rainfall is also expected to be normal to above. I use the two-tier category for reasons mentioned above and for all of Southeast Lower Michigan. Another trend clearly observed is rainfall is even more variable during the summer with convective rains - and sometimes it's feast or famine.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian