Spring Review and Summer 2005 Outlook for Southeast Lower Michigan

How about a warmer summer?

Written by: William R. Deedler, Weather Historian
National Weather Service Detroit/Pontiac, MI
June 1st, 2005

Quick jumps on this page:

Sea surface temperature forecast; click on image to enlarge As we move into the summer months, on a northern hemispheric scale, the weak El Niño has once again faded into oblivion and we open the door on this year's summer season under Neutral conditions. This upcoming summer will be our third summer with mainly weak El Niño to Neutral conditions over the Pacific. Latest indications are that the dominant neutral temperature pattern (or near normal Pacific) sea surface temperatures /SST/) are expected to hold throughout the summer and into the fall.

While downwind effects on the US from El Niño and La Niña decrease during the summertime, this is especially true during a Neutral State when both summertime lighter upper winds and neutral conditions prevail. Over the past several seasons, the upper wind pattern over the U.S. has been mainly amplified and progressive but with occasional "lock-in" patterns materializing (lock-in: meaning the placement of upper ridges and troughs "stall" over portions of the country). While the combination of these patterns limits any definite trend expectations for the summer, there are other more subtle patterns mentioned and investigated for this local summer outlook. The following is local researched data and subsequent summer outlook for Southeast Lower Michigan.


SUMMER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN:

TEMPERATURES

While the data reviewed is variable, look for temperatures to average around normal (if not a bit above) and this certainly would be warmer than the past few summers. I would be remiss, however, if I didn't mention of particular concern again for this summer's pattern is the cool and aggressive upper air pattern that persists over Eastern Canada (as was the case the past few summers). This was primarily responsible for our cool weather last summer and our recent cool spring that was expected across Southeast Lower Michigan. However, our analogue summers, recent hemispheric patterns and projections hint that the dominant below normal temperatures of the spring will tend to fade in June. Local data suggests temperatures will warm to more normal conditions as summer evolves (for more detail, see write up below).

RAINFALL

While our analogue summer years (Chart - 2) indicate a variety of summer conditions with variable precipitation amounts, one trend that is evident is that about half of the summers tended to start out dry but became wetter (or normal to above normal rainfall) as they evolved. Note, here we are interested more of the overall rainfall trend of the summer, and not necessarily each specific month's amount. This idea of starting the summer on a dry note certainly reflects (and continues) the trend of the last three months with Spring of 2005 being one of the driest springs on record! This trend will have to be watched because of its persistence. As of this time, however, look for rainfall to total around normal by summer's end (for more detail, see write up below).

RECAPPING THE SPRING ACTION AND RECENT TRENDS:

  • VERY DRY AND COOL SPRING
  • ONE OF THE DRIEST SPRINGS ON RECORD

The very stormy and long wet pattern of the winter died down considerably to a more tranquil and drier pattern during the spring (excluding the late April snowstorm, of course)! While early Spring of 2005 mimicked early Spring of 2004 with its notable change to drier weather, late Spring 2005 /May/ continued the notably dry pattern, whereas May of 2004 was just the inverse with a record setting wet month. Total spring precipitation was well below normal across all of Southeast Lower Michigan, so much so that all locations placed very high on the list (see Chart -1) for top 20 Driest Springs. In keeping with our all too familiar feast or famine regime, Spring of 2004, all cities ranked in the top ten wettest springs! The last time it was as dry or drier across the Metro Detroit Area was back in the Spring of 1988 (which was followed by our third hottest summer) when 3.53" of rain fell, which made it the second driest spring. At Flint, only one other spring was drier and that was in 1958 when just 3.22" fell (The Summer of '58 was also Detroit's driest spring with just 3.32"). Lastly at Saginaw, the last time it was as dry or drier than this spring was not 1988 (5.41" fell), it was back in 1979 when 4.65" (the Spring of '58 was Saginaw's second driest spring with 3.87").

  • ONE OF THE MOST INACTIVE SEVERE WEATHER SPRING FOLLOWS LAST SPRING'S MOST ACTIVE

With the lack of rainfall, perhaps it's not surprising that our 2005 Severe Weather Season started with a whimper rather than the big bang of last year. As far as events, Spring 2005 turned out to be the second least active since 1986 (1993 was the least active). This also is in stark contrast to last spring in which the season was the busiest. May of 2004, alone, was exceedingly rough with severe storms, heavy rain and flooding which lead to numerous severe weather warnings.

  • AFTER A WARM SPRING LAST YEAR, A COOL ONE THIS YEAR

The notably cold March and May were enough to erase the above normal departure of April across Southeast lower Michigan (unlike the Spring of 2004, which was a warm spring). On average, temperatures placed in the lower to mid 40s this spring which is a couple of degrees below normal.

