BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, DECEMBER 18, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME 3-DAY PRECIPITATION TOTAL REACHES 1.51 INCHES; SUMMIT SHROUDED IN DENSE FOG TODAY WITH VERY MILD TEMPERATURES Light to moderate rain fell overnight, ending around mid morning today. The precipitation total since Sunday afternoon has reached 1.51 inches. The precipitation was much needed and fell fairly steadily over the past 3 days. In fact, measurable precipitation fell for 44 consecutive hours, ending at 10 AM this morning. Light drizzle has been falling since then. Despite a brief period this morning of partial undercast with some partial clearing overhead, much of the day has seen the summit shrouded in dense fog. Visibility is near zero this afternoon. Temperatures are very warm, but still several degrees off of record high temperatures. The afternoon high has reached 50F! The low for the day thus far of 44F is likely to be pushed lower before the day ends as a cooler air mass is expected to begin filtering in later tonight. The month of December continues to run nearly 6 degrees above average! Today's observations: 7 A.M. Weather: Sky obscured by light rain and fog, light drizzle becoming light rain at unknown time, briefly moderate rain, light rain continued Temperature: 46F; Dew Point: 46F; Wind: E at 12G21 kts, Wind: Direction variable ENE-SE Sea-level pressure: 29.54 ins. Hg, falling then rising slightly Visibility: 3/4 mile, light rain and dense fog 6-hour precip: 0.38 inch 24-hour precip: 0.86 inch 6-hour min. temp: 44F BHO SA 1155 W4 X 3/4R-F 003/46/46/1012G21/954/ L-BCMG R-UKN BRFLY R R- CTD WND 07V13/ 8//// 55034 MANUAL 60038 ASOS 60038 MANUAL 70086 ASOS 70088 10046 20044 10 A.M. Weather: Sky obscured by light drizzle and fog, stratus drifting over summit, light rain shower began at 9:01 AM and ended at unknown time, light drizzle began at unknown time with occasional moderate drizzle, light drizzle continued Temperature: 49F; Dew Point: 49F; Wind: ESE at 5 kts. Sea-level pressure: 29.48 ins. Hg, falling Visibility: 3/4 mile, light drizzle and fog 3-hour precip: 0.17 inch BHO SA 1455 W4 X 3/4L-F 983/49/49/1205/948/ STRA DRFTG OVR SMT RW-B01 EUKN L-BUKN OCNL L L-CTD/ 8//// 57020 MANUAL 60017 ASOS 60019 1 P.M. Weather: Sky obscured by light drizzle and dense fog, stratus drifting over summit, light drizzle becoming very light at unknown time, light drizzle continued Temperature: 49F; Dew Point: 49F; Wind: W at 4 kts, Direction: Light, and direction gradually backing (counterclockise) over the past hour Sea-level pressure: 29.41 ins Hg, falling then more rapidly Visibility: 1/8 mile, light drizzle and dense fog 6-hour precip: 0.18 inch 6-hour max. temp: 50F BHO SA 1755 W3 X 1/8L-F 958/49/49/2804/941/ STRA DRFTG OVR SMT WND GRDLY BACKING PST HR WND LGT L- BCMG VRY LGT UKN L- CTD WND/ 8//// 58025 MANUAL 60018 ASOS 60020 10050 20046 WEATHER SUMMARY FOR MONDAY, DECEMBER 17 TEMPERATURE (DEGREES F) MAX.....44 NORMAL.....39 MIN.....36 NORMAL.....23 MEAN....40 NORMAL.....31 DEPARTURE FROM 30-YEAR NORMAL.....................+9 TOTAL DEPARTURE FOR THE MONTH...................+101 [+5.7 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............25 DEPARTURE.........-9 TOTAL HEATING UNITS FOR THE MONTH...........431 DEPARTURE.......-103 TOTAL HEATING UNITS FOR THE SEASON.........1581 DEPARTURE.......-214 TOTAL HEATING UNITS LAST SEASON TO DATE....1320 DIFFERENCE......+261 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............31 ENE AT 10:16 A.M. * AERO....................29 ENE AT 10:17 A.M. * ASOS....................31 ENE AT 10:46 A.M. DAVIS...................29 NE AT 4:13 A.M. RMY 30 THE FASTEST MILE FOR YESTERDAY.............24 ENE AT 10:15 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE..............22 ENE AT 10:17 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............21 ENE AT 10:16 A.M. AVERAGE WIND SPEED AND DIRECTION.........13.6 ENE ASOS..................13.0 DAVIS.................12.1 ENE [063 deg.] * last of several occurrences.... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.86 DEPARTURE..........+0.71 ASOS..............0.88 TOTAL PRECIPITATION FOR THE MONTH..........2.44 DEPARTURE..........-0.33 ASOS..............2.47 TOTAL PRECIPITATION FOR THE YEAR..........37.32 DEPARTURE.........-13.98 ASOS.............37.36 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........0.0 DEPARTURE..........-0.5 TOTAL SNOWFALL FOR THE MONTH...............0.9 DEPARTURE..........-5.4 TOTAL SNOWFALL FOR THE SEASON..............6.9 DEPARTURE..........-2.0 PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 2012 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust RMY: RMY = R.M. Young wind gust recording system added 8/9/2011 TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 12/1 34/25/30/-7/0.08/0.8/000/00 16 E AERO 14 MPH E RMY 16 12/2 52/32/42/+6/0.00/0.0/006/01 32 SSW AERO 32 MPH SSW RMY 34 12/3 57/43/50/+14/0.00/0.0/523/94 31 NW AERO 30 MPH NW RMY 32 12/4 56/40/48/+13/0.03/0.0/000/00 37 S AERO 39 MPH S RMY 38 12/5 56/31/44/+9/0.03/0.0/310/56 38 WNW AERO 37 MPH WNW RMY 40 12/6 38/25/32/-3/0.00/0.0/519/94 31 NW AERO 30 MPH NW RMY N/A 12/7 42/30/36/+2/0.02/0.0/000/00 18 SSW AERO 16 MPH SSW RMY 18 12/8 45/41/43/+9/0.35/0.0/000/00 21 ENE AERO 18 MPH ENE RMY N/A 12/9 45/38/42/+8/0.10/0.0/181/33 24 NNW AERO 24 MPH NNW RMY 25 12/10 59/39/49/+16/0.51/0.0/000/00 32 SSW AERO 33 MPH SSW RMY 35 12/11 54/30/42/+9/0.01/0.0/351/64 25 W AERO 25 MPH W RMY 23 12/12 38/26/32/-1/0.00/0.0/.../.. 20 NW AERO 18 MPH NW RMY N/A 12/13 42/29/36/+4/0.00/0.0/.../.. 18 NW AERO 15 MPH NW RMY N/A 12/14 47/29/38/+6/0.00/0.0/.../.. 28 W AERO 25 MPH W RMY 27 12/15 40/31/36/+4/0.00/0.0/.../.. 24 NNW AERO 22 MPH NNW RMY 21 12/16 36/31/34/+3/0.25/0.1/.../.. 25 E AERO 22 MPH E RMY N/A 12/17 44/36/40/+9/0.65/0.0/000/00 31 ENE AERO 29 MPH ENE RMY 30 12/18 morning low temp since midnight: 44F; the normal low is now 23F DAILY RECORDS FOR DECEMBER 2012 None so far. 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: Sean Fankhauser