BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, DECEMBER 21, 2019 ALL TIMES ARE IN EASTERN STANDARD TIME INCREASING CLOUDS AND SLIGHTLY WARMER TODAY... After some filtered sunshine this morning, denser high clouds and some lower clouds have filled the sky by mid-day. The temperature has climbed back to the low 30's for the first time since Wednesday after a chilly start at 16F this morning. Visibility started very good at 70-75 miles in many directions early today, but it has dropped to about 40 miles by afternoon.   Winds have been very light today with a peak gust so far of only 15 mph from the NNW shortly after midnight.   The high so far today is 30F, which is 7 degrees below the daily normal maximum of 37F. The low since midnight is 16F, which is 6 degrees below the normal minimum of 22F. Today's Observations: 7 A.M. Weather: Thin scattered cirrus fibratus, few altocumulus distant NE-S, few lower dense cirrus SE-S Temperature: 17F; Dew Point: 11F; Wind: NNW at 7 kts Sea-level pressure: 30.64 ins. Hg, falling then rising now higher Visibility: 75 miles 6-hr Max temp: 18F 6-hr Min temp: 16F 24-hr Precip:  0.00 ins. 24-hr Snowfall: 0.0 ins. Snow Depth: Trace BHO SA 1155 E250 SCT 75 375/17/11/3407/064/ FEW AC DSNT NE-S FEW LWR DNS CI SE-S/ 8/071 53002 10018 20016 10 A.M. Weather: Scattered stratocumulus, overcast cirrostratus and cirrus fibratus, few altocumulus, few lower dense cirrus SE-S, breaks in overcast distant NNW-N, thin spots in overcast all quadrants, partial halo Temperature: 26F; Dew Point: 13F; Wind: calm at 0 kts, Sea-level pressure: 30.65 ins. Hg, rising slowly Visibility: 70 miles 3-hr Precip:  0.00 ins. 3-hr Snowfall: 0.0 ins. BHO SA 1455 10 SCT 250 OVC 70 380/26/13/0000/065/ FEW AC FEW LWR DNS CI SE-S BINOVC DSNT NNW-N THN SPTS IOVC ALQDS PARTIAL HALO VSBY NE-ENE 55/ 8/577 53005 1 P.M. Weather: Scattered stratocumulus, broken cirrostratus, overcast cirrus fibratus, few altocumulus, thin spots in overcast, sun dimly visible Temperature: 30F; Dew Point: 22F; Wind: S at 5 kts, Wind: Light Sea-level pressure: 30.57 ins. Hg, falling then more quickly Visibility: 40 miles 6-hr Max temp: 30F 6-hr Min temp: 17F 6-hr Precip:  0.00 ins. 6-hr Snowfall: 0.0 ins. Snow Depth: Trace BHO SA 1755 25 SCT 200 BKN 230 OVC 40 353/30/22/1705/057/ FEW AC FEW THN SPTS IOVC SUN DMLY VSBL WND LGT/ 8/578 58027 10030 20017 SUMMARY FOR FRIDAY, DECEMBER 20, 2019 TEMPERATURE (DEGREES F) MAX.....29   NORMAL.....38 MIN.....11   NORMAL.....22 MEAN....20   NORMAL.....30 DEPARTURE FROM 30-YEAR NORMAL.....................-10 TOTAL DEPARTURE FOR THE MONTH.....................-51 [-2.8 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY...............45  DEPARTURE.......+10 TOTAL HEATING UNITS FOR THE MONTH..............687  DEPARTURE.......+49 TOTAL HEATING UNITS FOR THE SEASON............1924  DEPARTURE.......+24 TOTAL HEATING UNITS LAST SEASON TO DATE.......1975  DEPARTURE.......-51 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY....................32 W   AT 3:34 A.M.                      AERO.........................30 W   AT 3:34 A.M.                      ASOS.........................33 W   AT 3:34 A.M.                    DAVIS........................33 W   AT 3:31 A.M. RMY N/A FASTEST MILE FOR YESTERDAY......................23 NW  AT 9:20 A.M. * MAXIMUM 2-MINUTE ASOS AVERAGE...................22 NW  AT 9:22 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..................23 WNW AT 3:58 A.M. AVERAGE WIND SPEED AND DIRECTION..............13.3 NW                                      ASOS.......................13.2                    DAVIS......................13.6 NW  [308 deg.] * Last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.16                          ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........6.06  DEPARTURE......+2.82                          ASOS..............6.51 TOTAL PRECIPITATION FOR THE YEAR..........55.14  DEPARTURE......+3.36                          ASOS.............55.91 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.......-0.6 TOTAL SNOWFALL FOR THE MONTH...............19.1  DEPARTURE......+11.3 TOTAL SNOWFALL FOR THE SEASON..............19.2  DEPARTURE.......+8.8 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 12/20  29/11/20/-10/0.00/0.0/..../..          32 W   AERO 30 W   RMY 29 12/21 The low since midnight is 16F, daily normal minimum is 22F 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 21 HIGH 60 IN 1957 LOW -10 IN 1942 PRECIP 2.01 INS. IN 1946 SNOWFALL 11.4 INS. IN 1954 PEAK GUST 77 MPH SSE IN 1957 RECORDS FOR DECEMBER 22 HIGH 63 IN 2013 LOW -5 IN 1921 PRECIP 1.52 INS. IN 1975 SNOWFALL 8.8 INS. IN 1975 PEAK GUST 62 MPH WNW IN 1998 TODAY'S REPORT PREPARED BY: Mike Iacono