Saturday, December 19, 2020

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

SATURDAY, DECEMBER 19, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

SUNNY MORNING SKIES AND CONTINUED COLD TEMPERATURES AT BLUE HILL….

Yesterday afternoon beginning around 2:00 P.M. EST, the sun began to shine through the clouds. This morning, skies were almost completely clear, except for some distant stratus in the north-northeast to south-southeast which lingered throughout the morning and into the early afternoon. This resulted in a lower visibility in this direction, which was around 15-30 miles. Despite the cold temperatures, it was a pleasant morning with the shining sun and low winds, which were only blowing at around 1 MPH around 10:00 A.M. In the afternoon, more cirrus clouds began to move in, and by the late afternoon skies were overcast.

Last night, a minimum temperature of 13F was recorded just before the 7:00 A.M. observation. This is 10F below the normal minimum temperature of 23F, and it is one of the lowest temperatures recorded so far this month (a minimum of 13F was also measured on December 16th). In the afternoon, the temperature rose to a maximum of 30F by the 1:00 P.M. observation, which is 9F below the normal high temperature of 38F.

BHO GREATEST DECEMBER SNOWSTORMS, inches (1886-2020):
1) 24.3 on   5-7 Dec 2003
2) 21.0 on 11-12 Dec 1960
3) 19.9 on 19-20 Dec 1945
4) 19.0 on   5-6 Dec 1981
5) 18.8 on 29-30 Dec 1945
6) 18.0 on 25-26 Dec 1909
7) 17.5 on 23-24 Dec 1947
8) 16.9 on 26-27 Dec 2010
9) 16.8 on 23-25 Dec 1961
10) 16.5 on 16-17 Dec 2020

BHO GREATEST DECEMBER CALENDAR DAY SNOWFALLS, inches (1886-2020):
1) 20.3 on 12 Dec, 1960
2) 18.4 on 29 Dec, 1945
3) 17.5 on 26 Dec, 1909
4) 17.0 on  6 Dec, 2003
5) 15.1 on 17 Dec 2020
6) 15.0 on 12 Dec, 1992
7) 14.1 on 19 Dec, 1945
8) 13.7 on 20 Dec, 2009
9) 13.3 on 26 Dec, 2010
10) 13.1 on 29 Dec, 1976

Statistics Provide By: Mike Iacono (BHO Chief Scientist)
———————————————————–
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: Clear, few distant stratus NNE-SSE
Temperature: 14F; Dew Point: 9F; Relative Humidity: 81%
Wind: NNW @ 7 kts
Sea-level pressure: 30.39 in Hg; rising, then rising more rapidly
Visibility: 70 miles (20 miles NNE-SSE)
6-hr Max temp: 18F
6-hr Min temp: 13F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 10 ins.
BHO SA 1155 CLR 75 291/14/09/3407/038/ FEW ST DSNT NNE-SSE VSBY 15 NNE-SSE/ 8/600 4/010 53010 10018 20013

10 A.M.
Weather: Scattered cirrus, few distant stratus NNE-SSE, distant haze in all directions
Temperature: 26F; Dew Point: 14F; Relative Humidity: 60%
Wind: NE @ 1 kt
Wind speed: Light
Sea-level pressure: 30.40 in Hg; rising, then falling
Visibility: 70 miles (20 miles NNE-SSE)
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 250 SCT 70 296/26/14/0408/040/ DSNT HZ ALQDS FEW ST DSNT NNE-SSE VSBY 20 NNE-SSE WND LGT/ 8/601 51005

1 P.M.
Weather:
Temperature: 30F; Dew Point: 17F; Relative Humidity: 58%
Wind: WSW @ 1kt
Wind speed: Light
Sea-level pressure: 30.35 in Hg; falling, then falling more quickly
Visibility: 70 miles (30 miles NNE-SE)
6-hr Max temp: 30F
6-hr Min temp: 14F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 9 ins.
BHO SA 1755 250 BKN 277/30/17/2501/035/ FEW ST DSNT NNE-SE VSBY 30 NNE-SE WND LGT/ 8/601 4/009 58019 10030 20014

SUMMARY FOR FRIDAY, DECEMBER 18, 2020

TEMPERATURE (DEGREES F)
MAX…….27   NORMAL…..38
MIN…….18   NORMAL…..23
MEAN……23   NORMAL…..31

DEPARTURE FROM 30-YEAR NORMAL…………………-8
TOTAL DEPARTURE FOR THE MONTH………………..+18 [+0.8 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………42  DEPARTURE…….+7
TOTAL HEATING UNITS FOR THE MONTH…………..548  DEPARTURE……-20
TOTAL HEATING UNITS FOR THE SEASON…………1521  DEPARTURE…..-309
TOTAL HEATING UNITS LAST SEASON TO DATE…….1829  DEPARTURE…..-308

PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..28 N   @ 12:01 A.M.
AEROVANE (south tower)…..26 N   @ 12:01 A.M.
ASOS…………………..28 NNW @ 12:01 A.M.
DAVIS #1……………….27 NNW @ 12:01 A.M.
DAVIS #2 (south tower)…..24 N   @ 12:01 A.M.
RMY……………………29
VECTOR…………………27
MERLIN…………………N/A

FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..20 N   @ 12:03 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….20 NNW @ 12:03 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………19 N   @ 12:03 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………19 N   @ 12:03 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL….11.3 NNW [271 total miles] ASOS……………….11.0     [264 total miles] DAVIS #1……………11.7 N   [281 total miles] DAVIS #2……………11.8 N   [283 total miles] RMY………………..11.0     [264 total miles] VECTOR……………..11.7     [281 total miles]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.00  DEPARTURE….-0.16
ASOS………….0.00
TOTAL PRECIPITATION FOR THE MONTH………….5.01  DEPARTURE….+2.08
ASOS………….5.51
TOTAL PRECIPITATION FOR THE YEAR………….51.41  DEPARTURE….-0.05
ASOS………..52.84

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….+13.0
TOTAL SNOWFALL FOR THE SEASON……………..26.2  DEPARTURE….+16.9

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   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

The low since midnight is 13F, the daily normal low is 23F

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 19
HIGH 59 IN 1899
LOW -1 IN 1919
PRECIP 2.06 INS. IN 1986
SNOWFALL 14.1 INS. IN 1945
PEAK GUST 68 NE IN 1986

RECORDS FOR DECEMBER 20
HIGH 61 IN 1957
LOW -16 IN 1942
PRECIP 1.69 INS. IN 1936
SNOWFALL 13.7 INS. IN 2009
PEAK GUST 75 MPH S IN 2002

TODAY’S REPORT PREPARED BY: Lizzy Suzedell