BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, MAY 20, 2004 ALL TIMES ARE IN EASTERN DAYLIGHT TIME [unless otherwise noted] STRONG RADIATIONAL COOLING LAST NIGHT.... We experienced a relatively mild night last night here at the summit with our minimum temperature of 52 degrees running 4 degrees milder than the normal low for this date of 48 degrees. Low lying areas had much colder readings near 40 degrees at Norwood Airport and Taunton Airport. Martha's Vineyard Airport recorded a very cold 34 degrees early this morning. Today's observations: 5/20/2004 THU 8 a.m. clear with just a few high clouds visibility 15 miles in combo of dissipating light fog below inversion, top of which is 8 hundred feet as seen over the city north, but up to 50 miles to the west-northwest as the summit of Mt. Wachusett could be seen before 8 a.m. A smoke layer exists along the horizons and is most prominent over city to the north where visibility is only 12 miles; temp 57 dewpoint 52; wind west at 07 mph; six hourly minimum temp. 52 degrees, Norwood Airport, 3 miles southwest got down to 41 deg. this morning. BHO SA 1155 CLR 15 264/57/52/2806/031/ FEW CI ALQDS THN K LYR ALG HRZN S-W-NE ESTMTD TOP INVSN 8 HND OVR CTY N VSBY N 12 WNW 50 ABV INVSN THN F DSSPTNG BLO INVSN PST HR HAZY/ 8/001 51017 10057 20052 11 a.m. sunny with high thin cloudiness, vsibility of 50 miles; temp. 70 and dewpoint 41; rh 34%; wind se at 13 mph... BHO SA 1455 300 -SCT 50 263/70/41/1311/031/ WND 11V18/ 8/006 58001 WEATHER SUMMARY FOR WEDNESDAY MAY 19: TEMPERATURE (DEGREES F) MAX.....69 NORMAL.....68 HAZEN.....69.3 @ 1:04 p.m. MIN.....54 NORMAL.....48 HAZEN.....53.7 @ 11:59 p.m. ** MEAN....62 NORMAL.....58 DEPARTURE FROM 30-YEAR NORMAL.....+ 4 TOTAL DEPARTURE FOR THE MONTH.....+99 (+5.0 DEGREES/DAY) ** eastern standard time HEATING DEGREE DAYS TOTAL HEATING DEGREE DAYS FOR YESTERDAY....... 3 DEPARTURE....- 5 TOTAL HEATING DEGREE DAYS FOR THE MONTH......112 DEPARTURE....- 86 TOTAL HEATING DEGREE DAYS FOR THE SEASON....6105 DEPARTURE....- 119 TOTAL HEATING DEGREE DAYS FOR LAST SEASON...6662 DIFFERENCE...- 557 PEAK GUST AND AVERAGE WIND SPEED (MPH)(ALL TIMES LOCAL DAYLIGHT TIME) PEAK WIND GUST FOR YESTERDAY........25 NNW AT 8:52 a.m. AEROVANE.........29 NNW AT 8:52 a.m. ASOS.............23 NNW AT 8:56 a.m. DAVIS............26 N FASTEST MILE FOR YESTERDAY...........17 NW AT 8:30 a.m. ** MAXIMUM 2-MINUTE ASOS AVERAGE........18 SW AT 1:36 a.m. AVERAGE WIND SPEED AND DIRECTION... 10.0 WSW ASOS..............10.1 DAVIS.............10.3 WNW [290 deg] ** earlier occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EDT) TOTAL PRECIPITATION 24 HRS ENDING 8 A.M....0.00 DEPARTURE....-0.12 ASOS..............0.01 [non-real time] TOTAL PRECIPITATION FOR THE MONTH..........1.94 DEPARTURE....-0.43 ASOS..............1.94 TOTAL PRECIPITATION FOR THE YEAR..........19.29 DEPARTURE....-1.03 ASOS.............17.75 2003-2004 SNOWFALL (INCHES) TOTAL SNOWFALL FOR THE SEASON..............58.0 DEPARTURE....+1.7 PRELIMINARY CLIMATE SUMMARY FOR MAY 2004......CALENDAR DAY DATA DATA REPORTED: DATE MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane recording wind system when significant TSTM: Thunderstorm day ....: Data not yet available 5/1 78/50/64/+12/ 0/769/91 39 MPH SSW 5/2 72/56/64/+12/0.06/127/15 45 MPH S Aerovane 49 MPH S 5/3 61/47/54/ +1/0.66/000/00 35 MPH S 5/4 58/39/49/ -4/0.32/725/85 40 MPH WNW Aerovane 46 MPH WNW 5/5 65/38/52/ -1/ T/453/53 37 MPH S 5/6 70/45/58/ +4/ 0/711/83 28 MPH SSW 5/7 84/48/66/+12/0.04/730/85 40 MPH W Aerovane 41 MPH W 5/8 63/41/52/ -2/ 0/621/72 28 MPH S 5/9 55/44/50/-5/0.33/043/05 30 MPH SW 5/10 70/49/60/+5/0/632/73 29 MPH S 5/11 86/53/70/+15/T/573/66 27 MPH WNW 5/12 87/58/73/+17/0/513/59 24 MPH W 5/13 72/43/58/+2/T/610/70 31 MPH NE 5/14 77/45/61/+4/T/533/61 26 MPH S 5/15 88/58/73/+16/0/745/85 35 MPH WSW 5/16 68/49/59/+2/0.08/009/01 30 MPH ENE 5/17 69/49/59/+2/0/415/47 25 MPH S 5/18 71/51/61/+3/0.42/132/15 33 MPH SSW Aerovane 37 MPH SSW 5/19 69/54/62/+4/0.02/.../.. 25 MPH NNW Aerovane 29 MPH NNW 5/20 morning low temp. 52 deg... DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 20 HIGH 91F IN 1975,1996 LOW 37F IN 1948, 2002 PRECIP 1.65 INCHES IN 1969 PEAK GUST 57 MPH S IN 1963, WNW IN 1982 RECORDS FOR MAY 21 HIGH 92F IN 1921 LOW 35F IN 1907 PRECIP 1.61 INS IN 1954 PEAK GUST 69 MPH NW IN 1996 TODAY'S REPORT BY: Robert Skilling