BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, DECEMBER 30, 2018  ALL TIMES ARE IN EASTERN STANDARD TIME ALTOCUMULUS CLEARS AS TEMPERATURES RETURN TO SEASONAL NORMS.... Despite a near overcast layer of altocumulus at the time of the 10 A.M. observation, skies have cleared significantly, baring excellent visibility of up to 70 miles for the 10 A.M. and 1 P.M. observations.  Temperatures have dropped substantially following two days of exceptionally warm December days.  This plunge has returned readings to the proximity of what we expect this time of year.  The past two days have led to complete thawing of both Houghton's and Ponkapoag Ponds, with no signs of refreezing so far today.  With small chances of snow in today's forecast, no snowfall was observed on the hill, but a small shower was observed to the SE in the form of virga during the 10 A.M. observation. Winds have been noticeably very calm, especially towards the end of the morning and into the early afternoon, where wind speeds reached zero at different points.  Coupled  with the lack of wind today, there has been a marked shift in wind direction, with the late morning hours seeing the end of the prevailing north-westerlies that dominated yesterday's wind charts.     Today's Observations: 7 A.M. Weather: Scattered altocumulus, scattered altostratus Temperature: 23F; Dew Point: 11F; Wind: NNW at 4 kts     Sea-level pressure: 30.21 ins. Hg, steady, then increasing more rapidly       Visibility: 40 miles  6-hr Max temp: 27F 6-hr Min temp: 23F 24-hr Precip: 0.00 ins. 24-hr snowfall: 0.0 ins. Snow depth: 0 ins.  BHO SA 1155 E140 SCT 40 230/23/11/3404/021/ WND LGT/ 8/070 53020 10027 20023 10 A.M. Weather: Broken altocumulus, few lower altocumulus, virga SE Temperature: 26F; Dew Point: 14F; Wind: WSW at 2 kts (estimated) Sea-level pressure: 30.23 ins. Hg, increasing, then decreasing  Visibility: 70 miles 3-hr Precip: 0.00 ins.  BHO SA 1455 E100 BKN 70 238/26/14/E2802/023/ WND LGT FEW AC VIRGA SE/ 8/070 50008 1 P.M. Weather: Few distant altocumulus in all directions Temperature: 31F; Dew Point: 10F; Wind: WNW at 4 kts     Sea-level pressure: 30.17 ins. Hg, decreasing then decreasing more slowly       Visibility: 70 mileS  6-hr Max temp: 32F 6-hr Min temp: 22F 6-hr Precip: 0.00 ins. 6-hr snowfall: 0.0 ins.   Snow depth: 0 ins. BHO SA 1755 CLR 70 217/31/10/2904/017/ WND LGT FEW DSNT AC ALQDS/ 8/050 56021 10032 20022 SUMMARY FOR SATURDAY, DECEMBER 29, 2018  TEMPERATURE (DEGREES F) MAX.....54   NORMAL.....35 MIN.....30   NORMAL.....20 MEAN....42   NORMAL.....27 DEPARTURE FROM 30-YEAR NORMAL.......................+15 TOTAL DEPARTURE FOR THE MONTH.......................+56 [+1.8 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY..............23   DEPARTURE........-15 TOTAL HEATING UNITS FOR THE MONTH.............909   DEPARTURE........-58 TOTAL HEATING UNITS FOR THE SEASON...........2229   DEPARTURE..........0 TOTAL HEATING UNITS LAST SEASON TO DATE......2005   DIFFERENCE......+224 PEAK GUST AND AVERAGE WIND SPEED (MPH)  PEAK WIND GUST FOR YESTERDAY....................38 WNW AT 3:26 P.M.                    AERO.........................38 WNW AT 3:24 P.M.                    ASOS.........................40 W   AT 3:27 P.M.                     DAVIS........................40 WNW AT 3:27 P.M. RMY 38 FASTEST MILE FOR YESTERDAY......................30 WNW AT 2:02 P.M.  