BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, MAY 21, 2007   
ALL TIMES ARE IN EASTERN STANDARD TIME
 
THREE-DAY RAINFALL MAY 18-20TH REACHED 3.05 INCHES
INCLUDED RECORD DAILY RAINFALL ON THE 18TH
 
When the rainfall finally ended early last evening our 
total for the 3-day period, May 18-20, had reached 
3.05 inches including a record 1.93 inches which fell 
on the 18th.  This erased the previous record of 
1.58 inches set in 2002. May, which had only 0.10 inch
for the frist half of the month, now has a surplus of 
precipitation by over one inch. 
 
 
Today's observations:
 
7 A.M.   
Weather: Clear, cumulus, stratocumulus southeast through
southwest, through northwest  
Temperature: 50F, Dew point: 38F, Wind: WNW at 15G25 kts 
Sea-level pressure: 29.98 inches Hg, rising   
Visibility: 60 miles   
24-hourly precip: 0.36 inch
6- hourly min temp. 46 deg.  
BHO SA 1155 CLR 60 151/50/38/3015G25/998/ SC FRMG SE-SW-NW FEW 
ACSL DSNT NNW AND ENE FEW CI DSNT NE WND 27V34/ 8/541 53031 
MANUAL 70036 ASOS 70035 10052 20046 
 
10 A.M.
Weather: Broken stratocumulus clouds  
Temperature: 57F, Dew point: 43F, Wind: WNW at 10G18 kts 
Sea-level pressure: 30.03 inches Hg, rising    
Visibility: 60 miles   
BHO SA 1455 E35 BKN 60 170/57/43/2910G18/003/ SC XCPT DSNT NE-E/ 
8/500 51019  
 
1 P.M.
Weather: Overcast with breaks in stratocumulus   
Temperature: 59F, Dew point: 44F, Wind: W at 12G20 kts 
Sea-level pressure: 30.05 inches Hg, rising    
Visibility: 65-70 miles   
BHO SA 1755 E39 OVC 65 176/59/44/2812G20/005/ BINOVC VSBY NW 70/ 
8/500 51006 10060 20050
 
WEATHER SUMMARY FOR SUNDAY, MAY 20 
 
TEMPERATURE (DEGREES F)
MAX.....59    NORMAL.....68 
MIN.....49    NORMAL.....48
MEAN....54    NORMAL.....58
DEPARTURE FROM 30-YEAR NORMAL..........- 4
TOTAL DEPARTURE FOR THE MONTH..........+19 (+0.8 DEGREES/DAY)
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY...........11  DEPARTURE........+ 4
TOTAL HEATING UNITS FOR THE MONTH..........179  DEPARTURE........-15  
TOTAL HEATING UNITS FOR THE SEASON........5795  DEPARTURE.......-425
TOTAL HEATING UNITS LAST SEASON TO DATE...5662  DIFFERENCE......+144 
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY............30 W   AT 1:50 P.M. 
                   AEROVANE.............29 W   AT 1:50 P.M. 
                   ASOS.................28 W   AT 1:50 P.M.
                   DAVIS................32 W   AT 1:49 P.M. 
FASTEST MILE FOR YESTERDAY..............21 W   AT 1:49 P.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE...........21 W   AT 1:51 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE..........23 W   AT 1:51 P.M.  
AVERAGE WIND SPEED AND DIRECTION.........9.3 WNW
                   ASOS.................10.1 
                   DAVIS.................9.6 WSW [250 deg]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.36  DEPARTURE.....+0.24
                         ASOS..............0.35  
TOTAL PRECIPITATION FOR THE MONTH..........3.71  DEPARTURE.....+1.26 
                         ASOS..............3.64    
TOTAL PRECIPITATION FOR THE YEAR..........24.13  DEPARTURE.....+3.63
                         ASOS.............23.61    
 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.......0.0
TOTAL SNOWFALL FOR THE MONTH................0.0  DEPARTURE......-0.1 
TOTAL SNOWFALL FOR THE SEASON..............27.6  DEPARTURE.....-32.5  
    
PRELIMINARY CLIMATE SUMMARY FOR MAY 2007......CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
 
AERO: Aerovane recording wind system when significant
TSTM: Thunderstorm day
....: Data not yet available
 
5/1  67/44/56/+4/0/0/624/74      33 NW 
5/2  64/45/55/+3/0.06/0/381/45   36 NW    Aero 33 MPH WNW
5/3  67/42/55/+2/0/0/849/100     38 W     Aero 37 MPH W
5/4  66/44/55/+2/0/0/842/99      39 WNW   Aero 40 MPH WNW 
5/5  65/45/55/+2/0/0/384/45      33 N  
5/6  51/42/47/-7/T/0/514/60      36 N     Aero 33 MPH N 
5/7  68/39/54/0/0/0/798/93       25 S
5/8  77/43/60/+6/0/0/851/99      33 S     Aero 31 MPH S 
5/9  85/54/70/+15/0/0/707/92     30 S 
5/10 85/60/73/+18/0/0/692/80     29 S     Aero 27 MPH S
5/11 74/60/67/+12/0.02/0/355/41  23 S     TSTM A.M.  
5/12 63/47/55/-1/0.02/0/469/54   32 NE    
5/13 65/46/56/0/T/0/775/89       33 WNW   Aero 33 MPH WNW 
5/14 73/43/58/+1/0/0/822/94      30 SSW
5/15 80/50/65/+8/0.01/0/210/24   30 S     TSTM evening   
5/16 66/44/55/-2/0.54/0/527/60   40 NW    TSTM P.M.  
5/17 50/42/46/-11/0.01/0/009/01  28 NE  
5/18 42/39/41/-17/1.93/0/000/00  37 NNE
5/19 51/40/46/-12/0.71/0/000/00  25 NNW
5/20 59/49/54/-4/0.41/0/.../..   30 W     TSTM P.M. 
 
5/21 morning low temp. 46 deg; normal now 49 deg.  
 
NEW DAILY RECORDS FOR MAY:
5/18 Record low maximum temperature, 42, previous 48 in 1895 and 1956.
5/18 Record daily precipitation, 1.93, previous 1.58 inches in 2002.
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR MAY 21
HIGH 92F IN 1921
LOW 35F IN 1907
PRECIP 1.61 INS IN 1954
PEAK GUST 74 MPH WSW IN 2006

RECORDS FOR MAY 22
HIGH 93F IN 1911
LOW 35F IN 1907
PRECIP 3.75 INCHES IN 1920
PEAK GUST 49e MPH SSW IN 1947
 
TODAY'S REPORT PREPARED By: Robert Skilling/Nate McGee