BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY MONDAY, DECEMBER 17, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME PRECIPITATION BEGAN AS SOME LIGHT SNOW SUNDAY A CHANGE TO LIGHT FREEZING RAIN TOOK PLACE NON-FREEZING RAIN WAS OCCURRING LAST EVENING CONTINUED LIGHT RAIN AND DRIZZLE TODAY An estimated 0.1 inch of snow fell Sunday mid to late afternoon before precipitation changed to some freezing before finally changing to all rain. There was likely a short period of glaze here at the summit during mid to late afternoon. Light rain and some drizzle continued throughout last night as temperatures rose to 36F by midnight and then the low 40's during this morning. Total precipitation was just short of a half inch at 7 A.M. and 0.56 inch by 10 A.M. The event total precipitation through 1 P.M. was 0.65 inch. The year of 2012 had reached a precipitation deficit of 15 ins. yesterday but precipitation is gradually and slightly reducing that large deficit today. Today's observations: 7 A.M. Weather: Partial obscurement with 5/10 fog and low overcast of stratus fractus, stratus fractus drifting over the summit Temperature: 39F; Dew Point: 39F; Wind: ENE at 12 kts Sea-level pressure: 30.00 ins Hg, falling then rising slightly Visibility: 1 mile, variable 1/2 to 11/2 miles 6-hour min. temp: 37F 24-hour precip: 0.47 inch 24-hour snowfall: 0.1 inch BHO SA 1155 –X E4 OVC 1VR-F 158/39/39/0712/000/ F5 STRA DRFTG OVR SMT VSBY 1/2V11/2 VSBY NE 1/8 SW 11/2/ 8/7// 55003 ASOS 60019 MANUAL 6XXX/ MANUAL 70047 ASOS 70046 10039 20037 10 A.M. Weather: Obscurement with fog, light rain and light drizzle, fog Temperature: 41F; Dew Point: 41F; Wind: ENE at 14G24 kts, Sea-level pressure: 29.97 ins Hg, falling then more slowly Visibility: 1/8 mile, light rain, drizzle and fog 3-hour precip: 0.10 inch BHO SA 1455 W3 X 1/8R-L-F 149/41/41/0614G24/997/ 8//// 56009 ASOS 60010 MANUAL 6010/ 1 P.M. Weather: Obscurement with fog, light drizzle, occasionally moderate drizzle past hour Temperature: 43F; Dew Point: 43F; Wind: ENE at 11 kts, Direction: variable N-E Sea-level pressure: 29.93 ins Hg, falling then more rapidly Visibility: 1/8 mile, light drizzle and fog 6-hour max. temp: 43F 6-hour min. temp: 39F 6-hour precip: 0.18 inch BHO SA 1755 W3 X 1/8L-F 137/43/43/0711/993/ L- OCNL L PST HR WND 01V09/ 8//// 58012 ASOS 60019 MANUAL 6018/ 10043 20039 WEATHER SUMMARY FOR SUNDAY, DECEMBER 16 TEMPERATURE (DEGREES F) MAX.....36 NORMAL.....39 MIN.....31 NORMAL.....24 MEAN....34 NORMAL.....31 DEPARTURE FROM 30-YEAR NORMAL.....................+3 TOTAL DEPARTURE FOR THE MONTH....................+92 [+5.6 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............31 DEPARTURE.........-3 TOTAL HEATING UNITS FOR THE MONTH...........406 DEPARTURE........-93 TOTAL HEATING UNITS FOR THE SEASON.........1556 DEPARTURE.......-205 TOTAL HEATING UNITS LAST SEASON TO DATE....1288 DIFFERENCE......+268 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............25 E AT 1:40 P.M. AERO....................22 E AT 7:14 P.M. * ASOS....................23 ENE AT 11:59 P.M. DAVIS...................22 E AT 1:40 P.M. RMY N/A THE FASTEST MILE FOR YESTERDAY.............18 ESE AT 6:33 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE..............17 E AT 11:55 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............17 E AT 6:32 P.M. AVERAGE WIND SPEED AND DIRECTION.........11.3 E ASOS..................11.0 DAVIS.................10.1 E [100 deg.] * last of several occurrences.... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.47 DEPARTURE..........+0.31 ASOS..............0.46 TOTAL PRECIPITATION FOR THE MONTH..........1.58 DEPARTURE..........-1.04 ASOS..............1.59 TOTAL PRECIPITATION FOR THE YEAR..........36.46 DEPARTURE.........-14.69 ASOS.............36.48 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........0.1 DEPARTURE..........-0.4 TOTAL SNOWFALL FOR THE MONTH...............0.9 DEPARTURE..........-4.9 TOTAL SNOWFALL FOR THE SEASON..............6.9 DEPARTURE..........-1.5 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/..../0.1/.../.. 25 E AERO 22 MPH E RMY N/A 12/17 morning low temp: 36F; 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 17 HIGH 63 IN 2000 LOW -10 IN 1942 PRECIP 3.03 INS. IN 1888 SNOWFALL 7.5 INS. IN 1988 PEAK GUST 78 MPH SSE IN 2000 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 TODAY'S REPORT PREPARED BY: Robert Skilling, Patrick Peters