Friday, December 18, 2020
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
FRIDAY, DECEMBER 18, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME
COLD AND OVERCAST FOLLOWING YESTERDAY’S NOTABLE
SNOW EVENT….
Final measurement from yesterday’s storm is 16.5
inches with a snow-water equivalent (SWE) of 1.72
inches. This sets a new daily snowfall record of 15.1
inches for December 17th (see more stats below). The
busy east-northeast winds during the storm peaked at 55
MPH which actually disrupted the development of large,
healthy dendrites thus resulting in a meager water to
snow ratio of ~10:1 despite temps well below freezing.
To our distant northwest however, a different story
unfolded. Parts of central New York state, Vermont and
New Hampshire all recorded incredible 40+ inches of
snowfall. There, winds were calmer and air temperatures
much colder than here locally resulting in very impressive
snow ratios.
With the recording of yesterday’s precipitation, we have
officially climbed out of the annual drought. We now stand
with a surplus of +0.11 inches!
Today, skies are overcast with winds on the lighter
side. There is a sharp clearing line invading from the
northwest which will likely deliver us some sunshine before
sunset. Visibility has been exceptional – near perfect
with Mount Monadnock in very clear sight.
The high so far today is 26F, 12 degrees below the
daily normal high of 38F. The low since midnight is
20F, 3 degrees below the normal low of 23F.
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 Provided 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: Overcast Stratus (few breaks along the NW-N horizon,
virga ESE-SSE)
Temperature: 21F; Dew Point: 16F; Relative Humidity: 81%
Wind: N @ 10 kts
Sea-level pressure: 30.17 in Hg; rising, then rising more rapidly
Visibility: 80 miles (20 miles ESE-SSE)
6-hr Max temp: 21F
6-hr Min temp: 20F
24-hr Precip: 0.59 ins.
24-hr Snow: 7.1 ins.
Snow Depth: 10 ins.
BHO SA 1155 E24 OVC 80 216/21/16/3510/017/ FEW BINOVC ALNG
HRZN DSNT NW-N VSBY 20 ESE-SSE VIRGA ESE-SSE TOTAL NEW SNW
PST 24 HRS 7.1 INS STORM TOTAL 16.5 INS/ 8/6// 4/010 53013
70059 10021 20020
10 A.M.
Weather: Overcast Stratus (few breaks along the NW-N horizon)
Temperature: 24F; Dew Point: 16F; Relative Humidity: 72%
Wind: NNW @ 8G15 kts
Sea-level pressure: 30.22 in Hg; rising, then rising more rapidly
Visibility: 85 miles (25 miles ESE-SSE)
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 E45 OVC 85 232/24/16/3408G15/022/ FEW BINOVC
ALNG HRZN DSNT NW-N VSBY 25 ESE-SSE/ 8/6// 53016
1 P.M.
Weather: Broken Stratocumulus (clear sky band in the distant vicinity
extending SSW-NE)
Temperature: 25F; Dew Point: 14F; Relative Humidity: 62%
Wind: NNW @ 9kts
Sea-level pressure: 30.20 in Hg; falling, then rising
Visibility: 85 miles
6-hr Max temp: 26F
6-hr Min temp: 21F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 10 ins.
BHO SA 1755 E65 BKN 85 227/25/14/3409/020/ CLR SKY BND
DSNT VC XTDNG SSW-NE/ 8/400 4/010 55005 10026 20021
SUMMARY FOR THURSDAY, DECEMBER 17, 2020
TEMPERATURE (DEGREES F)
MAX…….31 NORMAL…..39
MIN…….19 NORMAL…..23
MEAN……25 NORMAL…..31
DEPARTURE FROM 30-YEAR NORMAL…………………-6
TOTAL DEPARTURE FOR THE MONTH………………..+26 [+1.3 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………40 DEPARTURE…….+6
TOTAL HEATING UNITS FOR THE MONTH…………..506 DEPARTURE……-27
TOTAL HEATING UNITS FOR THE SEASON…………1479 DEPARTURE…..-316
TOTAL HEATING UNITS LAST SEASON TO DATE…….1790 DEPARTURE…..-311
PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..55 ENE @ 5:45 A.M.
AEROVANE (south tower)…..56 ENE @ 4:05 A.M.
ASOS…………………..55 ENE @ 3:59 A.M.
DAVIS #1……………….54 E @ 3:59 A.M.
DAVIS #2 (south tower)…..55 ENE @ 5:44 A.M.
RMY……………………59
VECTOR…………………58
MERLIN…………………N/A
FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..38 ENE @ 4:05 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….36 ENE @ 4:05 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………38 E @ 4:05 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………36 ENE @ 4:05 A.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL….20.3 N [487 total miles]
ASOS……………….19.9 [478 total miles]
DAVIS #1……………20.0 NE [480 total miles]
DAVIS #2……………19.9 NE [478 total miles]
RMY………………..18.9 [454 total miles]
VECTOR……………..19.4 [466 total miles]
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.59 DEPARTURE….+0.43
ASOS………….0.72
TOTAL PRECIPITATION FOR THE MONTH………….5.01 DEPARTURE….+2.24
ASOS………….5.51
TOTAL PRECIPITATION FOR THE YEAR………….51.41 DEPARTURE….+0.11
ASOS………..52.84
SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..7.1 DEPARTURE…..+6.7
TOTAL SNOWFALL FOR THE MONTH………………19.7 DEPARTURE….+13.4
TOTAL SNOWFALL FOR THE SEASON……………..26.2 DEPARTURE….+17.3
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
The low since midnight is 20F, 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 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
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
TODAY’S REPORT PREPARED BY: Andrew Swanson