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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, JULY 20, 2018 
ALL TIMES ARE IN EASTERN STANDARD TIME

HIGH PRESSURE REMAINS IN CONTROL

Clear skies and light winds have dominated our weather again today. The wind
was near calm for several hours this morning before a sea breeze established
itself and allowed for a steadier northeasterly breeze after noontime. We've
hit a high of 82F so far today, a little warmer than yesterday which had a
high of 80F. Visibility has been very good again today, near to above 70
miles all day.

A very steep inversion was present this morning, with nearby Norwood, MA
dropping to 53F last night, while the summit here reached only as low as
62F. This inversion helped to cause an impressive looming phenomenon of 
mountains to the WNW-NW of the Observatory. Mt. Wachusett and the Monadnocks 
were refracted and distorted such that their appearance was considerably 
different than normal before the inversion eroded after 8AM. This phenomenon 
is not unheard of, but is fairly uncommon, especially to today's extent.

Today's Observations:

7 A.M.
Weather: Clear (SKC), thin smoke layer along horizon except ENE-SE,
mountains looming WNW-NW
Temperature: 67F; Dew Point: 59F; Wind: W at 9 kts
Sea-level pressure: 30.19 ins. Hg, rising, then more quickly
Visibility: 70 miles 
6-hr Max temp: 67F
6-hr Min temp: 62F
24-hr Precip: 0.00 ins.  
BHO SA 1155 CLR 70 222/67/59/2809/019/ SKC THN K LYR ALG HRZN 
XCPT ENE-SE MTNS LOOMING WNW-NW/ 8/000 53011 10067 20062

10 A.M.
Weather: Mostly clear, few cumulus all quadrants, thin smoke layer
above horizon N-ENE
Temperature: 80F; Dew Point: 52F; Wind: estimated S at 2 kts,
Wind: Light and variable
Sea-level pressure: 30.20 ins. Hg, rising then more slowly 
Visibility: 75 miles  
3-hr Precip: 0.00 ins. 
BHO SA 1455 CLR 75 227/80/52/E1802/020/ FEW CU ALQDS 
THN K LYR ABV HRZN N-ENE WND L/V/ 8/100 51005 

1 P.M.
Weather: Mostly clear, few cumulus all quadrants except NNE-E, few
moderate cumulus distant SE-S, few altocumulus formed by the spreading of
cumulus SSE-S, thin smoke layer above horizon NNE-E
Temperature: 81F; Dew Point: 54F; Wind: E at 11 kts
Sea-level pressure: 30.18 ins. Hg, rising then falling 
Visibility: 70 miles
6-hr Max temp: 82F
6-hr Min temp: 67F
6-hr precip: 0.00 ins. 
BHO SA 1755 CLR 70 220/81/54/0811/018/ FEW CU ALQDS XCPT NNE-E 
FEW MDT CU DSNT SE-S FEW ACCG SSE-S THN K LYR ABV HRZN NNE-E/ 
8/260 58007 10082 20067

SUMMARY FOR THURSDAY, JULY 19, 2018 

TEMPERATURE (DEGREES F)
MAX.....80   NORMAL.....81
MIN.....56   NORMAL.....63
MEAN....68   NORMAL.....72

DEPARTURE FROM 30-YEAR NORMAL.........................-4
TOTAL DEPARTURE FOR THE MONTH........................+52 [+2.5 DEGREES/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY...............3   DEPARTURE..........-5
TOTAL COOLING UNITS FOR THE MONTH.............176   DEPARTURE.........+46
TOTAL COOLING UNITS FOR THE SEASON............335   DEPARTURE.........+76
TOTAL COOLING UNITS LAST SEASON TO DATE.......356   DEPARTURE.........-21

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY....................21 S   AT 10:54 P.M.*
                   AERO.........................17 SSE AT 10:18 P.M.
                   ASOS.........................20 S   AT 10:29 P.M.
                   DAVIS........................19 S   AT  9:00 P.M. RMY 19
FASTEST MILE FOR YESTERDAY......................14 SE  AT  6:56 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................14 S   AT  9:43 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE..................14 SE  AT  6:57 P.M. 
AVERAGE WIND SPEED AND DIRECTION...............7.8 N
                   ASOS........................8.1
                   DAVIS.......................7.9 NNE [025 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..........2.65  DEPARTURE......+0.32
                         ASOS..............2.69 
TOTAL PRECIPITATION FOR THE YEAR..........32.82  DEPARTURE......+3.70
                         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 81/63/72/0/0.02/.../..         21 NW  AERO 22 NW  RMY 23 
7/19 80/56/68/-4/0.00/.../..        21 S   AERO 17 SSE RMY 19 

7/20 Low temp since midnight is 62F; 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 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 INS IN 1938
PEAK GUST 60e MPH WNW IN 1977

TODAY'S REPORT PREPARED BY: Jonathan O'Brien and Samantha Richard