BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, DECEMBER 12, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME SUNNY AND COLD TODAY WITH COLDEST TEMPERATURE OF THE SEASON SO FAR... The high and low temperatures were 26 and 20 on Friday, and the day averaged 9 degrees colder than normal. The low temperature this morning of 18 was the coldest of the season to date, and the coldest since 18 on March 24. It has been nearly clear all morning, with only a few small cumulus in the sky. The visibility has climbed to about 75 miles with the dew point in the single digits. The wind has slowed somewhat from yesterday, but there has been a peak gust to 31 kts, 36 mph W at 11:58 AM so far today. One inch of old snow remains on the summit today, and the local ponds have begun to show some ice cover after the cold morning today. Today's observations: 7 A.M. Weather: Clear, few stratocumulus NE-SSW, few altocumulus distant W-NW Temperature: 18F, Dew point: 5F, Wind: WSW at 13G20 kts, Sea-level pressure: 30.34 inches Hg, rising Visibility: 45 miles 6-hour minimum temp: 18F Average snow depth: 1 inch BHO SA 1155 CLR 45 275/18/5/2413G20/034/ FEW SC NE-SSW FEW AC DSNT W-NW/ 8/530 4/001 53030 10019 20018 10 A.M. Weather: Scattered small cumulus, few cumulus fractus Temperature: 24F, Dew point: 9F, Wind: W at 17G25kts, Wind: Direction variable SW-NW Sea-level pressure: 30.42 inches Hg, rising Visibility: 55 miles BHO SA 1455 35 SCT 55 300/24/9/2717G25/042/ CUFRA ALQDS WND 23V31/ 8/100 51025 1 P.M. Weather: Clear, few small cumulus and cumulus fractus Temperature: 28F, Dew point: 8F, Wind: W at 16G28kts, Wind Peak wind 31 kts W at 11:58 A.M. Sea-level pressure: 30.39 inches Hg, falling Visibility: 75 miles 6-hour maximum temp: 28F BHO SA 1755 CLR 75 290/28/8/2716G28/039/ FEW CU AND CUFRA ALQDS PK WND 2731/1658 WND 24V30/ 8/100 56010 10028 20018 WEATHER SUMMARY FOR FRIDAY, DECEMBER 11 TEMPERATURE (DEGREES F) MAX.....26 NORMAL.....40 MIN.....20 NORMAL.....25 MEAN....23 NORMAL.....32 DEPARTURE FROM 30-YEAR AVERAGE.............-9 TOTAL DEPARTURE FOR THE MONTH.............+25 [+2.1 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............42 DEPARTURE.......+10 TOTAL HEATING UNITS FOR THE MONTH...........314 DEPARTURE.......-23 TOTAL HEATING UNITS FOR THE SEASON.........1474 DEPARTURE......-152 TOTAL HEATING UNITS LAST SEASON TO DATE....1572 DIFFERENCE......-98 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............46 WSW AT 12:55 A.M. AEROVANE..............41 WSW AT 1:55 A.M. ASOS..................47 W AT 12:56 A.M. DAVIS.................47 W AT 1:48 A.M. THE FASTEST MILE FOR YESTERDAY...........34 WSW AT 12:54 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............33 W AT 9:44 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........33 WSW AT 12:56 A.M. AVERAGE WIND SPEED AND DIRECTION.......23.8 WSW ASOS................22.4 DAVIS...............21.0 WSW [254 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..........3.20 DEPARTURE....+1.55 ASOS..............3.25 TOTAL PRECIPITATION FOR THE YEAR..........52.77 DEPARTURE....+4.46 ASOS.............54.01 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE.....-0.3 TOTAL SNOWFALL FOR THE MONTH...............11.0 DEPARTURE.....+8.1 TOTAL SNOWFALL FOR THE SEASON..............14.0 DEPARTURE.....+8.2 PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 2009 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/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/-1/0/0/497/89 29 NW 12/2 51/33/42/+6/0.08/0/345/62 30 SSE 12/3 67/47/57/+22/1.01/0/428/77 69 SSE AERO 73 MPH SSE 12/4 52/40/46/+11/0/0/488/88 26 W 12/5 42/30/36/+1/0.79/4.7/000/00 36 N 12/6 33/25/29/-5/0.09/0.6/.../.. 36 NW 12/7 36/25/31/-3/0/0/.../.. 22 WSW 12/8 39/25/32/-3/0/0/.../.. 27 WNW 12/9 45/29/37/+4/1.23/5.7/000/00 52 ENE AERO 46 MPH ENE 12/10 40/26/33/0/0/0/.../.. 46 WSW AERO 39 MPH W 12/11 26/20/23/-9/0/0/.../.. 46 WSW AERO 41 MPH WSW 12/12 morning low temp: 18F; the normal low is now 25F 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 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 RECORDS FOR DECEMBER 13 HIGH 60 IN 1984 LOW 0 IN 1893 PRECIP 1.45 INS. IN 1983 SNOWFALL 9.2 INS. IN 2007 PEAK GUST 81e WNW IN 1976 TODAY'S REPORT PREPARED BY: Mike Iacono