Monthly Scoops:

Taking it by month, March of 2005 was one cold month across Southeast Lower Michigan with much of the time, played out like another winter month! While March was a relatively dry month precipitation-wise (melted snow and any rain), snow-wise the month totaled above normal most areas, since most of the time is just snowed. Temperatures averaged some 4 to 6 degrees below normal across the entire region. The very cold March placed in at 9th coldest for Flint and 13th coldest at Saginaw (but much of the month, that placement was higher up). The only reason Detroit didn't place was the "heat island effect" that moderated overnight lows. Our best analogue winters from the Winter Outlook had strongly suggested the likelihood of a cold March.

A respite from the cool spring did come the first three weeks of April as warmer weather moved into the region. In fact, temperatures peaked at record high levels with 83 degrees (DTW/FNT/MBS) on the 19th. Overall, April was another dry spring month, especially the period from late March into April. A very nice stretch of sunny, dry (actually too dry) weather commenced in late March and lasted into the first three weeks of April. So minimal was the rainfall that less than a quarter of an inch /.23/ fell between March 24th - April 20th (or almost four weeks) at Detroit. Here at White Lake /DTX/, from March 21st - April 20th, just .14 fell. Further north around Flint and Saginaw even more impressive dry data surfaced. At Flint, only one hundredth of an inch /.01"/ fell and while intra-monthly records are not available, monthly records are, and the least amount of precipitation ever recorded in a month was just .07" in January 1945 (but still higher than the recent .01"). Checking back in and around that period from Jan 4th - Feb 3rd 1945 revealed that just .05" fell, lower, but still not as low as the .01 of an inch. The minuscule .01" that fell between 3/20/05-4/19/05 was the driest 30 day period found for Flint since 1942. Saginaw only had .05" during the same period (3/20/05-4/19/05) but its all time driest month, September 1979, had no rainfall! After that sunny dry spell, residents of Southeast Lower Michigan paid for that nice streak of weather dearly by being hit with an impressive late season snowstorm. Most information is available on this storm and others that have hit the region late in the season.

The dominant cool weather trend held sway over the region through much of May with temperatures averaging considerably below normal. May also continued the trend of the very dry spring. This was in stark contrast to last May which had record rainfalls and some flooding across Southeast Lower Michigan.

Chart - 1
2005 - SPRING AVERAGE TEMPERATURE AND RAINFALL/DEPARTURES/RANK

  Detroit Flint Saginaw White Lake

MAR (T) 33.1/-3.8 29.1/-4.6 27.8/-5.7 29.1/-
(P) 0.74/-1.78 1.04/-1.1 1.13/-1.29 1.12/-
 
APR (T) 50.7/+2.6 48.3/+2.9 46.8/+1.3 48.4/+
(P) 1.66/-1.39 1.31/-1.82 1.51/-1.31 2.29/-
 
MAY (T) 56.6/-3.2 53.4/-3.7 53.8/-3.8 53.1/-
(P) 1.85/-1.09 1.40/-1.25 2.14/-0.65 1.66/-

Ave (T) 46.8/-1.5 43.6/ -1.8/14th 42.8/-2.7 43.5/--
Total (P) 4.25/4.37/3rd 3.75/-4.34/2nd 4.78/-3.35/11th 5.07/--
 
Note: White Lake has no official normals at this time; the -/N/+ just denotes an estimate of above/normal/below (-- is much below).

Will Summer Sizzle or Fizzle?

Comparing last summer's /2004/ research to this summer's reveals a similar temperature variability with even more complicated issues with nearly as many normal to above normal summers as below. In the summers that followed our two closest analogue winters (1926/1952) indicate that the "Summer of '26" started very cool and then warmed closer to normal by mid-late summer, while the "Summer of '52" was a warm to hot summer. In fact, the summer of 1952 ranks as Flint's hottest summer (remember, its official climate records only to back to 1942), while 1952 ranked as Detroit's eighth hottest summer. Curiously, the "Summer of '52" did not place in Saginaw's top 20 hottest summers at all (it is suspected Saginaw was closer to the storm track and may have been influenced more by the occasional cooler air mass). This overall warmer pattern displayed in those two summers (over the past few summers) also influenced in the final temperature projection of this outlook.

It is felt that the pattern of relatively dry and tranquil weather followed by notably wet and stormy periods of the past several seasons continues to persist (and each, possibly now for longer durations). While this still confirms the "feast or famine" regime we've become more accustom to the past several years, as stated above, we will have to keep watch for the possibility of the evolution of longer durations of each (wet and dry). As far as the overall variability in the summer "guidance", as in the winter, one possible speculation may be that the latter years of a Neutral Pacific pattern may result in a variety of outcomes in our seasonal weather since there is even a longer duration of negligible Pacific affects. When all temperature stats are averaged out, they do denote a normal to slightly above normal results (see Chart-2, below).

