Summer of 2019 - Started Cool and Wet; Ended Warm and Drier Record or Near Record Great Lake Water Levels

Summer of 2019 really started out on a down beat note with exceptionally cool weather relative to normal the first two-thirds of June. A one point (around the calendar beginning of summer); temperatures averaged over 3 degrees below normal. That may seem like small departure but for a summer month that was enough (at that point) to come close to the top 20 coolest Junes. The 20th coolest June temp ave is 64.8 and by the 21st we were in the mid 60s. The last week of June reversed course similar to some of the cooler and normal analogues to only average a solid degree below normal /68.2, -1.2/.

The analogue sample projected an ave of /68.6, -0.8/ with five below normal Junes (a degree or more). There were also five above normal Junes which complicated the call but the average and also trend for June was still below normal averaging about a degree /-0.8/ with warming later in the month prevalent.

From my Summer Outlook:
 
Let's start with June; a cool or below normal June? That's what all my data is pretty well showing; from analogues, to current and projected upper air patterns, CFS Climate model which looks out over  most of June and CFSv2 model, for all of June. Can't argue much with that; though anything can happen we all could be wrong ;-). Let's hope we can slide by with a "closer to normal" June. Also, many times changes occur mid or late month and this June could very well be one of those and warm up with time.

Even though they were just as many cool Junes as warm Junes in the analogues (5/5); the difference here was the cool June departures were more notable than the warm departures for June. The five cool Junes averaged in at 64.7; well below the June norm of 69.4. These cool Junes averaged just under five degrees below normal and were precisely why the average for all of the June sample came in below normal also, at 68.6 /-0.8/. On the flip-side; the warm June's averaged in at 71.9 or 2 1/2 degrees above the June normal (or just about half of the cool departure). There was just a couple of normal Junes in the 12 numbered sample.

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PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6)

