BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

SATURDAY, APRIL 17, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0500E
SUNSET:  1828E

OVERCAST WITH SOME LIGHT MORNING SNOW TO END
OFF THE RAIN/SNOW EVENT....

After measuring another 1.50 ins. of rainfall this morning,
a trace of snow fell between 7 A.M. and noontime. This left
an additional 0.02 inches of rainfall in the gauge as the
snow was intermittent with a very light drizzle. Visibility
has improved to 45 miles since this morning, where it was
closer to 20 miles due to fog. Skies remain filled in with
stratocumulus and altostratus clouds.

Temperatures are lower than normal from the overcast and
a consistent northwesterly wind. This carries cooler air
into the region following the weather we had yesterday.

The high so far today is 42F, this is 14 degrees below the
normal high of 56F. The low since midnight is 34F, which is
4 degrees below the daily normal low of 38F.


Today's Observations:

7 A.M.
Weather: Broken stratocumulus, overcast altostratus
Temperature: 35F; Dew Point: 34F; Relative Humidity: 94%
Wind: NW at 9G18 kts
Sea-level pressure: 29.70 in Hg, rising steadily  
Visibility: 25 miles, thin fog
6-hr Max temp: 35F
6-hr Min temp: 34F
24-hr Precip: 1.51 ins.
24-hr Snow: 3.6 ins.
Snow Depth: 1 in.
BHO SA 1155 E25 BKN 65 OVC 25 058/35/34/3309G18/970/ THN F ALQDS
TOTAL NEW SNW PST 24 HRS 3.6 INS/ 8/52/ 40001 51018 70151 10035 20034

10 A.M.
Weather: Overcast stratocumulus
Temperature: 34F; Dew Point: 34F; Relative Humidity: 100%
Wind: NNW @ 10 kts
Sea-level pressure: 29.75 in Hg; rising steadily
Visibility: 15 miles, thin fog
3-hr Precip: 0.01 ins.
3-hr Snow: Trace
BHO SA 1455 20 OVC 15 073/34/34/3410/975/ THN F ALQDS NEW SNW PST 3
HRS TRACE/ 8/8// 6001/ 51015

1 P.M.
Weather: Broken stratocumulus, overcast altostratus
Temperature: 41F, Dew point: 34F; Relative Humidity: 75%
Wind: NNW @ 7 kts
Sea-level pressure: 29.76 in Hg; rising steadily
Visibility: 45 miles
6-hr Max temp: 42F
6-hr Min temp: 34F
6-hr Precip: 0.02 ins.
6-hr Snow: Trace
Snow Depth: 1 ins.
BHO SA 1755 20 BKN 65 OVC 45 077/41/34/3407/976/ NEW SNW PST 6 HRS
TRACE/ 8/82/ 4/001 6002/ 51004 10042 20034


SUMMARY FOR FRIDAY, APRIL 16, 2021

TEMPERATURE (DEGREES F)
MAX.......39     NORMAL.....56
MIN.......31     NORMAL.....38
MEAN......35     NORMAL.....47

DEPARTURE FROM 30-YEAR (1981-2010) NORMAL.......-12
TOTAL DEPARTURE FOR THE MONTH...................+31 [+1.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............30  DEPARTURE......+12
TOTAL HEATING UNITS FOR THE MONTH..............305  DEPARTURE......-32
TOTAL HEATING UNITS FOR THE SEASON............5175  DEPARTURE.....-693
TOTAL HEATING UNITS LAST SEASON TO DATE.......5200  DEPARTURE......-73

PEAK WIND GUST (MPH):
                     420C/Official..............48 NNW @  1:55 P.M.
                     AEROVANE (south tower).....58 NNW @  1:10 P.M.
                     ASOS.......................53 NNW @  1:25 P.M.
                     DAVIS #1...................51 NNW @  1:26 P.M.
                     DAVIS #2 (south tower).....50 NNW @  1:12 P.M.
                     RMY........................58     @  2:02 P.M.
                     VECTOR.....................29     @  2:02 P.M.
                     MERLIN.....................50

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL..................35 NNW @  1:12 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................36 NNW @  1:38 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............38 NNW @  1:39 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............37 NNW @  1:12 P.M.
MAXIMUM 2-MINUTE RMY AVERAGE....................35 N   @  1:36 P.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE.................36     @  1:36 P.M.

