Friday, December 20, 2019

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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, DECEMBER 20, 2019
ALL TIMES ARE IN EASTERN STANDARD TIME

CLEAR SKIES, GREAT VISIBILITY, BUT THE COLD AND WIND PERSIST…

We observed clear skies throughout the day, providing us with
another spectacular bright day during what has been a relatively
cloudy month thus far. Despite an abundance of sunshine, temperatures
have only reached the mid-20s with a persistent, moderate northwest
wind peaking so far at 30 MPH, but has eased a bit heading deeper
into the afternoon. Visibility at 7 AM was noted to be 50 miles
increasing to a perfect/90 miles at the 1 PM observation!

The high so far today is 26F, which is 12 degrees below the
daily normal maximum of 38F. The low since midnight is 11F,
which is 11 degrees below the normal minimum of 22F.

PRELIMINARY STATS FOR NOVEMBER 2019

TEMPERATURE, Deg. F
Avg. Max. 46.0 [-4.0] Avg. Min. 30.3 [-3.2] Mean 38.2 [-3.5] 24-hour corrected mean: 38.0
Max. for month: 67F on the 1st
Min. for month: 15F on the 13th

HEATING DEGREE DAYS
Total heating units: 761 [+99] Total for the season: 1237 [-24] Total for last season: 1319

PRECIPITATION, Inches
Total: 3.74 [-1.02] Greatest in 24 hrs: 1.60 ins. on the 24th

SNOWFALL, Inches
Total: 0.1 [-2.2] Greatest in 24 hrs: 0.1 ins. on the 12th

WIND, mph
Avg. uncorrected wind speed: 12.5 mph
Avg. corrected wind speed: 12.9 mph
Prevailing wind direction: W [16%] Peak gust and direction: 67 S on the 1st

SUNSHINE:
Campbell-Stokes card minutes: 8652 minutes of possible 17010 or 51%
Astronomical total minutes: 8985 minutes of possible 17640 or 51%

Today’s Observations:

7 A.M.
Weather: Clear, Few Distant Cumulus Offshore
Temperature: 11F; Dew Point: 0F; Wind: WNW at 11G19 kts,
Sea-level pressure: 30.36 ins. Hg, rising then rising more rapidly
Visibility: 50 miles
6-hr Max temp: 12F
6-hr Min temp: 11F
Snow Depth: Trace
BHO SA 1155 CLR 50 281/11/0/3011G19/036/
FEW DSNT CU OFFSHR/ 8/100 53021 10012 20011

10 A.M.
Weather: Clear, Few Distant Cumulus Offshore
Temperature: 17F; Dew Point: 3F; Wind: NW at 14G23 kts,
Sea-level pressure: 30.45 ins. Hg, rising then rising more rapidly
Visibility: 85 miles
3-hr Precip: 0.00 ins.
3-hr Snowfall: 0.0 ins.
BHO SA 1455 CLR 85 310/17/3/3114G23/045/
FEW DSNT CU OFFSHR/ 8/100 53029

1 P.M.
Weather: Clear, Few Distant Cumulus Offshore
Temperature: 26F; Dew Point: 9F; Wind: NW at 11 kts,
Sea-level pressure: 30.44 ins. Hg, steady then decreasing
Visibility: 90 miles
6-hr Max temp: 26F
6-hr Min temp: 11F
6-hr Precip: 0.00 ins.
Snow Depth: Trace
BHO SA 1755 CLR 90 308/26/9/3211/044/
FEW DSNT CU OFFSHR/ 8/100 58002 10026 20011

SUMMARY FOR THURSDAY, DECEMBER 19, 2019

TEMPERATURE (DEGREES F)
MAX…..20 NORMAL…..38
MIN……9 NORMAL…..23
MEAN….15 NORMAL…..30

DEPARTURE FROM 30-YEAR NORMAL…………………-15
TOTAL DEPARTURE FOR THE MONTH…………………-41 [-2.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………50 DEPARTURE……..+15
TOTAL HEATING UNITS FOR THE MONTH…………..642 DEPARTURE……..+39
TOTAL HEATING UNITS FOR THE SEASON…………1879 DEPARTURE……..15
TOTAL HEATING UNITS LAST SEASON TO DATE…….1912 DEPARTURE…….-70

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………..51 W AT 1:44 A.M.
AERO…………………….47 W AT 1:43 A.M.
ASOS…………………….49 WNW AT 1:43 A.M.
DAVIS……………………51 WNW AT 1:42 A.M. RMY N/A
FASTEST MILE FOR YESTERDAY………………….39 W AT 1:41 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….37 WNW AT 1:44 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………40 W AT 1:42 A.M.
AVERAGE WIND SPEED AND DIRECTION…………..19.3 W
ASOS……………………18.3
DAVIS…………………..9.5 WNW [286 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0 DEPARTURE……-0.15
ASOS……………..0
TOTAL PRECIPITATION FOR THE MONTH……….6.06 DEPARTURE……+2.98
ASOS…………..6.51
TOTAL PRECIPITATION FOR THE YEAR……….55.14 DEPARTURE……+3.52
ASOS………….55.91

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………0 DEPARTURE…….-0.5
TOTAL SNOWFALL FOR THE MONTH……………19.1 DEPARTURE……+11.9
TOTAL SNOWFALL FOR THE SEASON…………..19.2 DEPARTURE…….+9.4

