Tuesday, December 22, 2020

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

TUESDAY, DECEMBER 22, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

PARTLY CLOUDY WITH AN INCREASING WESTERLY WIND….

Today we observed an increasing visibility, rising
from 15 miles this morning to more than 60 miles this
afternoon. Skies were partly cloudy, but are clearing
up as the day goes on. Wind has strengthened from 10
mph this morning to 20 mph on average, with frequent
gusts above 30 mph. Conditions are drying out as
pressure is on the rise, going from 95% this morning to
around 60% around 3 P.M.

The high so far today is 42F, 4 degrees above the daily
normal maximum of 38F. The low since midnight is 30F,
8 degrees above the normal minimum of 22F.

Today’s Observations:

7 A.M.
Weather: Scattered cirrostratus
Temperature: 30F; Dew Point: 28F; Relative Humidity:92%
Wind: WSW @ 9 kts
Sea-level pressure: 29.65 in Hg; rising steadily
Visibility: 15 miles, thin fog
6-hr Max temp: 32F
6-hr Min temp: 30F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 8 ins.
BHO SA 1155 250 SCT 15 039/30/28/2509/965/ THN F ALQDS/
8/006 4/008 53006 10032 20030

10 A.M.
Weather: Broken cirrostratus
Temperature: 36F; Dew Point: 29F; Relative Humidity: 75%
Wind: WNW @ 10G15 kts
Sea-level pressure: 29.69 in Hg; rising steadily
Visibility: 30 miles, hazy
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 250 BKN 30 051/36/29/2910G15/969/ HAZY/ 8/006
53012

1 P.M.
Weather: Broken cirrostratus
Temperature: 41F; Dew Point: 32F; Relative Humidity: 70%
Wind: W @ 12G19 kts
Sea-level pressure: 29.68 in Hg; rising then falling
Visibility: 60 miles
6-hr Max temp: 42F
6-hr Min temp: 30F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 7 ins.
BHO SA 1755 250 BKN 60 047/41/32/2812G19/968/ 8/006
4/007 55004 10042 20030

SUMMARY FOR MONDAY, DECEMBER 21, 2020

TEMPERATURE (DEGREES F)
MAX…….34   NORMAL…..38
MIN…….29   NORMAL…..22
MEAN……32   NORMAL…..30

DEPARTURE FROM 30-YEAR NORMAL…………………+2
TOTAL DEPARTURE FOR THE MONTH…………………+11 [+0.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………33  DEPARTURE…….-2
TOTAL HEATING UNITS FOR THE MONTH…………..660  DEPARTURE……-14
TOTAL HEATING UNITS FOR THE SEASON…………1633  DEPARTURE…..-302
TOTAL HEATING UNITS LAST SEASON TO DATE…….1965  DEPARTURE…..-332

PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..22 WNW @ 10:03 A.M.
AEROVANE (south tower)…..24 WNW @ 10:48 A.M.
ASOS…………………..22 W   @  9:59 P.M.
DAVIS #1……………….24 W   @  9:58 P.M.
DAVIS #2 (south tower)…..23 WNW @  9:58 P.M.
RMY……………………23
VECTOR…………………24
MERLIN…………………22

FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..16 W   @ 11:50 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….16 W   @ 11:48 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………16 W   @ 11:49 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………17 WNW @ 11:55 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL….6.8 W   [162 total miles] ASOS……………….7.7     [177 total miles] DAVIS #1……………7.6 WNW [174 total miles] DAVIS #2……………7.6 WNW [174 total miles] RMY………………..7.2 WNW [173 total miles] VECTOR……………..7.6     [174 total miles]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.00  DEPARTURE….-0.15
ASOS………….0.00
TOTAL PRECIPITATION FOR THE MONTH………….5.03  DEPARTURE….+1.64
ASOS………….5.53
TOTAL PRECIPITATION FOR THE YEAR………….51.43  DEPARTURE….-0.43
ASOS………..52.86

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..0.0  DEPARTURE…..-0.4
TOTAL SNOWFALL FOR THE MONTH………………19.7  DEPARTURE….+11.5
TOTAL SNOWFALL FOR THE SEASON……………..26.2  DEPARTURE….+15.4

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   The low since midnight is 30F, the daily normal low is 22F

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 22
HIGH 63 IN 2013
LOW -5 IN 1921
PRECIP 1.52 INS. IN 1975
SNOWFALL 8.8 INS. IN 1975
PEAK GUST 62 MPH WNW IN 1998

RECORDS FOR DECEMBER 23
HIGH 62 IN 1990
LOW -1 IN 1989
PRECIP 1.70 INS. IN 1947
SNOWFALL 11.9 INS. IN 1947
PEAK GUST 67 SSE IN 2004

TODAY’S REPORT PREPARED BY: Benjamin Turner