Chart-2

TEMPERATURES

SUMMERDETROITSAGINAWFLINT *
YearJun Jul Aug
187668.872.871.6Jun Jul Aug
188667.271.670.8
190066.672.075.566.371.375.1
191265.071.267.465.871.166.0
191974.075.070.273.672.767.4
192663.472.472.061.070.669.3Jun Jul Aug
193270.373.073.770.271.972.5
194766.070.976.563.368.774.864.468.976.0
195272.776.571.569.172.968.170.373.673.7
196469.676.069.167.872.565.866.671.765.3
197765.575.870.662.771.865.063.173.868.2
197866.870.671.964.269.269.765.169.670.0
198771.376.171.669.873.967.770.375.669.3
199571.674.877.170.073.173.668.472.474.3
200366.672.672.964.569.469.564.670.870.9
Averages68.473.472.266.871.569.666.672.171.0
Summer
Average
71.369.369.9*
Month
Norms
69.073.571.866.871.268.766.270.668.5
Summer
Norms
71.468.968.4
LEGEND:
Cool summer Highlighted summers reflect harsh winters beforehand (or closer analogy to this past winter under weak El Niño/Neutral conditions)
Normal summer
Warm summer
*Important note: Flint has the smallest data base and therefore has the least amount of weighting in the outlook.

SUMMERS IN THE STUDY - Temperatures:
DETROIT Hottest Summer: 1995/74.5 Coolest Summer: 1912/67.8 Normal Summer: 71.4
SAGINAW Hottest Summer: 1995/72.2 Coolest Summer: 1912/67.6 Normal Summer: 68.9
FLINT Hottest Summer: 1952/72.5 Coolest Summer: 1964/67.9 Normal Summer: 68.4

The most impressive data found for this summer was the large range of rainfalls, especially at Detroit.

RAINFALL

SUMMERDETROITSAGINAWFLINT *
YearJun Jul Aug
18761.515.942.46Jun Jul Aug
18862.072.452.02
19003.993.712.082.573.895.23
19121.923.874.050.766.422.73
19193.612.092.492.832.181.63
19262.811.248.332.583.065.34Jun Jul Aug
19321.353.114.021.853.822.93
19473.492.422.853.644.462.163.534.753.36
19521.063.142.180.646.383.000.904.532.71
19642.352.375.871.395.334.213.982.822.65
19773.163.282.231.792.645.194.701.913.15
19782.691.971.733.220.931.561.660.732.62
19877.042.206.874.830.786.721.602.205.03
19951.553.403.713.282.747.330.722.644.29
20032.502.594.372.102.641.002.161.743.79
Averages2.742.923.682.423.483.772.412.673.45
Summer
Average
9.34"9.67"8.53"
Month
Norm
3.553.163.103.062.503.383.073.173.43
Summer
Norm
9.81"8.94"9.67"
LEGEND:
+.50" Above NormalHighlighted summers reflect harsh winters beforehand (or closer analogy to this past winter under weak El Niño/Neutral conditions)
+/-.50" Near Normal
-.50" Below Normal

SUMMERS IN THE STUDY - Precipitation:
DETROIT Wettest Summer: 1987/16.11" Driest Summer: 1952/6.38" Normal Summer: 9.81"
SAGINAW Wettest Summer: 1995/13.35" Driest Summer: 1978/5.71" Normal Summer: 8.94"
FLINT Wettest Summer: 1947/11.64" Driest Summer: 1978/5.01" Normal Summer: 9.67"

The wide ranges in rainfall amounts really shows up in the rainfall data at Detroit. There is nearly a ten inch range from wettest summer to driest!

OTHER POSSIBLE INFLUENCING FACTORS FOR THE SUMMER

WHAT ABOUT THE COOLER THAN NORMAL GULF OF MEXICO WATERS ?

Sea surface temperature anomaly from May 17th, 2005; click on image to expand Sea surface temperature anomaly from March 1st, 2005; click on image to expand The waters in the Gulf of Mexico have averaged cooler than normal the past several months with the below normal departure actually growing somewhat since March. Note the two NOAA Satellite pictures of the Global Sea Surface Temperatures /SST/. The left image was taken on March 1st, 2005, while the right image was taken on May 17th, 2005. Note the expanded cooler than normal waters recently extending across portions of the tropics including much of the Gulf of Mexico. The cooler than normal Gulf waters may dampen, so to speak, the normal moisture influx from that area into our region for the immediate near term. This also lends support to the drier than normal late spring which could conceivably continue at least into early summer that our dominant analogue summers are suggesting (though the exact timing is uncertain).

Recapping:

TEMPERATURES

While the data reviewed is variable, look for temperatures to average around normal (if not a bit above) and this would be certainly warmer than the past few summers.

RAINFALL

While our analogue summer years (Chart-2) indicate a wide variety of summer precipitation amounts, one trend that is evident is that about half of the summers tended to become wetter (or contain normal to above normal rainfall) as they evolved. As of this time, however, look for rainfall to total around normal by summer's end.

If conditions warrant, look for an update mid summer.

Here's to good weather whenever and wherever your vacation falls this summer.

Check back in the early fall for this summer's write up and a brief fall outlook.


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