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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, MAY 9, 2018  
ALL TIMES ARE IN EASTERN STANDARD TIME

A PLEASANT DAY WITH ABOVE SEASONABLE TEMPERATURES, 
CLEAR SKIES, DRY AIR, AND LIGHT WIND...

Overall it was a very pleasant day on top of Great
Blue Hill. So far we have reached a high max of 72F,
which is 8 degrees above the daily normal of 64F. 
Overnight temperatures were also slightly above 
seasonable with a low of 49F since midnight, which 
is 3 degrees above the daily normal of 46F. 
Skies remained mostly clear today with clouds 
increasing in the afternoon as pressure began to drop. 
Humidity has been dropping all day but visibility was 
still obscured due to a lingering haze. Wind remained 
light and variable this morning picking up this 
afternoon with a peak gust so far of 20 kts (23 MPH) 
after the 1:00 P.M. observation. 
On this day May 9th in 1977 Blue Hill Observatory 
received 5.0 inches of snowfall in a rare May snowstorm.
The storm carried overnight into May 10th for a storm 
total of 7.8 ins of snowfall.

PRELIMINARY STATS FOR APRIL 2018
 
TEMPERATURE, Deg. F
Avg. Max. 52.4 [-3.3]
Avg. Min. 34.9 [-2.8]
Mean      43.7 [-3.0]
24-hour corrected mean: 43.1
Max. for month:  73F on 28th
Min. for month:  24F on  9th
 
HEATING DEGREE DAYS
Total heating units:    635  [+84]
Total for the season:  5693 [-342]
Total for last season: 5333

PRECIPITATION, Inches
Total: 6.51 [+1.96]
Greatest in 24 hrs: 2.85 on the 15-16th 

SNOWFALL, Inches
Total: 2.6 [-0.4]
Greatest in 24 hrs: 1.6 in. on 2nd
 
WIND, mph
Avg. uncorrected wind speed: 12.2
Avg. corrected wind speed: 12.6
Prevailing wind direction: WNW at 16%
Peak gust and direction: 56 NW on the 4th 
 
SUNSHINE:
Campbell-Stokes card minutes: 9744 minutes of possible 23250 or 42%
Astronomical total minutes:  10085 minutes of possible 24105 or 42%

Today's Observations:

7 A.M.
Weather: Clear, few cirrostratus ENE-SSE  
Temperature: 59F; Dew Point: 38F; Wind: WSW at 3 kts,
Wind: Light and variable, direction estimated 
Sea-level pressure: 30.19 ins. Hg, rising, then more slowly     
Visibility: 60 miles, distant haze in all directions
6-hr Max temp: 59F
6-hr Min temp: 49F
24-hr precip:  0.00 ins. 
BHO SA 1155 CLR 60 225/59/38/E2503/019/ FEW CS ENE-SSE 
THN K LYR ALNG HRZN W-NNW DSNT HZ ALQDS WND L/V/ 8/060 
51006 10059 20049    

10 A.M.
Weather: Clear, few cumulus distant SSW-NNW
Temperature: 72F; Dew Point: 47F; Wind: NE at 6 kts,
Wind: Light
Sea-level pressure: 30.19 ins. Hg, rising then falling   
Visibility: 40 miles, distant haze in all directions
3-hr precip: 0.00 ins.  
BHO SA 1455 CLR 40 222/72/47/0506/019/ FEW CU DSNT 
SSW-NNW FEW CS NE-SSE DSNT HZ ALQDS WND LGT/ 8/105 58003 

1 P.M.
Weather: Scattered cirrostratus, few cumulus distant S-NNW
few cirrus overhead  
Temperature: 72F; Dew Point: 45F; Wind: ENE at 6 kts,
Wind: Light
Sea-level pressure: 30.17 ins. Hg, falling steadily 
Visibility: 40 miles, distant haze in all directions 
6-hr Max temp: 72F
6-hr Min temp: 59F
6-hr precip:   0.00 ins
BHO SA 1755 250 SCT 50 217/72/45/0706/017/ FEW CU DSNT S-NNW 
FEW CI OVHD DSNT HZ ALQDS WND LGT/ 8/105 58005 10072 20059  
 
SUMMARY FOR TUESDAY, MAY 8, 2018

TEMPERATURE (DEGREES F)
MAX.....73   NORMAL.....64
MIN.....46   NORMAL.....45
MEAN....60   NORMAL.....55

DEPARTURE FROM 30-YEAR NORMAL..........................+5 
TOTAL DEPARTURE FOR THE MONTH.........................+85 [+10.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............5   DEPARTURE..........-5
TOTAL HEATING UNITS FOR THE MONTH.............36   DEPARTURE.........-57
TOTAL HEATING UNITS FOR THE SEASON..........5729   DEPARTURE........-398
TOTAL HEATING UNITS LAST SEASON TO DATE.....5439   DIFFERENCE.......+290

