BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, MAY 20, 2007   
ALL TIMES ARE IN EASTERN STANDARD TIME
 
RAIN SHOWERS BEGAN AT MID-MORNING....
 
More rainfall has arrived at mid-morning today in the 
form of light to moderate showers seen on the radar moving
from west to northwest to the east and southeast.   
 
THREE DAY PRECIPITATION TOTAL REACHES 2.69 INCHES 
SUN'S DISC SEEN DIMLY THROUGH THE LOW CLOUDS THIS MORNING
 
The three-day rainstorm precipitation total had reached 
2.69 inches after overnight drizzle and and even a few 
light rain showers quit by 7 a.m. this morning.  A new 
record daily rainfall total of close to 1.90 inches was
part of this event on the calendar day of May 18th.
 
Also, a very chilly mid-May day on Friday, the 18th, resulted 
in a new record low maximum temperature being established
at 42 degrees for the date; the previous record was way up
at 48 degrees in 1895 and 1956. 
 
Today's observations:
 
7 A.M.   
Weather: Sky obscured with heavy fog
Temperature: 50F, Dew point: 50F, Wind: SW at 05 kts 
Sea-level pressure: 29.70 inches Hg, steady   
Visibility: 1/16 mile    
24-hourly precip: 0.36 inch
6- hourly min temp. 49 deg.  
BHO SA 1155 W2 X 1/16F 057/50/50/2305/970/ 8////
56008 ASOS 60005 MANUAL 6005/ ASOS 70038 MANUAL 
70036 10050 20049 
 
10 A.M.
Weather: Obscurement with fog, light-moderate rain showers 
Temperature: 54F, Dew point: 54F, Wind: SW at 06 kts 
Sea-level pressure: 29.67 inches Hg, falling    
Visibility: 1/8 mile    
3-hourly rainfall: 0.10 in. 
BHO SA 1455 W3 X 1/8RW-F 049/54/54/2306/967/ RB40 OCNL MDT/ 
8//// 58008 MANUAL 6010/ ASOS 60009
  
WEATHER SUMMARY FOR SATURDAY, MAY 19 
 
TEMPERATURE (DEGREES F)
MAX.....51    NORMAL.....68 
MIN.....40    NORMAL.....48
MEAN....46    NORMAL.....58
DEPARTURE FROM 30-YEAR NORMAL..........-12
TOTAL DEPARTURE FOR THE MONTH..........+23 (+1.0 DEGREES/DAY)
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY...........19  DEPARTURE........+11
TOTAL HEATING UNITS FOR THE MONTH..........179  DEPARTURE........-19  
TOTAL HEATING UNITS FOR THE SEASON........5795  DEPARTURE.......-429
TOTAL HEATING UNITS LAST SEASON TO DATE...5654  DIFFERENCE......+141 
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY............25 NNW AT 1:32 A.M. 
                   AEROVANE.............23 NNW AT 1:32 A.M. 
                   ASOS.................24  N  AT 3:50 A.M.
                   DAVIS................26  N  AT 1:31 A.M. 
FASTEST MILE FOR YESTERDAY..............16 NNW AT 2:40 A.M. * 
MAXIMUM 2-MINUTE ASOS AVERAGE...........17 NNW AT 2:42 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE..........17 NNW AT 1:32 A.M. 
AVERAGE WIND SPEED AND DIRECTION.........6.5 NNW
                   ASOS..................7.0 
                   DAVIS.................6.3 NNW [330]
* last of several occurrences
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.36  DEPARTURE.....+0.24
                         ASOS..............0.38  
TOTAL PRECIPITATION FOR THE MONTH..........3.35  DEPARTURE.....+1.02 
                         ASOS..............3.29    
TOTAL PRECIPITATION FOR THE YEAR..........23.77  DEPARTURE.....+3.49
                         ASOS.............23.26    
 
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
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/.../0/000/00   37 NNE
5/19 51/40/46/-12/.../0/000/00   25 NNW
 
5/20 morning low temp. 49 deg; normal now 48 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.xx, 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 20
HIGH 91F IN 1975,1996
LOW 37F IN 1948, 2002
PRECIP 1.65 INCHES IN 1969
PEAK GUST 57 MPH S IN 1963, WNW IN 1982
 
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
 
TODAY'S REPORT PREPARED By: Robert Skilling