BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
  
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, MAY 6, 2009  
ALL TIMES ARE IN EASTERN STANDARD TIME

RAINFALL TOTAL REACHES 1.35 INCHES
FOR MAY 5-6

Rain which began by 10 A.M. yesterday 
morning totaled 1.35 inches in the 
standard rain gage and the same for ASOS. 
The maximum rainfall rate for one hour 
was 0.46 inch ending at 1:36 P.M. and a
total of 0.85 inch fell during a 3-hour
period ending at 1:49 p.m.  This was the
greatest single rainfall event since 1.42
inches was recorded on April 6. 

Today's observations:

7 A.M.   
Weather: Obscurement with fog, light drizzle occurring 
Temperature: 44F, Dew point: 44F, Wind: N at 5 kts  
Sea-level pressure: 30.08 inches Hg, steady
Visibility: 1/8 mile 
6-hour minimum temp: 43F
6-hour precipitation: 0.35 in.
24-hour precipitation: 1.35 ins. 
BHO SA 1155 W2 X 1/8L-F 186/44/44/3505/008/ 
PCPN VRY LGT/ 8//// 53004 ASOS 60035 MANUAL 6035/ 
ASOS 70135 MANUAL 70135 10044 20043  

10 A.M.   
Weather: Overcast stratus, bright spots in overcast  
Temperature: 48F, Dew point: 47F, Wind: NW at 4 kts 
Sea-level pressure: 30.10 inches Hg, rising
Visibility: 40 miles, NE-E 30 miles, W-NW 55 miles   
BHO SA 1455 E8 BKN 12 OVC 40 193/48/47/3104/010/
BRGHT SPTS IOVC VSBY NE-E 30 W-NW 55/ 8/6// 
53007 MANUAL 6000/ 

1 P.M.   
Weather: Overcast stratocumulus, breaks in overcast  
Temperature: 57F, Dew point: 48F, Wind: SW at 6 kts
Sea-level pressure: 30.08 inches Hg, falling
Visibility: 60 miles, 70 to the NW  
6-hour maximum temp: 57F   
6-hour precip: trace  
BHO SA 1755 E18 OVC 60 186/57/48/2206/008/
BINOVC VSBY NW 70/ 8/5// 
55007 MANUAL 6000/ 10057 20044
 
WEATHER SUMMARY FOR TUESDAY, MAY 5

TEMPERATURE (DEGREES F)
MAX.....52    NORMAL.....63
MIN.....44    NORMAL.....44
MEAN....48    NORMAL.....53

DEPARTURE FROM 30-YEAR NORMAL...........-5
TOTAL DEPARTURE FOR THE MONTH..........+16 [+3.0 DEGREES/DAY] 

HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............17  DEPARTURE.......+5
TOTAL HEATING UNITS FOR THE MONTH............46  DEPARTURE......-17
TOTAL HEATING UNITS FOR THE SEASON.........5942  DEPARTURE.....-147
TOTAL HEATING UNITS LAST SEASON TO DATE....5700  DIFFERENCE....+242

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY............43 NNE AT  1:33 P.M.   
                   AEROVANE.............40 NNE AT  1:33 P.M.    
                   ASOS.................40 NNE AT  3:23 P.M.    
                   DAVIS................40 NNE AT 11:17 A.M.  
FASTEST MILE FOR YESTERDAY..............28 NNE AT  1:45 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE...........25 NNE AT  1:37 P.M.     
MAXIMUM 2-MINUTE DAVIS AVERAGE..........26 NE  AT  1:36 P.M.  
AVERAGE WIND SPEED AND DIRECTION......14.6 N 
                   ASOS...............13.8   
                   DAVIS..............13.9 NE [040 DEG]
* last of several occurrences

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....1.35  DEPARTURE....+1.22
                         ASOS..............1.35 
TOTAL PRECIPITATION FOR THE MONTH..........1.41  DEPARTURE....+0.76
                         ASOS..............1.40  
TOTAL PRECIPITATION FOR THE YEAR..........16.02  DEPARTURE....-2.58
                         ASOS.............17.08   

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..............78.9  DEPARTURE.....18.8  
 
PRELIMINARY CLIMATE SUMMARY FOR MAY 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane recording wind system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized

5/1 64/53/59/+7/T/.../..          37 SSW   AERO 37 MPH SSW
5/2 68/52/60/+8/0.05/.../..       32 WNW 
5/3 64/48/56/+3/T/.../..          25 S 
5/4 64/48/56/+3/0.01/009/01       17 SSW 
5/5 52/44/48/-5/../000/00         43 NNE   AERO 40 MPH NNE

5/6 morning low temp: 43F; our normal low is now 44F 

NEW DAILY RECORDS FOR MAY 2009...
NONE

DAILY EXTREMES

Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR MAY 6
HIGH 90F IN 1930
LOW 29F IN 1891
PRECIP 1.04 INCHES IN 1890
SNOWFALL TRACE IN 1917,1996
PEAK GUST 65 MPH SSE IN 1989

RECORDS FOR MAY 7
HIGH 93F IN 1930
LOW 33F IN 1970
PRECIP 1.19 INCHES IN 2005 
SNOWFALL TRACE IN 1967
PEAK GUST 66e MPH WNW IN 1940

TODAY'S REPORT PREPARED BY: Robert Skilling