BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, MAY 3, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME CHILLY NE WINDS PERSIST; MORNING CLOUDS GIVE WAY TO AFTERNOON SUN The low temperature bottomed out at 42F this morning on the summit beneath a cloudy sky...a chilly start to say the least. The high temperature so far today has only managed to reach the lower 50s, despite dissipating clouds and a mostly sunny sky. A chilly air mass continues to pour in from the North Atlantic and Canadian Maritimes. That chilly air mass arrived Thursday afternoon with a vengeance! A backdoor cold front roared into the region, dropping temperatures into the mid 40s only 5-6 hours after high temperatures reached the mid 70s. A few sprinkles were observed behind the front, including here on the summit where a trace of rainfall was recorded. Very dry weather continues. From March 20 through today (45 days), Blue Hill has received only 2.44 inches of precipitation. That is only 34% of the 30-year normal of 7.17 inches. APRIL 2013 PRELIMINARY STATISTICS: (departures relative to 1981-2010 average) TEMPERATURE: Average Max Temp: 58.1F [+2.4F] Average Min Temp: 38.1F [+0.4F] Mean Temp: 48.1F [+1.4F] 24-hr. Corr. Mean Temp: 47.0F [+0.7F] Max Temp: 72F on 9th, 19th, 24th Min Temp: 26F on 4th Total heating degree day units (month): 502 [ -49] *NCDC method Total heating degree day units (season): 5,522 [-513] *start July 1 (NCDC) PRECIPITATION: Total precipitation: 2.29 inches [-2.26 inches] Greatest 24-hr precipitation: 0.61 inches on 11th/12th Total snowfall: Trace [-3.0 inches] Total seasonal snowfall: 99.0 inches [+36.3 inches] WIND: Avg wind speed: 13.3 MPH Avg corrected wind speed: 13.7 MPH Prevailing wind direction: S [14%] Peak gust: 51 MPH S on 7th Peak fastest mile: 40 MPH S on 7th SUNSHINE: Astronomical minutes: 14,392 of possible 24,094 or 60% Campbell-Stokes card minutes: 13,876 of possible 23,250 or 60% Today's observations: 7 A.M. Weather: Broken stratocumulus/cumulus all quadrants, few cumulus fractus S-W-N, hazy Temperature: 45F; Dew Point: 40F; Wind: NE at 10G17 kts, Wind: Direction variable N-E Sea-level pressure: 30.52 ins. Hg, rising Visibility: 35 miles, hazy 24-hr precip: Trace 6-hour min. temp: 42F BHO SA 1155 E10 BKN 35 334/45/40/0510G17/052/ SC/CU ALQDS FEW CUFRA S-W-N HAZY WND 01V08/ 8/500 51014 MANUAL 7000/ 10045 20042 10 A.M. Weather: Broken cumulus/stratocumulus, broken stratocumulus, cumulus all quadrants, line of moderate tops extending W-N, stratocumulus mostly E-S, few cumulus fractus all quadrants, few higher stratocumulus lenticularis NNW-ENE, distant haze Temperature: 50F; Dew Point: 40F; Wind: NE at 12 kts, Wind: Direction variable N-E Sea-level pressure: 30.52 ins. Hg, rising then falling Visibility: 50 miles, distant haze BHO SA 1455 E15 BKN 30 BKN 50 335/50/40/0512/052/ CU ALQDS LINE MDT TOPS XTNDNG W-N SC MSTLY E-S FEW CUFRA ALQDS FEW HIER SCSL NNW-ENE DSNT HZ WND 36V09/ 8/800 50001 1 P.M. Weather: Scattered cumulus, scattered stratocumulus, cumulus mostly ENE-SW, few moderate cumulus ESE-S, higher stratocumulus lenticularis NNE-SE, thin smoke layer aloft distant WSW-NW-NE, light distant haze Temperature: 53F; Dew Point: 40F; Wind: NE at 11G16 kts, Wind: Direction variable N-E Sea-level pressure: 30.48 ins. Hg, falling Visibility: 65 miles, light distant haze 6-hour max. temp: 53F BHO SA 1755 15 SCT 30 SCT 65 323/53/40/0511G16/048/ CU MSTLY ENE-SW FEW MDT CU ESE-S HIER SCSL NNE-SE THN K LYR ALF DSNT WSW-NW-NE LGT DSNT HZ WND 36V08/ 8/800 58012 10053 20045 WEATHER SUMMARY FOR THURSDAY, MAY 2, 2013 TEMPERATURE (DEGREES F) MAX.....75 NORMAL.....62 MIN.....43 NORMAL.....44 MEAN....59 NORMAL.....53 DEPARTURE FROM 30-YEAR NORMAL....................+6 TOTAL DEPARTURE FOR THE MONTH....................+9 [+4.3 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............6 DEPARTURE..........