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL......17.6 NNW [422 total miles]
                     ASOS.....................17.9
                     DAVIS #1.................17.2 N  
                     DAVIS #2.................17.1 N
                     RMY......................16.6 NNE
                     VECTOR...................16.2

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.......1.51  DEPARTURE....+1.36
                             ASOS.............1.47
TOTAL PRECIPITATION FOR THE MONTH.............3.51  DEPARTURE....+0.85
                             ASOS.............3.39
TOTAL PRECIPITATION FOR THE YEAR.............13.68  DEPARTURE....-2.97
                              ASOS...........13.90

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M...........3.6  DEPARTURE.... +3.5
TOTAL SNOWFALL FOR THE MONTH ..................3.6  DEPARTURE.....+1.3
TOTAL SNOWFALL FOR THE SEASON.................76.2  DEPARTURE....+14.7


PRELIMINARY CLIMATE SUMMARY FOR APRIL CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST
AERO: Aerovane wind recording system gust
RMY:  R.M. Young wind gust recording system
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
M:    Missing data

04/01   56/30/43/+2/0.89/T/000/00        44 NW   AERO 51 NW   RMY 49
04/02   37/24/31/-10/0.00/0.0/614/80     28 NW   AERO 32 NNW  RMY 30
04/03   48/23/36/-6/0.00/0.0/755/98      24 NW   AERO 25 NW   RMY 26
04/04   58/33/46/+4/0.00/0.0/734/95      38 NNW  AERO 41 NNW  RMY 41
04/05   57/41/49/+6/T/T/031/04           41 NNW  AERO 48 NNW  RMY 50
04/06   61/40/51/+8/0.00/0.0/412/53      26 NNW  AERO 25 NNW  RMY 31
04/07   57/41/49/+6/0.00/0.0/391/50      23 ENE  AERO 21 ENE  RMY 22
04/08   59/43/51/+7/0.00/0.0/745/95      22 ENE  AERO 22 ENE  RMY 24
04/09   69/42/56/+12/0.00/0.0/707/90     24 S    AERO  M   M  RMY 26
04/10   75/43/59/+14/0.00/0.0/576/73     26 SSW  AERO 28 SSW  RMY 30
04/11   53/40/47/+2/T/0.0/000/00         33 ENE  AERO 33 ENE  RMY 34
04/12   46/37/42/-3/0.05/0.0/000/00      36 ENE  AERO 37 ENE  RMY 41
04/13   56/37/47/+1/T/0.0/.../..         31 NE   AERO 30 NE   RMY 33
04/14   56/42/49/+3/0.00/0.0/.../..      22 ESE  AERO 23 ESE  RMY 22
04/15   51/37/44/-3/.../0.0/.../..       26 ESE  AERO 25 ESE  RMY 28
04/16   39/31/35/-12/..../3.6/.../..     48 NNW  AERO 58 NNW  RMY 58

04/17   The low since midnight is 34F, the daily normal low is 38F


DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)

RECORDS FOR APRIL 17
HIGH 93 IN 2002
LOW 21 IN 1908
PRECIP 1.68 IN 1954
SNOWFALL 1.0 IN. IN 1899
PEAK GUST 63 MPH ESE IN 2011

RECORDS FOR APRIL 18
HIGH 92 IN 1976
LOW 23 1887
PRECIP 1.48 IN 1954
SNOWFALL 4.3 IN. IN 2020
PEAK GUST 59 MPH S IN 1982

TODAY'S REPORT PREPARED BY: Benjamin Turner