Sunday, December 13, 2020

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

SUNDAY, DECEMBER 13, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

MOSTLY CLOUDY AND WARMER WITH LIMITED VISIBILITY
ATOP GREAT BLUE HILL….

After yesterday’s rain, 0.38 inches were left
in the gauge at the 7 A.M. observation. Today
started off very foggy, limiting visibility to
only a 1/16th mile. The morning sun came in
around 10 A.M. to burn off the layer of fog,
leaving a visibility of 40 miles for the observer
at 1 P.M. Conditions are mostly cloudy with
increasing wind. The average speed is around 18 mph
from the southwest, with a max gust of almost 25 mph.

The high so far today is 58F, 18 degrees above the
daily normal high of 40F. The low since midnight
is 41F, 16 degrees above the normal low of 25F.
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: Fog
Temperature: 45F; Dew Point: 45F; Relative Humidity: 100%
Wind: S at 11 kts
Sea-level pressure: 29.91 in Hg; falling steadily
Visibility: 1/16th mile, fog
6-hr Max temp: 58F
6-hr Min temp: 41F
24-hr Precip: 0.38 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1155 X W2 1/16F 130/45/45/1911/991/ 8//// 70038
56003 10045 20041

10 A.M.
Weather: Scattered altocumulus, broken cirrostratus,
and stratus fractus drifting over the summit
Temperature: 49F; Dew Point: 48F; Relative Humidity: 96%
Wind: ENE at 13G17 kts
Sea-level pressure: 29.92 in Hg; rising steadily
Visibility: 3 miles, fog
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 90 SCT 200 BKN 3F 135/49/48/2213G17/992/ STFRA
DRFTG OVR SMT/ 8/686 53005

1 P.M.
Weather: Broken cirrostratus
Temperature: 56F; Dew Point: 46F; Relative Humidity: 69%
Wind: WSW at 10G21 kts
Sea-level pressure: 29.86 in Hg; falling steadily
Visibility: 35 miles, hazy
6-hr Max temp: 58F
6-hr Min temp: 45F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth:  0 ins.
BHO SA 1755 BKN 250 35 117/56/46/2410G21/986/ HAZY/ 8/006
56018 10058 20045

SUMMARY FOR SATURDAY, DECEMBER 12, 2020

TEMPERATURE (DEGREES F)
MAX…….48   NORMAL…..40
MIN…….40   NORMAL…..25
MEAN……44   NORMAL…..33

DEPARTURE FROM 30-YEAR NORMAL………………. +11
TOTAL DEPARTURE FOR THE MONTH………………. +31 [+2.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………21  DEPARTURE……-11
TOTAL HEATING UNITS FOR THE MONTH…………..334  DEPARTURE……-32
TOTAL HEATING UNITS FOR THE SEASON…………1307  DEPARTURE…..-320
TOTAL HEATING UNITS LAST SEASON TO DATE…….1646  DEPARTURE…..-339

PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..25 E    AT  3:36 P.M.
AEROVANE (south tower)…..21 E    AT  3:28 P.M.
ASOS…………………..28 E    AT  3:36 P.M.
DAVIS #1……………….28 E    AT  3:38 P.M.
DAVIS #2 (south tower)…..24 E    AT  3:31 P.M.
RMY……………………25
VECTOR…………………27
MERLIN…………………25

FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..19 E   AT   3:35 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….18 E   AT   3:38 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………20 E   AT   3:38 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………18 E   AT   3:37 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL…..7.3 NE   [175 total miles] ASOS………………..8.1      [194 total miles] DAVIS #1…………….8.3 ENE  [199 total miles] DAVIS #2…………….8.3 NE   [199 total miles] RMY…………………7.9 ENE  [189 total miles] VECTOR………………8.3      [190 total miles]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.38  DEPARTURE….+0.21
ASOS………….0.40
TOTAL PRECIPITATION FOR THE MONTH………….3.19  DEPARTURE….+1.21
ASOS………….3.29
TOTAL PRECIPITATION FOR THE YEAR………….49.59  DEPARTURE….-0.92
ASOS………..50.62

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..0.0  DEPARTURE…..-0.4
TOTAL SNOWFALL FOR THE MONTH……………….2.8  DEPARTURE…..-1.2
TOTAL SNOWFALL FOR THE SEASON………………9.3  DEPARTURE…..+2.7

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/…./…/…/..      25 E    AERO 21 E    RMY 25

12/13 The low since midnight is 41F, the daily normal low is 25F

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

RECORDS FOR DECEMBER 13
HIGH 60 IN 1984
LOW 0 IN 1893
PRECIP 1.45 INS. IN 1983
SNOWFALL 9.2 INS. IN 2007
PEAK GUST 81e WNW IN 1976

RECORDS FOR DECEMBER 14
HIGH 62 IN 1901
LOW -6 IN 1893
PRECIP 1.94 INS. IN 2002
SNOWFALL 8.0 INS. IN 1907
PEAK GUST 78e ENE IN 1941

TODAY’S REPORT PREPARED BY: Benjamin Turner