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

DAILY DISCUSSION AND CLIMATE SUMMARY
SATURDAY, SEPTEMBER 15, 2018 
ALL TIMES ARE IN EASTERN STANDARD TIME

SKY BEGINS TO CLEAR AFTER A DENSE MORNING FOG...

We had dense fog and drizzle during the 7:00 A.M.
observation this morning. So far today we measured
0.01 ins. of rainfall at 7:00 A.M. and an additional 
trace by 1:00 P.M. High temperatures today have been
below normal with a high so far of 70F, this is 2 
degrees below the daily normal of 72F. Our overnight
temperatures continue a trend of being above normal
with a low of 62F. This is 7 degrees above the 
daily normal of 55F. Humidity started at 100% this 
morning but decreased down to 84% by 1:00 P.M. Fog
was dense the morning and began to lift early this
afternoon. The drop in humidity caused the visibility 
to increase from 1/16 of a mile to 45 miles by 1:00 P.M. 
So far today the wind has been very light and variable 
with at least 10 hours so far with zero or only one
mile of wind.  

Today's Observations:

7 A.M.
Weather: Very light drizzle and fog, overcast nimbostratus 
Temperature: 63F; Dew Point: 63F; Wind: SSE at 2 kts,
Wind: Light and variable, direction estimated  
Sea-level pressure: 30.24 ins. Hg, rising, then more slowly        
Visibility: 1/16 mile
6-hr Max temp: 63F
6-hr Min temp: 62F
24-hr Precip: 0.01 ins.   
BHO SA 1155 W2 X 1/16L-F 240/63/63/E1502/024/ PCPN 
VRY LGT WND L/V/ 8//// 51007 MANUAL 70001 10063 20062 

10 A.M.
Weather: Overcast stratus
Temperature: 65F; Dew Point: 65F; Wind: SW at 1 kts,
Wind: Light and variable, direction estimated  
Sea-level pressure: 30.24 ins. Hg, steady then steady
Visibility: 4 miles, fog 
3-hr Precip: Trace 
BHO SA 1455 –X E4 OVC 4F 239/65/65/E2201/024/ F2 WND 
L/V/ 8/6// 53001 MANUAL 600// 

1 P.M.
Weather: Broken stratocumulus  
Temperature: 70F; Dew Point: 64F; Wind: SE at 2 kts,
Wind: Light and variable, direction estimated
Sea-level pressure: 30.22 ins. Hg, falling, then more rapidly      
Visibility: 45 miles, distant fog in all directions 
6-hr Max temp: 70F
6-hr Min temp: 63F
6-hr Precip: Trace 
BHO SA 1755 E25 BKN 45 232/70/64/E1302/022/ DSNT FG ALQDS WND 
L/V/ 8/500 56007 MANUAL 600// 10070 20063 
  
SUMMARY FOR FRIDAY, SEPTEMBER 14, 2018 

TEMPERATURE (DEGREES F)
MAX.....75   NORMAL.....72
MIN.....61   NORMAL.....55
MEAN....68   NORMAL.....64

DEPARTURE FROM 30-YEAR NORMAL.......................+4
TOTAL DEPARTURE FOR THE MONTH......................+43 [+2.8 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............0   DEPARTURE..........-3
TOTAL HEATING UNITS FOR THE MONTH..............18   DEPARTURE.........-10
TOTAL HEATING UNITS FOR THE SEASON.............18   DEPARTURE.........-35
TOTAL HEATING UNITS LAST SEASON TO DATE........57   DIFFERENCE........-39

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY...............3  DEPARTURE..........+1
TOTAL COOLING UNITS FOR THE MONTH..............76  DEPARTURE.........+35
TOTAL COOLING UNITS FOR THE SEASON............829  DEPARTURE........+251
TOTAL COOLING UNITS LAST SEASON TO DATE.......643  DEPARTURE........+186

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY.....................13 NE  AT  4:01 P.M.*
                   AERO..........................12 ENE AT 11:45 A.M.
                   ASOS..........................13 NE  AT  4:01 P.M.
                   DAVIS.........................13 NE  AT  3:23 P.M. RMY 12
FASTEST MILE FOR YESTERDAY........................8 E   AT  5:53 P.M.*
MAXIMUM 2-MINUTE ASOS AVERAGE....................10 NE  AT  4:01 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE...................10 NE  AT  4:01 P.M.
AVERAGE WIND SPEED AND DIRECTION................5.3 NE
                   ASOS.........................5.7 
                   DAVIS........................5.6 E  [DEG 86]   
*LAST OF MULTIPLE OCCURRENCES

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.01  DEPARTURE......-0.13
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........2.95  DEPARTURE......+1.20
                         ASOS..............2.95 
TOTAL PRECIPITATION FOR THE YEAR..........40.90  DEPARTURE......+4.31
                         ASOS.............42.47 

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 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

9/01 75/58/67/-1/0.00/521/66        17 NE  AERO 15 NE  RMY 16 
9/02 83/61/72/+4/0.00/684/87        20 SSW AERO 18 SSW RMY N/A 
9/03 92/68/80/+13/0.00/650/83       24 WSW AERO 22 WSW RMY 25
9/04 88/70/79/+12/0.00/695/89       17 W   AERO 16 W   RMY 17 
9/05 89/67/78/+11/0.00/638/82       23 SSW AERO 23 SSW RMY 25 
9/06 92/70/81/+14/0.56/488/63       29 NNW AERO 29 NNW RMY N/A TSTM
9/07 70/63/67/+1/0.01/000/00        24 NE  AERO 22 NE  RMY N/A 
9/08 68/54/61/-5/0.00/031/04        22 NE  AERO 18 NE  RMY 21
9/09 61/53/57/-9/0.00/000/00        23 NE  AERO 21 NE  RMY N/A
9/10 62/56/59/-6/..../.../..        30 E   AERO 28 E   RMY 28
9/11 75/61/68/+3/..../.../..        23 E   AERO 21 E   RMY N/A TSTM 
9/12 69/63/66/+1/..../.../..        21 ENE AERO 21 ENE RMY 21  TSTM 
9/13 68/62/65/+1/..../.../..        21 NE  AERO 21 NE  RMY N/A TSTM 
9/14 75/61/68/+4/..../.../..        13 NE  AERO 12 ENE RMY 12 

9/15 Low temp since midnight is 62F; normal low is now 55F

DAILY RECORDS FOR SEPTEMBER

09/04/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 70F,
          BREAKS PREVIOUS RECORD OF 68F SET IN 1937 AND 1959

09/06/18: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 92F,
          TIES PREVIOUS RECORD OF 92F SET IN 1900 

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

RECORDS FOR SEPTEMBER 15
HIGH 89F IN 1931
LOW 35F IN 1913
PRECIP 3.93 INCHES IN 1904 (Extra-tropical storm making landfall 
in New England on 9/15/1904 passing east of BHO and bringing a 
storm total of 4.11 inches 9/14-15/1904)
PEAK GUST 65e MPH NW, WSW IN 1944 (In the wake of Great Atlantic 
Hurricane)

RECORDS FOR SEPTEMBER 16
HIGH 91F IN 1939,1941
LOW 39F IN 1984
PRECIP 5.12 INCHES IN 1933 (Hurricane)
PEAK GUST 59 MPH SSE IN 1999

TODAY'S REPORT PREPARED BY: Kaitlin Geagan