BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, DECEMBER 11, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME COLD FRONT MOVES THROUGH OVERNIGHT; MUCH COOLER CONDITIONS TODAY A cold front moved through the area early this morning, shifting the wind direction from SW to WNW, and dropping temperatures significantly. The high temperature for the day of 54F occurred just after midnight, before the cold front came through. Once the front passed, temperatures steadily dropped, reaching the lower 40s around mid-morning. The temperature did manage to warm briefly into the mid 40s this afternoon with the return of some sunshine. With yesterday's very warm conditions, the average temperature for the first 10 days of December is now more than 6 degrees above the 30-year normal. Brief, light rain showers this morning provided another 0.01 inch of precipitation, bringing our total up to 0.99 inch since rain began late on the 7th. Today's observations: 7 A.M. Weather: Scattered stratocumulus, overcast stratocumulus, few small cumulus over city to the N, lower cumulus/stratocumulus layer distant SW-NW, few breaks in overcast distant SE-SSE, light distant haze, rain shower distant W and distant N and distant NE moving ENE Temperature: 43F; Dew Point: 39F; Wind: WNW at 8 kts. Sea-level pressure: 29.73 ins Hg, rising Visibility: 50 miles, light distant haze 6-hour min. temp: 43F 6-hour precip: Trace 24-hour precip: 0.18 in. BHO SA 1155 20 SCT E50 OVC 50 067/43/39/3108/973/ FEW SML CU OVR CTY N LWR CU/SC LYR DSNT SW-NW FEW BINOVC DSNT SE-SSE LGT DSNT HZ SHRA DSNT W AND DSNT N AND DSNT NE MOVG ENE/ 8/8// 53020 MANUAL 6000/ MANUAL 70018 ASOS 70022 10051 20043 10 A.M. Weather: Scattered stratocumulus (2 levels), broken altocumulus, lower stratocumulus distant WSW-NW, higher stratocumulus distant NNE-SSE, few stratocumulus lenticularis and altocumulus lenticularis all quadrants, line of clearing distant WSW-NNW, light distant haze NNE-SSE, mountain NW 65 miles in cloud, rain shower distant NNE-E moving ENE Temperature: 43F; Dew Point: 39F; Wind: WNW at 8 kts, Wind: Direction variable W-NNW Sea-level pressure: 29.83 ins Hg, rising Visibility: 65 miles, lower NNE-SSE, light distant haze NNE-SSE 3-hour precip: 0.01 inch BHO SA 1455 15 SCT 50 SCT E80 BKN 65 102/43/39/3008/983/ LWR SC DSNT WSW-NW HIER SC DSNT NNE-SSE FEW SCSL AND ACSL ALQDS LINE CLRG DSNT WSW-NNW LGT DSNT HZ NNE-SSE VSBY LWR NNE-SSE MTN NW 65 INCLD SHRA DSNT NNE-E MOVG ENE WND 27V34/ 8/840 51035 MANUAL 60001 1 P.M. Weather: Scattered cumulus/stratocumulus, scattered altocumulus, scattered thin cirrus, stratocumulus NW-ENE, few moderate cumulus and stratocumulus tops NW-ESE, few altocumulus lenticularis distant SSE-SW, light distant haze Temperature: 45F; Dew Point: 31F; Wind: W at 13G21 kts, Wind: Direction variable WSW-NW Sea-level pressure: 29.85 ins Hg, rising Visibility: 75 miles, light distant haze 6-hour max. temp: 46F 6-hour precip: 0.01 inch BHO SA 1755 30 SCT 80 SCT 250 –SCT 75 110/45/31/2813G21/985/ SC NNW-ENE FEW MDT CU/SC TOPS NW-ESE FEW ACSL DSNT SSE-SW LGT DSNT HZ WND 25V31/ 8/541 53008 MANUAL 60001 10046 20043 WEATHER SUMMARY FOR MONDAY, DECEMBER 10 TEMPERATURE (DEGREES F) MAX.....59 NORMAL.....41 MIN.....39 NORMAL.....26 MEAN....49 NORMAL.....33 DEPARTURE FROM 30-YEAR NORMAL....................+16 TOTAL DEPARTURE FOR THE MONTH....................+67 [+6.5 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............16 DEPARTURE........-16 TOTAL HEATING UNITS FOR THE MONTH...........234 DEPARTURE........-67 TOTAL HEATING UNITS FOR THE SEASON.........1384 DEPARTURE.......-178 TOTAL HEATING UNITS LAST SEASON TO DATE....1126 DIFFERENCE......+258 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............32 SSW AT 1:10 P.M. AERO....................33 SSW AT 1:10 P.M. ASOS....................32 S AT 1:11 P.M. DAVIS...................34 S AT 1:10 P.M. RMY 35 THE FASTEST MILE FOR YESTERDAY.............24 S AT 2:07 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE..............23 S AT 2:18 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............24 SSW AT 1:10 P.M. AVERAGE WIND SPEED AND DIRECTION.........15.2 SSW ASOS..................14.5 DAVIS.................14.1 S [188 deg] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.18 DEPARTURE..........-0.01 ASOS..............0.22 TOTAL PRECIPITATION FOR THE MONTH..........1.10 DEPARTURE..........-0.55 ASOS..............1.13 TOTAL PRECIPITATION FOR THE YEAR..........35.98 DEPARTURE.........-14.20 ASOS.............36.02 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........0.0 DEPARTURE..........-0.4 TOTAL SNOWFALL FOR THE MONTH...............0.8 DEPARTURE..........-2.4 TOTAL SNOWFALL FOR THE SEASON..............6.8 DEPARTURE..........+1.0 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/.../.. 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/.../.. 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 morning low temp: 43F; the normal low is now 25F 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 11 HIGH 63 IN 1911 LOW -1 IN 1988 PRECIP 2.36 INS. IN 1992 SNOWFALL 6.0 INS. IN 1894 PEAK GUST 78 S IN 1969 RECORDS FOR DECEMBER 12 HIGH 67 IN 1979 LOW -3 IN 1988 PRECIP 3.94 INS. IN 1992 SNOWFALL 20.3 INS. IN 1960 PEAK GUST 75 MPH SSE IN 2008 TODAY'S REPORT PREPARED BY: Sean Fankhauser, Patrick Peters