BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA TUESDAY, DECEMBER 15, 2020 ALL TIMES ARE IN EASTERN STANDARD TIME SUNSHINE RETURNS, BUT WINDY AND COLD TODAY... After the rain changed over to snow yesterday afternoon, we picked up a quick 0.3 ins of accumulation, bringing the total snow/sleet accumulation to 0.4 ins! 0.10 ins of liquid was measured for the entire event. Today bright sunshine has returned, but it's been what we call ineffective sunshine. Despite the insolation, temperatures have been held to the low 30s today thanks to strong cold air advection taking place. The dew point has been dropping all day, from 15 degrees at 7 A.M. to 10 degrees at the 1 P.M. observation. It has dropped further since then now down in the middle single digits. This is an indication of an arctic air mass moving into the region. In addition to the dropping dew point, winds have been gusty today, again due to the cold air advection. Frequent gusts over 25 MPH have been observed today with a peak thus far to 32 MPH.   The high so far today is 33F, 6 degrees below the daily normal high of 39F. The low since midnight is 26F, 2 degrees above 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: Clear, few stratocumulus distant NW-NE-SE-SSW, few cirrus distant S-SW Temperature: 27F; Dew Point: 15F; Relative Humidity: 60% Wind: W at 12G18 kts Sea-level pressure: 30.08 in Hg; rising, then more slowly Visibility: 50 miles 6-hr Max temp: 30F 6-hr Min temp: 26F 24-hr Precip: 0.10 ins. 24-hr Snow: 0.4 ins. Snow Depth: Trace. BHO SA 1155 CLR 50 186/27/15/2812G18/008/ FEW SC DSNT NW-NE-SE-SSW FEW CI DSNT S-SW TOTAL NEW SNW PST 24 HRS 0.4 INS/ 8/501 4/000 51023 70010 10030 20026 10 A.M. Weather: Clear, few stratocumulus distant NW-NE-E, few cirrus SE-SW Temperature: 30F; Dew Point: 11F; Relative Humidity: 45% Wind: W at 12G24 kts, peak wind W 32 MPH at 9:31 A.M.   Sea-level pressure: 30.16 in Hg; rising, then more rapidly Visibility: 70 miles 3-hr Precip: 0.00 ins. 3-hr Snow: 0.0 ins. BHO SA 1455 CLR 70 213/30/11/2812G24/016/ FEW SC DSNT NW-NE-E FEW CI SE-SW PK WND 2828/31/ 8/501 53027 1 P.M. Weather: Thin scattered cirrus, few stratocumulus distant NW-NNW and distant NNE-ESE Temperature: 33F; Dew Point: 10F; Relative Humidity: 38% Wind: WNW at 12G21 kts Sea-level pressure: 30.16 in Hg; falling, then rising Visibility: 70 miles 6-hr Max temp: 33F 6-hr Min temp: 26F 6-hr Precip: 0.00 ins. 6-hr Snow: 0.0 ins. Snow Depth: Trace. BHO SA 1755 250 -SCT 70 213/33/10/2912G21/016/ FEW SC DSNT NW-NNW AND DSNT NNE-ESE/ 8/501 4/000 55000 10033 20026 SUMMARY FOR MONDAY, DECEMBER 14, 2020 TEMPERATURE (DEGREES F) MAX.......35   NORMAL.....40 MIN.......30   NORMAL.....24 MEAN......33   NORMAL.....32 DEPARTURE FROM 30-YEAR NORMAL...................  +1 TOTAL DEPARTURE FOR THE MONTH................... +47 [+3.2 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY...............32  DEPARTURE...... -1 TOTAL HEATING UNITS FOR THE MONTH..............384  DEPARTURE......-48 TOTAL HEATING UNITS FOR THE SEASON............1357  DEPARTURE.....-336 TOTAL HEATING UNITS LAST SEASON TO DATE.......1690  DEPARTURE.....-333 PEAK WIND GUST FOR YESTERDAY (MPH):                      420C/Official..............25 N    AT  9:05 A.M.                      AEROVANE (south tower).....25 N    AT  9:05 A.M.                      ASOS.......................26 NNE  AT  9:07 A.M.                      DAVIS #1...................26 N    AT  9:00 A.M.                      DAVIS #2 (south tower).....24 NNE  AT  8:59 A.M.                      RMY........................29                            VECTOR.....................28                          MERLIN.....................26 FASTEST MILE FOR YESTERDAY: CONTACTING/OFFICIAL.............................18 N   AT   9:00 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE...................18 N   AT   9:00 A.M. MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............18 N   AT   9:00 A.M. MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............19 N   AT   9:00 A.M. AVERAGE WIND SPEED AND DIRECTION:                      CONTACTING/OFFICIAL.... 7.5 NW   [179 total miles]                      ASOS................... 8.1      [194 total miles]                      DAVIS #1............... 8.0 NW   [192 total miles]                      DAVIS #2............... 8.2 NW   [197 total miles]                      RMY.................... 7.9 NW   [190 total miles]                      VECTOR................. 8.1      [194 total miles] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST): TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.......0.10  DEPARTURE....-0.06                              ASOS.............0.11 TOTAL PRECIPITATION FOR THE MONTH.............3.29  DEPARTURE....+0.99                              ASOS.............3.40 TOTAL PRECIPITATION FOR THE YEAR.............49.69  DEPARTURE....-1.14                               ASOS...........50.73 SNOWFALL (INCHES) THROUGH THIS MORNING (EST): TOTAL SNOWFALL 24 HOURS ENDING 7 A.M...........0.4  DEPARTURE..... 0.0 TOTAL SNOWFALL FOR THE MONTH...................3.2  DEPARTURE.....-1.6 TOTAL SNOWFALL FOR THE SEASON..................9.7  DEPARTURE.....+2.3 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 The low since midnight is 26F, the daily normal low is 24F DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): 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 RECORDS FOR DECEMBER 15 HIGH 64 IN 1975 LOW 4 IN 1900, 1905, 1933 PRECIP 1.80 INS. IN 1981 SNOW 7.5 INS. IN 1951 PEAK GUST 65 MPH NW IN 1991 TODAY'S REPORT PREPARED BY: Matt Douglas