BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, APRIL 19, 2011 ALL TIMES ARE IN EASTERN STANDARD TIME COOL AND CLOUDY, OCCASIONAL LIGHT RAIN SHOWERS The sky has been overcast with varying heights of clouds today. Light rain showers have occasionally occurred on the summit, with only a trace of total precipitation through 2 PM EDT. Visibility has dropped under 20 miles this afternoon due to rain showers in the area and hazy conditions. The high temperature of 49F this morning occurred just after midnight. The temperature has steadily dropped since that point, reaching a low of 44F through 2 PM EDT. The temperature is continuing to drop. Today's observations: 7 A.M. Weather: Light rain, scattered altocumulus, broken altostratus, overcast cirrostratus, thin smoke layer distant all quadrants, distant haze, virga/rain shower NNW-NNE moving E, rain shower began at 6:50 AM EST and ended at unknown time, precipitation very light Temperature: 46F, Dew point: 40F; Wind: N at 5 kts, Wind: Direction gradually backing (counter-clockwise) past 40 minutes Sea-level pressure: 30.05 ins. Hg, rising Visibility: 35 miles, except 45 miles WNW, light rain, distant haze 6-hour min. temp: 46F 6-hour precip: Trace 24-hour precip: Trace BHO SA 1155 80 SCT E120 BKN 200 OVC 35R- 176/46/40/0105/005/ THN K LYR DSNT ALQDS DSNT HZ VSBY WNW 45 VIRGA/SHRA NNW-NNE MOVG E WND GRDLY BACKING PST 40 MIN RW-B50EUKN PCPN VRY LGT/ 8/077 51027 MANUAL 6000/ 10049 20046 10 A.M. Weather: Light rain, scattered altocumulus, broken altostratus, overcast cirrostratus, few altocumulus lenticularis SW-N and overhead, distant haze, precipitation light Temperature: 45F, Dew point: 40F; Wind: NW at 11 kts, Wind: Direction variable WNW-N Sea-level pressure: 30.13 inches Hg, rising Visibility: 20 miles, light rain and distant haze 3-hour precip: Trace BHO SA 1455 60 SCT E100 BKN 200 OVC 20R- 202/45/40/3110/013/ FEW ACSL SW-N AND OVHD DSNT HZ WND 29V35 PCPN LGT/ 8/077 53026 MANUAL 6000/ 1 P.M. Weather: Light rain, scattered stratocumulus, broken stratus, overcast nimbostratus, higher nimbostratus layer visible, rain shower N-overhead-S moving E, hazy, precipitation light and intermittent Temperature: 44F, Dew point: 41F; Wind: NNE at 5 kts, Wind: Light and variable Wind: Direction gradually veering (clockwise) past hour Sea-level pressure: 30.13 inches Hg, rising slightly Visibility: 18 miles, light rain, hazy 6-hour precip: Trace 6-hour max. temp: 47F BHO SA 1755 10 SCT E20 BKN 50 OVC 18R- 203/44/41/0305/013/ HIER NS LYR VSBL SHRA N-OVHD-S MOVG E HAZY WND GRDLY VEERING PST HR WND LGT AND VRB PCPN LGT AND INTMT/ 8/52/ 51001 MANUAL 6000/ 10047 20044 WEATHER SUMMARY FOR MONDAY, APRIL 18 TEMPERATURE (DEGREES F) MAX.....59 NORMAL.....56 MIN.....40 NORMAL.....38 MEAN....50 NORMAL.....47 DEPARTURE FROM 30-YEAR NORMAL...................+3 TOTAL DEPARTURE FOR THE MONTH..................+25 [+1.2 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............15 DEPARTURE........-3 TOTAL HEATING UNITS FOR THE MONTH...........350 DEPARTURE.......-25 TOTAL HEATING UNITS FOR THE SEASON.........5748 DEPARTURE.......-91 TOTAL HEATING UNITS LAST SEASON TO DATE....5321 DIFFERENCE.....+427 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY..............39 SW AT 9:19 A.M. * AEROVANE...............38 WSW AT 7:48 A.M. ASOS...................38 W AT 9:19 A.M. DAVIS..................37 SW AT 6:59 A.M. THE FASTEST MILE FOR YESTERDAY............28 SW AT 9:18 A.M. * MAXIMUM 2-MINUTE ASOS AVERAGE.............26 W AT 9:19 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE............27 SW AT 9:02 A.M. AVERAGE WIND SPEED AND DIRECTION........16.2 SW ASOS.................15.5 DAVIS................15.3 SW [226 DEG] *last of several occurrences... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M...Trace DEPARTURE........-0.14 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........3.93 DEPARTURE........+1.25 ASOS............3.95 TOTAL PRECIPITATION FOR THE YEAR..........17.54 DEPARTURE........+1.23 ASOS..............18.34 ** ** ASOS data is in error due to system failure on 1/12-13 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE........-0.1 TOTAL SNOWFALL FOR THE MONTH................1.6 DEPARTURE........-0.3 TOTAL SNOWFALL FOR THE SEASON..............96.8 DEPARTURE.......+38.0 PRELIMINARY CLIMATE SUMMARY FOR APRIL 2011 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust when significant TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 4/1 36/31/34/-7/0.71/1.6/000/00 35 N AERO 40 MPH N 4/2 50/33/42/0/T/0.0/581/76 38 W AERO 41 MPH W 4/3 53/35/44/+2/0.00/0.0/753/98 41 W AERO 42 MPH W 4/4 46/38/42/0/0.43/T/000/00 33 SE AERO 36 MPH SE 4/5 61/35/48/+5/0.16/0.0/023/03 52 S AERO 55 MPH S 4/6 51/31/41/-2/0.00/0.0/490/63 43 WSW AERO 43 MPH WSW 4/7 52/32/42/-1/0.00/0.0/749/96 22 SSE 4/8 52/34/43/-1/0.00/0.0/422/54 25 SSE 4/9 60/33/47/+3/0.00/0.0/699/89 30 SE 4/10 63/37/50/+6/0.03/0.0/496/63 31 SSE 4/11 69/47/58/+13/0.02/0.0/308/39 35 S AERO 36 MPH S 4/12 61/43/52/+7/0.15/0.0/024/03 43 WNW AERO 45 MPH WNW 4/13 47/40/44/-1/1.13/0.0/000/00 39 ENE AERO 39 MPH ENE 4/14 63/39/51/+5/T/0.0/607/76 29 NNW 4/15 47/31/39/-7/0.00/0.0/730/91 28 NW 4/16 46/31/39/-7/0.18/0.0/266/33 45 ESE AERO 46 MPH ESE 4/17 61/46/54/+7/1.12/0.0/347/43 63 ESE AERO 63 MPH ESE 4/18 59/40/50/+3/T/0.0/.../.. 39 SW AERO 38 MPH WSW 4/19 our morning low temp: 46F; the normal low is now 38F DAILY RECORDS FOR APRIL 2011 4/17 - NEW RECORD PEAK GUST OF 63 MPH ESE; surpasses the previous record of 58 MPH NW in 1994 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR APRIL 19 HIGH 94 IN 1976 [RECORD FOR MONTH] LOW 21 IN 1890 PRECIP 1.71 IN 1969 SNOWFALL 6.0 IN. IN 1887 PEAK GUST 66 MPH E IN 1984 RECORDS FOR APRIL 20 HIGH 88 IN 1927 LOW 18 IN 1897 PRECIP 1.14 IN 1972 SNOWFALL 2.5 IN. IN 1904, 1972 PEAK GUST 76 MPH WNW IN 1963 TODAY'S REPORT PREPARED BY: Sean Fankhauser