BLUE HILL METEOROLOGICAL OBSERVATORY 
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, MAY 4, 2011
ALL TIMES ARE IN EASTERN STANDARD TIME
 
LOW OVERCAST ALL DAY INCLUDES PERIOD OF DENSE FOG 
A.M. DRIZZLE AMOUNTS TO ONLY A TRACE
 
Temperatures were much cooler today than yesterday
with its 74-degree maximum. Starting out with a
morning low of 56F this morning the high had only
reached 63F by early afternoon under a heavily
overcast sky with low clouds.  A brief period
of dense fog occurred this morning when the low
stratus cloud deck settled onto the summit.
A period of very drizzle was observed during the
time of heavy fog.
  
APRIL 2011 PRELIMINARY STATS
Average Max Temp:  56.6F [+1.1F]
Average Min Temp:  39.9F [+2.8F]
Mean Temp:  48.3F [+2.0F]
24-hr. Corr Mean Temp:  47.6F
Max Temp:  78F on 27th
Min Temp:  31F on 1st, 6th, 15th, 16th
Total precipitation:  4.61 ins. [+0.29 in.]
Total snowfall:  1.6 ins. [-1.5 ins. ]
Greatest 24-hour snowfall:  4.6 ins. (31st-1st)
Total heating degree day units (month):   497  [-65]
Total heating degree day units (season): 5895 [-131]
Avg wind speed:  13.9 MPH
Prevailing direction: S 15%
Avg corrected wind speed: 14.2 MPH S
Peak gust: 63 MPH ESE on 17th
Peak fastest mile: 42 MPH ESE on 17th, 42 MPH S on 28th
Sunshine (astronomical): 10227 minutes; 42% of total possible
Sunshine (Campbell-Stokes): 9858 minutes; 42% of possible 23250
 
Today's observations:
 
7 A.M.  
Weather: Low overcast stratus, ceiling and visibility lowering 
Temperature: 58F, Dew point: 58F; Wind: S at 14G26 kts,
Wind: Peak wind gust from S @ 28 kts at 6:08 a.m.,
Wind: Direction variable SE-SSW  
Sea-level pressure: 29.93 inches Hg, falling then rising
Visibility: 2 miles in thin fog and lowering   
6-hour min. temp: 56F  
BHO SA 1155 E3 OVC 2F 134/58/58/1714G26/993/ FEW STRA DRFTG OVR
SMT CIG/VSBY LWRG PK WND 1728/08/ WND 14V20/ 8/6// 55002
10059 20056 
 
10 A.M.  
Weather: Overcast stratus, thin fog 
Temperature: 61F, Dew point: 58F; Wind: S at 10 kts
Sea-level pressure: 29.91 inches Hg, falling 
Visibility: 10 miles, thin fog 
3-hourly precip: trace
BHO SA 1455 E7 OVC 10 130/61/58/1810/991/ THN F/ 8/6//
58004 MANUAL 6000/
 
1 P.M.  
Weather: Scattered cumulus, few moderate, broken
stratocumulus, overcast stratocumulus
Temperature: 62F, Dew point: 57F; Wind: SW at 6 kts,
Sea-level pressure: 29.87 inches Hg, falling
Visibility: 12 miles, thin fog and haze  
6-hour max. temp: 63F
6-hourly precip: trace
BHO SA 1755 22 SCT E30 BKN 34 OVC 12 116/62/57/2306/987/ 
FEW MDT CU THN FH/ 8/8// 58014 6000/ 10063 20057
 
WEATHER SUMMARY FOR TUESDAY, MAY 3
 
TEMPERATURE (DEGREES F)
MAX.....74     NORMAL.....62
MIN.....51     NORMAL.....43
MEAN....63     NORMAL.....53
 
DEPARTURE FROM 30-YEAR NORMAL..................+10
TOTAL DEPARTURE FOR THE MONTH..................+13 [+4.1 DEGREES/DAY]
 
HEATING DEGREE DAYS    
TOTAL HEATING UNITS FOR YESTERDAY.............2    DEPARTURE.......-11
TOTAL HEATING UNITS FOR THE MONTH............25    DEPARTURE.......-14
TOTAL HEATING UNITS FOR THE SEASON.........5920    DEPARTURE......-145
TOTAL HEATING UNITS LAST SEASON TO DATE....5482    DIFFERENCE.....+438
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY..............31 SSE AT  3:56 P.M.  
                   AEROVANE...............32 SSE AT  3:56 P.M.  
                   ASOS...................30 SSE AT  3:56 P.M. 
                   DAVIS..................29 SSE AT  3:55 P.M.  
THE FASTEST MILE FOR YESTERDAY............23 SSE AT  3:45 P.M.  
MAXIMUM 2-MINUTE ASOS AVERAGE.............22 SSE AT  3:57 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE............22 SE  AT  3:57 P.M.  
AVERAGE WIND SPEED AND DIRECTION........10.7 SE
                   ASOS.................10.2   
                   DAVIS................10.2 SSE [160 DEG]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE........-0.13
                         ASOS..............0.00  
TOTAL PRECIPITATION FOR THE MONTH..........0.00  DEPARTURE........-0.39
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE YEAR..........18.22  DEPARTURE........-0.12
                        ASOS..............18.96**
**ASOS data is in error due to system failure on 1/12-13   
 
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..............96.8  DEPARTURE.......+36.7
 
PRELIMINARY CLIMATE SUMMARY FOR APRIL & MAY 2011 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane wind recording system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
THUNDERSTORM DAYS HAVE BEEN ADDED TO THE LISTING…..
 
