BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, JULY 20, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME VERY HOT WITH OPPRESSIVE HUMIDITY AGAIN TODAY... HEAT WAVE EXTENDS TO SIX CONSECUTIVE DAYS... TOWERING CUMULUS BUILDING THIS AFTERNOON AS COLD FRONT DRAWS CLOSER... So far today, the temperature has reached 93F through 1 PM EST, which is well below the record for the date of 99 set in 1991. The low temperature on Friday of 76F is a new record high minimum for the date breaking the previous record of 72F set in 1949, 1991, 2005. This is also the sixth consecutive day that the record high minimum was tied or surpassed. The low temperature for day of 76F is also above the record high minimum for July 20th, though a lower temperature may be recorded before midnight today. The recent heat wave has been extended to six days at the Observatory with the reading of 93F today, though no record daily high maximum temperatures were tied or broken in this period. For the third consecutive day, the temperature at 7 AM EST was 80F or higher. Although higher temperatures have been recorded at this time of day in recent years, this may be the first occurrence on record of three straight days of 80F or higher at that time of day in records checked back about 50 years. Today also marks the tenth day this month with a high temperature of 90F or higher. This is among the greatest number of such days for any month on the entire period of record. Conditions are quite humid once again, with dew point temperatures in the middle 70s earlier this morning dropping to near 70 as of early afternoon due in part to increasing winds mixing slightly drier air down to the surface. 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 (through 7/20) 8) 9 in July 1911 9 in August 1928 10) 8 in August 1949 8 in July 1963 8 in July 1988 BHO Longest Heat Waves of Consecutive 90-Degree Days, (1885-2013) 1) 9 on 11-19 August 2002 2) 8 on 10-17 August 1944 3) 6 on 24-29 July 1963 6 on 16-21 July 1977 6 on 6-11 July 1988 6 on 16-21 July 1991 6 on 15-20 July 2013 BHO Highest 7AM EST Temperature, deg F (1960-2013) 1) 84 on 6 July 2010 2) 83 on 22 July 2011 3) 82 on 21 July 1991 82 on 18 July 2012 5) 81 on 2 August 1975 81 on 27 June 1999 81 on 18 July 2013 * 81 on 20 July 2013 * 9) 80 on 23 July 1978 80 on 23 July 1998 80 on 5 July 1999 80 on 6 July 1999 80 on 9 August 2001 80 on 4 July 2002 80 on 30 July 2002 80 on 2 August 2006 80 on 3 August 2006 80 on 21 June 2012 80 on 22 June 2012 80 on 19 July 2013 * Today's Observations: 7 A.M. Weather: Scattered altocumuus, scattered dense cirrus, thin broken cirrus, few altocumulus castellanus E-ESE, few cirrocumulus overhead Temperature: 81F; Dew Point: 74F; Wind: WSW at 10 kts. Sea-level pressure: 29.76 ins. Hg, rising slightly Visibility: 8 miles, hazy 6-hr min. temp: 76F BHO SA 1155 140 SCT 200 SCT 250 –BKN 8 077/81/74/2410/976/ FEW ACCAS E-ESE FEW CC OVHD HAZY/ 8/031 53003 10081 20076 10 A.M. Weather: Scattered altocumulus (two levels), scattered dense cirrus, thin broken cirrus, few cumulus forming WNW-NNW and distant ESE, few cirrocumulus overhead Temperature: 89F; Dew Point: 73F; Wind: SW at 11 kts, Sea-level pressure: 29.73 ins. Hg, falling Visibility: 10 miles, hazy BHO SA 1455 120 SCT 140 SCT 200 SCT 250 –BKN 10 067/89/73/2311/973/ FEW CU FRMG WNW-NNW AND DSNT ESE FEW CC OVHD HAZY/ 8/232 56010 1 P.M. Weather: Scattered cumulus, broken altocumulus, broken cirrus, moderate cumulus all quadrants, towering cumulus/cumulonimbus with pileus cloud distant NE moving NE Temperature: 90F; Dew Point: 72F; Wind: SW at 10G19 kts, Sea-level pressure: 29.68 ins. Hg, falling Visibility: 20 miles, hazy 6-hr max. temp: 93F BHO SA 1755 35 SCT 140 BKN 250 BKN 20 052/90/72/2310G19/968/ MDT CU ALQDS TCU/CB W/PILEUS DSNT NE MVNG NE HAZY/ 8/231 58015 10093 20081 WEATHER SUMMARY FOR FRIDAY, JULY 19, 2013 TEMPERATURE (DEGREES F) MAX.....95 NORMAL.....81 MIN.....76 NORMAL.....63 MEAN....86 NORMAL.....72 DEPARTURE FROM 30-YEAR NORMAL.....................+14 TOTAL DEPARTURE FOR THE MONTH....................+113 [+5.7 DEGREES/DAY] PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY................36 WSW AT 3:24 P.M. AERO.....................38 WSW AT 3:24 P.M. ASOS.....................38 SW AT 3:25 P.M. DAVIS....................36 WSW AT 3:25 P.M. RMY 38 FASTEST MILE FOR YESTERDAY..................28 SW AT 5:05 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE...............26 SW AT 5:15 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..............27 SSW AT 5:14 P.M. AVERAGE WIND SPEED AND DIRECTION..........15.5 SSW ASOS...................14.9 DAVIS..................13.7 SW [228 deg.] * last of several occurrences... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE............-0.13 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........1.01 DEPARTURE............-1.32 ASOS..............1.00 TOTAL PRECIPITATION FOR THE YEAR..........33.21 DEPARTURE............+3.91 ASOS..............N/A* *ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals PRELIMINARY CLIMATE SUMMARY FOR JULY 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/.../.. 22 SW AERO 23 MPH SW RMY 25 7/18 90/75/83/+11/0.00/.../.. 20 S AERO 21 MPH S RMY 22 7/19 95/76/86/+14/0.00/.../.. 36 WSW AERO 38 MPH WSW RMY 38 7/20 morning low temp: 76F; 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 EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR JULY 20 HIGH 99F IN 1991 LOW 47F IN 1890 PRECIP 1.64 INS IN 1938 WIND 56e MPH SSW IN 1943 RECORDS FOR JULY 21 HIGH 100F IN 1977 [RECORD FOR MONTH] LOW 48F IN 1890 PRECIP 2.09 INCHES IN 1938 PEAK GUST 60e MPH WNW IN 1977 TODAY'S REPORT PREPARED BY: Mike Iacono/Peter Volpe/Will Wilson