BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, MAY 20, 2012
ALL TIMES ARE IN EASTERN STANDARD TIME
 
WARMER, STILL VERY DRY AND SUNNY WEATHER TODAY...
SUMMIT REMAINS VERY MILD OVERNIGHT-LOW 57F LAST EVENING
WITH TEMPS. RISING TOWARD MIDNIGHT AND EARLY THIS MORNING
 
By late this morning our temperature had already reached
yesterday's maximum of 74F with bright sunshine and dry
air. It is a very beautiful May day. Dew point temperatures are
in the lower to mid 40's and the dry air mass over us
yesterday, last night and again today allowed radiational cooling
to produce close to a 12-13-degree temperature difference
early today.  The low temperature at the summit before
midnight last night was 57F, but 58F since midnight for
today's low. Nearby Norwood Airport and most other
locations at the lower elevations dropped into the 40's
 
The relative humidity has dropped to near 30% by late
this morning with light winds from east to east-southeast.
Visibility has risen from 35 miles earlier this morning to
55 miles with a distant haze by noon.
 
The thunderstorm on the 16th was the first of the year.
This is relatively late, though it was not the latest
first thunderstorm in any year. Looking back to 1950,
this occurred on June 21st in 1971. 
 
Latest First Thunderstorm, (1950-2012):
 
1) 21 June 1971
2) 19 June 1978
3)  3 June 1960
4) 20  May 1968
5) 19  May 1964
6) 16  May 2012
 
 
Today's observations:
 
7 A.M.
Weather: Thin broken cirrostratus, thin overcast cirrostratus,
(2 layers), few lower cirrus, break in overcast vicinity of
the station SW 
Temperature: 66F, Dew Point: 43F; Wind: ESE at 3 kts,
Wind: Light and direction gradually veering
Sea-level pressure: 30.25 inches Hg, rising, then more slowly
Visibility: 35 miles, except 25 miles NE, 50 miles WNW,
above dissipating inversion, hazy all quadrants  
6-hour min. temp: 58F
BHO SA 1155 250 –BKN 300 –OVC 35 252/66/43/1103/025/ FEW LWR CI
BINOVC VC SW VSBY NE 25 WNW 50 ABV DSSPTNG INVSN HAZY ALQDS
WND LGT/GRDLY VEERING/ 8/007 51018 100// 20058
 
10 A.M.
Weather: Thin scattered cirrus, 2 levels, patch lower cirrus
to the distant SSE-SSW 
Temperature: 74F, Dew Point: 41F; Wind: ESE at 6 kts,
Sea-level pressure: 30.27 inches Hg, rising, then more slowly 
Visibility: 55 miles, distant haze 
BHO SA 1455 250 –SCT 300 –SCT 55 252/74/41/1106/027/ PTCH LWR
CI DSNT SSE-SSW DSNT HZ/ 8/001 51008
 
12 NOON TEMP EDT IS 76F DEW POINT 46F
 
WEATHER SUMMARY FOR SATURDAY, MAY 19
 
TEMPERATURE (DEGREES F)
MAX.....74    NORMAL.....67
MIN.....51    NORMAL.....49
MEAN....63    NORMAL.....58
 
DEPARTURE FROM 30-YEAR NORMAL........................+5
TOTAL DEPARTURE FOR THE MONTH.......................+26 [+1.2 DEGREE/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY...............2   DEPARTURE..........-6
TOTAL HEATING UNITS FOR THE MONTH.............161   DEPARTURE.........-37
TOTAL HEATING UNITS FOR THE SEASON...........4875   DEPARTURE.......-1349
TOTAL HEATING UNITS LAST SEASON TO DATE......6112   DIFFERENCE......-1237
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............16 ENE AT 11:25 A.M.    
                   AERO..................15 ENE AT 11:25 A.M. *    
                   ASOS..................16 E   AT 11:25 A.M.  
                   DAVIS.................15 WNW AT  3:29 A.M. RMY 16 MPH
THE FASTEST MILE FOR YESTERDAY...........11 S   AT 10:21 P.M.  
MAXIMUM 2-MINUTE ASOS AVERAGE............12 S   AT 10:47 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE...........11 S   AT 10:21 P.M.  
AVERAGE WIND SPEED AND DIRECTION....... 7.7 ENE  
                   ASOS.................7.9 
                   DAVIS................7.2 ENE [070 deg.]
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00   DEPARTURE..........-0.14
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........2.95   DEPARTURE..........+0.60
                         ASOS..............2.87
TOTAL PRECIPITATION FOR THE YEAR..........12.56   DEPARTURE..........-8.34
                         ASOS.............12.60
     
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..............24.2    DEPARTURE.........-35.9
 
PRELIMINARY CLIMATE SUMMARY FOR MAY 2012 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
RMY:  RMY = R.M. Young wind gust recording system added 8/9/2011
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
5/1  47/42/45/-8/0.65/0.0/000/00    33 SE  AERO 36 MPH SE  RMY 37
5/2  50/43/47/-6/0.05/0.0/000/00    16 ENE AERO 16 MPH ENE RMY 17
5/3  51/44/48/-5/0.08/0.0/000/00    14 SSE AERO 16 MPH SSE RMY N/A
5/4  56/47/52/-2/0.01/0.0/000/00    21 SSW AERO 25 MPH SSW RMY 23
5/5  57/46/52/-2/0.04/0.0/034/04    14 NE  AERO 15 MPH NE  RMY 15
5/6  58/45/52/-2/0.00/0.0/532/62    21 ENE AERO 21 MPH ENE RMY 21
5/7  67/48/58/+3/0.00/0.0/740/86    23 S   AERO 25 MPH S   RMY 25
5/8  57/48/53/-2/0.18/0.0/000/00    40 S   AERO 46 MPH S   RMY 46
5/9  61/54/58/+3/0.36/0.0/000/00    25 S   AERO 28 MPH S   RMY N/A
5/10 65/46/56/+1/0.98/0.0/234/27    33 W   AERO 36 MPH W   RMY 37
5/11 62/42/52/-4/T/0.0/539/62       30 WNW AERO 33 MPH WNW RMY 34
5/12 77/46/62/+6/0.00/0.0/862/99    30 W   AERO 30 MPH W   RMY 29
5/13 82/57/70/+14/0.00/0.0/314/36   27 S   AERO 29 MPH S   RMY 29
5/14 71/52/62/+5/0.05/0.0/096/11    23 S   AERO 24 MPH S   RMY 23
5/15 72/57/65/+8/0.43/0.0/123/14    32 S   AERO 35 MPH S   RMY 33
5/16 71/58/65/+8/0.12/0.0/141/16    23 S   AERO 24 MPH S   RMY N/A
5/17 69/50/60/+3/0.00/0.0/.../..    31 WNW AERO 32 MPH WNW RMY 26
5/18 69/49/59/+1/0.00/0.0/.../..    17 ESE AERO 17 MPH ESE RMY 17
5/19 74/51/63/+5/0.00/0.0/.../..    15 WNW AERO 15 MPH WNW RMY 16
 
5/20 our morning low temp: 58F; the normal low is now 49F
 
DAILY RECORDS FOR MAY 2012
5/16 - Minimum temperature of 56F equals record high minimum
      for the date set in 1951 and 1961
 
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