BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY MONDAY, AUGUST 5, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME VISIBILITY UP TO 80 MILES UNDER A CLEAR SKY DEW POINTS DROPPING INTO THE 40'S TODAY LOW TEMPERATURE MAY APPROACH RECORD AUGUST 6 A clear and very cool start today brought the lowest temperature since June 20 or the last day of spring. The month of August is off to a slightly cooler than normal start and has been quite a turn around from the hot and humid weather of July. The first four days of this month have averaged over a degree cooler than normal. Dew points have fallen into the 40's and are the lowest since the month of June. The record low for August 6 is 48 degrees in 1934. We may possibly may challenge that reading tomorrow morning. COOLING DEGREE DAY DATA NOW PART OF DAILY DISCUSSION (see below) Starting 8/2/2013, these discussions will provide information on the daily, monthly and seasonal cooling degree day units, which are a measure of the degree to which the daily mean temperature is warmer than 65 deg F over a cooling season. A cooling degree day is recorded as the integer difference between the daily mean temperature and 65 deg F, when the mean temperature is higher than 65 deg F. The cooling degree day season extends from January to December. Additional July statistics can be found below. JULY 2013 PRELIMINARY STATISTICS: (departures relative to 1981-2010 average) TEMPERATURE: Average Max Temp: 83.2F [+2.4F] Average Min Temp: 66.9F [+4.0F] Mean Temp: 75.1F [+3.2F] 24-hr. Corr. Mean Temp: 74.1F [+3.3F] Max Temp: 95F on 19th Min Temp: 57F on 25th Total heating degree day units (month): 6 [-3] *NCDC method Total heating degree day units (season): 6 [-3] *start July 1 (NCDC) Total cooling degree day units (month): 327 [+105] *NCDC method Total cooling degree day units (season): 483 [+132] *start Jan 1 (NCDC) PRECIPITATION: Total precipitation: 3.09 inches [-0.93 inch] Greatest 24-hr precipitation: 1.03 on 25th/26th WIND: Avg wind speed: 9.5 MPH Avg corrected wind speed: 10.1 MPH Prevailing wind direction: SW [12%] Peak gust: 38 MPH SSW on 7th Peak fastest mile: 32 MPH SSW on 7th SUNSHINE: Astronomical minutes: 14,428 of a possible 27,729 or 52% Sun card minutes: 13,884 of a possible 26,682 or 52% BHO Warmest July's, deg F (1885-2013) 1) 75.1 in 2010 2) 74.9 in 1952 3) 74.1 in 1994 74.1 in 2013 5) 74.0 in 2011 6) 73.8 in 1999 7) 73.5 in 1949 8) 73.2 in 2012 BHO Warmest July Average Minimum Temperature, deg F (1885-2013) 1) 66.9 in 2013 2) 65.9 in 2010 3) 65.6 in 1994 4) 65.3 in 2006 5) 65.1 in 2008 BHO Greatest Number of 90-Degree Days per Month, (1885-2013) 1) 14 in July 1952 2) 13 in August 2002 3) 10 in August 1944 10 in July 1949 10 in July 1963 10 in July 2010 10 in July 2013 8) 9 in July 1911 9 in August 1928 10) 8 in August 1949 8 in July 1963 8 in July 1988 BHO July Greatest CDD Total, deg F (1885-2013) 1) 355 in 2010 2) 342 in 1952 3) 329 in 1994 4) 327 in 2013 5) 313 in 1949 6) 308 in 1999 7) 303 in 1911 BHO July Highest Vapor Pressure, mb (1932-2013) (DP = Dew Point) 1) 23.5 in 2013 (DP: 68F) 2) 22.5 in 1994 (DP: 67F) 3) 21.7 in 