BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, AUGUST 18, 2018 ALL TIMES ARE IN EASTERN STANDARD TIME WARM AND VERY MUGGY WITH BUILDING CUMULUS THIS MORNING... THUNDERSTORMS WITH HEAVY RAIN ARRIVE THIS AFTERNOON... The temperature reached 83F again today during a period of broken sunshine late this morning after a warm morning low of 71F. These readings are warmer than the normal high and low for the date of 79F and 62F. The maximum and minimum temperatures on Friday were 83F and 67F. The dew point has remained above 70F all day making it feel very warm and muggy. A few very light rain showers passed the Observatory between 7:35 AM EST and 8:45 AM EST this morning leaving only a trace. The skies became partly sunny by late morning, then clouds began to advance toward the southeast from an advancing cold front passing through New England today. A wind shift from W to NNW occurred at about 1:42 PM today due to the outflow from a line of thunderstorms that were moving toward the southeast by early afternoon. Only a trace of rainfall was observed through 1 PM EST, though light rain began again at 2:12 PM and thunder began at 2:15 PM as the line of storms approached the Observatory. A very close flash of lightning, within one-half mile, was observed with loud thunder at 2:20 PM EST. Roughly 0.20 inches of rain fell during the next 45 minutes through 3 PM EST with much of this falling in about 8 minutes from 2:37 to 2:45 PM, and thunder and in-cloud and cloud-to-cloud lightning continued. As this storm moved east, another approached from the west and moderate to heavy rain began shortly after 3 PM lasting about 10 minutes and amounting to another 0.10 inches as thunder and occasional lightning continued. After a short break, rain picked up and thunder became more frequent once again at 3:37 PM as a third thunderstorm passed the Observatory. A close cloud-to-cloud bolt of lightning flashed across the sky just west of the hill at 3:44 PM with moderate rain in progress. The rain became light again at 3:48 PM and distant thunder was continuing at 4:10 PM EST as the third thunderstorm receded to the southeast. The total rainfall between 2 PM and 4 PM EST was 0.37 inches. August is still running above normal for both precipitation and and temperature. Currently we are +0.69 ins above normal for rainfall and +4.3 degrees above normal for temperature. Today's Observations: 7 A.M. Weather: Broken stratus, overcast altocumulus, few lower stratus fractus Temperature: 71F; Dew Point: 70F; Wind: SW at 10 kts Sea-level pressure: 29.84 ins. Hg, rising, then falling Visibility: 25 miles, hazy 6-hr Max temp: 74F 6-hr Min temp: 71F 24-hr Precip: 0.02 ins. BHO SA 1155 E20 BKN 130 OVC 25 106/71/70/2210/984/ FEW LWR STFRA HAZY/ 8/57/ 58007 70002 10074 20071 10 A.M. Weather: Scattered cumulus, scattered altocumulus, broken cirrus and cirrostratus, towering cumulus distant north, few moderate cumulus distant NW-N, few lower altocumulus Temperature: 80F; Dew Point: 72F; Wind: W at 7 kts, Sea-level pressure: 29.82 ins. Hg, falling, then more quickly Visibility: 30 miles, hazy 3-hr Precip: Trace BHO SA 1455 55 SCT 130 SCT E220 BKN 30 099/80/72/2607/982/ TCU DSNT N FEW MDT CU DSNT NW-N FEW LWR AC HAZY/ 8/131 58007 6000/ 1 P.M. Weather: Scattered cumulus/cumulonimbus, broken altocumulus, overcast cirrus and cirrocumulus, few lower cumulus, cumulonimbus W-NE moving E, lightning distant NE Temperature: 83F; Dew Point: 71F; Wind: W at 10 kts Sea-level pressure: 29.79 ins. Hg, falling, then more quickly Visibility: 35 miles, hazy 6-hr Max temp: 83F 6-hr Min temp: 71F 6-hr Precip: Trace BHO SA 1755 55 SCT 120 BKN 220 OVC 35 089/83/71/2810/979/ FEW LWR CU FEW CB W-NE MVNG E LTG DSNT NE HAZY/ 8/231 58010 6000/ 10083 20071 SUMMARY FOR FRIDAY, AUGUST 17, 2018 TEMPERATURE (DEGREES F) MAX.....83 NORMAL.....79 MIN.....67 NORMAL.....62 MEAN....75 NORMAL.....71 DEPARTURE FROM 30-YEAR NORMAL.........................