BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, JULY 18, 2018 
ALL TIMES ARE IN EASTERN STANDARD TIME

YESTERDAY'S LARGE THUNDERSTORM LEAVES NEAR RECORD-BREAKING
PRECIPITATION ON TOP OF GREAT BLUE HILL... 

A thunderstorm began yesterday afternoon beginning in the 
NW and moving to the NE with frequent distant lightning
strikes. After a short shower around 3:00 P.M. we had a 
downpour between 4:00-5:00 P.M. with about 1.00 in of 
precipitation falling in this hour and ending before 8:00 P.M. 
Rain began again late last night and continued into the 
early morning. A total of 1.34 ins. fell yesterday, this is 
0.05 ins. below the record of 1.39 ins. set back in 1989. 
An additional 0.02 ins. fell so far today. The wind shifted
yesterday from the SSW-ENE before the storm bringing colder 
air into the area. After the shift temperatures quickly 
dropped 16 degrees from 88F-72F between 1:00 P.M. and 
3:00 P.M. This morning began humid with 94% humidity but 
dropped throughout down to 47% at 1:00 P.M. This allowed the 
visibility to increase from 40 miles at 7:00 A.M. to 70 miles 
by 10:00 A.M. High temperatures so far today have been close 
to seasonable with a max of 79F by 1:00 P.M. this is 2 degrees 
below the daily normal of 81F. Pressure rose throughout the 
day making for moderate wind gusts over 20 MPH (17 kts) and 
decreasing cloud cover. 

Today's Observations:

7 A.M.
Weather: Scattered stratocumulus, scattered altocumulus,
broken cirrostratus, few lower stratocumulus along horizon ESE-S
Temperature: 66F; Dew Point: 64F; Wind: NNW at 10G16 kts
Sea-level pressure: 29.86 ins. Hg, rising steadily 
Visibility: 40 miles, distant fog in all directions 
6-hr Max temp: 68F
6-hr Min temp: 66F
24-hr Precip: 1.36 ins.  
BHO SA 1155 65 SCT 100 SCT E250 BKN 40 113/66/64/3410G16/986/ 
FEW LWR SC ALNG HRZN ENE-S DSNT FG ALQDS/ 8/888 52018 MANUAL 
70136 ASOS 70138 10068 20066  

10 A.M.
Weather: Scattered altocumulus, scattered cirrostratus  
Temperature: 73F; Dew Point: 57F; Wind: N at 12G18 kts
Sea-level pressure: 29.88 ins. Hg, rising then steady
Visibility: 70 miles, distant haze in all directions  
3-hr Precip: 0.00 ins. 
BHO SA 1455 90 SCT 250 SCT 70 120/73/57/3412G18/988/ FEW CU 
DSNT ESE-W DSNT HZ ALQDS/ 8/185 51007 

1 P.M.
Weather: Scattered cirrostratus, few cumulus distant SSE-N 
Temperature: 78F; Dew Point: 56F; Wind: NW at 7G15 kts
Sea-level pressure: 29.88 ins. Hg, falling, then rising
Visibility: 25 miles, except SW-NW 15 miles, hazy
6-hr Max temp: 79F
6-hr Min temp: 66F
6-hr precip: 0.00 ins. 
BHO SA 1755 250 SCT 70 118/78/56/3207G15/988/ FEW CU DSNT 
SSE-N DSNT HZ ALQDS/ 8/105 55002 10079 20066  

SUMMARY FOR TUESDAY, JULY 17, 2018 

TEMPERATURE (DEGREES F)
MAX.....88   NORMAL.....81
MIN.....67   NORMAL.....63
MEAN....78   NORMAL.....72

DEPARTURE FROM 30-YEAR NORMAL.........................+6
TOTAL DEPARTURE FOR THE MONTH........................+56 [+2.9 DEGREES/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY..............13   DEPARTURE..........+6
TOTAL COOLING UNITS FOR THE MONTH.............166   DEPARTURE.........+52
TOTAL COOLING UNITS FOR THE SEASON............325   DEPARTURE.........+82
TOTAL COOLING UNITS LAST SEASON TO DATE.......329   DEPARTURE..........-4

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY....................31 SW  AT 12:14 P.M.
                   AERO.........................30 SW  AT 12:14 P.M.
                   ASOS.........................32 SW  AT 12:14 P.M.
                   DAVIS........................31 SW  AT 12:14 P.M. RMY 32
FASTEST MILE FOR YESTERDAY......................23 SW  AT 12:10 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................23 SSW AT 12:21 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE..................23 SW  AT 12:15 P.M. 
AVERAGE WIND SPEED AND DIRECTION..............11.0 SSW
                   ASOS.......................11.5
                   DAVIS.......................8.2 SSW [206 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....1.36  DEPARTURE......+1.22
                         ASOS..............1.38
TOTAL PRECIPITATION FOR THE MONTH..........2.65  DEPARTURE......+0.58
                         ASOS..............2.69 
TOTAL PRECIPITATION FOR THE YEAR..........32.82  DEPARTURE......+3.96
                         ASOS.............34.42

PRELIMINARY CLIMATE SUMMARY FOR JULY 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

7/01 94/72/83/+13/0.00/667/73       21 ESE AERO 18 ESE RMY 19 
7/02 90/68/79/+9/0.00/858/94        21 S   AERO 21 S   RMY 22
7/03 94/69/82/+11/0.00/657/72       20 SSW AERO 18 SW  RMY 19 TSTM
7/04 89/73/81/+10/0.00/884/97       17 NE  AERO 15 NE  RMY 16
7/05 91/73/82/+11/0.00/865/95       29 SSW AERO 28 SSW RMY N/A
7/06 80/59/70/-1/0.56/018/02        37 NNW AERO 38 SW  RMY 40 TSTM
7/07 78/54/66/-5/0.00/900/99        22 N   AERO 18 N   RMY N/A 
7/08 83/57/70/-2/0.00/890/98        23 S   AERO 21 S   RMY 22  
7/09 88/60/74/+2/0.00/852/94        23 SW  AERO 23 SW  RMY 24 
7/10 91/63/77/+5/0.10/751/83        24 W   AERO 22 W   RMY N/A
7/11 73/62/68/-4/0.63/705/78        28 NE  AERO 25 NE  RMY 27 TSTM
7/12 77/56/67/-5/0.00/.../..        16 NW  AERO 15 NW  RMY N/A 
7/13 84/61/73/+1/0.00/.../..        23 SSE AERO 23 SSE RMY 24
7/14 80/61/71/-1/0.00/.../..        18 S   AERO 16 S   RMY 19
7/15 84/65/75/+3/T/.../..           16 S   AERO 15 S   RMY 14 
7/16 83/67/75/+3/0.00/.../..        23 S   AERO 23 S   RMY 23 
7/17 88/67/78/+6/1.34/.../..        31 SW  AERO 30 SW  RMY 32 TSTM 

7/18 Low temp since midnight is 66F; normal low is now 63F

DAILY RECORDS FOR JULY 2018

07/01/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 72F, 
          TIES PREVIOUS RECORD OF 72F SET IN 1968

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):

RECORDS FOR JULY 18
HIGH 96F IN 1991, 1999
LOW 54F IN 1892, 1956, 1971
PRECIP 1.65 INS IN 2000
WIND 43e MPH SW IN 1949

RECORDS FOR JULY 19
HIGH 96F IN 1977, 1991
LOW 50F IN 1890
PRECIP 1.10 INS IN 1951
WIND 63 MPH SSW IN 1982

TODAY'S REPORT PREPARED BY: Kaitlin Geagan