2006 (DP: 66F) 4) 21.3 in 1988 (DP: 65F) 5) 21.2 in 1955 (DP: 65F) 21.2 in 1975 (DP: 65F) 7) 21.0 in 1967 (DP: 65F) BHO Monthly Highest Vapor Pressure, mb (1932-2013) 1) 23.5 in July 2013 2) 22.5 in July 1994 3) 21.7 in July 2006 4) 21.6 in August 1937 5) 21.5 in August 1988 6) 21.3 in July 1988 Today's Observations: 7 A.M. Weather: Clear, few stratocumulus along and near horizon distant to the W-N Temperature: 60F; Dew Point: 51F; Wind: WNW at 10G19 kts. Sea-level pressure: 29.98 ins. Hg, rising then more slowly Visibility: 80 miles, light distant haze 24-hr precip: Trace 6-hr min. temp: 54F BHO SA 1155 CLR 80 151/60/51/3010G19/998/ FEW SC ALG HRZN DSNT W-N LGT DSNT HZ/ 8/500 51016 10060 20054 10 A.M. Weather: Clear, few cumulus forming mostly distant ENE-S-SSW, few cirrus distant NNW Temperature: 66F; Dew Point: 47F; Wind: WNW at 10G18 kts, Wind: Direction variable WSW-NNW Sea-level pressure: 29.98 ins. Hg, falling slightly Visibility: 75 miles, light distant haze BHO SA 1455 CLR 75 150/66/47/2910G18/997/ SML CU FRMG MSTLY DSNT ENE-S-SSW FEW CI DSNT NNW LGT DSNT HZ WND 24V34/ 8/101 55001 1 P.M. Weather: Clear, few cumulus distant SE-SSE, few cirrus distant S-WSW, few cirrus distant NNW-NNE Temperature: 71F; Dew Point: 46F; Wind: W at 9 kts, Wind: Direction variable WSW-NNW Sea-level pressure: 29.97 ins. Hg, falling slightly Visibility: 75 miles, light distant haze 6-hr max. temp: 72F BHO SA 1755 CLR 75 148/71/46/2709/997/ FEW CU DSNT SE-SSE FEW CI DSNT S-WSW AND DSNT NNW-NNE WND 25V34/ 8/101 58002 10072 20060 WEATHER SUMMARY FOR SUNDAY, AUGUST 4, 2013 TEMPERATURE (DEGREES F) MAX.....79 NORMAL.....81 MIN.....58 NORMAL.....63 MEAN....69 NORMAL.....72 DEPARTURE FROM 30-YEAR NORMAL...................-3 TOTAL DEPARTURE FOR THE MONTH...................-5 [-1.5 DEGREE/DAY] COOLING DEGREE DAYS (SEASON JAN TO DEC) TOTAL COOLING UNITS FOR YESTERDAY.............4 DEPARTURE.........-3 TOTAL COOLING UNITS FOR THE MONTH............23 DEPARTURE.........-6 TOTAL COOLING UNITS FOR THE SEASON..........506 DEPARTURE.......+126 TOTAL COOLING UNITS LAST SEASON TO DATE.....492 DIFFERENCE.......+14 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY................25 WNW AT 4:55 P.M. AERO.....................24 WNW AT 4:55 P.M. * ASOS.....................25 WNW AT 4:56 P.M. DAVIS....................25 W AT 4:55 P.M. RMY 26 FASTEST MILE FOR YESTERDAY..................20 WNW AT 4:55 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE...............18 WNW AT 4:57 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..............17 WNW AT 4:57 P.M. AVERAGE WIND SPEED AND DIRECTION...........9.0 WNW ASOS....................8.8 DAVIS...................8.0 WNW[290 deg.] * Last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....TRACE DEPARTURE............-0.15 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........0.24 DEPARTURE............-0.36 ASOS..............0.23 TOTAL PRECIPITATION FOR THE YEAR..........35.53 DEPARTURE............