                                          STATION:   DETROIT MI

                                          MONTH:     JUNE

                                          YEAR:      2019

                                          LATITUDE:   42 13 N

                                          LONGITUDE:  83 20 W

  TEMPERATURE IN F:       :PCPN:    SNOW:  WIND      :SUNSHINE: SKY     :PK WND

================================================================================        

1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18

                                     12Z  AVG MX 2MIN

DY MAX MIN AVG DEP HDD CDD  WTR  SNW DPTH SPD SPD DIR MIN PSBL S-S WX    SPD DR       

================================================================================

 1  78  61  70   5   0   5 0.64  0.0    0  6.5 30 270   M    M   9 138    38 280

 2  72  53  63  -2   2   0    T  0.0    0 10.3 18 300   M    M   6 18     24 290

 3  67  45  56 -10   9   0 0.00  0.0    0  7.4 16 170   M    M   3        20 170

 4  75  51  63  -3   2   0 0.04  0.0    0  7.1 21 230   M    M   9 18     26 240

 5  83  62  73   7   0   8 0.17  0.0    0  9.2 24 340   M    M   9 138    35 310

 6  73  58  66  -1   0   1 0.00  0.0    0  4.7 12 360   M    M   9 18     14 350

 7  79  57  68   1   0   3 0.00  0.0    0  7.9 16  60   M    M   6 18     22  50              

 8  81  57  69   2   0   4 0.00  0.0    0 10.4 18  70   M    M   7        26 100

 9  77  67  72   4   0   7 0.04  0.0    0  7.4 14 240   M    M  10 18     18  70

10  73  55  64  -4   1   0 0.17  0.0    0 11.0 25 290   M    M   9 18     32 300

11  78  49  64  -4   1   0 0.00  0.0    0  6.4 16 300   M    M   2        23 250

12  77  58  68  -1   0   3 0.05  0.0    0  8.3 18 330   M    M   8 1      23 170

13  64  52  58 -11   7   0 0.15  0.0    0  8.3 21 320   M    M  10 18     28 320

14  75  48  62  -7   3   0 0.00  0.0    0 12.1 23 220   M    M   7        32 240

15  71  61  66  -4   0   1 0.04  0.0    0 12.2 22 210   M    M  10 18     29 210

16  64  56  60 -10   5   0 0.44  0.0    0  7.3 14  40   M    M  10 18     18  40

17  73  58  66  -4   0   1    T  0.0    0  3.9 12  10   M    M  10 8      15 360

18  78  58  68  -2   0   3 0.00  0.0    0  3.0 12 160   M    M   8 8      15 150

19  81  61  71   0   0   6    T  0.0    0  4.3 12 170   M    M   9 18     15 180

20  68  57  63  -8   2   0 0.51  0.0    0  8.9 17 360   M    M   9 1      23 350

21  78  55  67  -4   0   2 0.00  0.0    0  7.4 15 330   M    M   5        18 320

22  77  54  66  -5   0   1 0.00  0.0    0  5.8 12  90   M    M   5 8      17 120

23  79  54  67  -5   0   2    T  0.0    0  5.9 14 170   M    M   6        19 120

24  81  67  74   2   0   9 0.06  0.0    0 10.2 29 250   M    M   8 1      35 250

25  85  63  74   2   0   9 0.00  0.0    0 13.4 25 280   M    M   4        31 260

26  87  67  77   5   0  12 0.00  0.0    0  8.4 17 240   M    M   6        24 260

27  88  68  78   6   0  13    T  0.0    0  4.1 22 250   M    M   6 38     31 250

28  91  68  80   7   0  15 0.53  0.0    0  5.2 29 300   M    M   7 38     38 290

29  89  72  81   8   0  16 0.02  0.0    0  7.6 16 310   M    M   6 138    21 290

30  86  69  78   5   0  13    T  0.0    0  6.4 15  10   M    M   6 8      21  20

================================================================================

SM 2328 1761        32 134  2.86     0.0 231.0          M      219

================================================================================

AV 77.6 58.7                               7.7 FASTST   M    M   7    MAX(MPH)

                                 MISC ---->  # 30 270               # 38  280

================================================================================

NOTES:

# LAST OF SEVERAL OCCURRENCES

COLUMN 17 PEAK WIND IN M.P.H.

PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6) , PAGE 2

                                          STATION:  DETROIT MI

                                          MONTH:    JUNE

                                          YEAR:     2019

                                          LATITUDE:   42 13 N

                                          LONGITUDE:  83 20 W

[TEMPERATURE DATA]      [PRECIPITATION DATA]       SYMBOLS USED IN COLUMN 16

AVERAGE MONTHLY: 68.2   TOTAL FOR MONTH:   2.86    1 = FOG OR MIST

DPTR FM NORMAL:  -1.2   DPTR FM NORMAL:   -0.66    2 = FOG REDUCING VISIBILITY

While rainfall at Detroit Metro was 2/3 of an inch below normal it was more of an outlier as much of the region saw normal to well above as evidenced by the map below. Severe weather was limited for June and in fact; much of the summer. One event that the NWS DTX has recorded occurred on the first calendar day of the summer June 1st.

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While rainfall at Detroit Metro was 2/3 of an inch below normal it was more of an outlier as much of the region saw normal to well above as evidenced by the map below. Severe weather was limited for June and in fact; much of the summer. One event that the NWS DTX has recorded occurred on the first calendar day of the summer June 1st.

The month of July did an about face with above normal temperatures prevailing. The following map clearly shows the extent of the warmth with temperatures over Southeast Lower Michigan averaging 1 - 3 degrees degrees above normal. This was also the call in the analogues and Outlook


Things started to heat-up in July as well they should with six Julys above normal, averaging better than two degrees. The normal Julys placed a close second with five in number with only one cool July - a far cry from June's stats. Overall, the twelve Julys averaged +0.6 above normal but again not enough to declare the month - by average - a categorized above normal month (>+1.0). Still, there were quite a few notably warm Julys with the above normal six averaging 75.8 or better than two /+2.2/ above normal. (mention 76 degree summers).

The prevalent warm July's in the analogues averaged nearly 3 degrees above normal. 

 

Rainfall during July was quite variable with some areas getting dumped on by heavy storms while the majority of Southeast Lower Michigan beginning to dry out after month's of wetter conditions. While much of the region averaged below normal rain. A band of thunderstorms with wind damage and very heavy rain the region on the 2nd and 20th of July. Severe weather reports can be found here at the NWS DTX for July 2nd & July 20th.

