National Weather Service Weather Forecast Office

SUMMER 2002 OVERVIEW

THE SUMMER OF 2002 WILL BE REMEMBERED AS A HOT AND HUMID SUMMER ACROSS MUCH OF SOUTHEAST LOWER MICHIGAN. IN FACT, WITH AN AVERAGE TEMPERATURE OF 73.46, THE SUMMER OF 2002 BECAME THE 11TH HOTTEST SUMMER IN 132 YEARS IN METRO DETROIT. AND, WITH AN AVERAGE TEMPERATURE OF 71.66, IT WAS THE 7TH HOTTEST SUMMER IN 60 YEARS (SINCE OFFICIAL RECORDS BEGAN IN 1942) IN THE FLINT AREA. IT WAS, HOWEVER, A BIT COOLER FURTHER NORTH IN THE SAGINAW VALLEY REGION. SAGINAW'S AVERAGE TEMPERATURE OF 70.33 DID NOT EVEN PLACE IN THE TOP 20 WARMEST SUMMERS.

                      CHART-2

         DETROIT       FLINT       SAGINAW
           90S+         90S+         90S+
---------------------------------------------
JUNE        6            5            5 
JULY       12           13            7
AUGUST      3            2            0
SEPTEMBER   4 (9/12)     4  (9/12)    1 (9/12)
---------------------------------------------
2002       25           24           13

RECORD:
1988       39           36          N/A

LAST TIME A YEAR WAS AS HOT OR HOTTER:
1995       20           12          N/A  

WHILE 1988 HOLDS THE RECORD FOR NUMBER OF DAYS OF 90 DEGREE OR HIGHER DAYS (SAGINAW IS NOT AVAILABLE), THE SUMMER OF 1995 WAS THE LAST TIME THE SUMMER RESEMBLED THIS PAST SUMMER FOR HEAT (BUT IT ACTUALLY WAS A BIT HOTTER AT ALL THREE CITIES). IT IS INTERESTING TO NOTE, HOWEVER, THAT IN EVEN IN THE HOTTER SUMMER OF 1995, NEITHER DETROIT NOR FLINT HAD AS MANY 90S+ AS THIS YEAR. IN ADDITION, IN 1988 AT DETROIT, A WHOPPING 39 DAYS RECORDED 90S+ BUT THE SUMMER STILL AVERAGED A BIT COOLER THAN IN 1995 (*NOTE THAT THE NUMBER OF 90S+ DO NOT NECESSARILY HAVE TO FALL IN THE SUMMER MONTHS OF JUN-AUG LIKE THE REST OF THE SUMMER DATA AND THE 2002 DATA GOES THROUGH 9/12).

