BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY MONDAY, APRIL 20, 2009 PATRIOTS DAY ALL TIMES ARE IN EASTERN STANDARD TIME DENSE HIGH OVERCAST WITH SOME DIMMED SUNSHINE INCREASING EAST WINDS GUSTING OVER 30 MPH High cirrostratus clouds are allowing only some filtered sunshine today and are the forerunners of an important rain area approaching from the south and southwest. East winds were steadily increasing and by early afternoon averaged near 25 MPH gusting to 37 MPH. The air is very dry with dew points dropping to the lower 20's along with relative humidity down to 33%. Today's weather observations: 7 A.M. Weather: Scattered stratus clouds, high thin overcast of cirrus clouds, fog and stratus dissipating during the past hour Temperature: 40F, Dew point: 38F, Wind: ENE at 9 kts Sea-level pressure: 30.28 inches Hg, rising Visibility: 15 miles, N-NE 30 miles, S 10, W 15 6-hour minimum temperature: 36F BHO SA 1155 5 SCT 220 SCT 250 –BKN 300 –OVC 15 255/40/38/0709/028/ FG/STRA DSSPTNG PST HR VSBY N-NE 30 S 10 W 15 THN FG/ 8/601 53010 10040 20036 10 A.M. Weather: High dense cirrostratus overcast with a few thin spots northeast, very dimmed sunshine, few cumulus distant W-NW Temperature: 47F, Dew point: 26F, Wind: E at 14G23 kts, Wind: Direction variable NE to ESE Sea-level pressure: 30.29 inches Hg, falling Visibility: 60 miles, NW 70 miles BHO SA 1455 E220 OVC 60 259/47/28/0814G23/029/ FEW CU DSNT W-NW FEW THN SPTS IOVC NE VSBY NW 70 WND 05V11/ 8/107 50004 1 P.M. Weather: High dense cirrostratus overcast with lower altocumulus lenticularis Temperature: 48F, Dew point: 22F, Wind: E at 22G32 kts, Wind: Peak wind gust 32 kts ENE at 12:53 P.M. Wind: Direction variable ENE to ESE Sea-level pressure: 30.25 inches Hg, falling Visibility: 60 miles, NW 70 miles BHO SA 1755 E200 OVC 60 245/48/22/0822G32/025/ FEW ACSL VSBY NW 70 PK WND 0732/53/ WND 06V12 8/047 57014 10051 20040 WEATHER SUMMARY FOR SUNDAY, APRIL 19, 2009 TEMPERATURE (DEGREES F) MAX.....52 NORMAL......57 MIN.....38 NORMAL......38 MEAN....45 NORMAL......47 DEPARTURE FROM 30-YEAR NORMAL..................-2 TOTAL DEPARTURE FOR THE MONTH.................+15 [+0.6 DEGREE/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............20 DEPARTURE........+2 TOTAL HEATING UNITS FOR THE MONTH............378 DEPARTURE.......-15 TOTAL HEATING UNITS FOR THE SEASON..........5796 DEPARTURE.......-61 TOTAL HEATING UNITS LAST SEASON TO DATE.....5486 DIFFERENCE.....+310 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY............33 NNE AT 6:33 A.M. AEROVANE.............28 NNE AT 6:33 A.M. ASOS.................31 NNE AT 6:33 A.M. DAVIS................28 N AT 6:33 A.M. FASTEST MILE FOR YESTERDAY..............21 NNE AT 6:38 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE...........20 NE AT 1:29 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..........20 NE AT 1:29 P.M. AVERAGE..............11.2 NW ASOS.................10.9 DAVIS................11.3 N [360 deg] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.....0.00 DEPARTURE.........-0.14 ASOS...............0.00 TOTAL PRECIPITATION FOR THE MONTH...........3.31 DEPARTURE.........+0.49 ASOS...............3.34 TOTAL PRECIPITATION FOR THE YEAR...........13.39 DEPARTURE.........-3.06 ASOS..............14.47 # # Includes erroneous ASOS precipitation data on 1/1/09, 1/2/09 and 2/27/09. SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE.........-0.1 TOTAL SNOWFALL FOR THE MONTH................0.2 DEPARTURE.........-1.8 TOTAL SNOWFALL FOR THE SEASON..............78.9 DEPARTURE........+20.0 PRELIMINARY CLIMATE SUMMARY FOR APRIL 2009 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/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 4/1 43/31/38/-3/0.13/0/015/02 24 SE 4/2 52/39/46/+4/0.02/0/000/00 20 SSE 4/3 58/45/52/+10/0.70//000/00 39 SSE AERO 38 MPH SSE TSTM 4/4 51/38/45/+3/0.01/0/015/02 48 WSW AERO 48 MPH WSW 4/5 58/37/48/+5/0/0/551/71 40 W AERO 37 MPH W 4/6 55/38/47/+4/1.42/0/047/006 42 SE AER0 40 MPH SE TSTM 4/7 50/34/42/-1/T/0/109/14 36 WSW AERO 35 MPH WSW 4/8 45/32/39/-5/0/0/149/19 33 SW AERO 31 MPH SW 4/9 60/34/47/+3/0/0/692/88 36 SSW AERO 33 MPH SSW 4/10 65/41/53/+9/0.18/0/544/69 37 SSW AERO 35 MPH SSW 4/11 44/33/39/-6/0.77/0.2/000/00 35 N AERO 30 MPH N 4/12 43/29/36/-9/0/0/541/68 45 NW AERO 43 MPH WNW 4/13 52/29/41/-4/0/0/734/92 38 W AERO 35 MPH W 4/14 58/37/48/+2/0/0/696/87 25 E 4/15 49/36/43/-3/0/0/.../.. 35 NE AERO 31 MPH NE 4/16 50/34/42/-4/0/0/.../.. 29 NNE 4/17 69/35/52/+5/0/0/.../.. 37 W AERO 33 MPH W 4/18 64/44/54/+7/0.05/0/.../.. 28 W 4/19 52/38/45/-2/0.03/0/773/95 33 NNE AERO 28 MPH NNE 4/20 morning low temp: 36F; our normal low is now 39F NEW DAILY RECORDS FOR APRIL 2009... None to date.. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): 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 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 TODAY'S REPORT PREPARED BY: Robert Skilling