BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, SEPTEMBER 18, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME Today's observations: 7 A.M. Weather: Clear, few cirrus Temperature: 51F, Dew point: 49F, Wind: SSW at 9 kts Sea-level pressure: 30.00 inches Hg, falling Visibility: 15 miles, thin fog 6-hour minimum temp: 47F 24-hour precipitation: 0.0 BHO SA 1155 CLR 15 160/51/49/2109/000/ FEW CI THN FG/ 8/001 58003 10051 20047 10 A.M. Weather: Clear, few cumulus Temperature: 64F, Dew point: 53F, Wind: SW at 12G21 kts Wind: Variable direction S to W Sea-level pressure: 29.96 inches Hg, falling Visibility: 25 miles, hazy BHO SA 1455 CLR 25 146/64/53/2212G21/996/ FEW CU HAZY WND 18V27/ 8/100 58014 1 P.M. Weather: Scattered cumulus Temperature: 70F, Dew point: 52F, Wind: W at 16G28 kts Wind: Peak gust past hour 29 kts W at 12:23 P.M. Wind: Variable dirction SSE to W Sea-level pressure: 29.90 inches Hg, falling Visibility: 25 miles, hazy 6-hour max. temp: 70F BHO SA 1755 40 SCT 25 126/70/52/2616G28/990/ HAZY PK WND 2629/23 WND 16V26/ 8/100 56020 10070 20051 WEATHER SUMMARY FOR THURSDAY, SEPTEMBER 17 TEMPERATURE (DEGREES F) MAX.....60 NORMAL.....71 MIN.....49 NORMAL.....53 MEAN....55 NORMAL.....62 DEPARTURE FROM 30-YEAR AVERAGE...........-7 TOTAL DEPARTURE FOR THE MONTH...........-23 [-1.6 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............10 DEPARTURE.......+5 TOTAL HEATING UNITS FOR THE MONTH............51 DEPARTURE.......-2 TOTAL HEATING UNITS FOR THE SEASON...........85 DEPARTURE.......+1 TOTAL HEATING UNITS LAST SEASON TO DATE......38 DIFFERENCE.....+47 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............27 N AT 3:18 A.M. AEROVANE..............22 NNE AT 1:36 A.M. ASOS..................24 NNE AT 3:19 A.M. DAVIS................ 26 N AT 7:16 A.M. FASTEST MILE FOR YESTERDAY...............17 WSW AT 10:58 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE............16 W AT 10:59 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........17 NNE AT 3:20 A.M. AVERAGE WIND SPEED AND DIRECTION........8.9 N ASOS.................9.1 DAVIS................8.4 NNE [012 DEG] * last of several occurrences.... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE....-0.14 ASOS..............0.00 TOTAL PRECIPITATION FOR MONTH..............2.29 DEPARTURE....-0.02 ASOS..............2.33 TOTAL PRECIPITATION FOR THE YEAR..........37.06 DEPARTURE....+1.28 ASOS.............38.25 PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 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 9/1 71/51/61/-6/0/773/98 17 NW 9/2 76/54/65/-1/0/786/100 22 S 9/3 77/56/67/+1/0/587/75 19 SW 9/4 77/60/69/+3/0/764/98 18 NE 9/5 81/59/70/+5/0/591/76 25 NNW 9/6 64/53/59/-6/0/743/96 31 NNE 9/7 70/52/61/-4/0/709/92 20 WSW 9/8 75/56/66/+1/0/369/48 18 WSW 9/9 68/55/62/-2/0/352/46 36 NNE AERO 33 MPH NNE 9/10 65/53/59/-5/0/603/79 31 ENE 9/11 61/54/58/-6/0.49/000/00 30 NE 9/12 63/60/62/-1/1.74/000/00 30 NNE 9/13 76/58/67/+4/0.06/393/52 28 NW 9/14 74/55/65/+2/0/699/93 22 WSW 9/15 75/56/66/+4/0/.../.. 22 WNW 9/16 61/53/57/-5/T/.../.. 31 NNE 9/17 60/49/55/-7/0/.../.. 27 N AERO 22 MPH NNE 9/18 our morning low temp: 47F; the normal low is now 53F NEW DAILY RECORDS FOR SEPTEMBER 2009 TO DATE... None. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR SEPTEMBER 18 HIGH 88F IN 1906 LOW 36F IN 1919 PRECIP 4.25 INCHES IN 1996 PEAK GUST 77e MPH WNW IN 1948 RECORDS FOR SEPTEMBER 19 HIGH 87F IN 1906,1983 LOW 37F IN 1929 PRECIP 3.69 INCHES IN 1936 PEAK GUST 48 MPH NE IN 1972 TODAY'S REPORT PREPARED BY: Stephanie Radner