BLUE HILL METEOROLOGICAL OBSERVATORY 
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, APRIL 13, 2011
ALL TIMES ARE IN EASTERN STANDARD TIME
 
HEAVY RAIN THIS MORNING INCLUDED THUNDERSTORM
RAINFALL TOTAL REACHES OVER ONE INCH BY 1 PM EDT
GUSTY ENE-E WINDS REACH SPEEDS OF 30 TO 39 MPH
 
Yesterday's rainfall amounted to only a trace
during the morning and afternoon hours before
measureable rain began by 10 PM EDT. During the
day yesterday rain advancing from the southwest
encountered dry air near the surface resulting
in considerable "virga" or precipitation aloft not
reaching the ground thus only very light showers
were observed.
 
After the rain got started last evening it ended
after by about 1 AM EDT after only 0.15 inch when
dry air moved back in with the relative humidity
falling to near 60%. Rain began again a couple hours
later about 3 AM EDT. Rainfall became heavy between 8
and 9 AM EDT and one rumble of thunder was heard
at 8:40 AM.  Moderate to briefly heavy rain was
observed during the rest of the morning hours before
becoming light early this afternoon. Over one inch
was recorded starting last evening. The rain was much
heavier with thunderstorms for several hours this
morning just to our east and southeast as a conduit
of heavy convective activity moved NNE. Our total
rainfall for April 12-13 through 2 PM EDT is 1.10 ins. 
 
Gusty ENE to E winds averaged up to 25 MPH gusting
to nearly 40 MPH before diminishing by noon.
 
Today's observations:
 
7 A.M.  
Weather: Overcast stratus fractus, ceiling ragged,
light rain and thin fog 
Temperature: 41F, Dew point: 41F; Wind: E at 14G22 kts,
Wind: Peak wind gust 33 kts ENE @ 5:56 AM EST
Wind: Direction variable NE-ESE
Sea-level pressure: 30.11 ins. Hg, rising 
Visibility: 7 miles, 4 miles southeast, 9 miles NW-N  
24-hour precip: 0.34 inch
6-hour min. temp: 41F
BHO SA 1155 E13 OVC 7R- 197/41/41/0814G22/011/ CIG RGD VSBY SE 4
NW-N 9 PK WND 0633/1056/ WND 05V12/ 8/7// 55009 ASOS 60018 MANUAL
6019/ ASOS 70033 MANUAL 70034 10047 20041
 
10 A.M.  
Weather: Overcast stratus fractus, ceiling ragged,
moderate rain and fog
Temperature: 43F, Dew point: 43F; Wind: E at 16G25 kts,
Wind: Direction variable NE-ESE
Sea-level pressure: 30.03 inches Hg, FALLING RAPIDLY
Visibility:  4 miles, moderate rain and fog
3-hour precip: 0.40
BHO SA 1455 E5 OVC 4RF 171/43/43/0816G25/003/
CIG RGD/ WND 04V11 PRESFR/ 8/7//
MANUAL 6040/ ASOS 60041
 
1 P.M.  
Weather: Overcast stratus fractus, ceiling ragged,
stratus fractus drifting over and below summit,
light rain and fog
Temperature: 44F, Dew point: 44F; Wind: ENE at 7 kts,
Wind: Direction gradually backing  
Sea-level pressure: 29.99 inches Hg, falling
Visibility: 2 miles, light rain and thin fog,
stratus drifting over summit 
6-hour precip: 0.76 inch 
6-hour max. temp: 44F  
BHO SA 1755 E3 OVC 2R-F 156/44/44/0607/999/ CIG RGD STRA DRFTG
OVR/BLO SMT WND GRDL BACKING/ 8/7// 58015 MANUAL 6076/ ASOS 60078
10044 20041 
 
WEATHER SUMMARY FOR TUESDAY, APRIL 12
 
TEMPERATURE (DEGREES F)
MAX.....61     NORMAL.....54
MIN.....43     NORMAL.....36
MEAN....52     NORMAL.....45
 
DEPARTURE FROM 30-YEAR NORMAL...................+7
TOTAL DEPARTURE FOR THE MONTH..................+25 [+1.9 DEGREES/DAY]
 
HEATING DEGREE DAYS    
TOTAL HEATING UNITS FOR YESTERDAY............13    DEPARTURE.........7
TOTAL HEATING UNITS FOR THE MONTH...........237    DEPARTURE.......-25
TOTAL HEATING UNITS FOR THE SEASON.........5635    DEPARTURE.......-91
TOTAL HEATING UNITS LAST SEASON TO DATE....5201    DIFFERENCE.....+434
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY..............43 WNW AT  4:23 A.M. 
                   AEROVANE...............45 WNW AT  4:23 A.M.  
                   ASOS...................43 WNW AT  4:23 A.M.
                   DAVIS..................45 WNW AT  4:23 A.M. 
THE FASTEST MILE FOR YESTERDAY............30 W   AT  4:25 A.M. *   
MAXIMUM 2-MINUTE ASOS AVERAGE.............28 WNW AT  4:18 A.M. 
MAXIMUM 2-MINUTE DAVIS AVERAGE............30 W   AT  4:24 A.M. 
AVERAGE WIND SPEED AND DIRECTION........12.6 ENE
                   ASOS.................11.5
                   DAVIS................12.3 WNW [295 DEG]
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.34  DEPARTURE........+0.19
                         ASOS..............0.33     
TOTAL PRECIPITATION FOR THE MONTH..........1.69  DEPARTURE........-0.11
                           ASOS............1.65
TOTAL PRECIPITATION FOR THE YEAR..........15.30  DEPARTURE........-0.13
                        ASOS..............16.04 **
** 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........-0.1
TOTAL SNOWFALL FOR THE MONTH................1.6  DEPARTURE........+0.3
TOTAL SNOWFALL FOR THE SEASON..............96.8  DEPARTURE.......+38.6
 
PRELIMINARY CLIMATE SUMMARY FOR APRIL 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
 
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
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/.../..    35 S    AERO 36 MPH S
4/12 61/43/52/+7/..../0.0/024/03     43 WNW  AERO 45 MPH WNW
 
4/13 our morning low temp: 41F; the normal low is now 36F
 
DAILY RECORDS FOR APRIL 2011
None so far
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR APRIL 13
HIGH 85 IN 1945
LOW 22 IN 1939
PRECIP 2.51 IN. IN 2004
SNOWFALL 6.8 IN. IN 1933
PEAK GUST 59 MPH SSW IN 1995
 
RECORDS FOR APRIL 14
HIGH 80 IN 1945
LOW 21 IN 1923
PRECIP 2.22 IN. IN 1895
SNOWFALL 8.4 IN. IN 1953
PEAK GUST 71e MPH W IN 1943
 
TODAY'S REPORT PREPARED BY: Robert Skilling