As was found in the 12 previous summer months, August also followed the temperature pattern researched in the analogues. Hot spells backed off some and thus; the average temperature for August was just a degree /1.1/ above normal with an average of 73.1. All of Southeast Michigan shared in the near normal regime. From the Outlook...

By August; a bit closer to a normal temperatures were found but with the above normal Augusts just winning out at five; there were four normal Augusts and three cool Augusts. Average temperatures dropped slightly to 72.3 for all 12 August months.  However; again like the Julys, the warmer, above normal Augusts averaged at 74.7; nicely above /+2.7/ over the 72.0 norm.

 

Rainfall continued sporadic in August with normal to above central and south; below in the Saginaw Valley. While no severe weather has been documented at DTX in event summaries; a narrow band of regenerating storms with torrential rains hit the North-Northeast on August 12th (see map of Metro Detroit) created flooding in the targeted areas near and north of the Walter Reuther Freeway. 

August 12th

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SUMMER 2019

Much of Michigan (including Southeast Lower Michigan) had a relatively normal summer as far as temperatures with reading averaging around a degree of normal.

Rainfall was somewhat sporadic but on the whole averaged around normal to slightly above for the Lower Peninsula; below normal west and around normal was seen east in the U.P. In Southeast Michigan; pockets of below average were also observed within the normal to slightly above, especially in the Thumb.

SUMMER 2019 - FACTS AND FIGURES

Summer Analogue Verification

Comparisons of analogue temperature projections to actual at Detroit find some interesting parallels and differences. As noted above, the researched temperature trend and subsequent forecast for all of Southeast Lower Michigan worked very well compared to normal. Basically, the summer had a cool beginning; warm middle and typical temperate end. 

As far as actual temperatures in the Summer Outlook the following was forecast:

Temperatures:

Overall; I look for temperatures to average around normal or within -1 1/2 to +1 1/2 degrees of the normals for Southeast Lower Michigan. As far as the patterns researched and analogue projections; see my Temperature trends discussion under analogues.
 
As shown by the state and Southeast Michigan temperature departure map and Detroit departure of +1.0; verified. Temperature actual pattern; verified.

Rainfall:

Look for the general pattern of above normal rainfall to continue into the summer across Southeast Lower Michigan. Analogue summers showed many wet summers with rainfall a couple of inches above normal on average. As far as the pattern researched and analogue projections, see my Rainfall trends discussion under analogues.

As shown by Southeast Lower Michigan's precipitation departure map; most areas saw normal to above rainfall but with notable exceptions; therefore a mixed verification. Given the perplexity of rainfall forecasts for a summer this isn't surprising.

I'll end the summer discussion on an quirky rainfall statistic result at Detroit. Metro Detroit Arpt /DTW/.The summer total rainfall indeed ended below normal with 8.63 /-1.26/. If you'll note the three other drier summers; they all averaged in a unusually tight range of only a few hundredths in the mid 8.60's. Here's the fourth now this summer; at 8.63. Remarkable

Many Great Lake Levels Highest in Recorded Modern History

Great Lakes, Lake St. Clair break 100-year-old water level records

Excellent articles on scattered places around the Lakes in the NY Times...

Great Lake Levels and Projected Levels into October 

US Army Corps of Engineers - Detroit District

The majority of the Great Lakes have entered their seasonal declines at this time but levels are still relatively high compared to long term averages. Lake Superior and Lake St. Clair are both forecasted to be an inch above their highest monthly average for September on the 13th, with Lake Erie forecasted to be 2 inches above. Lakes Michigan-Huron and Ontario are predicted to be only 5 inches below their highest monthly average for September on the 13th. Lake levels are forecasted to continue their seasonal decline headed into October with predicted net decreases of 1 inch on Lake Superior, 3 inches on Lake Michigan-Huron, 5 inches on both Lake St. Clair and Erie, and 8 inches on Lake Ontario. See our Daily Levels web page for more water level information.

