BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, SEPTEMBER 17, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME Today's observations: 7 A.M. Weather: Overcast stratocumulus, few lower stratus fractus Temperature: 52F, Dew point: 46F, Wind: N at 10G19 kts, Wind: direction variable NW to NE Sea-level pressure: 30.30 inches Hg, falling Visibility: 30 miles, higher NW to NE 6-hour minimum temp: 50F 24-hour precipitation: Trace BHO SA 1155 E32 OVC 30 261/52/46/0110G19/030/ FEW LWR STFRA ALQDS VSBY HIER NW-NE WND 31V04/ 8/5// 56003 10053 20050 10 A.M. Weather: Overcast stratocumulus, bright spots in overcast Temperature: 55F, Dew point: 45F, Wind: N at 11 kts, Wind: direction variable NW to NNE Sea-level pressure: 30.30 inches Hg, steady Visibility: 50 miles BHO SA 1455 E35 OVC 50 261/55/45/3611/030/ BRGHT SPTS IOVC ALQDS WND 32V03/ 8/5// 56000 1 P.M. Weather: Broken cumulus, overcast stratocumulus Temperature: 57F, Dew point: 48F, Wind: N at 9 kts, Wind: direction variable NW to E Sea-level pressure: 30.24 inches Hg, falling Visibility: 60 miles 6-hour max. temp: 60F BHO SA 1755 E25 BKN 40 OVC 60 242/57/48/3609/024/ BRGHT SPTS IOVC ALQDS WND 31V08/ 8/8// 58019 10060 20052 WEATHER SUMMARY FOR WEDNESDAY, SEPTEMBER 16 TEMPERATURE (DEGREES F) MAX.....61 NORMAL.....71 MIN.....53 NORMAL.....53 MEAN....57 NORMAL.....62 DEPARTURE FROM 30-YEAR AVERAGE...........-5 TOTAL DEPARTURE FOR THE MONTH...........-16 [-1.2 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............8 DEPARTURE.......+4 TOTAL HEATING UNITS FOR THE MONTH............41 DEPARTURE.......-7 TOTAL HEATING UNITS FOR THE SEASON...........75 DEPARTURE.......-4 TOTAL HEATING UNITS LAST SEASON TO DATE......36 DIFFERENCE.....+39 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............31 NNE AT 9:39 A.M. * AEROVANE..............29 NNE AT 9:39 A.M. * ASOS..................30 NE AT 9:39 A.M. DAVIS................ 32 NE AT 8:21 A.M. FASTEST MILE FOR YESTERDAY...............23 NNE AT 9:40 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............22 NE AT 9:45 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........22 NNE AT 9:41 A.M. AVERAGE WIND SPEED AND DIRECTION.......13.7 NNE ASOS................13.6 DAVIS...............13.2 NNE [033 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 MONTH..............2.29 DEPARTURE....+0.12 ASOS..............2.33 TOTAL PRECIPITATION FOR THE YEAR..........37.06 DEPARTURE....+1.42 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 our morning low temp: 50F; 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 17 HIGH 86F IN 1915,1941,1991 LOW 38F IN 1959 PRECIP 2.73 INCHES IN 1933 PEAK GUST 60 MPH WNW IN 1999 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 TODAY'S REPORT PREPARED BY: Stephanie Radner