Thursday, December 17, 2020
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
THURSDAY, DECEMBER 17, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME
FIRST MAJOR SNOW STORM OF THE SEASON ATOP
GREAT BLUE HILL….
Conditions were very snowy starting later on
yesterday night, and 9.4 inches of snow was
measured at 7 A.M. Since then, another 7 inches
fell primarily between the 7 A.M. and 1 P.M.
observations. Light snow has persisted since
then, but is not accumulating. The sun is
breaking through at times, and the storm has
mostly moved offshore.
Liquid amounts from this storm totaled 1.69
inches! The snowfall since midnight of at least
15 inches will be a new record for December 17th.
Wind was very significant today, reaching a
peak gust of 53 mph this morning. Average
wind speed was above 20 mph for the whole
storm, with frequent gusts of 30 and even
40 mph at times. We noticed a wind shift
from ENE to NNE this morning. This kept
temperatures well below normal, bringing
in a lot of colder air from the north.
The high so far today is 31F, 8 degrees below the
daily normal high of 39F. The low since midnight is
20F, 4 degrees below the normal low of 24F.
PRELIMINARY STATS FOR NOVEMBER 2020
TEMPERATURE, Deg. F
Avg. Max. 56.3 [+6.3]
Avg. Min. 38.6 [+5.1]
Mean 47.5 [+5.8]
24-hour corrected mean: 46.9
Max. for month: 75F on the 7th
Min. for month: 18F on the 19th
HEATING DEGREE DAYS
Total heating units: 521 [-177]
Total for the season: 973 [-288]
Total for last season: 1237
PRECIPITATION, Inches
Total: 5.23 [+1.77]
Greatest in 24 hrs: 1.77 ins. on the 23rd
SNOWFALL, Inches
Total: TRACE
Greatest in 24 hrs: T on the 2nd
WIND, mph
Avg. uncorrected wind speed: 12.9 mph
Avg. corrected wind speed: 13.2 mph
Prevailing wind direction: SSW [14%]
Peak gust and direction: 81 SSE on the 30th
SUNSHINE:
Campbell-Stokes card minutes: 9066 minutes of a possible 17010 or 53%
Astronomical total minutes: 9382 minutes of a possible 17593 or 53%
Today’s Observations:
7 A.M.
Weather: Heavy snow
Temperature: 31F; Dew Point: 31F; Relative Humidity: 100%
Wind: NE at 26G43 kts, peak of 53 mph ENE at 6:38 A.M.
Sea-level pressure: 29.84 in Hg; falling then rising
Visibility: 1/4 mile, fog and blowing snow
6-hr Max temp: 31F
6-hr Min temp: 27F
24-hr Precip: 1.13 ins.
24-hr Snow: 9.4 ins.
Snow Depth: 9 ins.
BHO SA 1155 X W2 1/4S+BSF 104/31/31/0526G43/984/ DRFTG SNW
PK WND 0746/38 TOTAL NEW SNW PST 24 HRS 9.4 INS/ 8//// 4/009
50001 6//// 70113 10031 20027
10 A.M.
Weather: Snow
Temperature: 22F; Dew Point: 22F; Relative Humidity: 100%
Wind: N at 21G32 kts, peak of 51 mph NNE at 9:08 A.M.
Sea-level pressure: 29.86 in Hg; falling then rising
Visibility: 3/4 mile, fog and blowing snow
3-hr Precip: 0.44 ins.
3-hr Snow: 4.3 ins.
BHO SA 1455 X W2 3/4SBSF 112/22/22/0121G32/986/ DRFTG SNW
PK WND 0244/08/ TOTAL NEW SNW PST 3 HRS 4.3 INS/ 8//// 53008
6044/
1 P.M.
Weather: Broken stratus fractus, overcast nimbostratus,
sun occasionally dimly visible, light snow
Temperature: 20F; Dew Point: 20F; Relative Humidity: 100%
Wind: N at 18G28 kts, peak of 35 mph N at 11:58 A.M.
Sea-level pressure: 29.85 in Hg; falling, then rising
Visibility: 1 and 1/2 miles, fog and blowing snow
6-hr Max temp: 31F
6-hr Min temp: 20F
6-hr Precip: 0.56 ins.
6-hr Snow: 7.0 ins.
Snow Depth: 14 ins.
BHO SA 1755 E13 BKN 20 OVC 11/2S-BSF 108/20/20/3518G28/985/ SUN OCLY DMLY VSBL PK WND 3530/1658/ TOTAL NEW SNW PST 6 HRS 7.0 INS/ 8/6// 4/014 56004 6056/ 10031 20020
SUMMARY FOR WEDNESDAY, DECEMBER 16, 2020
TEMPERATURE (DEGREES F)
MAX…….27 NORMAL…..39
MIN…….13 NORMAL…..24
MEAN……20 NORMAL…..31
DEPARTURE FROM 30-YEAR NORMAL………………. -11
TOTAL DEPARTURE FOR THE MONTH………………. +32 [+1.8 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………45 DEPARTURE……+11
TOTAL HEATING UNITS FOR THE MONTH…………..466 DEPARTURE……-33
TOTAL HEATING UNITS FOR THE SEASON…………1439 DEPARTURE…..-322
TOTAL HEATING UNITS LAST SEASON TO DATE…….1754 DEPARTURE…..-315
PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..38 E AT 11:30 P.M.
AEROVANE (south tower)…..37 E AT 11:28 P.M.
ASOS…………………..38 E AT 11:31 P.M.
DAVIS #1……………….36 E AT 11:30 P.M.
DAVIS #2 (south tower)…..36 E AT 11:33 P.M.
