BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, DECEMBER 10, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME YESTERDAY'S STORM BROUGHT 50 MPH WIND GUSTS LONG AFTER SNOW HAD CHANGED TO RAIN A THUNDERSTORM WITH AT LEAST ONE RUMBLE OF THUNDER WAS REPORTED DURING THE EARLY EVENING COLDER, DRIER AIR ARRIVING TODAY ON GUSTY WSW WINDS AFTER 40-DEGREE TEMPS. OVERNIGHT MELTED AWAY MUCH OF THE NEARLY SIX INCHES OF SNOWFALL The storm which left 5.7 inches of snow during yesterday morning also brought 1.23 inches of rain and melted snow. Peak wind gusts reached 52 MPH from the ENE during mid-afternoon yest- erday while temperatures rose to a maximum of 45F at 3:50 P.M. Winds dimished rapidly during the late afternoon as the barometer dropped to near 29.20 inches. Much of the snow which fell yesterday melted away in above freezing overnight temperatures. However, colder drier air began arriving today on gusty west-southwest winds with temperatures rising to 40 degrees as dew points dropping to near 20 degrees. Today's observations: 7 A.M. Weather: Scattered altocumulus, few lenticularis, layer NE-SE-SW receding, sky clearing. Temperature: 35F, Dew point: 27F, Wind: SW at 13G20 kts, Wind: Variable in direction SSW to W Sea-level pressure: 30.03 inches Hg, falling Visibility: 35 miles, light haze 6-hour minimum temp: 35F 24-hour precipitation: 1.10 inches 24-hour snowfall: 4.0 inches Total snow depth: 2 inches BHO SA 1155 130 SCT 35 945/35/27/2313G20/937/ AC LYR NE-SE-SW RCDNG SKY CLRG LGT HZ WND 20V26 TOTAL NEW SNW PST 24 HRS 4.0 INS/ 8/070 4/002 51013 ASOS 70104 MANUAL 70110 10040 20035 10 A.M. Weather: Clear, stratocumulus forming W-N Temperature: 39F, Dew point: 24F, Wind: WSW at 17G29 kts, Wind: Peak gust to 29 kts from SW at 9:53 a.m., Wind: Direction variable from SSW to W Sea-level pressure: 29.45 inches Hg, rising Visibility: 50 miles BHO SA 1455 CLR 50 974/39/24/2417G29/945/ SC FRMG W-N PK WND 2329/53/ WND 20V28/ 8/500 51029 1 P.M. Weather: Broken variable scattered stratocumulus clouds Temperature: 39F, Dew point: 21F, Wind: WSW at 18G28 kts, Wind Peak wind gust 30 kts from WSW at 12:44 p.m. Wind: Direction variable SW to WNW Sea-level pressure: 29.42 inches Hg, falling Visibility: 70 miles, mountain in cloud 70 NW 6-hour maximum temp: 40F BHO SA 1755 E55 BKN 70 964/39/21/2518G28/942/ BKN V SCT MTN INCLD 70 NW PK WND 2530/44/ WND 22V29/ 8/500 58010 10040 20034 WEATHER SUMMARY FOR WEDNESDAY, DECEMBER 9 TEMPERATURE (DEGREES F) MAX.....45 NORMAL.....40 MIN.....29 NORMAL.....26 MEAN....37 NORMAL.....33 DEPARTURE FROM 30-YEAR AVERAGE.............+4 TOTAL DEPARTURE FOR THE MONTH.............+34 [+3.6 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............28 DEPARTURE........-4 TOTAL HEATING UNITS FOR THE MONTH...........240 DEPARTURE.......-33 TOTAL HEATING UNITS FOR THE SEASON.........1400 DEPARTURE......-162 TOTAL HEATING UNITS LAST SEASON TO DATE....1527 DIFFERENCE.....-127 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............52 ENE AT 1:56 P.M. * AEROVANE..............46 ENE AT 1:56 P.M. ASOS..................51 ENE AT 1:56 P.M. DAVIS.................48 ENE AT 1:56 P.M. * other peak gusts: 55 MPH Maximum Maestro; Maximum Merlin 51 MPH ENE THE FASTEST MILE FOR YESTERDAY...........40 ENE AT 1:56 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............38 ENE AT 1:56 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........37 ENE AT 1:56 P.M. AVERAGE WIND SPEED AND DIRECTION.......17.2 ENE ASOS................16.4 DAVIS...............16.1 E [080 DEG] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....1.10 DEPARTURE....+0.95 ASOS..............1.04 TOTAL PRECIPITATION FOR THE MONTH..........3.20 DEPARTURE....+1.85 ASOS..............3.25 TOTAL PRECIPITATION FOR THE YEAR..........52.77 DEPARTURE....+4.76 ASOS.............54.01 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........4.0 DEPARTURE.....+3.7 TOTAL SNOWFALL FOR THE MONTH...............11.0 DEPARTURE.....+8.7 TOTAL SNOWFALL FOR THE SEASON..............14.0 DEPARTURE.....+8.8 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 our morning low temp: 35F; 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 10 HIGH 62 IN 1946 LOW -6 IN 1902 PRECIP 1.67 INS. IN 1907 SNOWFALL 6.0 INS. IN 1905 PEAK GUST 66e SW IN 1940 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 TODAY'S REPORT PREPARED BY: Robert Skilling