-6 TOTAL HEATING UNITS FOR THE MONTH............15 DEPARTURE.........-10 TOTAL HEATING UNITS FOR THE SEASON.........5537 DEPARTURE........-523 TOTAL HEATING UNITS LAST SEASON TO DATE....4752 DIFFERENCE.......+785 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............29 NE AT 2:45 P.M. AERO....................26 NE AT 2:59 P.M. * ASOS....................30 NE AT 2:46 P.M. DAVIS...................28 NE AT 2:45 P.M. RMY: 29 THE FASTEST MILE FOR YESTERDAY.............22 NE AT 2:45 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE..............21 ENE AT 3:21 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............21 NE AT 2:47 P.M. AVERAGE WIND SPEED AND DIRECTION..........8.2 ENE ASOS...................8.3 DAVIS..................7.3 ENE [069 deg] *last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M...Trace DEPARTURE...........-0.12 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH.........Trace DEPARTURE...........-0.24 ASOS..............0.00 TOTAL PRECIPITATION FOR THE YEAR..........16.38 DEPARTURE...........-2.41 ASOS..............N/A* *ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........0.0 DEPARTURE.............0.0 TOTAL SNOWFALL FOR THE MONTH...............0.0 DEPARTURE.............0.0 TOTAL SNOWFALL FOR THE SEASON.............99.0 DEPARTURE...........+36.3 PRELIMINARY CLIMATE SUMMARY FOR APRIL AND MAY 2013 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust RMY: RMY = R.M. Young wind gust recording system added 8/9/2011 TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 4/1 61/31/46/+5/0.34/0.0/458/60 40 W AERO 44 MPH WNW RMY 46 TSTM 4/2 40/27/34/-7/T/T/460/60 45 W AERO 42 MPH W RMY 47 4/3 45/27/36/-6/0.00/0.0/755/98 44 W AERO 43 MPH W RMY 47 4/4 55/26/41/-1/0.00/0.0/719/93 30 WSW AERO 27 MPH WSW RMY 31 4/5 59/36/48/+5/0.00/0.0/403/52 33 NNW AERO 28 MPH NNW RMY 38 4/6 47/30/39/-4/0.00/0.0/747/96 38 NW AERO 35 MPH NW RMY 40 4/7 52/31/42/-1/0.00/0.0/391/50 51 S AERO 46 MPH S RMY 50 4/8 65/43/54/+10/T/0.0/494/63 29 SSW AERO 22 MPH SSW RMY N/A 4/9 72/44/58/+14/T/0.0/456/58 35 WNW AERO 35 MPH WNW RMY 39 TSTM 4/10 64/43/54/+9/0.13/0.0/426/54 23 SE AERO 20 MPH SE RMY 25 4/11 52/40/46/+1/0.09/0.0/063/08 18 ENE AERO 14 MPH ENE RMY N/A 4/12 40/34/37/-8/0.58/T/000/00 38 E AERO 32 MPH E RMY 41 4/13 52/34/43/-3/0.04/0.0/128/16 31 NNE AERO 27 MPH NNE RMY 31 4/14 52/36/44/-2/0.00/0.0/216/27 31 WNW AERO 27 MPH WNW RMY 32 4/15 55/35/45/-2/0.00/0.0/514/64 21 ESE AERO 15 MPH S RMY N/A 4/16 62/38/50/+3/T/0.0/540/67 44 S AERO 40 MPH S RMY 45 4/17 67/48/58/+11/T/0.0/769/95 29 SSW AERO 25 MPH SSW RMY N/A 4/18 65/43/54/+6/0.00/0.0/503/62 30 S AERO 25 MPH S RMY N/A 4/19 72/50/61/+13/0.07/0.0/195/24 47 SSW AERO 48 MPH SSW RMY 50 4/20 62/39/51/+2/0.48/0.0/147/18 43 SSW AERO 41 MPH SSW RMY N/A 4/21 53/31/42/-7/0.00/0.0/819/100 31 WNW AERO 25 MPH WNW RMY N/A 4/22 49/35/42/-7/0.00/0.0/551/67 32 E AERO 28 MPH E RMY 33 4/23 40/38/39/-11/0.50/0.0/000/00 35 NNE AERO 30 MPH NNE RMY 35 4/24 72/40/56/+6/0.01/0.0/463/56 36 SSW AERO 33 MPH SSW RMY N/A 4/25 64/44/54/+4/0.05/0.0/581/70 38 W AERO 32 MPH W RMY N/A 4/26 58/42/50/-1/0.00/0.0/607/73 28 ENE AERO 22 MPH ENE RMY N/A 4/27 62/42/52/+1/0.00/0.0/802/96 21 S AERO 17 MPH S RMY 22 4/28 69/44/57/+5/0.00/0.0/771/92 25 S AERO 21 MPH S RMY 27 4/29 69/46/58/+6/0.00/0.0/697/83 25 S AERO 30 MPH S RMY 26 4/30 67/47/57/+5/0.00/0.0/717/85 23 ENE AERO 21 MPH ENE RMY 23 5/1 67/45/56/+3/0.00/.../.. 18 E AERO 16 MPH E RMY 17 5/2 75/43/59/+6/T/.../.. 29 NE AERO 26 MPH NE RMY 29 5/3 morning low temp: 42F; the normal low is now 44F DAILY RECORDS FOR APRIL 2013 None DAILY RECORDS FOR MAY 2013 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 3 HIGH 92F IN 2001 LOW 31F IN 1888 PRECIP 2.25 INS IN 1900 SNOWFALL TRACE IN 1908, 1985 PEAK GUST 71 MPH W IN 2002 RECORDS FOR MAY 4 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 TODAY'S REPORT PREPARED BY: Sean Fankhauser