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

WEDNESDAY, DECEMBER 30, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

OVERCAST SKIES RETURN, COLD PERSISTS...

We've seen a return to overcast skies after starting
the day mostly clear. Winds have also switched around
to the south-southwest around noontime. This is out
ahead of a low-pressure system approaching the northeast.
Temperatures have been slow to warm thanks to the blanket
of clouds, but we have managed the low-30s by early
afternoon. Visibility has held steady around 70 miles
since sunrise with a max distance of 75 miles.

Winds were the main story yesterday. Winds began
cranking late morning peaking at 48 MPH. This resulted
in wind chill values in the teens! Winds have relaxed
since then with much less of a bite to the air now. 

The high so far today is 33 degrees, which is 2 degrees
below the daily normal high of 35. The low since midnight
is 20F, which is equal to the daily normal low of 20F.


Today's Observations:
7 A.M.
Weather: Scattered Altocumulus & Altostratus
Temperature: 19F; Dew Point: 6F; Relative Humidity: 56%
Wind: W @ 8 kts
Sea-level pressure: 30.45 in Hg; rising, unsteadily
Visibility: 75 miles
6-hr Max temp: 20F
6-hr Min temp: 19F
24-hr Precip: 0.0 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1155 200 SCT 75 313/19/6/2708/045/ 8/030 52004 10020 20019

10 A.M.
Weather: Scattered Altocumulus & Altostratus, (thin) Overcast Cirrus,
(dark smoke layer along horizon SW to SE)
Temperature: 26F; Dew Point: 9F; Relative Humidity: 50%
Wind: WSW @ 7 kts (wind light)
Sea-level pressure: 30.46 in Hg; falling, then rising
Visibility: 65 miles 
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 140 SCT E250 -OVC 65 316/26/9/2406/046/ DRK K LYR ALG HRZN SW-SE WND LGT/ 8/031 53003

1 P.M.
Weather: Broken Altocumulus & Altostratus, (thin) Overcast Cirrus,
thin smoke layer along horizon NNW to ENE)
Temperature: 33F, Dew point: 9F; Relative Humidity: 37%
Wind: SSW @ 9kts,
Sea-level pressure: 30.35 inches Hg, falling, then falling more slowly
Visibility: 75 miles
6-hr Max temp: 33F
6-hr Min temp: 19F
Snow Depth: 0 ins.
BHO SA 1755 E140 BKN E300 -OVC 75 276/33/9/2009/035/ THN K LYR ALG HRZN NNW-ENE/ 8/031 56040 10033 20019

SUMMARY FOR TUESDAY, DECEMBER 29, 2020 

TEMPERATURE (DEGREES F)
MAX.......38   NORMAL.....35
MIN.......20   NORMAL.....20
MEAN......29   NORMAL.....27

DEPARTURE FROM 30-YEAR NORMAL......................+2
TOTAL DEPARTURE FOR THE MONTH.....................+72 [+2.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............36  DEPARTURE.......-2
TOTAL HEATING UNITS FOR THE MONTH..............893  DEPARTURE......-74
TOTAL HEATING UNITS FOR THE SEASON............1866  DEPARTURE.....-363
TOTAL HEATING UNITS LAST SEASON TO DATE.......2191  DEPARTURE.....-325

PEAK WIND GUST FOR YESTERDAY (MPH):
                     420C/Official..............48 WNW @ 11:18 P.M.
                     AEROVANE (south tower).....50 WNW @ 11:18 P.M 
                     ASOS.......................49 WNW @ 11:19 P.M
                     DAVIS #1...................49 NW  @ 11:18 P.M
                     DAVIS #2 (south tower).....48 WNW @ 11:18 P.M
                     RMY........................56     @ 11:18 P.M.
                     VECTOR.....................57     @ 11:18 P.M
                     MERLIN.....................54

FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL.............................36 WNW @ 11:18 P.M
MAXIMUM 2-MINUTE ASOS AVERAGE...................33 WNW @ 11:19 P.M
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............35 NW  @ 11:18 P.M
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............36 NW  @ 11:19 P.M
MAXIMUM 2-MINUTE RMY AVERAGE....................33 NW  @ 11:17 P.M
MAXIMUM 2-MINUTE VECTOR AVERAGE.................34     @ 11:16 P.M

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL...15.2 WNW [364 total miles]
                     ASOS..................14.1     [338 total miles]
                     DAVIS #1..............15.7 NW  [377 total miles]
                     DAVIS #2..............16.3 NW  [391 total miles]
                     RMY...................14.2 NW  [341 total miles]
                     VECTOR................15.1     [362 total miles]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M......TRACE  DEPARTURE....-0.14
                             ASOS.............0.00
TOTAL PRECIPITATION FOR THE MONTH.............7.18  DEPARTURE....+2.57
                             ASOS.............7.77
TOTAL PRECIPITATION FOR THE YEAR.............53.58  DEPARTURE....+0.44
                              ASOS...........55.10