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 67/35/51/+5/0.12/0.0/534/86 67 S AERO M M RMY N/A
11/02 50/31/41/-5/0.00/0.0/612/99 17 WNW AERO 14 W RMY N/A
11/03 53/35/44/-2/0.00/0.0/567/92 25 WSW AERO 23 W RMY 26
11/04 53/33/43/-2/0.00/0.0/546/89 24 S AERO 20 S RMY 24
11/05 54/44/49/+4/0.33/0.0/000/00 22 S AERO 18 WNW RMY 28
11/06 51/36/44/-1/0.00/0.0/596/98 28 WSW AERO 23 W RMY 27
11/07 55/38/47/+2/0.27/0.0/000/00 30 S AERO 26 SSW RMY 32
11/08 38/23/31/-13/0.00/0.0/555/92 38 NW AERO 37 WNW RMY 44
11/09 39/20/30/-14/0.00/0.0/583/97 22 S AERO 18 S RMY N/A
11/10 51/30/41/-3/0.00/0.0/174/29 30 SW AERO 30 SW RMY 31
11/11 52/39/46/+3/T/0.0/000/00 23 NE AERO 22 NE RMY 23
11/12 42/20/31/-12/0.08/0.1/000/00 37 WNW AERO 37 WNW RMY 41
11/13 28/15/22/-21/0.00/0.0/592/100 32 WNW AERO 32 WNW RMY 35
11/14 36/17/28/-14/0.00/0.0/136/23 18 SW AERO 17 SW RMY 20
11/15 51/32/42/0/0.00/0.0/553/94 25 WNW AERO 25 WNW RMY N/A
11/16 35/22/29/-13/0.00/0.0/580/99 35 NNW AERO 35 NNW RMY N/A
11/17 40/21/31/-10/T/T/000/00 28 ENE AERO 27 ENE RMY 29
11/18 36/32/34/-7/0.45/0.0/000/00 28 NNE AERO 29 N RMY 31
11/19 42/36/39/-2/0.22/0.0/000/00 12 SSW AERO 9 NNW RMY N/A
11/20 38/33/36/-4/0.23/T/000/00 20 NW AERO 18 NW RMY 21
11/21 46/30/38/-2/0.00/0.0/536/93 21 NW AERO 21 NW RMY N/A
11/22 52/32/42/+2/0.13/0.0/000/00 46 W AERO 47 W RMY 47
11/23 44/27/36/-3/0.00/0.0/503/88 29 WNW AERO 29 WNW RMY N/A
11/24 44/35/40/+1/1.60/0.0/000/00 45 N AERO 44 NE RMY 46 TSTM
11/25 50/34/42/+3/0.00/0.0/329/58 32 WNW AERO 35 WNW RMY 23
11/26 59/39/49/+11/0.00/0.0/544/96 28 SSW AERO 27 SSW RMY 29
11/27 50/42/46/+8/0.24/0.0/011/02 30 W AERO 32 W RMY N/A TSTM
11/28 48/30/39/+1/0.07/T/062/11 42 NW AERO 44 NW RMY 44
11/29 39/27/33/-4/0.00/0.0/433/77 35 NW AERO 36 NW RMY 39
11/30 35/22/29/-8/0.00/0.0/539/96 30 NW AERO 28 WNW RMY 31

DAILY RECORDS FOR NOVEMBER

11/13/19: DAILY RECORD LOW MAXIMUM TEMPERATURE OF 28F,
BREAKS PREVIOUS RECORD OF 30F SET IN 1920.
It was also the third earliest maximum temperature
colder than 30F on record, behind only 28F on 11/8/1894
and 29F on 11/12/1894.

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 32/16/24/-13/…./5.8/…/.. 33 ENE AERO 32 ENE RMY N/A
12/02 37/25/31/-5/…./2.7/…/.. 52 NE AERO 47 NE RMY 53
12/03 30/23/27/-9/…./4.6/…/.. 32 N AERO 35 N RMY 36
12/04 34/22/28/-7/…./0.0/…/.. 23 WNW AERO 23 NNW RMY N/A
12/05 41/26/34/-1/…./0.0/…/.. 33 NW AERO 35 NW RMY 37
12/06 33/23/28/-7/0.02/0.1/…/.. 25 NW AERO 23 NW RMY 29
12/07 31/18/25/-9/0.00/0.0/…/.. 25 NW AERO 23 NW RMY N/A
12/08 36/15/26/-8/0.00/0.0/…/.. 31 SSW AERO 32 SSW RMY N/A
12/09 57/36/47/+13/…./0.0/…/.. 53 S AERO 52 S RMY 54
12/10 58/37/48/+15/…./0.0/…/.. 35 SW AERO 39 SW RMY N/A
12/11 36/23/30/-3/…./3.0/…/.. 25 NW AERO 25 NW RMY N/A
12/12 29/17/23/-10/…./1.8/…/.. 29 W AERO 30 W RMY 25
12/13 46/22/34/+2/…./0.0/…/.. 25 SSE AERO 25 SSE RMY N/A
12/14 58/46/52/+20/…./0.0/…/.. 45 S AERO 41 S RMY N/A
12/15 48/28/38/+6/0.00/0.0/…/.. 53 W AERO 53 W RMY 50
12/16 30/25/28/-3/0.00/0.0/…/.. 36 W AERO 36 W RMY N/A
12/17 35/23/29/-2/…./1.0/…/.. 22 NNW AERO 21 NE RMY 23
12/18 33/18/26/-5/…/0.0/…/.. 44 WNW AERO 45 WNW RMY N/A
12/19 20/9/15/-15/…/0.0/…/.. 51 W AERO 47 W RMY N/A