BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, DECEMBER 15, 2018 ALL TIMES ARE IN EASTERN STANDARD TIME WARM DECEMBER DAY WITH MORNING FOG... Yesterday's shift to southerly winds helped usher in a mass of warm air that has swiftly brought temperatures high above seasonal values. With the month of December starting off cold and dry, today's weather proved to be anomalous, with a high temperature of 50 F reached by the 1 P.M. observation. The Great Blue Hill spent most of its morning encapsulated by fog before the fog lifted in the afternoon. Light rain and drizzle were also observed this morning, with a rainfall total of 0.06 ins. accumulated throughout this duration. As fog cleared off the hill, a marked shift in both wind speed and direction were observed, with magnitudes approaching zero at times, and direction trending northwesterly; this change should inhibit any further advective warming. By 1 P.M., skies remain near overcast with pressure readings still trending towards relatively low values. Today's Observations: 7 A.M. Weather: Light rain, light drizzle, fog Temperature: 45F; Dew Point: 45F; Wind: WSW at 10G17 kts Sea-level pressure: 30.18 ins. Hg, rising slowly Visibility: 1/16 mile 6-hr Max temp: 45F 6-hr Min temp: 43F 24-hr Precip: 0.02 ins. 24-hr snowfall: 0.0 ins. Snow depth: 0 ins. BHO SA 1155 W2 X 1/16R-L-F 221/45/45/2510G17/018/ 8//// 53003 6002/ 70002 10045 20043 10 A.M. Weather: Sky obscured in dense fog Temperature: 45F; Dew Point: 45F; Wind: WSW at 5 kts, Wind: Light Sea-level pressure: 30.21 ins. Hg, rising steadily Visibility: 1/16 mile 3-hr Precip: 0.04 ins. BHO SA 1455 W2 X 1/16F 230/45/45/2405/021/ WND LGT/ 8//// 52009 6004/ 1 P.M. Weather: Broken altocumulus, overcast cirrostratus, few lower altocumulus, hazy, sun dimly visible Temperature: 49F; Dew Point: 45F; Wind: NW at 3 kts, Wind: Light Sea-level pressure: 30.14 ins. Hg, falling quickly then more slowly Visibility: 45 miles, 35 miles NE-E, 65 miles WNW-NW 6-hr Max temp: 50F 6-hr Min temp: 45F 6-hr Precip: 0.04 ins. 6-hr snowfall: 0.0 ins. Snow depth: 0 ins. BHO SA 1755 E70 BKN 200 OVC 45 208/49/45/3103/014/ FEW LWR AC BINOVC NW-NE VSBY NE-E 35 WNW-NW 65 HAZY SUN DMLY VSBL WND LGT/ 8070/ 56022 6004/ 10050 20045 SUMMARY FOR FRIDAY, DECEMBER 14, 2018 TEMPERATURE (DEGREES F) MAX.....46 NORMAL.....40 MIN.....28 NORMAL.....24 MEAN....37 NORMAL.....32 DEPARTURE FROM 30-YEAR NORMAL........................+5 TOTAL DEPARTURE FOR THE MONTH.......................-46 [-3.5 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY..............28 DEPARTURE.........-5 TOTAL HEATING UNITS FOR THE MONTH.............477 DEPARTURE........+45 TOTAL HEATING UNITS FOR THE SEASON...........1797 DEPARTURE.......+104 TOTAL HEATING UNITS LAST SEASON TO DATE......1386 DIFFERENCE......+411 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY....................28 SSW AT 10:13 P.M. AERO.........................28 SSW AT 10:11 P.M. ASOS.........................28 S AT 10:16 P.M. DAVIS........................26 SSW AT 10:15 P.M. RMY 29 FASTEST MILE FOR YESTERDAY......................21 SSW AT 10:08 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE...................22 S AT 10:16 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..................20 SSW AT 10:16 P.M. AVERAGE WIND SPEED AND DIRECTION..............10.9 S ASOS.......................11.1 DAVIS......................10.6 S [186 deg.] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02 DEPARTURE.......-0.14 ASOS..............0.01 TOTAL PRECIPITATION FOR THE MONTH..........1.06 DEPARTURE.......-1.24 ASOS..............1.79 * TOTAL PRECIPITATION FOR THE YEAR..........64.43 DEPARTURE......+13.79 ASOS.............67.42 * * ASOS MONTHLY AND ANNUAL PRECIPITATION IS SUSPECT SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE........-0.4 TOTAL SNOWFALL FOR THE MONTH................0.0 DEPARTURE........-4.9 TOTAL SNOWFALL FOR THE SEASON...............7.6 DEPARTURE........+0.1 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 Low temp since midnight is 42F; normal low is 24F DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): 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 RECORDS FOR DECEMBER 16 HIGH 61 IN 1971 LOW -2 IN 1930 PRECIP 1.67 INS. IN 1960 SNOW 8.5 INS. IN 2007 WIND 73 MPH SSE IN 1982 TODAY'S REPORT PREPARED BY: Nate Iannuccillo