BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, DECEMBER 5, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME DEVELOPING COASTAL STORM BRINGING LIGHT RAIN AND INCREASING WINDS...SNOWFALL POSSIBLE LATER THIS EVENING... The sun was dimly visible for a few minutes through an altostratus overcast early this morning, but lower clouds and light rain have moved in at mid-day. Light rain began at 9:40 AM, and it has continued since that time. A total of 0.05 inch has fallen in the six hours ending at 1 PM. As heavier precipitation moves in later today, the rain may change to a period of snow this evening with several inches of accumulation expected. Light winds earlier began increasing before noon, and the peak gust for the day is 33 mph NNE at 2:24 PM. The temperature has dropped from an early morning high of 42 to a low for the day so far of 38 as of early afternoon. Today's observations: 7 A.M. Weather: Scattered altocumulus, overcast altostratus Temperature: 42F, Dew point: 31F, Wind: NNE at 8 kts Sea-level pressure: 30.15 inches Hg, rising Visibility: 50 miles 6-hour minimum temp: 41F 24-hour precipitation: 0.00 in. BHO SA 1155 65 SCT E80 OVC 50 210/42/31/0208/015/ THN K LYR ALG HRZN S-NW WND LGT/ 8/07/ 55000 10042 20041 10 A.M. Weather: Scattered stratocumulus, overcast nimbostratus, light rain Temperature: 41F, Dew point: 33F, Wind: NNE at 8 kts Sea-level pressure: 30.11 inches Hg, falling Visibility: 35 miles 3-hour precipitation: trace BHO SA 1455 25 SCT E45 OVC 35R- 198/41/33/0208/011/ R-B40 WND LGT/ 8/52/ 56012 6000/ 1 P.M. Weather: Broken stratocumulus, overcast nimbostratus, light rain Temperature: 40F, Dew point: 39F, Wind: NNE at 15G22 kts, Sea-level pressure: 29.97 inches Hg, falling rapidly Visibility: 8 miles 6-hour maximum temp: 42F 6-hour precipitation: 0.05 inch BHO SA 1755 15 SCT E20 BKN 30 OVC 8R- 149/40/39/0215G22/ 997/ THN FG PRESFR/ 8/052 56049 6005/ 10042 20040 WEATHER SUMMARY FOR FRIDAY, DECEMBER 4 TEMPERATURE (DEGREES F) MAX.....52 NORMAL.....42 MIN.....40 NORMAL.....28 MEAN....46 NORMAL.....35 DEPARTURE FROM 30-YEAR AVERAGE............+11 TOTAL DEPARTURE FOR THE MONTH.............+38 [+9.3 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............19 DEPARTURE.......-11 TOTAL HEATING UNITS FOR THE MONTH............80 DEPARTURE.......-38 TOTAL HEATING UNITS FOR THE SEASON.........1240 DEPARTURE......-167 * TOTAL HEATING UNITS LAST SEASON TO DATE....1339 DIFFERENCE......-99 * The seasonal departure is corrected from the value reported on the 4th. PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............26 W AT 12:25 A.M. AEROVANE..............26 W AT 12:25 A.M. * ASOS..................N/A DAVIS.................26 W AT 12:15 A.M. THE FASTEST MILE FOR YESTERDAY...........19 W AT 12:16 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............18 WNW AT 3:56 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........20 W AT 12:20 A.M. AVERAGE WIND SPEED AND DIRECTION.........9.8 W ASOS..................8.9 DAVIS.................8.6 W [265 DEG] * Last of several occurrences. PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE....-0.15 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........1.09 DEPARTURE....+0.49 ASOS..............1.17 TOTAL PRECIPITATION FOR THE YEAR..........50.66 DEPARTURE....+3.40 ASOS.............51.93 * * ASOS yearly total is corrected from previous reports. SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE.....-0.2 TOTAL SNOWFALL FOR THE MONTH................0.0 DEPARTURE.....-0.8 * TOTAL SNOWFALL FOR THE SEASON...............3.0 DEPARTURE.....-0.7 * * Monthly and seasonal snowfall departures are corrected from yesterday's report. PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 2009 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust when significant TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 12/1 41/28/35/-1/0/0/.../.. 29 NW 12/2 51/33/42/+6/.../.../.. 30 SSE 12/3 67/47/57/+22/.../.../.. 69 SSE AERO 73 SSE 12/4 52/40/46/+11/0/.../.. 26 W 12/5 morning low temp: 41F; the normal low temp. is now 27F NEW DAILY RECORD FOR DECEMBER 2009 12/3 NEW RECORD HIGH MAXIMUM TEMPERATURE of 67F; surpasses previous record of 61F in 1932, 1950. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR DECEMBER 5 HIGH 65 IN 2001 LOW -1 IN 1926 PRECIP 2.86 INS. IN 1993 SNOWFALL 7.0 INS. IN 1926 and 1981 PEAK GUST 67 MPH WNW IN 1961, S IN 1973 RECORDS FOR DECEMBER 6 HIGH 70 IN 2001 LOW 5 IN 1901,1935 PRECIP 2.36 INS. IN 1945 SNOWFALL 12.0 INS. IN 1886, 1981 PEAK GUST 74 MPH NW IN 1981 TODAY'S REPORT PREPARED BY: Mike Iacono