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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, MAY 17, 2018  
ALL TIMES ARE IN EASTERN STANDARD TIME
 
SKY BEGINS TO CLEAR AFTER MORNING SHOWERS AND FOG...

Rain showers began yesterday afternoon and continued 
intermittently until just after the 7:00 A.M. observation
this morning. In total we measured 0.02 ins. of rain, 
mostly falling in the early hours of this morning. We 
observed an undercast layer at 7:00 A.M. this morning 
which only allowed for 5 miles of visibility. Fog began 
to dissipate mid-morning and we could see 40 miles at 
10:00 A.M and 1:00 P.M. Skies remained mostly cloudy 
today with clouds beginning to decrease this afternoon. 
The wind has been light and mostly from the SW but 
became lighter and more variable this afternoon.
Temperature were consistent for most of the day but have
recently began to quickly rise with a max temperature so
far of 67F, which is also the daily normal. The air today 
has been very humid close to 100% for most of the day with 
slightly drier conditions in the afternoon. 

Today's Observations:

7 A.M.
Weather: Very light rain and fog, scattered stratus fractus, 
broken altocumulus, overcast altostratus, complete undercast
conditions below the summit 
Temperature: 53F; Dew Point: 53F; Wind: SW at 5 kts,
Wind: Light 
Sea-level pressure: 30.01 ins. Hg, rising unsteadily    
Visibility: 5 miles
6-hr Max temp: 53F
6-hr Min temp: 51F
24-hr precip: 0.02 ins.
BHO SA 1155 5 SCT E90 BKN 100 OVC 5L-F 164/53/53/2305/001/ 
COMPLETE UNDERCAST CDN BLO SMT ALQDS PCPN VRY LGT WND LGT/ 
8/72/ 52009 MANUAL 70002 ASOS 70002 10053 20051 

10 A.M.
Weather: Scattered stratus fractus, scattered stratocumulus,
overcast altostratus, sun dimly visible 
Temperature: 60F; Dew Point: 59F; Wind: SW at 3 kts,
Wind: Light
Sea-level pressure: 30.02 ins. Hg, rising unsteadily 
Visibility: 40 miles, distant fog in all directions
3-hr precip: Trace 
BHO SA 1455 5 SCT 60 SCT E110 OVC 40 166/60/59/2303/002/ SUN 
DMLY VSBL DSNT FG ALQDS WND LGT/ 8/72/ 51002 MANUAL 600// 

1 P.M.
Weather: Broken altocumulus, broken cirrostratus, few 
stratocumulus distant along the horizon E-SSW
Temperature: 66F; Dew Point: 59F; Wind: W at 2 kts,
Wind: Light and variable, direction estimated 
Sea-level pressure: 30.03 ins. Hg, rising, then falling
Visibility:  40 miles, distant fog in all directions
6-hr Max temp: 57F
6-hr Min temp: 53F
6-hr precip:  Trace 
BHO SA 1755 E150 BKN 250 BKN 40 168/66/59/E2802/003/ 
FEW SC DSNT ALNG HRZN E-SSW DSNT FG ALQDS WND L/V/ 8/578 
50002 MANUAL 600// 10067 20053 

SUMMARY FOR WEDNESDAY, MAY 16, 2018

TEMPERATURE (DEGREES F)
MAX.....56   NORMAL.....66
MIN.....49   NORMAL.....48
MEAN....53   NORMAL.....57

DEPARTURE FROM 30-YEAR NORMAL..........................-4 
TOTAL DEPARTURE FOR THE MONTH........................+102 [+6.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY.............12   DEPARTURE..........+3
TOTAL HEATING UNITS FOR THE MONTH.............94   DEPARTURE.........-75
TOTAL HEATING UNITS FOR THE SEASON..........5787   DEPARTURE........-416
TOTAL HEATING UNITS LAST SEASON TO DATE.....5553   DIFFERENCE.......+234

