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

WEDNESDAY, APRIL 21, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0454E
SUNSET:  1833E

BREEZY WITH DROPPING PRESSURE AND INCREASING CLOUDS....

Wind is very active today with a max speed over 40 mph.
This is a southerly breeze with an average speed over
20 mph. This may be due to the rapidly decreasing
pressure and the approaching front from the west,
as there was virga seen in that direction at the 1 P.M.
observation. Skies went from partly cloudy to almost
overcast over the course of the day, with some light
rain starting quickly after 1 P.M.  

The high so far today is 68F, this is 10 degrees above the
normal high of 58F. The low since midnight is 47F, which
is 7 degrees above the daily normal low of 40F.


Today's Observations:

7 A.M.
Weather: Scattered altocumulus, broken cirrostratus
Temperature: 52F; Dew Point: 47F; Relative Humidity: 81%
Wind: S at 18G23 kts
Sea-level pressure: 29.79 in Hg, falling steadily  
Visibility: 20 miles, hazy
6-hr Max temp: 52F
6-hr Min temp: 47F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0.0 ins.
BHO SA 1155 80 SCT 250 BKN 20 091/52/47/1818G23/979/ HAZY/
8/088 58016 10052 20047

10 A.M.
Weather: Scattered cumulus and altocumulus, broken
cirrostratus
Temperature: 65F; Dew Point: 50F; Relative Humidity: 58%
Wind: S @ 21G34 kts, peak of 40 mph S at 9:38 A.M.  
Sea-level pressure: 29.70 in Hg; falling, then more rapidly
Visibility: 40 miles
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 40 SCT 80 SCT 250 BKN 35 061/65/50/1821G34/970/
PK WND 1835/38/ 8/188 58030

1 P.M.
Weather: Scattered stratocumulus, broken altocumulus and
cirrostratus, virga off to the west
Temperature: 65F, Dew point: 47F; Relative Humidity: 51%
Wind: WSW @ 18G25 kts, peak wind S 45 mph at 12:22 P.M.
Sea-level pressure: 29.60 in Hg; falling rapidly
Visibility: 40 miles, except 20 miles SW-N
6-hr Max temp: 68F
6-hr Min temp: 52F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1755 50 SCT 140 BKN 250 BKN 40 024/65/47/1919G31/960/
VIRGA SW-N VSBY 20 SW-N PK WND 1739/22/ 8/888 58037 10068 20052


SUMMARY FOR TUESDAY, APRIL 20, 2021

TEMPERATURE (DEGREES F)
MAX.......72     NORMAL.....58
MIN.......45     NORMAL.....40
MEAN......59     NORMAL.....49

DEPARTURE FROM 30-YEAR (1981-2010) NORMAL.......+10
TOTAL DEPARTURE FOR THE MONTH...................+42 [+1.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY................6  DEPARTURE......-10
TOTAL HEATING UNITS FOR THE MONTH..............362  DEPARTURE......-43
TOTAL HEATING UNITS FOR THE SEASON............5184  DEPARTURE.....-705
TOTAL HEATING UNITS LAST SEASON TO DATE.......5298  DEPARTURE.....-114

PEAK WIND GUST (MPH):
                     420C/Official..............38 SW  @ 11:07 A.M.
                     AEROVANE (south tower).....39 WSW @  2:37 P.M.
                     ASOS.......................37 SSW @ 11:07 A.M.
                     DAVIS #1...................37 WSW @ 11:06 A.M.
                     DAVIS #2 (south tower).....40 SW  @  2:38 P.M.
                     RMY........................40     @  2:19 P.M.
                     VECTOR.....................42     @ 11:05 A.M.
                     MERLIN.....................36

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL..................25 SW  @ 10:24 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................26 SSW @ 10:25 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............28 W   @  1:03 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............27 SW  @ 10:24 A.M.
MAXIMUM 2-MINUTE RMY AVERAGE....................25 SW  @ 10:22 A.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE.................26     @ 10:21 A.M.

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL......13.8 WSW [331 total miles]
                     ASOS.....................13.8
                     DAVIS #1.................13.7 WSW  
                     DAVIS #2.................14.2 WSW
                     RMY......................13.3 WSW
                     VECTOR.................. 13.7


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.............3.53  DEPARTURE....+0.32
                             ASOS.............3.42
TOTAL PRECIPITATION FOR THE YEAR.............13.70  DEPARTURE....-3.50
                              ASOS...........13.93

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M...........0.0  DEPARTURE.....-0.1
TOTAL SNOWFALL FOR THE MONTH ..................3.6  DEPARTURE.....+1.0
TOTAL SNOWFALL FOR THE SEASON.................76.2  DEPARTURE....+14.4


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/-3/0.30/0.0/.../..      26 ESE  AERO 25 ESE  RMY 28
04/16   39/31/35/-12/2.22/3.6/.../..     48 NNW  AERO 58 NNW  RMY 58
04/17   45/34/40/-7/0.07/T/.../..        27 NNW  AERO 30 NNW  RMY 29
04/18   60/38/49/+1/0.00/0.0/.../..      28 NW   AERO 28 NW   RMY 31
04/19   66/44/55/+7/T/0.0/.../..         22 SSW  AERO 25 SSW  RMY 28
04/20   72/45/59/+10/0.00/0.0/.../..     38 SW   AERO 37 WSW  RMY 40

04/21   The low since midnight is 47F, the daily normal low is 40F


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

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

RECORDS FOR APRIL 22
HIGH 85 IN 1977, 2001
LOW 26 IN 1981
PRECIP 2.60 IN. IN 2019
SNOWFALL 3.0 IN. IN 1940
PEAK GUST 68e MPH NW IN 1945


TODAY'S REPORT PREPARED BY: Benjamin Turner