BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, MAY 4, 2004 ALL TIMES ARE EASTERN DAYLIGHT TIME [unless otherwise noted] CLASSIC GRAVITY WAVE EARLY THIS MORNING.... PRESSURE RISES 2 MB IN 3 MINUTES THEN FALLS 5 MB IN 25 MINUTES A sharp rise followed by a sudden plunge in barometric pressure was recorded by our barographs here this morning and was likely the result of the passage of a "gravity wave". The pressure changes are as follows: FROM MICROBAROGRAPH.... Up 0.06 inch or 2 mb in 3 mins. 2:23 to 2:26 a.m. EDT down 0.15 inch or 5.1 mb in 25 mins. 2:26 to 2:51 a.m. EDT There was a windshift from NW to W early during the rapid descent in pressure but then a shift back to NNW close to the end of the fall. Wind gusts were generally in the range of 20 to 27 kts throughout the episode. Rainfall was heaviest during period ending at 2:28 a.m. with a total of 0.05 inch in 4 minutes. Here's an additional report of this occurrence I found this morning. Please see chart of this pressure change provided by Chris Seeber in Charlestown RI: http://www.onsite1.com/pres_graph.shtml TODAY'S OBS... 8 a.m. broken clouds with 70 miles visibility and 43 deg; wind wnw at 17 gusts 25 mph; six hour precip. 0.25; 24 hour precipitation 0.98 inch BHO SA 1155 E15 BKN 20 BKN 60 BKN 70 087/43/39/2915G22/979/ CIG RGD BKN V OVC HIER SC LYR DSNT NNE-ESE/ 8/500 51025 ASOS 60025 MANUAL 6025/ ASOS 70095 MANUAL 70098 10044 20039 11 a.m. broken clouds with 70 miles visibility; 49 deg; wind wnw 21 gusts 35 mph... BHO SA 1455 E38 BKN 70 101/49/33/2918G30/983/ VIRGA DSNT WNW MTN INCLD 70 NW PK WND 3034/29/ 8/500 51014 2 p.m. mostly sunny with 80 miles visibility and 52 deg; wind wnw at 18 gusting 28 mph; six hour maximum 53 deg; BHO SA 1755 48 SCT 80 113/52/30/2916G24/986/ PK WND 2930/1657/ 8/400 53012 10053 20043 WEATHER SUMMARY FOR MONDAY, MAY 3: TIMES ARE LOCAL DAYLIGHT TIME... TEMPERATURE (DEGREES F) MAX.....61 NORMAL.....62 HAZEN...61.0 @ 10:54 A.M. MIN.....47 NORMAL.....43 HAZEN...47.0 @ 11:59 P.M. ** MEAN....54 NORMAL.....53 DEPARTURE FROM 30-YEAR NORMAL.....+1 TOTAL DEPARTURE FOR THE MONTH.....+25 (8.1 DEGREES/DAY) ** eastern standard time HEATING DEGREE DAYS - COOLING DEGREE DAYS TOTAL HEATING DEGREE DAYS FOR YESTERDAY........11 DEPARTURE....- 2 TOTAL HEATING DEGREE DAYS FOR THE MONTH...... 13 DEPARTURE....-24 TOTAL COOLING DEGREE DAYS FOR THE MONTH.........0 TOTAL HEATING DEGREE DAYS FOR APRIL..........501 DEPARTURE....-61 TOTAL COOLING DEGREE DAYS FOR APRIL............1 DEPARTURE....- 2 TOTAL HEATING DEGREE DAYS FOR THE SEASON....6006 DEPARTURE....-59 TOTAL HEATING DEGREE DAYS FOR LAST SEASON...6484 DIFFERENCE..