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BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
MONDAY, DECEMBER 21, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME
FOGGY WITH A LIGHT NORTHWESTERLY WIND, CLEARING UP
A LITTLE IN THE AFTERNOON….
Today we observed foggy conditions, which limited
visibility to a 1/16th mile. This improved after
noontime, increasing to 5 miles by 2 P.M. Wind was
on the lighter side today, barely reaching 10 mph.
Last night’s precipitation left us a trace of snow
and 0.02 inches of liquid in the gauge at the 7 A.M.
observation.
The high so far today is 33F, 5 degrees below the daily
normal maximum of 38F. The low since midnight is 29F,
7 degrees above the normal minimum of 22F.
Today’s Observations:
7 A.M.
Weather: Fog
Temperature: 31F; Dew Point: 31F; Relative Humidity: 100%
Wind: W @ 5 kts, wind light
Sea-level pressure: 29.89 in Hg; falling unsteadily
Visibility: 1/16th mile, fog
6-hr Max temp: 32F
6-hr Min temp: 29F
24-hr Precip: 0.02 ins.
24-hr Snow: Trace
Snow Depth: 8 ins.
BHO SA 1155 X W3 1/16F 125/31/31/2705/989/ WND LGT NEW SNW
PST 24 HRS TRACE/ 8//// 4/008 70002 56011 10032 20029
10 A.M.
Weather: Fog
Temperature: 31F; Dew Point: 31F; Relative Humidity: 100%
Wind: NW @ 7 kts
Sea-level pressure: 29.84 in Hg; rising, then falling
Visibility: 1/16th mile, fog
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 X W3 1/16F 108/31/31/3207/984/ 8//// 56017
1 P.M.
Weather: Overcast stratus
Temperature: 33F; Dew Point: 33F; Relative Humidity: 100%
Wind: NNW @ 5 kts, wind light
Sea-level pressure: 29.75 in Hg; falling, then falling more
quickly
Visibility: 2 miles, fog
6-hr Max temp: 33F
6-hr Min temp: 31F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 8 ins.
BHO SA 1755 10 OVC 2F 075/33/33/3405/975/ WND LGT/ 8/6//
4/008 58033 10033 20031
SUMMARY FOR SUNDAY, DECEMBER 20, 2020
TEMPERATURE (DEGREES F)
MAX…….36 NORMAL…..38
MIN…….24 NORMAL…..22
MEAN……30 NORMAL…..30
DEPARTURE FROM 30-YEAR NORMAL…………………0
TOTAL DEPARTURE FOR THE MONTH…………………+9 [+0.3 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………35 DEPARTURE…….+0
TOTAL HEATING UNITS FOR THE MONTH…………..627 DEPARTURE……-11
TOTAL HEATING UNITS FOR THE SEASON…………1600 DEPARTURE…..-300
TOTAL HEATING UNITS LAST SEASON TO DATE…….1924 DEPARTURE…..-324
PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..14 S @ 7:51 A.M.
AEROVANE (south tower)…..16 SW @ 12:16 A.M.
ASOS…………………..14 SSW @ 6:01 P.M.
DAVIS #1……………….14 SW @ 12:24 A.M.
DAVIS #2 (south tower)…..15 SW @ 12:57 A.M.
RMY……………………14
VECTOR…………………15
MERLIN…………………N/A
FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..12 SW @ 12:14 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….12 SW @ 8:53 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………12 WSW @ 12:57 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………13 SW @ 12:26 A.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL….7.2 SW [172 total miles]
ASOS……………….7.8 [177 total miles]
DAVIS #1……………7.5 SW [180 total miles]
DAVIS #2……………8.3 SW [188 total miles]
RMY………………..7.7 SW [185 total miles]
VECTOR……………..8.2 [186 total miles]
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.02 DEPARTURE….-0.14
ASOS………….0.02
TOTAL PRECIPITATION FOR THE MONTH………….5.03 DEPARTURE….+1.93
ASOS………….5.53
TOTAL PRECIPITATION FOR THE YEAR………….51.43 DEPARTURE….-0.20
ASOS………..52.86
SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………Trace DEPARTURE…..-0.6
TOTAL SNOWFALL FOR THE MONTH………………19.7 DEPARTURE….+11.9
TOTAL SNOWFALL FOR THE SEASON……………..26.2 DEPARTURE….+15.8
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 The low since midnight is 29F, the daily normal low is 22F
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
RECORDS FOR DECEMBER 21
HIGH 60 IN 1957
LOW -10 IN 1942
PRECIP 2.01 INS. IN 1946
SNOWFALL 11.4 INS. IN 1954
PEAK GUST 77 MPH SSE IN 1957
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
TODAY’S REPORT PREPARED BY: Benjamin Turner