+4 TOTAL DEPARTURE FOR THE MONTH........................+87 [+4.9 DEGREES/DAY] COOLING DEGREE DAYS (SEASON JAN TO DEC) TOTAL COOLING UNITS FOR YESTERDAY..............10 DEPARTURE..........+4 TOTAL COOLING UNITS FOR THE MONTH.............198 DEPARTURE.........+83 TOTAL COOLING UNITS FOR THE SEASON............653 DEPARTURE........+187 TOTAL COOLING UNITS LAST SEASON TO DATE.......540 DEPARTURE........+113 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.....................23 SSW AT 8:35 P.M. AERO..........................23 SSW AT 8:35 P.M. ASOS..........................24 SSW AT 7:00 P.M. DAVIS.........................24 SSW AT 8:49 P.M. RMY 25 FASTEST MILE FOR YESTERDAY.......................17 SSW AT 7:56 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE....................18 SSW AT 7:58 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...................18 SSW AT 7:57 P.M. AVERAGE WIND SPEED AND DIRECTION................9.3 ENE ASOS.........................9.7 DAVIS........................8.8 SE [131 deg.] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02 DEPARTURE......-0.11 ASOS..............0.02 TOTAL PRECIPITATION FOR THE MONTH..........3.05 DEPARTURE......+0.69 ASOS..............3.04 TOTAL PRECIPITATION FOR THE YEAR..........37.06 DEPARTURE......+3.89 ASOS.............38.62 PRELIMINARY CLIMATE SUMMARY FOR AUGUST CALENDAR DAY DATA DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST AERO: Aerovane wind recording system gust RMY: R.M. Young wind gust recording system TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized M: Missing data 8/1 82/66/74/+2/T/199/23 31 S AERO 30 S RMY 31 8/2 92/74/83/+11/0.00/761/88 30 SW AERO 28 SW RMY 31 8/3 88/74/81/+9/0.19/492/57 35 NW AERO 32 NW RMY 35 TSTM 8/4 82/69/76/+4/1.16/301/35 28 SW AERO 25 SW RMY 30 TSTM 8/5 89/66/78/+6/0.00/815/95 20 W AERO 18 W RMY 19 8/6 92/71/82/+10/0.00/822/96 20 W AERO 16 WSW RMY N/A 8/7 92/73/83/+11/0.00/682/80 25 S AERO 23 S RMY 26 8/8 88/71/80/+8/0.70/.../.. 25 SSW AERO 25 SSW RMY N/A TSTM 8/9 86/70/78/+6/0.07/.../.. 29 SW AERO 28 SW RMY N/A TSTM 8/10 85/66/76/+5/T/.../.. 17 NW AERO 16 NW RMY N/A 8/11 70/66/68/-3/..../.../.. 18 SE AERO 17 SE RMY 18 8/12 73/66/70/-1/..../.../.. 23 NNE AERO 18 NNE RMY 21 8/13 69/64/67/-4/0.17/.../.. 23 ENE AERO 21 ENE RMY 21 8/14 83/69/76/+5/0.00/.../.. 25 S AERO 23 S RMY 24 8/15 86/68/77/+6/0.00/.../.. 20 W AERO 17 W RMY 19 8/16 87/70/79/+8/0.00/.../.. 20 W AERO 18 W RMY 20 8/17 83/67/75/+4/..../.../.. 23 SSW AERO 23 SSW RMY N/A 8/18 Low temp since midnight is 71F; normal low is now 62F DAILY RECORDS FOR AUGUST 2018 08/03/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 74F, BREAKS PREVIOUS RECORD OF 71F SET IN 1928, 1969, AND 1979 08/07/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 73F, BREAKS PREVIOUS RECORD OF 72F SET IN 1988 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR AUGUST 18 HIGH 93F IN 2002 LOW 47F IN 1824 PRECIP 5.75 INCHES IN 1955 [DIANE] PEAK GUST 46 MPH WNW IN 2007 RECORDS FOR AUGUST 19 HIGH 90F IN 1906, 1966, 2002 LOW 48F IN 1958 PRECIP 7.02 INCHES IN 1955 [DIANE - RECORD FOR MONTH] PEAK GUST 78 MPH ENE IN 1991 – HURRICANE BOB TODAY'S REPORT PREPARED BY: Mike Iacono