BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA THURSDAY, DECEMBER 17, 2020 ALL TIMES ARE IN EASTERN STANDARD TIME FIRST MAJOR SNOW STORM OF THE SEASON ATOP GREAT BLUE HILL.... Conditions were very snowy starting later on yesterday night, and 9.4 inches of snow was measured at 7 A.M. Since then, another 7 inches fell primarily between the 7 A.M. and 1 P.M. observations. Light snow has persisted since then, but is not accumulating. The sun is breaking through at times, and the storm has mostly moved offshore. Liquid amounts from this storm totaled 1.69 inches! The snowfall since midnight of at least 15 inches will be a new record for December 17th. Wind was very significant today, reaching a peak gust of 53 mph this morning. Average wind speed was above 20 mph for the whole storm, with frequent gusts of 30 and even 40 mph at times. We noticed a wind shift from ENE to NNE this morning. This kept temperatures well below normal, bringing in a lot of colder air from the north.     The high so far today is 31F, 8 degrees below the daily normal high of 39F. The low since midnight is 20F, 4 degrees below the normal low of 24F.   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: Heavy snow Temperature: 31F; Dew Point: 31F; Relative Humidity: 100% Wind: NE at 26G43 kts, peak of 53 mph ENE at 6:38 A.M. Sea-level pressure: 29.84 in Hg; falling then rising Visibility: 1/4 mile, fog and blowing snow 6-hr Max temp: 31F 6-hr Min temp: 27F 24-hr Precip: 1.13 ins. 24-hr Snow: 9.4 ins. Snow Depth: 9 ins. BHO SA 1155 X W2 1/4S+BSF 104/31/31/0526G43/984/ DRFTG SNW PK WND 0746/38 TOTAL NEW SNW PST 24 HRS 9.4 INS/ 8//// 4/009 50001 6//// 70113 10031 20027 10 A.M. Weather: Snow Temperature: 22F; Dew Point: 22F; Relative Humidity: 100% Wind: N at 21G32 kts, peak of 51 mph NNE at 9:08 A.M.   Sea-level pressure: 29.86 in Hg; falling then rising Visibility: 3/4 mile, fog and blowing snow 3-hr Precip: 0.44 ins. 3-hr Snow: 4.3 ins. BHO SA 1455 X W2 3/4SBSF 112/22/22/0121G32/986/ DRFTG SNW PK WND 0244/08/ TOTAL NEW SNW PST 3 HRS 4.3 INS/ 8//// 53008 6044/ 1 P.M. Weather: Broken stratus fractus, overcast nimbostratus, sun occasionally dimly visible, light snow Temperature: 20F; Dew Point: 20F; Relative Humidity: 100% Wind: N at 18G28 kts, peak of 35 mph N at 11:58 A.M. Sea-level pressure: 29.85 in Hg; falling, then rising Visibility: 1 and 1/2 miles, fog and blowing snow 6-hr Max temp: 31F 6-hr Min temp: 20F 6-hr Precip: 0.56 ins. 6-hr Snow: 7.0 ins. Snow Depth: 14 ins. BHO SA 1755 E13 BKN 20 OVC 11/2S-BSF 108/20/20/3518G28/985/ SUN OCLY DMLY VSBL PK WND 3530/1658/ TOTAL NEW SNW PST 6 HRS 7.0 INS/ 8/6// 4/014 56004 6056/ 10031 20020     SUMMARY FOR WEDNESDAY, DECEMBER 16, 2020 TEMPERATURE (DEGREES F) MAX.......27   NORMAL.....39 MIN.......13   NORMAL.....24 MEAN......20   NORMAL.....31 DEPARTURE FROM 30-YEAR NORMAL................... -11 TOTAL DEPARTURE FOR THE MONTH................... +32 [+1.8 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY...............45  DEPARTURE......+11 TOTAL HEATING UNITS FOR THE MONTH..............466  DEPARTURE......-33 TOTAL HEATING UNITS FOR THE SEASON............1439  DEPARTURE.....-322 TOTAL HEATING UNITS LAST SEASON TO DATE.......1754  DEPARTURE.....-315 PEAK WIND GUST FOR YESTERDAY (MPH):                      420C/Official..............38 E    AT 11:30 P.M.                      AEROVANE (south tower).....37 E    AT 11:28 P.M.                      ASOS.......................38 E    AT 11:31 P.M.                      DAVIS #1...................36 E    AT 11:30 P.M.                      DAVIS #2 (south tower).....36 E    AT 11:33 P.M.                      RMY........................39                            VECTOR.....................40                          MERLIN.....................N/A FASTEST MILE FOR YESTERDAY: CONTACTING/OFFICIAL.............................25 E   AT  11:36 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE...................25 E   AT  11:34 P.M. MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............27 E   AT  11:33 P.M. MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............26 E   AT  11:39 P.M. AVERAGE WIND SPEED AND DIRECTION:                      CONTACTING/OFFICIAL.....9.8 NNW  [234 total miles]                      ASOS...................10.4      [250 total miles]                      DAVIS #1...............10.3 NE   [247 total miles]                      DAVIS #2...............10.3 NE   [247 total miles]                      RMY.....................9.6 ENE  [229 total miles]                      VECTOR.................10.1      [234 total miles] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST): TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.......1.13  DEPARTURE....+0.98                              ASOS.............1.39 TOTAL PRECIPITATION FOR THE MONTH.............4.42  DEPARTURE....+0.83                              ASOS.............4.79 TOTAL PRECIPITATION FOR THE YEAR.............50.82  DEPARTURE....-1.30                               ASOS...........52.12 SNOWFALL (INCHES) THROUGH THIS MORNING (EST): TOTAL SNOWFALL 24 HOURS ENDING 7 A.M...........9.4  DEPARTURE.....+8.9 TOTAL SNOWFALL FOR THE MONTH...................3.2  DEPARTURE.....+6.8 TOTAL SNOWFALL FOR THE SEASON..................9.7  DEPARTURE....+10.7 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/+11/0.38/0.0/.../..      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 The low since midnight is 20F, the daily normal low is 23F DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR DECEMBER 17 HIGH 63 IN 2000 LOW -10 IN 1942 PRECIP 3.03 INS. IN 1888 SNOWFALL 7.5 INS. IN 1988 PEAK GUST 78 MPH SSE IN 2000 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 TODAY'S REPORT PREPARED BY: Benjamin Turner