RMY……………………39
VECTOR…………………40
MERLIN…………………N/A
FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..25 E AT 11:36 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….25 E AT 11:34 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………27 E AT 11:33 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………26 E AT 11:39 P.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL…..9.8 NNW [234 total miles]
ASOS……………….10.4 [250 total miles]
DAVIS #1……………10.3 NE [247 total miles]
DAVIS #2……………10.3 NE [247 total miles]
RMY…………………9.6 ENE [229 total miles]
VECTOR……………..10.1 [234 total miles]
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….1.13 DEPARTURE….+0.98
ASOS………….1.39
TOTAL PRECIPITATION FOR THE MONTH………….4.42 DEPARTURE….+0.83
ASOS………….4.79
TOTAL PRECIPITATION FOR THE YEAR………….50.82 DEPARTURE….-1.30
ASOS………..52.12
SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..9.4 DEPARTURE…..+8.9
TOTAL SNOWFALL FOR THE MONTH……………….3.2 DEPARTURE…..+6.8
TOTAL SNOWFALL FOR THE SEASON………………9.7 DEPARTURE….+10.7
PRELIMINARY CLIMATE SUMMARY FOR NOVEMBER 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
11/01 49/36/43/-3/0.69/0.0/006/01 38 W AERO 40 W RMY 39
11/02 40/31/36/-10/T/T/425/69 61 WNW AERO 62 WNW RMY 62
11/03 43/29/36/-10/0.00/0.0/473/77 48 WNW AERO 53 WNW RMY 48
11/04 54/30/42/-3/0.00/0.0/550/90 30 SSW AERO 30 SSW RMY 30
11/05 69/49/59/+14/0.00/0.0/548/90 37 SSW AERO 40 SSW RMY 38
11/06 72/55/64/+19/0.00/0.0/394/65 28 SW AERO 28 SW RMY M
11/07 75/54/65/+20/0.00/0.0/562/93 21 WSW AERO 21 WSW RMY 21
11/08 73/54/64/+20/0.00/0.0/584/97 18 W AERO 18 W RMY 19
11/09 74/52/63/+19/0.00/0.0/593/99 20 WSW AERO 18 WSW RMY 21
11/10 74/53/64/+20/0.00/0.0/597/100 30 SW AERO 28 SW RMY 31
11/11 73/58/66/+23/0.04/0.0/137/23 40 SW AERO 44 SW RMY 45
11/12 64/46/55/+12/0.04/0.0/000/00 32 NNW AERO 31 NNW RMY 33
11/13 48/38/43/0/0.30/0.0/000/00 22 NW AERO 21 NW RMY 25
11/14 49/32/41/-1/0.00/0.0/276/47 26 NW AERO 28 NW RMY 29
11/15 58/30/44/+2/0.62/0.0/311/53 60 S AERO 67 S RMY 65
11/16 53/39/46/+4/0.00/0.0/526/90 40 WNW AERO 41 WNW RMY 43
11/17 47/32/40/-1/0.00/0.0/204/35 28 NW AERO 28 NW RMY 30
11/18 32/19/26/-15/0.00/0.0/580/100 40 NW AERO 46 NW RMY 43
11/19 44/18/31/-10/0.00/0.0/393/68 37 SW AERO 39 SW RMY 43
11/20 63/44/54/+14/0.00/0.0/495/86 33 SSW AERO 35 SSW RMY 37
11/21 62/40/51/+11/0.00/0.0/339/59 24 W AERO 23 W RMY 27
11/22 45/33/39/-1/T/0.0/006/01 28 SE AERO 28 SE RMY 31
11/23 58/32/45/+6/1.77/0.0/000/00 42 WNW AERO 48 WNW RMY 46 TSTM
11/24 42/27/35/-4/0.00/0.0/569/100 31 WNW AERO 32 WNW RMY 33
11/25 50/26/38/-1/0.01/0.0/017/03 23 SSE AERO 23 SSE RMY 26
11/26 58/45/52/+14/0.36/0.0/000/00 36 S AERO 37 S RMY 41
11/27 53/46/50/+12/0.00/0.0/056/10 23 WNW AERO 23 WNW RMY 23
11/28 52/36/44/+6/T/0.0/180/32 28 WNW AERO 30 WNW RMY 27
11/29 52/33/43/+6/0.00/0.0/561/100 21 SSW AERO 21 SSW RMY 22
11/30 62/40/51/+14/1.35/0.0/000/00 81 SSE AERO 82 SSE RMY 86
DAILY RECORDS FOR NOVEMBER 2020
11/06/20: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 72F,
BREAKS PREVIOUS RECORD OF 71F SET IN 1959 AND 2015
11/07/20: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 75F,
TIES PREVIOUS RECORD OF 75F SET IN 1938
11/08/20: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 73F,
BREAKS PREVIOUS RECORD OF 72F SET IN 1938
11/09/20: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 74F,
BREAKS PREVIOUS RECORD OF 72F SET IN 1975
11/11/20: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 58F,
BREAKS PREVIOUS RECORD OF 56F IN 2002
DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 73F,
BREAKS PREVIOUS RECORD OF 68F IN 1984
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 The low since midnight is 20F, the daily normal low is 23F
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
RECORDS FOR DECEMBER 17
HIGH 63 IN 2000
LOW -10 IN 1942
PRECIP 3.03 INS. IN 1888
SNOWFALL 7.5 INS. IN 1988
PEAK GUST 78 MPH SSE IN 2000
RECORDS FOR DECEMBER 18
HIGH 59 IN 1928
LOW -11 IN 1919
PRECIP 1.44 INS. IN 1915
SNOWFALL 7.0 INS. IN 1904
PEAK GUST 76e W IN 1978
TODAY’S REPORT PREPARED BY: Benjamin Turner
