BLUE HILL OBSERVATORY MILTON, MA MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, SEPTEMBER 26, 2010 ALL TIMES ARE IN EASTERN STANDARD TIME NEAR-RECORD MAXIMUM ON SATURDAY...MUCH COOLER TODAY Yesterday's maximum temperature of 86F fell just one degree short of the daily record of 87F set in 1970. Combined with an abnormally warm minimum temperature of 64F, the mean temperature on Saturday was 16 degrees above normal, thus pushing the monthly departure to more than 3 degrees above normal. Persistent northeasterly winds and mostly cloudy skies have cooled temperatures significantly this afternoon. After an overnight low of 59F, the air temperature only managed to reach 67F as of 2:00 PM EDT. Today's observations: 7 A.M. Weather: Broken dense cirrus, few altocumulus, ENE-S, few thin cirrus overhead, thin smoke layer NNW-N and S-SSW Temperature: 61F, Dew point: 51F; Wind: N at 8 kts Wind: Direction variable NW to NE Sea-level pressure: 30.04 inches Hg, rising Visibility: 45 miles, SSE-SSW 30 miles 6-hour minimum temp: 59F BHO SA 1155 E250 BKN 45 174/61/51/3608/004/ FEW AC ENE-SE FEW THN CI OVHD THN K LYR NNW-N AND S-SSW VSBY SSE-SW 30 ND 32V04/ 8/032 52017 10063 20059 10 A.M. Weather: Overcast thin cirrus, few cumulus NNW-N, few altocumulus SE-SSW, few cirrocumulus SE, few dense cirrus and virga all quadrants, thin spots in overcast W-NNE and E-SSE Temperature: 65F, Dew point: 54F; Wind: NE at 13 kts, Wind: Direction variable N to E Sea-level pressure: 30.09 inches Hg, rising Visibility: 50 miles BHO SA 1455 250 -OVC 50 189/65/54/0413/009/ FEW CU NNW-N FEW AC SE-SSW FEW CC SE FEW DENS CI ALQDS VIRGA ALQDS THN SPTS IOVC W-NNE AND E-SSE WND 36V08/ 8/132 51015 1 P.M. Weather: Overcast stratus, few stratus fractus all quadrants, hazy/thin fog N-NE Temperature: 61F, Dew point: 57F; Wind: NNE at 15 kts Wind: Direction variable NNW to E Sea-level pressure: 30.13 inches Hg, rising Visibility: 40 miles, SSE-SW 50 miles, N-NE 15 miles 6-hour maximum temp: 67F BHO SA 1755 E10 OVC 40 204/61/57/0315/013/ FEW STRAFRA ALQDS VSBY SSE-SW 50 N-NE 15 HAZY/THN FG N-NE WND 33V09/ 8/6// 51015 10067 20061 WEATHER SUMMARY FOR SATURDAY, SEPTEMBER 25 TEMPERATURE (DEGREES F) MAX.....86 NORMAL.....68 MIN.....63 NORMAL.....50 MEAN....75 NORMAL.....59 DEPARTURE FROM 30-YEAR NORMAL.............+16 TOTAL DEPARTURE FOR THE MONTH.............+83 [+3.1 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............0 DEPARTURE........-7 TOTAL HEATING UNITS FOR THE MONTH............57 DEPARTURE.......-43 TOTAL HEATING UNITS FOR THE SEASON...........70 DEPARTURE.......-61 TOTAL HEATING UNITS LAST SEASON TO DATE.....118 DIFFERENCE......-48 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............28 WSW AT 10:45 A.M. * AEROVANE..............29 WSW AT 10:45 A.M. * ASOS..................28 WSW AT 10:46 A.M. DAVIS.................31 SSW AT 1:39 A.M. THE FASTEST MILE FOR YESTERDAY...........23 S AT 1:40 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............23 S AT 2:04 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........24 S AT 1:41 A.M. AVERAGE WIND SPEED AND DIRECTION.......14.4 S ASOS................13.2 DAVIS...............14.4 SW [220 DEG] * last of several occurrences... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M...Trace DEPARTURE........-0.14 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........1.08 DEPARTURE........-2.35 ASOS..............1.05 TOTAL PRECIPITATION FOR THE YEAR..........47.11 DEPARTURE.......+10.21 ASOS.............46.89 ** ** ASOS missing rainfall due to system failure on 6/24-25 PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2010 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 9/1 93/73/83/+16/0.00/765/97 18 SW 9/2 93/72/83/+17/0.00/740/94 25 SSW 9/3 83/69/76/+10/0.47/039/05 25 NNE 9/4 79/62/71/+5/0.00/672/86 37 WSW AERO 39 MPH WSW 9/5 73/55/64/-1/0.00/778/100 28 SW AERO 32 MPH SW 9/6 76/54/65/0/T/768/99 22 SSW 9/7 84/62/73/+8/0.00/440/57 30 SSW AERO 32 MPH S 9/8 80/59/70/+5/0.08/300/39 35 W AERO 40 MPH W TSTM 9/9 72/55/64/0/T/352/46 28 W 9/10 67/55/61/-3/0.00/260/34 26 WNW 9/11 68/53/61/-3/0.00/723/95 18 NE 9/12 63/54/59/-4/T/045/06 22 ENE AERO 24 MPH NE 9/13 67/54/61/-2/0.02/091/12 22 S 9/14 74/53/64/+1/T/489/65 31 WSW AERO 32 MPH WSW 9/15 67/49/58/-4/0.00/660/88 28 W AERO 31 MPH W 9/16 70/46/58/-4/0.26/530/71 43 S 9/17 68/53/61/-1/0.25/000/00 45 S 9/18 65/53/59/-2/0.00/193/26 15 SE 9/19 76/54/65/+4/T/451/61 17 SW AERO 22 MPH SW 9/20 69/50/60/-1/0.00/707/96 29 NW AERO 33 MPH NW 9/21 70/46/58/-2/0.00/711/97 31 S AERO 35 MPH S 9/22 84/58/71/+11/T/.../.. 32 SSW AERO 36 MPH SSW 9/23 73/58/66/+6/0.00/.../.. 20 SSE 9/24 81/58/70/+11/T/.../.. 29 S 9/25 86/63/75/+16/0.00/.../.. 28 WSW 9/26 our overnight low temp: 59F; the normal low is now 50F NEW DAILY RECORDS FOR SEPTEMBER 2010 9/1 - High maximum temperature of 93F equals the previous record of 93F set in 1969 9/1 - High minimum temperature of 73F surpasses the previous record of 71F in 1898, 1959 9/2 - High minimum temperature of 72F surpasses the previous record of 71F in 1959 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR SEPTEMBER 26 HIGH 91F IN 2007 LOW 36F IN 1905,1922,1978 PRECIP 3.84 INCHES IN 1888 PEAK GUST 54e MPH S IN 1977 RECORDS FOR SEPTEMBER 27 HIGH 84F IN 1998 LOW 32F IN 1947 PRECIP 2.26 INCHES IN 1962 PEAK GUST 100 MPH SSE IN 1985 (HURRICANE GLORIA) TODAY'S REPORT PREPARED BY: Eli Melaas