MAXIMUM 2-MINUTE ASOS AVERAGE...................28 W   AT 1:34 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..................30 W   AT 1:34 P.M. AVERAGE WIND SPEED AND DIRECTION..............16.2 WNW                    ASOS.......................15.4                    DAVIS......................16.2 WNW [286 deg.]    PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE.......-0.14                          ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........3.55  DEPARTURE.......-1.06                          ASOS..............4.22 * TOTAL PRECIPITATION FOR THE YEAR..........66.92  DEPARTURE......+13.97                          ASOS.............69.85 * * ASOS MONTHLY AND ANNUAL PRECIPITATION IS SUSPECT SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE........-0.5 TOTAL SNOWFALL FOR THE MONTH................0.1  DEPARTURE.......-12.2 TOTAL SNOWFALL FOR THE SEASON...............7.7  DEPARTURE........-7.2 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 41/28/35/-2/0.00/0.0/391/70          20 NNW AERO 18 NNW RMY N/A 12/02 52/35/44/+8/1.04/0.0/000/00          28 ESE AERO 25 ESE RMY 27 12/03 54/38/46/+10/0.00/0.0/178/32         35 W   AERO 35 W   RMY 38  12/04 38/23/31/-4/0.00/0.0/516/93          30 WNW AERO 31 WNW RMY 33 12/05 33/18/26/-9/0.00/0.0/432/78          16 NNW AERO 15 NNW RMY N/A 12/06 37/24/31/-4/0.00/0.0/354/64          29 W   AERO 28 W   RMY 30 12/07 37/21/29/-5/0.00/0.0/546/99          29 NW  AERO 29 NW  RMY 32 12/08 27/15/21/-13/0.00/0.0/518/94         28 NW  AERO 27 NW  RMY 29 12/09 34/17/26/-8/0.00/0.0/391/71          23 SSW AERO 21 SSW RMY 22 12/10 36/22/29/-4/0.00/0.0/544/99          24 NNW AERO 23 NNW RMY 22 12/11 36/17/27/-6/0.00/0.0/543/99          16 WSW AERO 14 WSW RMY N/A 12/12 35/18/27/-6/0.00/0.0/471/86          30 NW  AERO 29 NW  RMY M 12/13 31/16/24/-8/0.00/0.0/088/16          16 NNE AERO 12 SE  RMY N/A 12/14 46/28/37/+5/0.00/0.0/399/73          28 SSW AERO 28 SSW RMY 29 12/15 49/33/43/+11/0.04/0.0/000/00         28 NE  AERO 27 NE  RMY 30 12/16 40/37/39/+8/..../0.0/.../..          38 NE  AERO 38 NE  RMY 40 12/17 37/32/35/+4/..../0.0/.../..          39 NNE AERO 37 NNE RMY N/A 12/18 34/20/27/-4/0.02/0.1/.../..          48 NW  AERO 55 NW  RMY 48 12/19 38/17/28/-2/0.00/0.0/.../..          23 WNW AERO 23 WNW RMY N/A 12/20 47/30/39/+9/0.00/0.0/.../..          23 SW  AERO 22 SW  RMY N/A 12/21 62/43/53/+23/..../0.0/.../..         60 SSE AERO 62 SSE RMY 63 12/22 54/31/43/+14/..../0.0/.../..         41 W   AERO 45 W   RMY 43 12/23 38/27/33/+4/0.00/0.0/.../..          30 WNW AERO 32 WNW RMY N/A 12/24 34/27/31/+2/0.01/T/.../..            21 W   AERO 21 W   RMY N/A 12/25 35/23/29/+1/0.00/0.0/.../..          28 NW  AERO 28 NW  RMY 29 12/26 36/20/28/0/0.00/0.0/.../..           24 NW  AERO 24 NW  RMY 25 12/27 35/26/31/+3/0.00/0.0/.../..          23 NW  AERO 22 NW  RMY N/A 12/28 54/30/42/+14/..../0.0/.../.. 44 SSW AERO M  M   RMY 47 12/29 54/30/42/+15/..../0.0/.../..         38 WNW AERO 38 WNW RMY 38 12/30 Low temp since midnight is 23F; normal low is 19F DAILY RECORDS FOR DECEMBER 2018 12/21/18: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 62F,           BREAKS PREVIOUS RECORD OF 60F SET IN 1957 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR DECEMBER 30 HIGH 60 IN 1984 LOW -18 IN 1933 PRECIP 1.48 INS. IN 1891 SNOWFALL 7.5 INS. IN 1956 PEAK GUST 81 MPH WNW IN 1962 RECORDS FOR DECEMBER 31 HIGH 62 IN 1965 LOW -12 IN 1917 PRECIP 0.96 INS. IN 1906 SNOWFALL 7.5 INS. IN 2008 PEAK GUST 78 MPH NW IN 1990 TODAY'S REPORT PREPARED BY: Nate Iannuccillo