-478 PEAK GUST AND AVERAGE WIND SPEED (MPH) TIME: EDT PEAK WIND GUST FOR YESTERDAY........35 S AT 3:05 A.M. AEROVANE.........36 S AT 3:05 A.M. ASOS.............33 S AT 3:05 A.M. FASTEST MILE FOR YESTERDAY..........N/A MAXIMUM 2-MINUTE ASOS AVERAGE.......26 S AT 3:21 A.M. AVERAGE WIND SPEED AND DIRECTION... N/A ASOS............ 10.9 PRECIPITATION (INCHES) THROUGH THIS MORNING TIME: EDT TOTAL PRECIPITATION 24 HRS ENDING 8 A.M....0.98 ASOS..............0.95 TOTAL PRECIPITATION FOR THE MONTH..........1.04 DEPARTURE....+0.65 ASOS..............1.01 TOTAL PRECIPITATION FOR THE YEAR..........18.39 DEPARTURE....+0.05 ASOS.............15.99 TOTAL SNOWFALL FOR THE SEASON..............58.0 DEPARTURE....+1.8 PRELIMINARY CLIMATE SUMMARY FOR APRIL 2004 and MAY 2004.....CALENDAR DAY DATA DATA REPORTED: 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 41/36/39/-2/3.47/0/000/00 44 MPH NE 4/2 37/36/36/-5/0.30/0/000/00 41 MPH NE 4/3 38/35/37/-5/ 0/0/0/000/00 25 MPH NE 4/4 47/35/41/-1/0.22/0/008/01 32 MPH NW 4/5 40/27/34/-9/0.09/0.5/178/23 45 MPH NW Aerovane 46 MPH NW 4/6 49/26/38/-5/ 0/0/747/96 52 MPH WNW Aerovane 56 MPH WNW 4/7 55/32/44/+1/ 0/0/530/68 31 MPH WSW 4/8 58/32/45/+1/ 0/0/564/72 25 MPH S 4/9 60/39/50/+6/ T/0/550/70 32 MPH W 4/10 57/34/46/+2/ 0/0/718/91 40 MPH W 4/11 51/36/44/-1/ 0/0/063/08 21 MPH W 4/12 47/36/42/-3/0.07/0/341/43 30 MPH ENE 4/13 59/37/48/+3/2.51/0/000/00 56 MPH S Aerovane 61 MPH S 4/14 59/44/52/+6/0.41/0/000/00 62 MPH S Aerovane 64 MPH S 4/15 52/37/45/-1/0.13/0/297/37 36 MPH N Aerovane 38 MPH NNW 4/16 51/33/42/-3/ 0/0/605/75 32 MPH NNW 4/17 74/34/55/+8/ 0/0/501/62 29 MPH S 4/18 63/46/55/+8/ 0/0/608/75 32 MPH SE 4/19 83/44/64/+17/ 0/0/447/55 43 MPH SSW 4/20 67/44/56/+8/ 0/0/326/40 45 MPH W Aerovane 46 MPH W 4/21 62/42/52/+4/ 0/0/450/55 28 MPH SSE 4/22 79/48/64/+15/ T/0/402/49 35 MPH S 4/23 62/39/51/+2/0.88/0/000/00 35 MPH NE 4/24 64/37/51/+2/0.04/0/637/77 46 MPH WNW 4/25 52/34/44/-6/0.04/0/497/60 31 MPH NW 4/26 52/37/45/-5/0.94/0/000/00 28 MPH SSE 4/27 67/47/57/+7/0.28/350/42 38 MPH S 4/28 57/41/49/-2/T/0/560/67 36 MPH WNW Aerovane 37 MPH WNW 4/29 72/42/57/+6/0/0/771/92 43 MPH SSW Aerovane 44 MPH SSW 4/30 81/51/66/+14/0/0/563/67 32 MPH SSW DAILY SNOWFALL REPORTS DISCONTINUED AT THE END OF APRIL 5/1 78/50/64/+12/0/0/.../.. 39 MPH SSW 5/2 72/56/64/+12/0.06/.../.. 45 MPH S Aerovane 49 MPH S 5/3 61/47/54/+1/N/A/000/00 35 MPH S 5/4 morning low temp. 39 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 04 HIGH 90F IN 2001 LOW 27F IN 1911 (RECORD FOR MAY) PRECIP 1.92 INCHES IN 1893 SNOWFALL 0.1 INCHES IN 1920 PEAK GUST 60 MPH NW IN 1966 RECORDS FOR MAY 5 HIGH 92F IN 1949 LOW 30F IN 1891 PRECIP 2.74 INCHES IN 1922 SNOWFALL 3.0 INCHES IN 1917 PEAK GUST 58 MPH S IN 1966 & 58e MPH SW IN 1976 TODAY'S REPORT BY: Robert Skilling