WHILE THERE WAS A GENEROUS HELPING OF HEAT AND HUMIDITY THIS PAST SUMMER IN SOUTHEAST LOWER MICHIGAN, MOTHER NATURE WAS MORE STINGY WHEN IT CAME TO RAINFALL. EVEN DESPITE SOME HEAVY CONVECTIVE RAINS, OVERALL IN SOUTHEAST LOWER MICHIGAN, IT WAS A DRY SUMMER. THIS WAS ESPECIALLY TRUE ACROSS DETROIT'S NORTHERN SUBURBS AND FLINT (WHERE THE LARGEST RAINFALL DEFICITS WERE NOTED) AND EXTENDED NORTH INTO PORTIONS OF THE THUMB AND SAGINAW VALLEY. THE FLINT AREA HAD THE 8TH DRIEST SUMMER ON RECORD /TIED WITH 1944/ AND WAS THE ONLY CITY OF THE THREE TO MAKE THE TOP 20 DRIEST SUMMERS LIST. IT SHOULD BE NOTED THAT EVEN THOUGH THERE IS NO TOP 20 DRIEST SUMMERS LIST FOR DETROIT'S NORTHERN SUBURBS...THIS PAST SUMMER WAS CERTAINLY ONE OF THE DRIER ONES. WHAT MAKES THIS EVEN MORE APPARENT IS THAT IT COMES ON THE BACK OF A NEARLY IDENTICAL (AS FAR AS RAINFALL AT WHITE LAKE) DRY SUMMER LAST YEAR /2001/. LAST SUMMER'S TOTAL RAINFALL WAS 6.63; THIS SUMMER'S, 6.61 INCHES. WHAT MAKES THESE TWO SUMMER FIGURES EVEN MORE DRAMATIC IS WHEN ONE COMPARES THEM TO THE SUMMER OF 2000. THE TOTAL RAINFALL FOR THE SUMMER OF 2000 WAS A WHOPPING 17.07 INCHES AT WHITE LAKE, MORE THAN TWO AND A HALF TIMES THIS (OR LAST) SUMMER'S RAINFALL TOTAL, AND STILL ABOUT ONE AND A THIRD TIMES HIGHER THAN THE TWO SUMMERS PUT TOGETHER! IT SHOULD BE NOTED THAT THE SUMMER OF 1999 WAS ALSO WET WITH 14.96 INCHES FALLING AT WHITE LAKE. THIS CLEARLY DEMONSTRATES THE "FEAST OR FAMINE" SCENARIO WHEN IT COMES TO SUMMER RAINFALL. RESIDENTS FAMILIAR WITH THE INLAND LAKES ACROSS THE NORTHERN SUBURBS OF DETROIT CAN SURELY ATTEST TO THESE RECENT DRAMATIC RAINFALL CONTRASTS, AND SUBSEQUENT LAKE LEVEL FLUCTUATIONS.

THE ACTIVE STORM TRACK THAT BROUGHT HEAVY RAINS TO MUCH OF SOUTHEAST LOWER MICHIGAN DURING THE SPRING ABATED DRAMATICALLY IN MID JUNE, WHEN HIGH PRESSURE IN THE UPPER ATMOSPHERE PUT A HALT TO ANY ROUTINE RAINFALL AND STARTED A NOTABLE DRY SPELL THAT TOOK HOLD OF THE REGION FOR AT LEAST A MONTH. SOME AREAS ACTUALLY REACHED MODERATE DROUGHT CONDITIONS FOR A TIME BY MID-LATE JULY.

DATA RESEARCHED FOR PREVIOUS SUMMERS

COLD MAY--SUMMER INDICATOR?

ONE OF THE MORE INTERESTING (AND SOMEWHAT SURPRISING) DATA REVIEWED WAS THE COLDEST MAY DATA AND THE SUBSEQUENT SUMMERS. LAST MAY WAS INDEED IN THE TOP 20 COLDEST (IN FACT, UP UNTIL THE LAST FIVE DAYS OF MAY, THE MONTH HOVERED AROUND THE THIRD COLDEST MAY IN DETROIT, SECOND COLDEST IN FLINT AND THE COLDEST MAY IN SAGINAW). A WARM SPELL LATE IN THE MONTH RESULTED IN DETROIT "WARMING" TO THE 16TH COLDEST MAY, FLINT THE 11TH COLDEST AND SAGINAW THE 12TH COLDEST MAY. THEREFORE, THE PREVIOUS TOP 20 COLDEST MAYS IN DETROIT AND THEIR SUBSEQUENT SUMMERS WERE RESEARCHED TO SEE IF THERE WAS MUCH OF A CORRELATION BETWEEN A COLD MAY AND COOL SUMMER. AND, WHILE THE DATA SUGGESTED THERE WAS A DECENT CHANCE A COOL SUMMER WOULD FOLLOW OUR COLD MAY (OUT OF THE 20 COLDEST MAYS IN DETROIT, 16 SUBSEQUENT SUMMERS AVERAGED BELOW NORMAL), THIS CERTAINLY WAS NOT THE CASE THIS PAST SUMMER. IT MUST BE NOTED (AND ALSO MENTIONED IN THE COLDEST MAY RESEARCH) THAT A BELOW NORMAL AVERAGE TEMPERATURE FOR ANY MAY DID NOT SUGGEST A COOLER THAN NORMAL SUMMER, SINCE ONLY THE TOP 20 COLDEST MAYS WERE CHECKED.