BRIEF AUTUMN OUTLOOK

Well since the analogues overall did well in the summer; what about the fall? Granted the hemispheric patterns based on a weakening El Nino are getting long in the tooth but since the ENSO is fading into to basically a Neutral state, little affects are the norm. And, not surprising that's what came up in the analogues; normal. Actually; under our category numbers; normal to below dominated along with drier than normal conditions.

TEMPERATURES 

At five cooler than average analogue falls, four normal and three above; the autumn temperature projection is pretty well split with a balance at normal at 52.9 /+0.1/.  Though below normal falls topped the count at five; the actual average statistic came in a hair above normal but well within the normal range of a degree (+/- 1.0).  




Therefore; generally a typical but nice overall autumn is expected but we'll follow the trend of the analogues with a warmer beginning; then normal to below as we advance through mid to late fall. Look for temperatures to average -1.0 to +1.5 of the statistical norm.

PRECIPITATION

Clearly, our analogues project a drier than normal fall with an average departure of -2.00". The drier falls were accompanied by three normal or average rainfall autumns and just one above normal /2003/ at 9.98". Though this September has started out on the wetter side; this wet then dry pattern started mid summer and is typical into the fall. Analogues suggested even with wetter Septembers; still normal to below rainfall dominated in the fall with the exception of 2003.

Therefore; a two-tier range seems suitable with normal to below but with the emphasis on below.

Notable Dates Autumn into Winter:

Autumn Begins: Later this year; Mon - Sep 23rd at 3:50 AM EDT
Halloween:  Thu - Oct 31st
Thanksgiving:  Late this year; Thu - Nov 28th

Winter Begins: Sat - Dec 21st 11:19 PM EDT
Christmas: Wed - Dec 25th
New Years Day - Wed Jan 1st 2021

Look for the important Winter 2019-20 Outlook early - mid November

Quick Early Summer Review for June and the Outlook for the Rest of the Summer.

June's actual weather followed very well the main trend that was forecast by my research and the analogues which also were supported by general computer forecast trends. From the Outlook...

"Let's start with June; a cool or below normal June? That's what all my data is pretty well showing; from analogues, to current and projected upper air patterns, CFS Climate model which looks out over most of June and CFSv2 model, for all of June. Can't argue much with that; though anything can happen we could be all wrong ;-) Let's hope we can slide by with a "closer to normal" June. Also, many times changes occur mid or late month and this June could very well be one of those and warm up with time".

Result...

That's exactly what happened as a cool June for over half of the month, moderated then a warmed to an above normal temperature trend later in the month. This ate away at the cool, below normal temperatures to just about a degree below at Detroit, a few tenths at Flint and degree and a half at Saginaw. This is reflected nicely in the next two temperature maps with the coolest of weather not surprisingly over Michigan's Thumb Region; downwind of a cooler than normal Lake Huron.

As they say; a picture(s) is worth a thousand words. June's Temperature & Rainfall Maps.

 On average; Southeast Lower Michigan averaged a degree or two below normal in June.

While cooler than normal weather prevailed, so did wetter than normal with most stations recording above to well above normal rain amounts. Ironically; the official climate station for Detroit averaged about 2/3rds of an inch below normal. The general trend reflects well the lesser amounts of rain anomaly over the extreme Southeast edge of Lower Michigan. The heavy amounts of stratiform and convective rains in the central and southern Lakes region added to the already near record high water levels from spring snow-melt and rains in that region (see posted videos and pictures in Facebook SE_ WeatherHistorian).

Rest of the Summer from the "Summer Outlook">>>

Things started to heat-up in July as well they should with six Julys above normal, averaging better than the degree needed for an above normal month. The normal Julys placed a close second with five in number with only one cool July - a far cry from June's stats. Overall, the July temperature averaged +0.6 above normal but again not enough to declare the month - by the one degree average - a categorized above normal month. Still, there were quite a few notably warm Julys with the above normal six averaging 75.8 or better than two /+2.2/ above normal.

By August; a bit closer to a normal temperatures were found but with the above normal Augusts just winning out at five; there were four normal Augusts and three cool Augusts. Average temperatures dropped slightly to 72.3 for all 12 August months. However; again like the Julys, the warmer, above normal Augusts average at 74.7; nicely above /+2.7/ over the 72.0 norm.

