Lake Michigan Water & Air Temperature Records in 2012

Air Temperature Over Lake Michigan Reaches Record Level

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
934 PM CDT SAT JUL 28 2012 /1034 PM EDT SAT JUL 28 2012/

...MORE RECORDS BROKEN AT SOUTHERN LAKE MICHIGAN MID-LAKE BUOY...

AT APPROXIMATELY 1 AM ON JULY 26TH THE AIR TEMPERATURE AT THE
SOUTHERN LAKE MICHIGAN MID LAKE BUOY CLIMBED TO 85.1F...BREAKING
THE ALL TIME RECORD WARM AIR TEMPERATURE EVER RECORDED AT THE
SOUTH BUOY. PREVIOUSLY...THE WARMEST AIR TEMPERATURE ON RECORD AT
THE SOUTH BUOY WAS 84.5F SET BACK ON AUGUST 18 1988.

IN ADDITION...AN ALL TIME RECORD WARM AIR TEMPERATURE FOR THE
MONTH OF JUNE WAS ALSO SET THIS YEAR BACK ON JUNE 28TH WHEN THE
TEMPERATURE CLIMBED TO 78.6F WHICH BROKE THE PREVIOUS RECORD
WARMEST AIR TEMPERATURE IN THE MONTH OF JUNE WHICH WAS 77.5
DEGREES BACK ON JUNE 18TH 1994.

WATER TEMPERATURES ARE ALSO RUNNING VERY ABOUT 5F TO 6F ABOVE
AVERAGE AND VERY NEAR DAILY RECORD WARM LEVELS.

RECORDS AT THE SOUTH BUOY DATE BACK APPROXIMATELY 30 YEARS TO
JULY 15 1981.

$$

IZZI

Water Temperature Over Lake Michigan Reaches Earliest 80°

PUBLIC INFORMATION STATEMENT 
NATIONAL WEATHER SERVICE CHICAGO IL 
1003 PM CDT FRI JUL 6 2012 /1103 PM EDT FRI JUL 6 2012/ 

...OPEN WATER TEMPERATURES OF SOUTHERN LAKE MICHIGAN REACH 80 DEGREES... 

THE WATER TEMPERATURE AT THE SOUTH BUOY ON LAKE MICHIGAN REACHED 
80 DEGREES ON FRIDAY JULY 6TH...WHICH IS REMARKABLE WARMTH FOR THE 
LAKE TO BEGIN WITH...BUT UNPRECEDENTED FOR THIS EARLY IN THE SUMMER 
SEASON. MONTHLY AIR TEMPERATURES HAVE BEEN ABOVE NORMAL FOR NINE 
CONSECUTIVE MONTHS IN CHICAGO...AND THAT WARMTH HAS TRANSLATED 
INTO WARM WATER TEMPERATURES ACROSS THE LAKE. THE PROLONGED HEAT 
WAVE OF EARLY JULY OVER THE REGION FURTHER ESCALATED THE WARMING OF 
THE LAKE AS WATER TEMPERATURES ROSE 10 DEGREES BETWEEN JULY 1ST AND 
6TH! 

THERE HAVE ONLY BEEN SIX PRIOR EPISODES SINCE 1981 WHERE THE 
SOUTH BUOY WATER TEMPERATURE HAS REACHED 80 DEGREES. THESE WERE: 

PERIOD    NUMBER OF HOURS AT OR ABOVE 80    MAX WATER TEMPERATURE 
----------------------------------------------------------------- 
AUG 88                11                             80 
AUG 95                 5                             81 
SEP 96                 1                             80 
AUG 01                 3                             80 
LATE JUL-AUG 10       13                             80 
JUL 11                 1                             80 

ON FRIDAY...THE BUOY RECORDED TWO HOURLY READINGS OF 80 DEGREES. 
THESE WERE THE EARLIEST 80 DEGREE WATER TEMPERATURES ON RECORD AT 
THIS SITE. THIS SURPASSES THE PREVIOUS RECORD OF JULY 21ST SET BOTH 
IN THE PAST TWO YEARS OF 2010 AND 2011. 

WHAT IS EQUALLY AS REMARKABLE IS HOW FAR ABOVE AVERAGE THE WATER 
TEMPERATURE IS. LOOKING BACK AT THE AVERAGE JULY 6TH WATER
TEMPERATURE AT THAT BUOY SINCE 1981...THAT AVERAGE IS 63 DEGREES. 
THE AVERAGE ON JULY 6TH 2012 WAS 78 DEGREES...15 DEGREES ABOVE 
NORMAL! 

FOR POINT OF REFERENCE...THE SOUTH BUOY IS LOCATED 43 NAUTICAL 
MILES EAST SOUTHEAST OF MILWAUKEE. THE WATER DEPTH IS 528 FEET.
THE WATER TEMPERATURE IS RECORDED ABOUT 2 FT BELOW THE WATER 
SURFACE.

Seen below is a look at the lake breeze on the KLOT Doppler Radar from Friday afternoon. The lake breeze often acts as a source of cooling and relief from oppressive heat if it can push inland. While it did so gradually on Friday afternoon, temperatures behind the lake breeze were not much of a relief due in great part to the warm water temperatures. In addtion, dew points rose in many places behind the lake breeze. This can be seen below in Gary's observation, where the dew point had climbed to 75°. Dew point factors into the heat index, and thus led heat index readings to be similar if not higher than prior to the lake breeze passage.