BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, APRIL 21, 2005 ALL TIMES EASTERN DAYLIGHT TIME UNLESS OTHERWISE NOTED TODAY'S DISCUSSION.....AT 2 P.M. Yesterday's high temp. of 86 was two degrees short of the record high of 88 degrees for the date.... TEMPERATURE REACHES SUMMER-LIKE READING OF 86 DEGREES YESTERDAY STRONG BACK DOOR COLD FRONT DROPS TEMPERATURE 16 DEGREES IN JUST 10 MINUTES LAST EVENING...NNE WINDS GUST PAST 40 MPH... The temperature soared to 86.3 degrees at 2:21 p.m. yesterday afternoon but fell sharply from 71 degrees at 9:42 p.m. to 55 degrees just ten minutes later at 9:52 p.m. last evening. During the first minute or so of the precipitous drop it may have been as much as 3 to 5 degrees in one minute. The wind went from near calm at 9:42 p.m. to a peak gust of 44 MPH NNE just six minutes later. The sudden change to more typical weather for mid-April brought a period of light to briefly moderate showers ending up as some light drizzle by 6:30 a.m. this morning. The total was 0.16 inch for the standard rain gage but only 0.12 in the ASOS weighing gage. Last evening's temperature plunge was not at all unlike a similar event just two years on April 16, 2003. The temperature fell 20 degrees in ten minutes on a back-door cold front, from the mid-80's to the mid-60's, and 32 degrees in in 40 minutes from 82 to 50. Peak wind gusts were recorded to 55 MPH NE. TODAY'S OBSERVATIONS 4/21/2005 THU 8 a.m. low overcast with 50 miles visibility; temp. 39; dewpoint 34; wind north at 13 mph; six hourly min. temp. 38; 24 hourly precip. 0.16 inch... BHO SA COR 1155 E30 OVC 50 117/39/34/3511/988/ LWR CUFRA/CU ALQDS MTN 45 WNW INCLD PK WND 3631/09/ 8/8// 53040 ASOS 60007 MANUAL 6010/ ASOS 70012 MANUAL 70016 10047 20038 11 a.m. broken clouds with 70 miles visibility and temp. 47; dewpoint 34; wind nw at 12 gusting 20 mph; BHO SA 1455 E35 BKN 70 131/47/34/3110G17/992/ WND 26V35/ 8/500 51014 2 p.m. clear with few CU SE-SW and visibility of 80 miles; temp. 55; dewpoint 21; wind wnw at 09 with gust to 24 mph past hour; six hourly max. temp. 55 deg; six hourly min. temp. 39 BHO SA 1755 CLR 80 130/55/21/3008/991/ FEW SML CU SE-SW WND 27V35 GST 21 KTS PST HR/ 8/100 55001 10055 20039 WEATHER SUMMARY FOR WEDNESDAY APRIL 20: TEMPERATURE (DEGREES F) MAX.....86 NORMAL.....57 HAZEN 86.3 @ 2:21 p.m. MIN.....47 NORMAL.....39 HAZEN 47.2 @ 11:59 p.m. ** MEAN....67 NORMAL.....48 DEPARTURE FROM 30-YEAR NORMAL......+ 19 TOTAL DEPARTURE FOR THE MONTH......+ 100(+4.8 DEGREES/DAY) ** Eastern Standard Time PRECIPITATION (INCHES) THROUGH THIS MORNING TOTAL PRECIPITATION 24 HRS ENDING 8 A.M....0.16 DEPARTURE....+0.02 ASOS..............0.12 TOTAL PRECIPITATION FOR THE MONTH..........2.20 DEPARTURE....-0.76 ASOS..............2.16 TOTAL PRECIPITATION FOR THE YEAR..........18.66 DEPARTURE.....+2.22 TOTAL FOR ASOS FOR THE YEAR...............17.64 SNOWFALL (INCHES) THROUGH THIS MORNING TOTAL SNOWFALL 24 HRS ENDING 8 A.M........ 0.0 DEPARTURE....- 0.1 TOTAL SNOWFALL FOR THE MONTH.............. 0.2 DEPARTURE....- 1.9 TOTAL SNOWFALL FOR THE SEASON.............119.4 DEPARTURE.....+60.1 YESTERDAY'S PEAK GUSTS AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY........44 NNE AT 9:48 P.M. AEROVANE.........43 NNE AT 9:48 P.M. ASOS.............38 SSW AT 9:56 P.M. DAVIS............40 N AT 9:48 P.M. FASTEST MILE FOR YESTERDAY......... 30 NNE AT 9:50 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE.......30 NNE AT 9:50 P.M. MAXIMUM 1-MINUTE DAVIS AVERAGE......31 S AT 5:35 P.M. OUR AVERAGE SPEED AND DIRECTION.....17.5 WSW ASOS AVERAGE AND DIRECTION..........18.2 SW [220 deg] DAVIS AVERAGE AND DIRECTION.........17.8 SW [230 deg] THE PRELIMINARY CLIMATE SUMMARY FOR APRIL 2005...... CALENDAR DAY DATA DATA REPORTED HERE ENDING MIDNIGHT STANDARD TIME DATE MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane recording wind system when significant TSTM: Thunderstorm day ....: Data not yet available 4/1 56/36/46/+5/0.01/0/283/37 23 MPH SE 4/2 56/35/46/+4/1.04/0/000/00 53 MPH SE 4/3 53/39/46/+4/0.63.0/254/33 54 MPH SE Aero 55 MPH SE 4/4 52/37/45/+3/0.01/0/131/17 32 MPH W 4/5 63/35/49/+6/0/0/721/93 32 MPH WNW Aero 35 MPH WNW 4/6 66/43/55/+12/0/0/591/76 25 MPH S 4/7 70/44/57/+14/0.07/0/164/21 46 MPH SSW 4/8 56/43/50/+6/0.25/0/212/27 32 MPH NW 4/9 58/39/49/+5/0/0/786/100 22 MPH NW 4/10 70/39/55/+11/0/0/742/94 38 MPH NNE 4/11 48/36/42/-3/0/0/744/94 32 MPH NNE 4/12 48/28/38/-7/0.03/0.2/413/52 32 MPH NE 4/13 50/28/39/-6/0/0/622/78 22 MPH WNW 4/14 50/36/43/-3/0/0/.../.. 23 MPH WNW 4/15 48/34/41/-5/0/0/.../.. 35 MPH NE 4/16 55/35/45/-1/0/0/.../.. 22 MPH ESE 4/17 74/37/56/+9/0/0/784/97 23 MPH WNW 4/18 70/48/59/+12/0/0/795/98 27 MPH NW Aero 30 MPH WNW 4/19 78/46/62/+15/0/0/.../.. 27 MPH SSW 4/20 86/47/67/+19/0.16/0/458/56 44 MPH NNE 4/21 Morning low 38 degrees... DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR APRIL 21 HIGH 85 IN 1923 LOW 22 IN 1908 PRECIP 3.18 IN. IN 1991 SNOWFALL 0.8 IN. IN 1947 PEAK GUST 76e MPH NE IN 1940 RECORDS FOR APRIL 22 HIGH 85 IN 1977, 2001 LOW 26 IN 1981 PRECIP 1.85 IN. IN 2000 SNOWFALL 3.0 IN. IN 1940 PEAK GUST 68e MPH NW IN 1945 TODAY'S REPORT BY: Robert Skilling