ONE ITEM, HOWEVER, NOTED IN THE MAY DATA THAT DID COME TO PASS WAS THE FOLLOWING:

"THIS DATA STRONGLY SUGGESTS THAT WHEN RESEARCHING THE TOP 20 COOL MAYS ONLY, THE COOL LATE SPRING PATTERN BASICALLY TENDED TO "HANG AROUND" INTO, AT LEAST, EARLY SUMMER."

AS WAS THE CASE THIS SUMMER, TEMPERATURES AVERAGED BELOW NORMAL THROUGH MID JUNE BEFORE MOTHER NATURE TURNED ON THE HEAT AND TURNED OFF THE WATER.

SUMMER RESULTS AND COMPARISONS

SIMILAR TEMPERATURE PATTERN TO 1930-31 AND 1952-53 CONTINUES:

THE WINTER OF 1930-31 LIKE OUR PAST WINTER WAS ONE OF THE WARMEST /19TH/ ON RECORD. AND, THE SPRING OF 1931 NEARLY MIRRORED OUR PAST SPRING WITH COOLER THAN NORMAL SPRING AVERAGE TEMPERATURE OF 47.0 DEGREES (AND JUST 0.6 OF A DEGREE DIFFERENT FROM THIS PAST SPRING /46.4/). AND OF COURSE, OUR JUST COMPLETED SUMMER AVERAGE TEMPERATURE OF 73.5 DID IN FACT MIRROR THE SUMMER OF 1931 /73.5/. IT WAS ALSO NOTED THAT A SIMILAR TEMPERATURE PATTERN SET UP FROM THE WINTER OF 1952-53 (8TH WARMEST), TO A COOLER THAN NORMAL SPRING (AVERAGE TEMPERATURE 47.3), TO ANOTHER WARM SUMMER (14TH WARMEST) WITH AN AVERAGE OF 72.9 DEGREES. HOWEVER, THE SAME PERIOD IN 1990-91 DID NOT FOLLOW THIS EXACT TREND SINCE WE HAD A MUCH WARMER SPRING /52.9/ (QUITE THE CONTRARY TO THIS PAST SPRING; IT WAS THE WARMEST SPRING ON RECORD IN DETROIT).

THE FOLLOWING AUTUMNS BREED CURIOSITY

SINCE THE TEMPERATURE CYCLE TRENDS OF BOTH LATE 1930 - MID 1931 AND LATE 1952 - MID 1953 RESEMBLE OUR PAST NINE MONTH TEMPERATURE CYCLE (AND WE WILL INCLUDE 1991 JUST FOR ITS WINTER AND NEARLY DUPLICATE SUMMER TEMPERATURE CYCLE), SOME VERY INTERESTING TRENDS ABOUT THE FOLLOWING FALLS ARISE. ALL DATA AGAIN IS BASED ON THE LONGEST CLIMATE BASE, DETROIT (BUT NOTES ABOUT FLINT AND SAGINAW ARE INCLUDED FOR INTERESTS).

AUTUMN OUTLOOK

THERE WERE INDEED SOME NOTEWORTHY WARM FALLS IN 1931 AND 1953, WHILE RAINFALL AVERAGED AROUND NORMAL TO BELOW (ESPECIALLY IN 1953). THEREFORE, THE FALL DATA SUGGESTS THAT THE WARMER AND DRIER WEATHER OF THE SUMMER COULD CONCEIVABLY CONTINUE INTO THE FALL WITH NORMAL TO ABOVE NORMAL TEMPS, AND NORMAL TO BELOW NORMAL PRECIPITATION. WE SHALL SEE.