BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, DECEMBER 18, 2018  ALL TIMES ARE IN EASTERN STANDARD TIME A COOL DECEMBER DAY DOMINATED BY DRY AIR,  STRONG NORTHWESTERLY WINDS, AND INCREASING  PRESSURE.... Today started of almost overcast, but cleared up as pressure increased almost 7 millibars since this morning. Strong  northwest winds persisted throughout the day, frequently  reaching speeds above 30 mph. The highest gust of 48 mph  occurred around 4 A.M. today. Humidity was at or below 50% following 9 A.M., allowing 70 miles of visibility at the  10 A.M. and 1 P.M. observations. Snowfall this morning  amounted to a 1/10th of an inch. The high temperature so far today is 29F, which is 9 degrees below the daily normal maximum of 38F. The low since midnight is 20F, 3 degrees under the normal minimum of 23F.   Today's Observations: 7 A.M. Weather: Broken altostratus and cirrostratus Temperature: 20F; Dew Point: 10F; Wind: NW at 18G31 kts, Peak wind: 39 mph (34 kts) NW at 6:05 A.M.    Sea-level pressure: 29.73 ins. Hg, rising rapidly        Visibility: 45 miles  6-hr Max temp: 34F 6-hr Min temp: 20F 24-hr Precip: 0.02 ins. 24-hr snowfall: 0.0 ins. Snow depth: 0 ins.    BHO SA 1155 E90 BKN 250 BKN 45 067/20/10/3118G31/973/ FEW CU ALQDS PK WND 3134/05/ 8/128 70002 53031 10034 20020  10 A.M. Weather: Broken altocumulus   Temperature: 25F; Dew Point: 11F; Wind: NW at 22G32 kts, Peak wind: 41 mph (36 kts) NW at 9:33 A.M.     Sea-level pressure: 29.81 ins. Hg, rising rapidly Visibility: 70 miles 3-hr Precip: 0.00 ins.  BHO SA 1455 E110 BKN 70 096/25/11/3122G36/981/  PK WND 3136/33/ 8/070 51029 1 P.M. Weather: Clear, few distant cumulus    Temperature: 29F; Dew Point: 12F; Wind: NW at 22G32 kts, Peak wind: 37 mph (32 kts) NW at 12:55 P.M.      Sea-level pressure: 29.83 ins. Hg, rising steadily       Visibility: 70 miles 6-hr Max temp: 29F 6-hr Min temp: 21F 6-hr Precip: 0.00 ins. 6-hr snowfall: 0.0 ins. Snow depth: 0 ins.    BHO SA 1755 CLR 70 103/29/12/3122G32/983/ FEW DSNT CU ALQDS PK WND 3132/55/ 8/100 53007 10029 30021   SUMMARY FOR MONDAY, DECEMBER 17, 2018  TEMPERATURE (DEGREES F) MAX.....37   NORMAL.....39 MIN.....32   NORMAL.....23 MEAN....35   NORMAL.....31 DEPARTURE FROM 30-YEAR NORMAL........................+4 TOTAL DEPARTURE FOR THE MONTH.......................-23 [-1.2 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY..............30   DEPARTURE.........-4 TOTAL HEATING UNITS FOR THE MONTH.............555   DEPARTURE........+22 TOTAL HEATING UNITS FOR THE SEASON...........1875   DEPARTURE........+80 TOTAL HEATING UNITS LAST SEASON TO DATE......1517   DIFFERENCE......+358 PEAK GUST AND AVERAGE WIND SPEED (MPH)  PEAK WIND GUST FOR YESTERDAY....................39 NNE AT 12:05 A.M.                    AERO.........................37 NNE AT 12:05 A.M.                     ASOS.........................41 NE  AT 12:08 A.M.                     DAVIS........................39 ENE AT 12:07 A.M. RMY N/A FASTEST MILE FOR YESTERDAY......................26 NNE AT 12:06 A.M.  MAXIMUM 2-MINUTE ASOS AVERAGE...................26 NE  AT 12:08 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..................27 NE  AT 12:08 A.M. AVERAGE WIND SPEED AND DIRECTION..............15.2 WNW                    ASOS.......................14.6                    DAVIS......................15.2 NW [324 deg.]    PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02  DEPARTURE.......-0.13                          ASOS..............0.02 TOTAL PRECIPITATION FOR THE MONTH..........1.95  DEPARTURE.......-0.82                          ASOS..............2.68 * TOTAL PRECIPITATION FOR THE YEAR..........65.32  DEPARTURE......+14.21                          ASOS.............68.31 * * ASOS MONTHLY AND ANNUAL PRECIPITATION IS SUSPECT SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.1  DEPARTURE........-0.4 TOTAL SNOWFALL FOR THE MONTH................0.1  DEPARTURE........-6.2 TOTAL SNOWFALL FOR THE SEASON...............7.7  DEPARTURE........-1.2 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/.../..          29 NW  AERO 29 NW  RMY 32 12/08 27/15/21/-13/0.00/0.0/.../..         28 NW  AERO 27 NW  RMY 29 12/09 34/17/26/-8/0.00/0.0/.../..          23 SSW AERO 21 SSW RMY 22 12/10 36/22/29/-4/0.00/0.0/.../..          24 NNW AERO 23 NNW RMY 22 12/11 36/17/27/-6/0.00/0.0/.../..          16 WSW AERO 14 WSW RMY N/A 12/12 35/18/27/-6/0.00/0.0/.../..          30 NW  AERO 29 NW  RMY M 12/13 31/16/24/-8/0.00/0.0/.../..          16 NNE AERO 12 SE  RMY N/A 12/14 46/28/37/+5/0.00/0.0/.../..          28 SSW AERO 28 SSW RMY 29 12/15 49/33/43/+11/..../.../.../..         28 NE  AERO 27 NE  RMY 30 12/16 40/37/39/+8/..../.../.../..          38 NE  AERO 38 NE  RMY 40 12/17 37/32/35/+4/..../.../.../..          39 NNE AERO 37 NNE RMY N/A 12/18 Low temp since midnight is 20F; normal low is 23F 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: Benjamin Turner