Latest Observations at the Opening of July

Indications are the upper low trough that was dominant in the spring into early summer over the eastern half of North America has retreated somewhat north allowing more typical heat and humidity into the region under the summertime ridge. While the the current pattern is typical; the strength and persistence of the upper trough over eastern North America leaves me to believe reprieves from warmer or hotter than normal weather will be refreshingly; intermittent.  Thus; the remainder of the summer of near normal temperatures looks status quo with above normal and below normal balancing out. I see no reason to adjust the previous Outlook; I still look for temperatures to average -1 1/2 to +1 1/2 of the Southeast Lower Michigan norm.

Rainfall has been above to well above normal over nearly all of the region as strongly projected by the analogues. With the upper ridge finally nosing and breaking into the region late June; rainfall patterns will follow more typical summer-time patterns of heavy to light convection rains. I wouldn't be surprised to see even more typical dry spells seen during the summer. Still; general above normal rains should be the rule over the majority of the region relating to entire summer totals.

Enjoy the rest of the summer!

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

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The Summer That Wasn't - Summer of 1992

With our cool June and wet weather in most areas thus far; I'm reminded of a time where the summer weather was actually, all downhill from here. Early June 1992, had been nicer than this June. BTW, that 67.0 degree average for the Summer of '92 in Detroit is about what we've averaged thus far this June. This gives you an idea how the whole summer felt like. Picture it; Spring of '92 (27 years ago)...

Temperatures during the late Spring of 1992 by all accounts were quite normal across Southeast Lower Michigan. May was generally a pleasant but dry month with temperatures averaging near normal. However, a subtle but definite change was beginning to evolve in the weather pattern late in the month.

After a warm spell occurred mid-May with high temperatures climbing into the mid 80s, a strong cold front raced southeast across the region on the 23rd, bringing with it thunderstorms and much colder weather. The high on the 23rd reached 80 degrees in Detroit and 74 at Flint, but on the 24th, the best the mercury could do was a cool 52 in Detroit and only 49 at Flint. Though the 52 at Detroit was not a record low maximum (that chilly honor belongs to a "high" reading of only 44 in 1925), the 49 degree reading at Flint was, and both were more than 20 degrees below the normal.

Both cities did, however, establish record lows the following morning when the temperature skidded down to 35 at Detroit and 30 at Flint. The rest of May remained below normal which brought the monthly averages back to near normal. This turn to sharply colder weather late in the month reflected a temporary shift in the Jet Stream. A strong northwesterly wind blew from the Arctic southward into the Great Lakes region. When looking back, this temporary shift in the upper wind pattern was a foreboding of things to come during the Summer of '92.

Like its predecessor, the first half of the month of June was similar to the first half of May with a rather dry and benign weather pattern. Temperatures averaged slightly above normal with only minor deviations. Ironically, an abrupt change to much colder weather was heralded in around the official start of summer (11:14 pm on June 20th), between the 19th and 21st. In retrospect, this chilly annunciation of summer was uncannily accurate and most fitting for what became the second coldest summer ever recorded in Detroit and the coldest at Flint since records began.

Just before the arrival of the unseasonably cold air mass, temperatures climbed to what would be one of two 90s in Detroit and the only 90 in Flint that year.  An unusually strong and vigorous cold front was pushed across Southeast Lower Michigan by a massive, cool high pressure system in southern Canada. The temperature change between the 17th and 20th was quite impressive over the region. Detroit and Flint both rose into the lower 90s (Detroit-92, Flint-93) on the 17^th but on the 20th, the day after frontal passage, readings barely climbed above the 50 degree mark (Detroit-52, Flint-51), a forty degree drop! Both of these readings were record low maximums for the date. Low temperatures the next few mornings were in the upper 30s to mid 40s with Detroit establishing a record low of 42 on the 21st and Flint missing its record low by two degrees with a low of 39 on the 22nd. These are normal low temperatures in Southeast Lower Michigan for late April.