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M...........0.0  DEPARTURE.....-0.5
TOTAL SNOWFALL FOR THE MONTH..................19.7  DEPARTURE.....+7.7
TOTAL SNOWFALL FOR THE SEASON.................26.2  DEPARTURE....+11.3


PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 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

12/01   62/40/51/+14/0.61/0.0/.../..      60 S    AERO 67 W    RMY 64
12/02   42/32/37/+1/0.00/0.0/.../..       32 SW   AERO 32 SW   RMY 35
12/03   49/30/40/+4/0.00/0.0/.../..       25 SSW  AERO 25 SSW  RMY 28
12/04   58/40/49/+14/0.06/0.0/.../..      35 SSW  AERO 35 SSW  RMY 37
12/05   42/32/37/+2/2.13/2.8/.../..       58 NNW  AERO 58 NNW  RMY 67
12/06   34/26/30/-5/0.01/T/.../..        E44 WNW  AERO 44 WNW  RMY 49
12/07   33/22/28/-6/T/T/.../..            24 NW   AERO 26 NW   RMY 26
12/08   29/22/26/-8/T/T/.../..            24 NW   AERO 25 NW   RMY 28
12/09   34/19/27/-7/T/T/.../..            16 W    AERO 17 W    RMY 19
12/10   42/30/36/+3/0.00/0.0/.../..       30 WNW  AERO 31 WNW  RMY 29
12/11   50/31/41/+8/0.00/0.0/.../..       32 SW   AERO 35 SW   RMY 34
12/12   48/40/44/+11/0.38/0.0/.../..      25 E    AERO 21 E    RMY 25
12/13   58/35/47/+15/0.00/0.0.../..       28 W    AERO 31 WSW  RMY 31
12/14   35/30/33/+1/0.10/0.4/.../..       25 N    AERO 25 N    RMY 29
12/15   34/21/28/-4/0.00/0.0/.../..       32 WNW  AERO 33 WNW  RMY 38
12/16   27/13/20/-11/..../1.4/.../..      38 E    AERO 37 E    RMY 39
12/17   31/19/25/-6/..../15.1/.../..      55 ENE  AERO 56 ENE  RMY 59
12/18   27/18/23/-8/0.00/0.0/.../..       28 N    AERO 26 N    RMY 27
12/19   29/13/21/-9/0.00/0.0/.../..       16 SW   AERO 16 S    RMY 16
12/20   36/24/30/0/0.02/T/.../..          14 S    AERO 16 SW   RMY 14
12/21   34/29/32/+2/0.00/0.0/.../..       22 WNW  AERO 24 WNW  RMY 23
12/22   42/30/36/+7/0.00/0.0/.../...      34 WNW  AERO 35 WNW  RMY 38
12/23   37/26/32/+3/0.00/0.0/.../..       30 WNW  AERO 28 WNW  RMY 31
12/24   53/30/42/+13/..../.../.../..      46 SSE  AERO 50 SSE  RMY 55
12/25   61/37/49/+21/..../.../.../..      68 SSE  AERO 77 SSE  RMY 84
12/26   37/25/31/+3/0.00/0.0/.../..       38 SW   AERO 44 SW   RMY 43
12/27   38/22/30/+2/0.00/0.0/../..        18 W    AERO 18 W    RMY 20
12/28   49/27/38/+10/T/0.0/../..          35 SSW  AERO 36 -    RMY 37
12/29   38/20/29/+2/0.00/0.0/../..        48 WNW  AERO 50 WNW  RMY 56

12/30 The low since midnight is 19F, the daily normal low is 19F

DAILY RECORDS FOR DECEMBER 2020
12/17/20: DAILY RECORD SNOWFALL OF 15.1 INCHES,
          BREAKS PREVIOUS RECORD OF 7.5 INCHES SET IN 1988

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

RECORDS FOR DECEMBER 30
HIGH 60 IN 1984
LOW -18 IN 1933
PRECIP 1.48 INS. IN 1891
SNOWFALL 7.5 INS. IN 1956
PEAK GUST 81 MPH WNW IN 1962

RECORDS FOR DECEMBER 31
HIGH 62 IN 1965
LOW -12 IN 1917
PRECIP 0.96 INS. IN 1906
SNOWFALL 7.5 INS. IN 2008
PEAK GUST 78 MPH NW IN 1990

TODAY'S REPORT PREPARED BY: Andrew Swanson