BLUE HILL OBSERVATORY MILTON, MA MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, SEPTEMBER 18, 2010 ALL TIMES ARE IN EASTERN STANDARD TIME FINAL RAINFALL TOTAL THURSDAY TO FRIDAY 0.51 INCH... DRIER AND PARTLY SUNNY TODAY WITH LIGHT WINDS... A total of 0.51 inch of rainfall occurred from Thursday evening to Friday afternoon, with the precipitation ending as light drizzle around 5 PM EST Friday. Slightly drier air has moved in today with dew points in the low 50s, though low clouds have limited the sunshine much of the day. Today's observations: 7 A.M. Weather: Overcast stratocumulus, few stratocumulus castellanus ESE, few lower cumulus fractus, clearing line NNE-S Temperature: 56F, Dew point: 54F; Wind: NE at 8 kts, WInd: Light Sea-level pressure: 30.25 inches Hg, rising Visibility: 55 miles, visibility NW 40, SW 30 24-hour precip: 0.05 inch 6-hour minimum temp: 54F BHO SA 1155 E40 OVC 55 243/56/54/0408/025/ FEW SCCAS ESE FEW LWR CUFRA CLRNG LINE NNE-S VSBY NW 40 SW 30 THN K LYR ALG HRZN SSW-NE WND LGT/ 8/5// 53010 70005 10056 20054 10 A.M. Weather: Scattered cumulus, few altocumulus distant ENE-SSW Temperature: 64F, Dew point: 52F; Wind: ENE at 6 kts, Wind: Gradually light and variable Sea-level pressure: 30.26 inches Hg, rising Visibility: 60 miles BHO SA 1455 45 SCT 60 246/64/52/0606/026/ FEW AC DSNT ENE-SSW WND LGT AND VRB/ 8/230 50003 1 P.M. Weather: Overcast stratocumulus, clearing line N-SSE Temperature: 64F, Dew point: 50F; Wind: NNE at 7 kts, Wind: Light and variable Sea-level pressure: 30.21 inches Hg, falling Visibility: 70 miles 6-hourly max. temp: 65F BHO SA 1755 35 SCT E45 OVC 70 231/64/50/0207/021/ CLRNG LINE N-SSE WND LGT AND VRB/ 8/5// 58015 10065 20056 WEATHER SUMMARY FOR FRIDAY, SEPTEMBER 17 TEMPERATURE (DEGREES F) MAX.....68 NORMAL.....71 MIN.....53 NORMAL.....53 MEAN....61 NORMAL.....62 DEPARTURE FROM 30-YEAR NORMAL..............-1 TOTAL DEPARTURE FOR THE MONTH.............+40 [+2.2 DEGREES/DAY] PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............45 S AT 12:18 A.M. AEROVANE..............Missing*** ASOS..................47 S AT 12:23 A.M. DAVIS.................49 SSW AT 12:12 A.M. THE FASTEST MILE FOR YESTERDAY...........36 S AT 12:19 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............35 S AT 12:20 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........33 S AT N/A AVERAGE WIND SPEED AND DIRECTION.......10.8 NNE ASOS.................9.5 DAVIS...............10.5 SSW [105 DEG] * Last of several occurrences *** Aerovane gust missing due to equipment malfunction PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.05 DEPARTURE........-0.09 ASOS..............0.05 TOTAL PRECIPITATION FOR THE MONTH..........1.08 DEPARTURE........-1.23 ASOS..............1.05 TOTAL PRECIPITATION FOR THE YEAR..........47.11 DEPARTURE.......+11.33 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 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/.../.. 28 W AERO 31 MPH W 9/16 70/46/58/-4/.../.../.. 43 S 9/17 68/53/61/-1/.../.../.. 45 S 9/18 morning low temp: 53F; the normal low is now 61F 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 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: Mike Iacono