June averaged 2.2 degrees below normal at Detroit with a mean temperature of 65.5, while Flint was 1.7 below normal with a mean temperature of 64.2. Had it not been for the above normal temperatures the first half of the month, the monthly temperature departures would have been greater. Like May, June was again on the dry side across Southeast Lower Michigan with about two-thirds the normal rainfall.

The timing of the lousiest weather during the summer could have not been worse, coming right at the time when the summer is usually at its best, July into August. These months are usually heavy tourist and vacation months in the Great Lakes. The month of July was just about a total wash-out, figuratively and literally. Not only was the month abnormally cool, it was extremely wet, especially across the northern suburbs of Detroit into Flint (where it ended up with the honor of being the wettest July ever with 9.35 inches of rain, a hefty 6.54 above the normal). Across the northern suburbs of Detroit, over 7 inches (7.32) fell in Farmington and nearly 7 inches (6.92) was recorded in West Bloomfield. Officially at Detroit Metropolitan Airport, 5.91 was tallied up during the month which was 2.81 above normal. To add insult to injury, when it did rain, many times it was on or near the weekend. Every weekend showed rain falling either on one or both of the days and sometimes it wasn't just a passing shower. Flint measured nearly three inches of rain (2.72) on Saturday the 18th. Then, later in the month at the start of the weekend on Friday, the 31st, another 2.18 inches was dumped on the area. In Detroit, during the 4th of July weekend, a half an inch of rain fell on Saturday. Then on the following Saturday and Sunday (11th-12th), 1.24 inches accumulated, not to mention the 1.04 that fell on Monday, the 13th. In fact, if your vacation fell during that week of the 11th through the 19th, it rained every day but the last with the rain totaling 3.75 inches. It was even worse in Flint, where rainfall measured a whopping 4.70 inches for that vacation week!

July 1992 ended up the second coldest July on record at Detroit since 1870 with a mean temperature of 68.8 (the coldest occurred in 1891 with 67.2). It was the coldest July ever in Flint back to 1942 with a mean temperature of 66.9 (see Chart-1). Also, while it was the 11th wettest July at Detroit, it made the top of the list at Flint with the 9.35 inches that fell. When combining the cool temperatures and heavy rainfall, all of Southeast Lower Michigan experienced the worst weather in July on record. The other 10 wetter Julys in Detroit were not as cool, nor was the coolest July in 1891 a wet one. Interestingly enough, there were no record lows set in either Detroit or Flint. One explanation would be with all the rainfall, cloud cover averaged above normal (over 7 out of 10 tenths coverage for the month) and thus, this would somewhat hold up the overnight low temperatures. While on the subject of cloud cover, sunshine at Detroit averaged at pitiful 49 percent, down significantly from the 68 percent normally enjoyed in July. As would be expected, there were record low maximum temperatures set, two in both Detroit and Flint (see Chart-1). There were no 90 degree temperature days in Southeast Lower Michigan during July, the month that usually has the most with an average of 5.

It remained unseasonably cool right through August across Southeast Lower Michigan, though it did begin to dry up somewhat with normal to below normal rainfall. An average temperature of 66.7, which was 3.8 below normal, made it the 3rd coldest August on record in Detroit. In Flint, the temperature averaged 65.2 degrees which was 3.3 degrees below normal, making it the second coldest August on record. The temperature did manage to top 90 (91) only for the second and last time in Detroit that summer on August 10th, while Flint flirted with, but just missed its second 90 (89) the same day. Both cities only had six days during the month that averaged above normal reflecting a series of cold fronts that routinely pushed through the area. Two more record low maximums were established in Detroit, while one was set at Flint (see Chart-1) but again, no record lows were managed.

The cooler than normal weather held into early fall with both Detroit and Flint averaging a degree or two below normal in September. Precipitation again rose to above normal levels with Detroit reporting the 7th wettest September on record with 5.55 inches or rain.

While there were a few theories floating around as to the cause of our unusually cool summer, the most accepted and credited was the eruption of Mt. Pinatubo which occurred exactly one year earlier (June 14-15th, 1991) in the Philippines. The volcanic ash that was spewed into the atmosphere, circumnavigated the globe and caused a slight decrease in solar warming into the following year.

