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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, DECEMBER 13, 2019
ALL TIMES ARE IN EASTERN STANDARD TIME

OVERCAST SKIES AND MILDER TEMPERATURES ATOP GREAT BLUE HILL...

We observed mostly cloudy to overcast skies here as
our weekend rain-maker approaches. With an area of deep high
pressure slipping east, winds today have prevailed from the
southeasterly direction ushering in somewhat milder temperatures
compared to yesterday. We therefore noted our snow depth of
3 inches at 7 AM melting & compacting to 2 inches at the 1 PM observation.

The high so far today is 38F, which is 2 degrees below the daily
normal maximum of 40F. The low since midnight is 22F, which is 3
degrees below the normal minimum of 25F.


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: N/A 

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: Few Cumulus N-NE; Few Altocumulus/Altostratus in all directions;
Broken Cirrocumulus/Cirrostratus
Temperature: 27F; Dew Point: 23F; Wind: SE at 14 kts,
Sea-level pressure: 30.53 ins. Hg, decreasing unsteadily
Visibility: 30 miles
Snow Depth: 3 ins.
BHO SA 1155 E200 BKN 30 340/27/23/14014/053/ FEW CU N-NE 
FEW AC/AS ALQDS/ 8/898 4/003 57024 10027 20023

10 A.M.
Weather: Broken Altostratus; Overcast Cirrocumulus/Cirrostratus;
Breaks in Overcast NW
Temperature: 34F; Dew Point: 29F; Wind: SE at 9 kts 
Sea-level pressure: 30.50 ins. Hg, decreasing, then more slowly
Visibility: 30 miles
3-hr Precip: 0.00 ins.
3-hr Snowfall: 0.0 ins.
BHO SA 1455 E140 BKN E250 OVC 30 328/34/29/14009/050/ BINOVC NW/ 
8/018 56012

1 P.M.
Weather: Overcast Altostratus
Temperature: 37F; Dew Point: 33F; Wind: SE at 8 kts,
Wind: Light
Sea-level pressure: 30.43 ins. Hg, decreasing steadily
Visibility: 30 miles
6-hr Max temp: 38F
6-hr Min temp: 27F
6-hr Precip:  0.00 ins.
Snow Depth: 2 ins.
BHO SA 1755 E50 OVC 30 306/37/33/14008/043/ 8/01/ 4/002 58025 
10038 20027


SUMMARY FOR THURSDAY, DECEMBER 12, 2019 

TEMPERATURE (DEGREES F)
MAX.....29   NORMAL.....40
MIN.....17   NORMAL.....25
MEAN....23   NORMAL.....33

DEPARTURE FROM 30-YEAR NORMAL.....................-10
TOTAL DEPARTURE FOR THE MONTH.....................-44 [-3.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............42  DEPARTURE........+9
TOTAL HEATING UNITS FOR THE MONTH..............409  DEPARTURE.......+43
TOTAL HEATING UNITS FOR THE SEASON............1646  DEPARTURE.......+19
TOTAL HEATING UNITS LAST SEASON TO DATE.......1727  DEPARTURE.......-81

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY....................29 W  AT  2:22 A.M.  
                   AERO.........................30 W  AT  2:08 A.M.   
                   ASOS.........................30 NW AT  2:21 A.M. 
                   DAVIS........................31 W  AT  2:09 A.M. RMY 25
FASTEST MILE FOR YESTERDAY......................23 W  AT  2:09 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE...................22 WNW AT 2:11 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE..................24 W  AT  2:10 A.M.
AVERAGE WIND SPEED AND DIRECTION................8.9 W                   
                   ASOS.........................8.6 
                   DAVIS........................9.3 W [273 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.17
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........3.81  DEPARTURE......+1.83
                         ASOS..............4.09
TOTAL PRECIPITATION FOR THE YEAR..........52.89  DEPARTURE......+2.37
                         ASOS.............53.49

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.......-0.4
TOTAL SNOWFALL FOR THE MONTH...............18.0  DEPARTURE......+14.0
TOTAL SNOWFALL FOR THE SEASON..............18.1  DEPARTURE......+11.5


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/..../0.0/000/00            28 NNE AERO 29 N   RMY 31
11/19  42/36/39/-2/..../0.0/000/00            12 SSW AERO  9 NNW RMY N/A
11/20  38/33/36/-4/..../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/+2/0.12/0.0/000/00            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/+1/1.49/0.0/000/00            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/..../0.0/011/02            30 W   AERO 32 W   RMY N/A TSTM
11/28  48/30/39/+1/..../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/..../0.0/.../..            25 NW  AERO 25 NW  RMY N/A
12/12  29/17/23/-10/..../0.0/.../..           29 W   AERO 30 W   RMY 25

12/13 The low since midnight is 22F, daily normal minimum is 25F 


DAILY RECORDS FOR DECEMBER

12/01/19: DAILY RECORD SNOWFALL OF 5.8 INS.,
          BREAKS PREVIOUS RECORD OF 2.0 INS. SET IN 1902.

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: Andrew Swanson