4/1  36/31/34/-7/0.71/1.6/000/00     35 N    AERO 40 MPH N
4/2  50/33/42/0/T/0.0/581/76         38 W    AERO 41 MPH W
4/3  53/35/44/+2/0.00/0.0/753/98     41 W    AERO 42 MPH W
4/4  46/38/42/0/0.43/T/000/00        33 SE   AERO 36 MPH SE TSTM
4/5  61/35/48/+5/0.16/0.0/023/03     52 S    AERO 55 MPH S
4/6  51/31/41/-2/0.00/0.0/490/63     43 WSW  AERO 43 MPH WSW
4/7  52/32/42/-1/0.00/0.0/749/96     22 SSE 
4/8  52/34/43/-1/0.00/0.0/422/54     25 SSE
4/9  60/33/47/+3/0.00/0.0/699/89     30 SE
4/10 63/37/50/+6/0.03/0.0/496/63     31 SSE
4/11 69/47/58/+13/0.02/0.0/308/39    35 S    AERO 36 MPH S
4/12 61/43/52/+7/0.15/0.0/024/03     43 WNW  AERO 45 MPH WNW
4/13 47/40/44/-1/1.13/0.0/000/00     39 ENE  AERO 39 MPH ENE TSTM
4/14 63/39/51/+5/T/0.0/607/76        29 NNW
4/15 47/31/39/-7/0.00/0.0/730/91     28 NW
4/16 46/31/39/-7/0.18/0.0/266/33     45 ESE  AERO 46 MPH ESE 
4/17 61/46/54/+7/1.12/0.0/347/43     63 ESE  AERO 63 MPH ESE
4/18 59/40/50/+3/T/0.0/486/60        39 SW   AERO 38 MPH WSW
4/19 49/38/44/-3/0.09/0.0/000/00     20 NW
4/20 44/38/41/-7/T/0.0/000/00        31 NE   AERO 32 MPH NE
4/21 54/35/45/-3/0.00/0.0/703/86     60 W    AERO 62 MPH W
4/22 52/33/43/-6/0.00/0.0/517/63     21 WNW
4/23 52/36/44/-5/0.43/0.0/000/00     42 SSE  AERO 42 MPH SSE
4/24 74/51/63/+14/0.05/0.0/297/36    39 WSW  AERO 41 MPH W
4/25 56/45/51/+1/0.06/0.0/008/01     17 NE
4/26 64/45/55/+5/T/0.0/357/43        24 NNE 
4/27 78/58/68/+18/0.01/0.0/375/45    36 S    AERO 39 MPH S
4/28 65/60/63/+12/0.04/0.0/000/00    54 S    AERO 54 MPH S TSTM
4/29 74/53/64/+13/0.00/0.0/662/79    37 S    AERO 37 MPH S
4/30 60/49/55/+3/0.00/0.0/320/38     28 WNW 
 
5/1  55/43/49/-3/0.00/0.0/.../..     30 NE
5/2  73/42/58/+6/0.00/0.0/.../..     24 SSW
5/3  74/51/63/+10/0.00/0.0/.../..    31 SSE
 
5/4  our morning low temp: 56F; the normal low is 43F
 
DAILY RECORDS FOR APRIL 2011
4/17 - NEW RECORD PEAK GUST OF 63 MPH ESE;
surpasses the previous record of 58 MPH NW in 1994
4/27 - NEW RECORD HIGH MINIMUM TEMPERATURE OF 58F;
surpasses the previous record of 57F in 1900,1979
4/28 - NEW RECORD HIGH MINIMUM TEMPERATURE OF 60F;
surpasses the previous record of 57F in 1935,2009
 
DAILY RECORDS FOR MAY 2011
None so far...
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR MAY 4
HIGH 90F IN 2001
LOW 27F IN 1911 (RECORD FOR MAY)
PRECIP 1.92 INCHES IN 1893
SNOWFALL 0.1 INCHES IN 1920
PEAK GUST 60 MPH NW IN 1966
 
RECORDS FOR MAY 5
HIGH 92F IN 1949
LOW 30F IN 1891
PRECIP 2.74 INCHES IN 1922
SNOWFALL 3.0 INCHES IN 1917
PEAK GUST 58 MPH S IN 1966 & 58e MPH SW IN 1976
 
TODAY'S REPORT PREPARED BY: Robert Skilling/Caroline Corbett