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

DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, MAY 21, 2018  
ALL TIMES ARE IN EASTERN STANDARD TIME

WARM DRY AIR AND ABOVE SEASONABLE TEMPERATURES RETURN
TO GREAT BLUE HILL...

Yesterday was a warm humid day with afternoon rain showers, 
heavy at times. We measured a total of 0.20 ins. of rainfall 
since yesterday morning at 7:00 A.M. The air today was much
drier than yesterday, with 32% humidity at 1:00 P.M. The lower 
humidity allowed for excellent visibility at 80 miles all day. 
Temperatures have been above seasonable today with a max of 
75F so far. This is 7 degrees above the daily normal of 68F.
Wind has been light and variable for most of the day. 

Today's Observations:

7 A.M.
Weather: Clear, few cirrostratus distant along the horizon
WNW-W
Temperature: 57F; Dew Point: 48F; Wind: NNW at 9 kts
Sea-level pressure: 30.16 ins. Hg, rising, then more slowly    
Visibility: 80 miles 
6-hr Max temp: 57F
6-hr Min temp: 52F
24-HR Precip: 0.20
BHO SA 1155 CLR 80 215/57/48/3409/016/ FEW CS DSNT ALNG HRZN 
WNW-W/ 8/005 MANUAL 70020 ASOS 70021 51019 10057 20052 

10 A.M.
Weather: Clear, few cumulus distant NNE-SSE, few cirrostratus 
SE-SW
Temperature: 67F; Dew Point: 43F; Wind: W at 3 kts,
Wind: Light and variable, direction estimated 
Sea-level pressure: 30.18 ins. Hg, rising, then falling
Visibility: 80 miles
3-hr Precip: 0.00 in
BHO SA 1455 CLR 80 221/67/43/E2703/018/ FEW CU DSNT NNE-SSE 
FEW CS SE-SW WND L/V/ 8/106 50006 

1 P.M.
Weather: Scattered cirrus, few cumulus E-SE
Temperature: 72F; Dew Point: 41F; Wind: W at 5 kts, 
Wind: Light and Variable 
Sea-level pressure: 30.15 ins. Hg, rising then falling
Visibility: 80 miles
6-hr Max temp: 75F
6-hr Min temp: 57F
6-hr precip:   0.00 ins.
BHO SA 1755 250 SCT 80 209/72/41/2705/015/ FEW CU E-SE WND L/V/ 
8/101 58012 10075 20057 

SUMMARY FOR SUNDAY, MAY 20, 2018

TEMPERATURE (DEGREES F)
MAX.....77   NORMAL.....68
MIN.....54   NORMAL.....49
MEAN....66   NORMAL.....58

DEPARTURE FROM 30-YEAR NORMAL.........................+8
TOTAL DEPARTURE FOR THE MONTH.......................+102 [+4.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............0   DEPARTURE..........-8
TOTAL HEATING UNITS FOR THE MONTH............124   DEPARTURE.........-76
TOTAL HEATING UNITS FOR THE SEASON..........5817   DEPARTURE........-418
TOTAL HEATING UNITS LAST SEASON TO DATE.....5560   DIFFERENCE.......+257

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY...............1   DEPARTURE...........0
TOTAL COOLING UNITS FOR THE MONTH..............37   DEPARTURE.........+28
TOTAL COOLING UNITS FOR THE SEASON.............37   DEPARTURE.........+26
TOTAL COOLING UNITS LAST SEASON TO DATE........56   DEPARTURE.........-19

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................33 SW AT 9:41 A.M.
                   AERO........................31 SW AT 9:40 A.M. 
                   ASOS........................34 E  AT 9:41 A.M.
                   DAVIS.......................33 M  AT 9:43 A.M.** RMY N/A
FASTEST MILE FOR YESTERDAY.....................24 SW AT 9:44 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................24 SW AT 9:43 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE.................24 M  AT 9:44 A.M.**
AVERAGE WIND SPEED AND DIRECTION.............14.1 SSW
                   ASOS......................13.9
                   DAVIS.....................13.7 M**
** Davis direction malfunctioning 

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......+0.07
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........1.78  DEPARTURE......-0.70
                         ASOS..............1.77  
TOTAL PRECIPITATION FOR THE YEAR..........27.09  DEPARTURE......+6.24
                         ASOS.............28.69

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 72/51/62/+5/0.02/0.0/.../..    17 SW  AERO 14 SW  RMY N/A
5/18 62/43/53/-5/0.00/0.0/.../..    35 ENE AERO 33 ENE RMY N/A
5/19 57/43/50/-8/.../0.0/.../..     22 E   AERO 17 E   RMY N/A
5/20 77/54/66/+8/.../0.0/.../..     33 SW  AERO 31 SW  RMY 33 TSTM

5/21 Low temp since midnight is 52F; normal low is now 49F

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 21
HIGH 92F IN 1921
LOW 35F IN 1907
PRECIP 1.61 INS IN 1954
PEAK GUST 74 MPH WSW IN 2006

RECORDS FOR MAY 22
HIGH 93F IN 1911
LOW 35F IN 1907
PRECIP 3.75 INCHES IN 1920
PEAK GUST 49e MPH SSW IN 1947

TODAY'S REPORT PREPARED BY: Kaitlin Geagan