BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, MAY 5, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME COOL, DRY CONDITIONS CONTINUE The low temperature fell to 37F at the summit this morning, our coldest reading of the month so far and well below the average morning low for this time of year of 45F. With winds coming in off the ocean again today, temperatures have been held below 60F, topping out at 57F so far by 1PM this afternoon, which is below our average for this date of 63F. We are on track for our third straight day of below average temperatures. The day began with broken stratocumulus clouds covering a large portion of the sky, but these gradually decreased in coverage through late morning and early afternoon, allowing for plenty of sunshine with cirrus clouds moving in. Visibility has been held to 40 miles or less today as we have once again had to deal with quite a bit of haze. Very dry weather continues. From March 20 through today (47 days), Blue Hill has received only 2.44 inches of precipitation. That is only 33% of the 30-year normal of 7.42 inches for this time period. No measurable precipitation has fallen since April 25. 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: 13,872* of possible 23,250 or 60% *Corrected total Today's observations: 7 A.M. Weather: Broken stratocumulus Temperature: 45F; Dew Point: 40F; Wind: N at 6 kts Sea-level pressure: 30.34 ins. Hg, rising Visibility: 30 miles, hazy 6-hour min. temp: 37F BHO SA 1155 E10 BKN 30 275/45/40/0106/034/ HAZY/ 8/500 52010 10045 20037 10 A.M. Weather: Broken stratocumulus, few lower cumulus fractus, few altocumulus E-SE, few cirrus NW-NE Temperature: 51F; Dew Point: 40F; Wind: ENE at 8 kts, Wind: Direction variable N-E Sea-level pressure: 30.34 ins. Hg, rising then falling Visibility: 35 miles, distant haze BHO SA 1455 E15 BKN E120 BKN E250 BKN 35 274/51/40/0608/034/ FEW LWR CUFRA FEW AC E-SE FEW CI NW-NE DSNT HZ WND 35V10/ 8/571 58001 1 P.M. Weather: Clear, few stratocumulus ENE-SSE, cirrus SW-NNE Temperature: 57F; Dew Point: 40F; Wind: ENE at 8 kts, Wind: Direction variable NNE-ESE Sea-level pressure: 30.32 ins. Hg, falling Visibility: 40 miles, distant haze 6-hour max. temp: 57F BHO SA 1755 CLR 40 268/57/40/0708/032/ FEW SC ENE-SSE CI SW-NNE DSNT HZ WND 30V11 8/501 57006 10057 20045 WEATHER SUMMARY FOR SATURDAY, MAY 4, 2013 TEMPERATURE (DEGREES F) MAX.....55 NORMAL.....63 MIN.....40 NORMAL.....44 MEAN....48 NORMAL.....54 DEPARTURE FROM 30-YEAR NORMAL....................-6 TOTAL DEPARTURE FOR THE MONTH....................-2 [-0.3 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............17 DEPARTURE..........+5 TOTAL HEATING UNITS FOR THE MONTH............32 DEPARTURE..........+1 TOTAL HEATING UNITS FOR THE SEASON.........5571 DEPARTURE........-512 TOTAL HEATING UNITS LAST SEASON TO DATE....4782 DIFFERENCE.......+789 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............21 NE AT 9:36 A.M. AERO....................23 NE AT 9:36 A.M. ASOS....................23 NE AT 1:28 P.M. DAVIS...................22 ENE AT 1:21 P.M. RMY: 23 THE FASTEST MILE FOR YESTERDAY.............18 NE AT 1:19 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE..............17 E AT 12:39 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............15 ENE AT 1:22 P.M. AVERAGE WIND SPEED AND DIRECTION..........9.8 ENE ASOS...................9.1 DAVIS..................8.8 ENE [060 deg] * Last of several occurrences... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE...........-0.12 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH.........Trace DEPARTURE...........-0.49 ASOS..............0.00 TOTAL PRECIPITATION FOR THE YEAR..........16.38 DEPARTURE...........-2.66 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 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 54/42/48/-5/0.00/.../.. 24 NE AERO 25 MPH NE RMY 28 5/4 55/40/48/-6/0.00/.../.. 21 NE AERO 23 MPH NE RMY 23 5/5 morning low temp: 37F; the normal low is now 45F 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 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 RECORDS FOR MAY 6 HIGH 90F IN 1930 LOW 29F IN 1891 PRECIP 1.04 INCHES IN 1890 SNOWFALL TRACE IN 1917,1996 PEAK GUST 65 MPH SSE IN 1989 TODAY'S REPORT PREPARED BY: Jonathan O'Brien