BLUE HILL METEOROLOGICAL OBSERVATORY 
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, APRIL 20, 2011
ALL TIMES ARE IN EASTERN STANDARD TIME
 
LOW OVERCAST WITH STRATUS AND VERY COOL
 
A heavy layer of low stratus clouds is
shutting out any hint of sunshine today and
along with light northeast winds temperatures
are stuck in the lower 40's, far below the
normal maximum for the date which is 57 degrees.
In addition, a little very light drizzle is
falling intermittently falling from the low
status clouds.
 
Today's observations:
 
7 A.M.  
Weather: Overcast stratocumulus, few cumulus fractus distant
NNW-N 
Temperature: 41F, Dew point: 34F; Wind: ENE at 16G24 kts,
Wind: Peak wind gust 27 kts ENE @ 6:41 A.M.,
Wind: Direction variability NNE to E  
Sea-level pressure: 30.04 ins. Hg, rising 
Visibility: 35 miles, except 45 miles WNW, light rain, distant haze
6-hour min. temp: 38F
6-hour precip: None
24-hour precip: 0.09 inch  
BHO SA 1155 E18 OVC 30 173/41/34/0616G24/004/ FEW CUFRA DSNT NNW-N
DSNT HZ PK WND 0727/41/ WND 03V09/ 8/8// 55011 MANUAL 70009 ASOS 70007
10041 20038
 
10 A.M.  
Weather: Low overcast stratus, fog
Temperature: 41F, Dew point: 40F; Wind: NE at 8 kts,
Wind: Direction gradually backing
Wind: Direction variable N-ENE
Sea-level pressure: 29.93 inches Hg, FALLING RAPIDLY  
Visibility: 5 miles, lowering all quadrants past hour 
3-hour precip: none 
BHO SA 1455 E5 OVC 5F 146/41/40/0408/993/ CIG/VSBY LWRG ALQDS PST HR
WND GRDLY BACKING WND 35V07 PRESFR/ 8/6// 56027
 
1 P.M.   
Weather: Partial obscurement with fog, low overcast stratus,
intermittent very light drizzle and fog, fog obscuring
5/10 of sky 
Temperature: 41F, Dew point: 41F; Wind: NNE at 6 kts,
Sea-level pressure: 29.85 inches Hg, falling 
Visibility: 1/2 mile variable, 1/4 to 3/4 mile, 1/8 mile N,
briefly 1 mile SE-SW
6-hour precip: trace
6-hour max. temp: 42F
BHO SA 1755 –X 3 OVC 1/2VL-F 107/41/41/0306/985/ F5
STRA DRFTG OVR SMT VSB 1/4V3/4 VSBY N 1/8 BRFLY 1 SE-SW
PCPN INTMT VRY LGT/ 8/6// 56039 MANUAL 6000/ 10042 20040
 
WEATHER SUMMARY FOR TUESDAY, APRIL 19
 
TEMPERATURE (DEGREES F)
MAX.....49     NORMAL.....57
MIN.....38     NORMAL.....38
MEAN....44     NORMAL.....47
 
DEPARTURE FROM 30-YEAR NORMAL...................-3
TOTAL DEPARTURE FOR THE MONTH..................+22 [+1.0 DEGREES/DAY]
 
HEATING DEGREE DAYS    
TOTAL HEATING UNITS FOR YESTERDAY............21    DEPARTURE........+3
TOTAL HEATING UNITS FOR THE MONTH...........371    DEPARTURE.......-22
TOTAL HEATING UNITS FOR THE SEASON.........5769    DEPARTURE.......-88
TOTAL HEATING UNITS LAST SEASON TO DATE....5339    DIFFERENCE.....+430
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY..............20 NW  AT 10:13 A.M.  
                   AEROVANE...............21 NW  AT 10:13 A.M. 
                   ASOS...................20 NW  AT 10:13 A.M.   
                   DAVIS..................22 NW  AT 10:12 A.M.  
THE FASTEST MILE FOR YESTERDAY............14 NW  AT 10:12 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE.............15 NNW AT 10:14 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE............15 NW  AT 10:14 A.M.
AVERAGE WIND SPEED AND DIRECTION.........6.9 NNE
                   ASOS..................6.9
                   DAVIS.................6.6 NNE [020 DEG]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.09  DEPARTURE........-0.05
                         ASOS..............0.07     
TOTAL PRECIPITATION FOR THE MONTH..........4.02  DEPARTURE........+1.20
                           ASOS............4.02
TOTAL PRECIPITATION FOR THE YEAR..........17.63  DEPARTURE........+1.18
                        ASOS..............18.41 **
** 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........-0.4
TOTAL SNOWFALL FOR THE SEASON..............96.8  DEPARTURE.......+37.9
 
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/+13/0.02/0.0/308/39    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
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/.../..        39 SW   AERO 38 MPH WSW
4/19 49/38/44/-3/0.09/0.0/000/00     20 NW
 
4/20 our morning low temp: 38F; the normal low is now 39F 
 
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
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR APRIL 20
HIGH 88 IN 1927
LOW 18 IN 1897
PRECIP 1.14 IN 1972
SNOWFALL 2.5 IN. IN 1904, 1972
PEAK GUST 76 MPH WNW IN 1963
 
RECORDS FOR APRIL 21
HIGH 85 IN 1923
LOW 22 IN 1908
PRECIP 3.18 IN. IN 1991
SNOWFALL 0.8 IN. IN 1947
PEAK GUST 76e MPH NE IN 1940
 
TODAY'S REPORT PREPARED BY: Robert Skilling