BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, AUGUST 20, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME HIGH OF 89F YESTERDAY ENDS HEATWAVE; RECORD HIGH MINIMUM TEMP OF 71F FOR AUGUST 19 MATCHED YESTERDAY THUNDERSTORMS ARRIVE JUST AFTER 2:00 PM EDT Yesterday's high temperature of 89F fell one degree short of the record of 90F set in 1906, 1966, and 2002. The high of 89F put an official end to the heat wave which lasted three days, with high temperatures of 90F, 91F, and 91F on August 16th, 17th, and 18th. Yesterday's low temperature of 71F tied the record high minimum for the date which was set in 2002. A strong thunderstorm began this afternoon with the first rumble of thunder at 2:20PM EDT, followed by several cloud to ground lightning strikes visible to the west-southwest of the Observatory and periods of heavy rainfall. Today's observations: 7 A.M. Weather: Overcast stratocumulus with numerous breaks Temperature: 72F, Dew point: 66F, Wind: NE at 9 kts Sea-level pressure: 30.00 inches Hg, rising Visibility: 10 miles, hazy 6-hour minimum temp: 70F BHO SA 1155 E45 OVC 10 159/72/66/0509/000/ NMRS BRKS IOVC HAZY/ 8/500 53007 10073 20070 10 A.M. Weather: Scattered stratocumulus, broken cirrostratus Temperature: 79F, Dew point: 69F, Wind: ESE at 5 kts Wind: Light and variable Sea-level pressure: 30.01 inches Hg, rising Visibility: 12 miles, hazy BHO SA 1455 60 SCT E220 BKN 12 164/79/69/1205/001/ FEW SCSL W-N HAZY WND LGT AND VRB/ 8/207 51005 1 P.M. Weather: Broken stratocumulus, overcast cirrus, moderate and few towering cumulus all quadrants, virga distant SW Temperature: 80F, Dew point: 70F, Wind: NE at 7 kts, Wind: Direction variable N to ENE Sea-level pressure: 29.98 inches Hg, falling Visibility: 10 miles, hazy 6-hourly max. temp: 83F BHO SA 1755 E60 BKN 250 OVC 10 154/80/70/0407/998/ MDT CU AND FEW TCU ALQDS VIRGA DSNT SW HAZY WND 35V07/ 8/207 56010 10083 20071 WEATHER SUMMARY FOR WEDNESDAY, AUGUST 19 TEMPERATURE (DEGREES F) MAX.....89 NORMAL.....79 MIN.....71 NORMAL.....61 MEAN....80 NORMAL.....70 DEPARTURE FROM 30-YEAR AVERAGE..........+10 TOTAL DEPARTURE FOR THE MONTH...........+43 [+2.1 DEGREES/DAY] HEATING DEGREE DATA WILL RESUME IN SEPTEMBER PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............23 SW AT 3:33 P.M. AEROVANE..............20 W AT 4:02 P.M. * ASOS..................21 WSW AT 3:33 P.M. DAVIS.................22 SW AT N/A FASTEST MILE FOR YESTERDAY...............17 SSW AT 12:04 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............16 SW AT 12:46 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........N/A AVERAGE WIND SPEED AND DIRECTION........9.4 SW ASOS.................9.4 DAVIS................9.2 SW [229 DEG] * last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE....-0.13 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........0.84 DEPARTURE....-1.60 ASOS..............0.84 TOTAL PRECIPITATION FOR THE YEAR..........32.10 DEPARTURE....+0.25 ASOS.............33.22 PRELIMINARY CLIMATE SUMMARY FOR AUGUST 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 8/1 83/63/73/+1/0/823/95 18 SSE 8/2 77/64/71/-1/T/104/12 25 SSE 8/3 84/67/76/+4/0/638/74 17 SW 8/4 83/66/75/+3/0/714/83 23 S 8/5 86/67/77/+5/T/378/44 27 SSW TSTM 8/6 76/61/69/-3/0/564/66 18 SSE 8/7 79/58/69/-2/0/836/98 32 W 8/8 74/55/65/-6/0/791/93 21 WNW 8/9 76/59/68/-3/T/178/21 25 SSE 8/10 87/66/77/+6/0.12/584/69 27 W TSTM 8/11 84/66/75/+4/0.54/684/81 25 NE TSTM 8/12 67/63/65/-6/T/000/00 18 N 8/13 66/60/63/-8/0.18/042/05 23 NNE 8/14 83/58/71/+1/0/762/91 16 S 8/15 88/66/77/+7/0/810/97 18 S 8/16 90/68/79/+9/0/749/90 22 S 8/17 91/69/80/+10/0/.../.. 21 WSW 8/18 91/72/82/+12/0/.../.. 29 SSW 8/19 89/71/80/+10/0/.../.. 23 SW 8/20 our morning low temp: 70F; the normal low is now 61F NEW DAILY RECORDS FOR AUGUST 2009 TO DATE... 8/19: RECORD HIGH MINIMUM TEMPERATURE 71F; equals record previously set in 2002 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR AUGUST 20 HIGH 93F IN 1937 LOW 48F IN 1896, 1905, 1949 PRECIP 2.71 INCHES IN 1970 PEAK GUST 47 MPH W 1983 RECORDS FOR AUGUST 21 HIGH 92F IN 1937, 1995 LOW 47F IN 1982 PRECIP 2.84 INCHES IN 1888 PEAK GUST 54 MPH WSW 2004 TODAY'S REPORT PREPARED BY: Stephanie Radner