BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY MONDAY, MAY 25, 2009, MEMORIAL DAY ALL TIMES ARE IN EASTERN STANDARD TIME SUNDAY AFTERNOON THUNDERSTORM BRINGS DOWNPOUR AND BRIEFLY HALF INCH HAIL JUST AFTER 2 PM EDT HALF INCH OF RAIN IN 10 MINUTES, 0.7 IN 20 MINUTES A thunderstorm began by 1:30 P.M. EDT yesterday afternoon and considerable lightning and heavy rain was observed to our west through north well before the downpour hit here about 2:10 p.m. The first rain included a short period of dime size hail. The thunderstorm had a wind gust of just 25 MPH NW-WNW. Rainfall intensity included: 0.30 inch in 5 minutes ending about 2:20 p.m.; 0.54, in 10 minutes, 0.66 in 15 minutes, 0.72 in 20 minutes through about 2:30 p.m. When all of the rain had ended there was was a total of 0.87 inch through 2:45 p.m. Additional rainfall with thunder later during the afternoon brought the total to 1.05 inches and including 0.02 which fell in the early morning. We recorded 1.07 inches for the day. Today's observations: 7 A.M. Weather: Scattered altocumulus, altocumulus castellanus (SE-SW) and cirrus, all clouds NE-SE-SW and moving away Temperature: 62F, Dew point: 50F, Wind: NNW at 5 kts Sea-level pressure: 30.01 inches Hg, rising Visibility: 40 miles, light haze, NE-S 35 miles, W-NW 55 miles 6-hour minimum temp: 56F 24-hour precipitation: 1.05 inches BHO SA 1155 N/A 10 A.M. Weather: Clear, cumulus fractus forming, altocumulus and cirrus/cirrostratus layer distant southeast to southwest Temperature: 69F, Dew point: 47F, Wind: W at 5 kt, Sea-level pressure: 30.01 inches Hg, falling Visibility: 50 miles except 35 miles northeast to southeast BHO SA 1455 CLR 50 161/69/47/2805/001/ FEW CUFRA FRMG FEW AC AND CI/CS LYR SE-SW VSBY NE-SE 35 LGT HZ ALQDS/ 8/148 58001 1 P.M. Weather: Scattered cirrus, cirrostratus, layer SE-WSW, few small cumulus and cumulus fractus all quadrants Temperature: 75F, Dew point: 41F, Wind: WSW at 6 kts Sea-level pressure: 29.98 inches Hg, falling Visibility: 60 miles, northwest 70 miles 6-hour maximum temp: 75F BHO SA 1755 250 SCT 60 152/75/41/2506/998/ FEW CUFRA AND SML CU ALQDS C/CS LYR XTDNG SE-WSW VSBY NW 70/ 8/108 58009 10075 20062 WEATHER SUMMARY FOR SUNDAY, MAY 24 TEMPERATURE (DEGREES F) MAX.....80 NORMAL.....70 MIN.....50 NORMAL.....50 MEAN....65 NORMAL.....60 DEPARTURE FROM 30-YEAR NORMAL...........+5 TOTAL DEPARTURE FOR THE MONTH..........+73 [+2.8 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............0 DEPARTURE.......-6 TOTAL HEATING UNITS FOR THE MONTH...........164 DEPARTURE......-68 TOTAL HEATING UNITS FOR THE SEASON.........6060 DEPARTURE.....-198 TOTAL HEATING UNITS LAST SEASON TO DATE....5884 DIFFERENCE....+176 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............25 WNW AT 1:22 P.M. * AEROVANE..............23 WNW AT 1:22 P.M. * ASOS..................24 NW AT 1:19 P.M. DAVIS.................28 W AT 1:18 P.M. FASTEST MILE FOR YESTERDAY...............17 WNW AT 1:22 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............18 WNW AT 1:23 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........21 WNW AT 1:20 P.M. AVERAGE WIND SPEED AND DIRECTION.......10.1 SSW ASOS................10.8 DAVIS................9.5 SSW [200 DEG] * last of several occurrences.... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....1.05* DEPARTURE....+0.93 ASOS..............1.06 TOTAL PRECIPITATION FOR THE MONTH..........3.45 DEPARTURE....+0.52 ASOS..............3.45 TOTAL PRECIPITATION FOR THE YEAR..........18.06 DEPARTURE....-2.82 ASOS.............19.13 * included a trace of 1/2 inch hail 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/T/.../.. 28 NE 5/24 80/50/65/+5/1.07/.../.. 25 WNW TSTM TRACE DIME SIZE HAIL 5/25 morning low temp: 56F; our normal low is now 50F 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 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) RECORDS FOR MAY 26 HIGH 89F IN 1914,1965 LOW 37F IN 1972 PRECIP 1.73 INS IN 2003 SNOWFALL TRACE IN 1967 (Fell as ice pellets in nor'easter) PEAK GUST 62 MPH NE IN 1967 TODAY'S REPORT PREPARED BY: Robert Skilling