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