BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, MAY 24, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME WARMER WITH A SEVERE THUNDERSTORM EARLY THIS AFTERNOON A severe thunderstorm, providing significant lightning and dime-size hail, moved across the area at 2 P.M. EDT. Heavy rain was observed and preliminary analysis indicates that 0.75 inches of precipitation fell between 2 P.M. and 2:30 P.M. EDT. Temperatures reached 80 degrees before the thunderstorm. Today's observations: 7 A.M. Weather: Scattered stratocumulus; broken altocumulus Temperature: 56F, Dew point: 55F, Wind: S at 13 kt Sea-level pressure: 30.01 inches Hg, falling Visibility: 8 miles 6-hour minimum temp: 50F 24-hour precipitation: 0.02 inch 6-hour precipitation: 0.02 inch BHO SA 1155 80 SCT 150 BKN 8 164/56/55/1913/001/ HAZY/ 8/740 58009 6002/ 70002 10056 20050 10 A.M. Weather: Scattered altostratus; broken cirrus Temperature: 72F, Dew point: 60F, Wind: SW at 12G16 kt, Sea-level pressure: 30.01 inches Hg, falling Visibility: 15 miles BHO SA 1455 150 SCT 200 BKN 15 161/72/60/2312G16/001/ HAZY/ 8/043 58003 1 P.M. Weather: Cumulonimbus and thunderstorm to the northeast moving east; copious cloud to ground lightning; virga SW-N; wind backing; Temperature: 78F, Dew point: 61F, Wind: SSE at 14G20 Sea-level pressure: 29.95 inches Hg, falling Visibility: 20 miles prevailing; 15 to the southwest; 10 to the northwest; 3 to the north 6-hour maximum temp: 80F 6-hour precipitation: None BHO SA 1755 30 SCT 150 BKN 200 OVC 20T 142/78/61/1614G20/995/ FEW BINOVC E-S TB40 T NW-N MOVG E LTGCG VIRGA SW-N VSBY SW 15 W 10 N 3 WND BACKING/ 8/943 58019 10080 20056 WEATHER SUMMARY FOR SATURDAY, MAY 23 TEMPERATURE (DEGREES F) MAX.....65 NORMAL.....69 MIN.....50 NORMAL.....49 MEAN....58 NORMAL.....59 DEPARTURE FROM 30-YEAR NORMAL...........-1 TOTAL DEPARTURE FOR THE MONTH..........+68 [+2.8 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............7 DEPARTURE........0 TOTAL HEATING UNITS FOR THE MONTH...........164 DEPARTURE......-62 TOTAL HEATING UNITS FOR THE SEASON.........6060 DEPARTURE.....-192 TOTAL HEATING UNITS LAST SEASON TO DATE....5877 DIFFERENCE....+183 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............28 NE AT 7:13 A.M. AEROVANE..............24 NE AT 7:13 A.M. ASOS..................26 ENE AT 7:13 A.M. DAVIS.................24 NE AT 7:13 A.M. FASTEST MILE FOR YESTERDAY...............23 NE AT 7:14 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............18 ENE AT 7:15 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........20 NE AT 7:15 A.M. AVERAGE WIND SPEED AND DIRECTION.......10.2 NE ASOS.................9.8 DAVIS...............10.0 NE [55 DEG] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02 DEPARTURE....-0.10 ASOS..............0.02 TOTAL PRECIPITATION FOR THE MONTH..........2.40 DEPARTURE....-0.41 ASOS..............2.39 TOTAL PRECIPITATION FOR THE YEAR..........17.01 DEPARTURE....-3.75 ASOS.............18.07 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE..... 0.0 TOTAL SNOWFALL FOR THE MONTH................0.0 DEPARTURE.....-0.1 TOTAL SNOWFALL FOR THE SEASON..............78.9 DEPARTURE.....18.8 PRELIMINARY CLIMATE SUMMARY FOR MAY 2009 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane recording wind system gust when significant TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 5/1 64/53/59/+7/T/000/00 37 SSW AERO 37 MPH SSW 5/2 68/52/60/+8/0.05/263/31 32 WNW 5/3 64/48/56/+3/T/068/08 25 S 5/4 64/48/56/+3/0.01/009/01 17 SSW 5/5 52/44/48/-5/0.95/000/00 43 NNE AERO 40 MPH NNE 5/6 63/43/53/-1/0.40/189/22 24 SSE 5/7 68/49/59/+5/0.60/009/01 29 S 5/8 75/52/64/+10/0/690/80 28 S 5/9 71/55/63/+8/0.14/104/12 31 W TSTM 5/10 65/46/56/+1/0/840/97 53 W Aero 50 MPH W 5/11 63/41/52/-3/0/781/90 24 WNW 5/12 63/45/54/-2/0/696/80 22 ENE 5/13 70/45/58/+2/0/732/84 31 SSE AERO 29 MPH SSE 5/14 62/47/55/-2/0.10/166/19 53 S AERO 52 MPH S 5/15 76/54/65/+8/0/474/54 38 S AERO 38 MPH S 5/16 68/54/61/+4/T/457/52 35 S AERO 35 MPH S 5/17 61/49/55/-2/0.09/009/01 35 WNW AERO 33 MPH WNW 5/18 53/42/48/-10/0.04/168/19 27 NE 5/19 70/42/56/-2/0/813/92 28 S 5/20 82/49/66/+8/0/771/87 31 SSW 5/21 89/59/74/+15/0/870/98 37 S AERO 34 MPH S 5/22 87/59/73/+14/0/.../.. 31 N 5/23 65/50/58/-1/../../.. 28 NE NEW DAILY RECORDS FOR MAY 2009... 5/14: RECORD PEAK WIND GUST 53 MPH S; surpasses previous record of 50 MPH SW in 1976 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 24 HIGH 92F IN 1964 LOW 35F IN 1956 PRECIP 2.13 INS IN 1951 PEAK GUST 54 MPH NNE IN 2005 RECORDS FOR MAY 25 HIGH 91F IN 2007 LOW 37F IN 1967 PRECIP 3.73 INS IN 1967 PEAK GUST 83 MPH NE IN 1967 (RECORD FOR MAY) TODAY'S REPORT PREPARED BY: Andrew Hoell