The average temperature for the three month (June-August 1992) summer period in Detroit was 67.0 which was 3.1 below the normal of 70.1 degrees. This made the Summer of 1992 the second coldest on record back to 1870. The coldest was just a half degree colder at 66.5 and occurred way back in 1915. The difference between that summer and the Summer of  92 was June of 1915 was cooler (ave: 63.1) than June of 1992, while July was warmer (ave: 70.4) and August again cooler (ave: 66.0). In Flint, the temperature averaged 65.4 degrees which made it the coldest summer on record back to 1942. Normally the summer temperature averages 68.4 through the three month period (see Chart-1).

                                                       C H A R T - 1

                                                       Summer of 1992

___________________________________________________________________

                                                      

T    E   M   P   E   R   A   T   U   R    E    S          ---                       PRECIPITATION                 

Monthly Average/Depart - Record Low Max - Record Low - Rainfall/Depart

                                                Dates                        Dates         

___________________________________________________________________

-MAY        

DETROIT    58.3     + .2        -----                        35/25th           1.33/ -1.44

FLINT        57.3     + .9        49/24th                   30/25th           1.64/ -1.14

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-JUNE

DETROIT   65.5    - 2.2         52/20th                   42/21st           2.35/ -1.08

FLINT       64.2    - 1.7         51/20th                    46/28th          2.26/  - .97

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-JULY

DETROIT   68.8    - 3.1         65/23rd, 65/30th     -----              5.91/ +2.81

FLINT       66.9    - 3.2         64/23rd, 64/30th      -----              9.35/ +6.54

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-AUGUST

DETROIT   66.7    - 3.8         65/14th, 62/28th     -----               2.50/  +.71 

FLINT       65.2    - 3.3           59/28th                    -----               3.50/  +.12

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-SEPTEMBER

DETROIT   61.4    - 1.9          -----                                                  5.55/ +3.30

FLINT       60.2    - 1.0          -----                     * 34/23rd            2.50/ +  .15

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-SUMMER OF  92  (June - August)

DETROIT   67.0    - 3.1

FLINT        65.4    - 3.0

___________________________________________________________________

* superseded in 1995 with 27 degrees

Making weather fun while we all learn, 

Bill Deedler - SEMI_WeatherHistorian

Summer Outlook 2019 for Southeast Lower Michigan - Cool Spring; Cool Summer?

Temperatures:

Overall; I look for temperatures to average around normal or within -1 1/2 to +1 1/2 degrees of the normals for Southeast Lower Michigan. As far as the patterns researched and analogue projections; see my Temperature trends discussion under analogues.

Rainfall:

Look for the general pattern of above normal rainfall to continue into the summer across Southeast Lower Michigan. Analogue summers showed many wet summers with rainfall a couple of inches above normal on average. As far as the pattern researched and analogue projections, see my Rainfall trends discussion under analogues.

Spring Finally Sprung 

The upper air pattern has been very repetitious as of late; basically continuing the general pattern of the winter albeit with obviously; somewhat warmer weather. But not that warm as the Spring of 2019 has gone down in history as a cooler than average spring. May averaged about a degree below normal across Southeast Lower Michigan; April came in-line with normal while March was the biggest offender; averaging close to three degrees below normal! On the whole; Southeast Lower Michigan averaged a degree or two below normal for the entire spring, depending location. Coolest was across the Saginaw Valley and Thumb.

And yes, it's been a wet spring across much of Southeast Lower Michigan with the exception over the Saginaw Valley. The wettest month relative to normal was April.

 

Hemispheric Discussion 

Above average SST's continue the weak El Nino over the Pacific for our summer with SST's hovering just a titch above normal. Look for the SST's to return closer to normal later this Fall. As of this writing; next winter the ENSO looks to be either a Neutral ENSO or possibly even the beginnings of a La Nina. Note the latest CFv2 is hinting at a collapse of SST's later this summer into the Autumn.

