BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, SEPTEMBER 29, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME SHOWERS AND A THUNDERSTORM LAST NIGHT ACCOMPANIED BY A PEAK GUST TO 43 MPH W RAINFALL INCLUDED A COUPLE OF DOWNPOURS A line of showers and thunderstorms moved eastward through eastern Massachusetts last evening bringing gusty winds which reached a peak of 43 MPH W at 9:40 p.m. EDT. The fastest mile was 28 MPH W at the same time. Several downpours of rain brought as much as 0.14 inch in 5 minutes and a maximum 60-minute total of 0.31 inch. The final rain- fall total after six hours of precipitation was one half inch ending very early this morning. Today's observations: 7 A.M. Weather: Clear, few thin stratus fractus overhead through northeast through south, few altocumulus distant NW-N and altocumulus and altocumulus castellanus distant NE-SSE, the castellanus to the distant SSE was quite impressive and included one nice towering cumulus element Temperature: 55F, Dew point: 54F, Wind: SSW at 11 kts Sea-level pressure: 29.54 inches Hg, rising Visibility: 10 miles, E-SE 4 miles, thin fog all quadrants 6-hour minimum temp: 54F 6-hourly precip: 0.07 inch 24-hour precipitation: 0.50 inch BHO SA 1155 CLR 10 002/55/54/2011/954/ FEW THN STFRA DSSPTNG OVHD-NE-S FEW AC DSNT NW-N AND AC/ACC DSNT NE-SSE THN FG ALQDS VSBY E-S 4/ 8/680 53007 ASOS 60006 MANUAL 6007/ ASOS 70049 MANUAL 70050 10056 20054 10 A.M. Weather: Clear, cumulus fractus and cumulus forming in all quadrants Temperature: 61F, Dew point: 49F, Wind: SW at 13G22 kts. Wind: Peak wind gust 27 kts SSW at 9:29 a.m., Wind: Direction variable from S to W Sea-level pressure: 29.54 inches Hg, falling Visibility: 50 miles, light distant haze BHO SA 1455 CLR 50 003/61/49/2213G22/954/ CUFRA/CU FRMG ALQDS PK WND 2027/29/ WND 18V26/ 8/100 50001 1 P.M. Weather: Scattered cumulus, moderate cumulus, distant cumulonimbus tops visible distant WNW-NW Temperature: 66F, Dew point: 46F, Wind: SSW at 14G30 kts, Wind: Peak wind gust 30 kts S at 12:47 p.m., Wind: Direction variable S-WSW Sea-level pressure: 29.50 inches Hg, falling Visibility: 55 miles, light distant haze 6-hour max. temp: 67F BHO SA 1755 45 SCT 200 SCT 55 990/66/46/2114G30/950/ MDT CU CB TOPS DSNT WNW-NW PK WND 1930/47/ WND 17V24/ 8/203 56013 10067 20055 WEATHER SUMMARY FOR MONDAY, SEPTEMBER 28 TEMPERATURE (DEGREES F) MAX.....73 NORMAL.....67 MIN.....55 NORMAL.....49 MEAN....64 NORMAL.....58 DEPARTURE FROM 30-YEAR AVERAGE...........+6 TOTAL DEPARTURE FOR THE MONTH...........-11 [-0.6 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............1 DEPARTURE.......-7 TOTAL HEATING UNITS FOR THE MONTH...........105 DEPARTURE......-17 TOTAL HEATING UNITS FOR THE SEASON..........139 DEPARTURE......-14 TOTAL HEATING UNITS LAST SEASON TO DATE.....111 DIFFERENCE.....+28 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............43 W AT 8:40 P.M. AEROVANE..............39 W AT 8:40 P.M. ASOS..................40 W AT 8:40 P.M. DAVIS.................45 WSW AT 8:40 P.M. FASTEST MILE FOR YESTERDAY...............28 W AT 8:40 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............28 W AT 8:41 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........30 W AT 8:40 P.M. AVERAGE WIND SPEED AND DIRECTION.......14.5 S ASOS................14.4 DAVIS...............13.9 SSW [210 DEG] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.50 DEPARTURE....+0.36 ASOS..............0.49 TOTAL PRECIPITATION FOR MONTH..............3.11 DEPARTURE....-0.74 ASOS..............3.14 TOTAL PRECIPITATION FOR THE YEAR..........37.88 DEPARTURE....+0.56 ASOS.............39.06 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 TSTM * 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/+4/0/682/91 22 WNW 9/16 61/53/57/-5/T/060/08 31 NNE AERO 29 MPH NNE 9/17 60/49/55/-7/0/022/03 27 N 9/18 71/47/59/-2/T/571/77 35 WSW AERO 30 MPH WSW 9/19 65/45/55/-6/0/716/97 30 NW AERO 28 MPH WNW 9/20 71/45/58/-3/0/721/98 22 SW 9/21 76/50/63/+3/0/703/96 20 S 9/22 74/55/65/+5/0/124/17 27 SSW 9/23 78/61/70/+10/0/145/20 35 SSW 9/24 77/57/67/+8/0/348/48 25 SW 9/25 63/50/57/-2/0/.../.. 33 NW 9/26 62/43/53/-6/0/.../.. 24 S 9/27 65/49/57/-1/0.32/000/00 32 SE AERO 31 MPH SE 9/28 73/55/64/+6/0.38/.../.. 43 W AERO 39 MPH W; DAVIS 45 MPH WSW TSTM 9/29 our morning low temp: 54F; the normal low is now 49F * TSTM DAY added for 12th 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 29 HIGH 85F IN 1952 LOW 28F IN 1914 (SEPTEMBER MINIMUM RECORD) PRECIP 2.61 INCHES IN 1907 PEAK GUST 62 MPH S IN 2005 RECORDS FOR SEPTEMBER 30 HIGH 84F IN 1986 LOW 31F IN 1992 PRECIP 1.93 INCHES IN 1946 PEAK GUST 58 MPH SSE IN 1999 TODAY'S REPORT PREPARED BY: Robert Skilling