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY...............0   DEPARTURE..........-1
TOTAL COOLING UNITS FOR THE MONTH..............36   DEPARTURE.........+30
TOTAL COOLING UNITS FOR THE SEASON.............36   DEPARTURE.........+28
TOTAL COOLING UNITS LAST SEASON TO DATE........20   DEPARTURE.........+16

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................51 ENE AT 7:40 A.M.
                   AERO........................50 ENE AT 7:31 A.M. 
                   ASOS........................50 ENE AT 7:41 A.M.
                   DAVIS.......................50 M   AT 7:40 A.M.** RMY 54
FASTEST MILE FOR YESTERDAY.....................23 ENE AT 7:31 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................24 ENE AT 7:31 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE.................23 M   AT 7:31 A.M.**
AVERAGE WIND SPEED AND DIRECTION..............8.2 ENE
                   ASOS.......................8.6 
                   DAVIS......................8.1 M**
** Davis direction malfunctioning 

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02  DEPARTURE......-0.10
                         ASOS..............0.02
TOTAL PRECIPITATION FOR THE MONTH..........1.37  DEPARTURE......-0.58
                         ASOS..............1.32  
TOTAL PRECIPITATION FOR THE YEAR..........26.68  DEPARTURE......+6.36
                         ASOS.............28.24

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.........0.0
TOTAL SNOWFALL FOR THE MONTH................0.0  DEPARTURE.........0.0
TOTAL SNOWFALL FOR THE SEASON..............92.8  DEPARTURE.......+30.0

PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/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

5/01 65/39/52/-1/0.00/0.0/625/74    25 WNW AERO 21 WNW RMY 25
5/02 88/59/74/+21/0.00/0.0/584/69   37 WSW AERO 29 WSW RMY 35 
5/03 90/67/70/+26/..../0.0/433/51   36 SW  AERO 32 WSW RMY 36  
5/04 84/67/74/+20/..../0.0/102/12   39 SSW AERO 37 SSW RMY N/A
5/05 73/54/64/+10/0.00/0.0/615/72   56 W   AERO 55 W   RMY N/A
5/06 65/48/57/+3/0.21/0.0/000/00    24 NE  AERO 18 NE  RMY 21
5/07 62/49/56/+1/0.00/0.0/713/83    26 ENE AERO 22 NE  RMY 24
5/08 73/46/60/+5/0.00/0.0/852/99    25 SSE AERO 21 ESE RMY 23 
5/09 74/48/61/+6/..../0.0/768/89    23 ESE AERO 18 ESE RMY 21 
5/10 73/48/61/+6/..../0.0/.../..    33 S   AERO 30 S   RMY 32 
5/11 70/51/61/+5/..../0.0/.../..    26 WNW AERO 24 NW  RMY 28
5/12 51/47/49/-7/0.19/0.0/.../..    25 E   AERO 23 E   RMY N/A
5/13 58/46/52/-4/T/0.0/.../..       20 S   AERO 17 S   RMY 16 
5/14 73/47/60/+3/0.00/0.0/.../..    23 S   AERO 18 S   RMY 21
5/15 83/54/69/+12/..../0.0/.../..   51 NW  AERO 50 NW  RMY 54 TSTM
5/16 56/49/53/-4/T/0.0/.../..       32 ENE AERO 28 ENE RMY 30

5/17 Low temp since midnight is 51F; normal low is now 48F

DAILY RECORDS FOR MAY 2018

5/03/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 67F,
         BREAKS PREVIOUS RECORD OF 66F SET IN 2001

5/04/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 67F,
         BREAKS PREVIOUS RECORD OF 66F SET IN 2001

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

RECORDS FOR MAY 17
HIGH 90F IN 2017
LOW 34F IN 1956, 1957
PRECIP 2.07 INS IN 1916
PEAK GUST 52 MPH SW IN 1967, W IN 1974

RECORDS FOR MAY 18
HIGH 96F IN 2017
LOW 35F IN 2002
PRECIP 1.93 INS IN 2007
SNOW TRACE IN 2002 (Ice pellets)
PEAK GUST 64 MPH SSW IN 2000

TODAY'S REPORT PREPARED BY: Kaitlin Geagan