The Analogues for the Summer show some interesting trends:

Temperatures Trends by Month: 

Let's start with June; a cool or below normal June? That's what all my data is pretty well showing; from analogues, to current and projected upper air patterns, CFS Climate model which looks out over  most of June and CFSv2 model, for all of June. Can't argue much with that; though anything can happen we could be all wrong ;-) Let's hope we can slide by with a "closer to normal" June. Also, many times changes occur mid or late month and this June could very well be one of those and warm up with time.

Even though they were just as many cool Junes as warm Junes in the analogues (5/5); the difference here was the cool June departures were more notable than the warm departures for June. The five cool Junes averaged in at 64.7; well below the June norm of 69.4. These cool Junes averaged just under five degrees below normal and were precisely why the average for all of the June sample came in below normal also, at 68.6 /-0.8/. On the flip-side; the warm June's averaged in at 71.9 or 2 1/2 degrees above the June norm or just about half of the cool departure. There was just a couple of normal Junes in the 12 numbered sample

Things started to heat-up in July as well they should with six Julys above normal, averaging better than the degree needed for an above normal month. The normal Julys placed a close second with five in number with only one cool July - a far cry from June's stats. Overall, the July temperature averaged +0.6 above normal but again not enough to declare the month - by average - a categorized above normal month. Still, there were quite a few notably warm Julys with the above normal six averaging 75.8 or better than two /+2.2/ above normal.

By August; a bit closer to a normal temperatures were found but with the above normal Augusts just winning out at five; there were four normal Augusts and three cool Augusts. Average temperatures dropped slightly to 72.3 for all 12 August months.  However; again like the Julys, the warmer, above normal Augusts average at 74.7; nicely above /+2.7/ over the 72.0 norm.

Summers:

What all this data leads to is five cool summers; four warm summers and three normal - or average summers in our sample this go-around. And as one would think: this averages to a strong likelihood of a normal or average summer with ironically the mean temperature at Detroit coming in right at normal with 71.7 degrees on the analogues.

Analogue trends suggest a cooler than average June and a normal to above normal July and August. This then leads to basically a normal summer. A lot will deal with the evolution of the upper air pattern that's been overall; holding to the pattern established way back in the winter. The Pacific jet fighting for dominance - and winning more often than not- over the Polar Jet over central and eastern Canada. This would be expected for two reasons once the normal retraction of the summer-time Polar Jet and two; the Pacific Jet remains somewhat energized due the the warm waters of the Pacific.

Rainfall:

The strongest trend seen in the rainfall side of the analogues is above normal rainfall. Half of the analogues showed above normal rainfall with another three denoting normal or average summer rainfall. That only leaves three drier than average summers in the sample of 12. While the average rainfall for all of the summers comes in at 11 1/2" of rain /11.54"/ and well above the 9.89" normal; this doesn't average just the wet summers. At that pace; the six about normal rainfalls average in at a whopping 13.90" - a very wet signal. Being these are just half of the analogue members; generally that's not strong enough of a signal to use alone. However; besides the six wet summers, there were the three normal which boost it up to nine normal to above normal rains which leaves us with an average rainfall of 12 1/2"  /12.49'/; still comfortably above the 9.89" Even the drier summers weren't all that terribly dry with the three averaging at 8.66". A quite interesting and sort of a weird fluke; all three dry summers totaled at: 8.67, 8.66, 8.66".

While all months averaged above normal for rainfall; basically as the summer went on the chances are it gets warmer and wetter. That's pretty simplistic but in some regards; makes sense. As the warmer air surges northward more often during the summer, I look for more occurrences of severe weather.

Model Projections:

The models temperatures projections are in fairly good agreement for the monthly outlooks with generally a near normal outlook; while the three month season is in good agreement. Looking at the month's individually: June does suggest a lean toward below normal, July; a lean toward above normal and August normal - not unlike the detailed analogues. Therefore; the monthly computer broad-scale projections of the model do  reflect the analogue details.

 

 

 

A consensus of the foreign models suggest a near normal temperature summer also. Interestingly; the large area of below normal temperatures in the mid part of the country is reflected by both the foreign models and American and actually; encroaches the western Great Lakes.

I'll be back during the summer for noteworthy weather events; many on the FB WeatherHistorian chat and have a great summer.

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