+3.94 ASOS..............N/A* *ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals PRELIMINARY CLIMATE SUMMARY FOR JULY & AUGUST 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 7/1 82/69/76/+6/0.05/247/27 29 S AERO 31 MPH SSW RMY 32 7/2 82/61/72/+2/T/100/11 23 SSW AERO 23 MPH SSW RMY 25 7/3 87/62/75/+4/T/556/61 28 SW AERO 30 MPH SW RMY 30 7/4 90/71/81/+10/0.00/811/89 25 WSW AERO 26 MPH SW RMY 28 7/5 92/73/83/+12/0.00/874/96 24 W AERO 25 MPH WSW RMY 25 7/6 90/73/82/+11/0.00/836/92 25 WNW AERO 25 MPH WNW RMY 26 7/7 91/72/82/+11/0.21/508/56 38 SSW AERO 43 MPH SSW RMY 44 TSTM 7/8 82/64/73/+1/0.04/617/68 18 NE AERO 20 MPH NE RMY 20 TSTM 7/9 72/63/68/-4/0.01/054/06 14 ENE AERO 14 MPH ENE RMY 14 7/10 84/65/75/+3/T/335/37 32 S AERO 36 MPH S RMY 35 7/11 79/69/74/+2/0.62/009/01 23 W AERO 23 MPH W RMY N/A TSTM 7/12 70/62/66/-6/0.00/162/18 29 NE AERO 29 MPH NE RMY 30 7/13 75/62/69/-3/0.08/009/01 21 ENE AERO 20 MPH ENE RMY N/A 7/14 89/71/80/+8/0.00/477/53 16 W AERO 16 MPH W RMY 16 7/15 91/72/82/+10/0.00/665/74 17 NW AERO 16 MPH NW RMY 18 7/16 91/71/81/+9/0.00/843/94 18 NNW AERO 16 MPH NNW RMY 16 7/17 93/74/84/+12/0.00/841/94 22 SW AERO 23 MPH SW RMY 25 7/18 90/75/83/+11/0.00/724/81 20 S AERO 21 MPH S RMY 22 7/19 95/76/86/+14/0.00/723/81 36 WSW AERO 38 MPH WSW RMY 38 7/20 93/72/83/+11/0.00/570/64 29 W AERO 30 MPH W RMY 31 TSTM 7/21 82/68/75/+3/0.00/568/64 16 NE AERO 16 MPH NE RMY 17 7/22 80/67/74/+2/T/514/58 17 NE AERO 17 MPH NE RMY 19 TSTM 7/23 82/68/75/+3/0.82/159/18 35 WSW AERO 36 MPH WSW RMY 39 7/24 84/64/74/+2/0.00/627/71 23 N AERO 23 MPH N RMY 23 7/25 64/57/61/-11/0.43/000/00 24 NNE AERO 24 MPH NNE RMY 25 7/26 67/59/63/-9/0.70/000/00 23 NNW AERO 23 MPH N RMY 23 7/27 82/60/71/-1/0.00/535/61 22 S AERO 23 MPH S RMY 23 7/28 78/66/72/0/0.03/149/17 16 ENE AERO 16 MPH ENE RMY 15 7/29 81/66/74/+2/0.10/402/46 20 S AERO 18 MPH S RMY 21 TSTM 7/30 81/61/71/-1/0.00/766/88 20 WNW AERO 18 MPH WNW RMY 20 7/31 80/61/71/-1/0.00/747/86 16 S AERO 15 MPH S RMY 16 8/1 81/62/72/0/0.01/.../.. 25 S AERO 26 MPH S RMY 27 8/2 81/62/72/0/0.23/.../.. 26 W AERO 26 MPH W RMY 28 8/3 77/63/70/-2/T/.../.. 22 WSW AERO 23 MPH WSW RMY 23 8/4 79/58/69/-3/T/.../.. 25 WNW AERO 21 MPH WNW RMY 26 8/5 morning low temp: 54F; the normal low is now 63F DAILY RECORDS FOR JULY 2013 7/14 - TIED DAILY RECORD HIGH MINIMUM TEMPERATURE OF 71F; ties previous record of 71F set in 1997 7/15 - NEW DAILY RECORD HIGH MINIMUM TEMPERATURE OF 72F; surpasses previous record of 70F set in 1901, 1934, 1995 7/16 - TIED DAILY RECORD HIGH MINIMUM TEMPERATURE OF 71F; ties previous record of 71F set in 1901, 1958, 1968 7/17 - TIED DAILY RECORD HIGH MINIMUM TEMPERATURE OF 74F; ties previous record of 74F set in 1900 7/18 - NEW DAILY RECORD HIGH MINIMUM TEMPERATURE OF 75F; surpasses previous record of 73F set in 1900, 1999 7/19 - NEW DAILY RECORD HIGH MINIMUM TEMPERATURE OF 76F; surpasses previous record of 72F set in 1949, 1991, 2005 DAILY RECORDS FOR AUGUST 2013 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR AUGUST 5 HIGH 98F IN 1955 LOW 48F IN 1929,1972 PRECIP 3.03 INCHES IN 1893 PEAK GUST 60e MPH SW 1977 RECORDS FOR AUGUST 6 HIGH 95F IN 1931 LOW 48F IN 1934 PRECIP 1.47 INCHES IN 1995 PEAK GUST 44e MPH SSW IN 1940 TODAY'S REPORT PREPARED BY: Robert Skilling, Marc Douglas, Mark Medlinskas