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY...............0   DEPARTURE...........0
TOTAL COOLING UNITS FOR THE MONTH..............32   DEPARTURE.........+30
TOTAL COOLING UNITS FOR THE SEASON.............32   DEPARTURE.........+29
TOTAL COOLING UNITS LAST SEASON TO DATE........20   DEPARTURE.........+12

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................25 SSE AT 7:03 P.M.* 
                   AERO........................21 ESE AT 6:57 P.M. 
                   ASOS........................23 ESE AT 4:40 P.M.
                   DAVIS.......................25 M   AT 7:02 P.M.** RMY 23
FASTEST MILE FOR YESTERDAY.....................16 SSE AT 7:08 P.M.*
MAXIMUM 2-MINUTE ASOS AVERAGE..................17 S   AT 7:00 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE.................18 M   AT 7:05 P.M.**
AVERAGE WIND SPEED AND DIRECTION..............6.6 SE
                   ASOS.......................6.7 
                   DAVIS......................6.7 M**

*  Last of multiple occurrences 
** Davis direction malfunctioning 

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.12
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........0.39  DEPARTURE......-0.60
                         ASOS..............0.37  
TOTAL PRECIPITATION FOR THE YEAR..........25.70  DEPARTURE......+6.34
                         ASOS.............27.29

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 APRIL 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
*   : Estimated data 

4/01 58/33/46/+5/0.00/0.0/336/44   45 SSW AERO 43 SSW RMY N/A  
4/02 38/30/34/-7/0.13/1.6/077/10   20 SSW AERO 15 SSW RMY 17
4/03 48/30/39/-3/0.54/0.0/238/31   28 SSE AERO 25 SSE RMY 25
4/04 54/36/45/+3/0.21/0.0/000/00   56 WNW AERO 56 WNW RMY 54
4/05 40/27/34/-9/0.00/0.0/760/98   53 WNW AERO 53 WNW RMY 52 
4/06 41/25/33/-10/0.25/1.0/156/20  37 S   AERO 36 S   RMY 38
4/07 46/32/35/-4/0.00/0.0/312/40   32 WNW*AERO 35 WNW RMY 34
4/08 41/29/35/-9/0.00/0.0/290/37   35 WNW*AERO 31 WNW RMY 34
4/09 45/24/35/-9/0.00/0.0/715/01   28 WNW AERO 25 WNW RMY 29
4/10 39/31/35/-10/T/T/000/00       14 SSW AERO 13 SSW RMY N/A
4/11 48/29/39/-6/T/0.0/364/46      24 SSE AERO 23 SSE RMY 25 
4/12 61/33/47/+2/0.03/0.0/500/63   39 SSW AERO 38 SSW RMY 41 
4/13 65/47/56/+10/T/0.0/096/12     37 SSW AERO 37 SSW RMY N/A
4/14 51/36/44/-2/0.00/0.0/328/41   33 ENE AERO 31 ENE RMY N/A
4/15 36/30/33/-14/0.32/T/000/00    39 ENE AERO 39 ENE RMY N/A
4/16 55/32/44/-3/2.63/000/00       41 ENE AERO 43 ENE RMY 41
4/17 48/36/42/-5/0.00/0.0/210/26   37 W   AERO 33 W   RMY 37
4/18 53/32/43/-5/0.00/0.0/633/78   35 W   AERO 31 W   RMY 34
4/19 41/34/38/-10/0.22/T/000/00    28 WNW AERO 25 WNW RMY N/A 
4/20 52/31/42/-7/0.00/0.0/522/64   34 NW  AERO 33 NW  RMY 36
4/21 60/33/47/-2/0.00/0.0/811/99   28 NW  AERO 26 NW  RMY 29
4/22 61/36/49/0/0.00/0.0/821/100   25 NW  AERO 24 NW  RMY 26 
4/23 62/40/51/+1/0.00/0.0/816/99   25 S   AERO 25 S   RMY 26
4/24 67/39/53/+3/0.00/0.0/645/78   31 S   AERO 29 S   RMY 32
4/25 57/47/52/+2/0.94/0.0/000/00   32 SE  AERO 32 SE  RMY 33 
4/26 66/48/57/+6/0.28/0.0/308/37   36 WNW AERO 35 WNW RMY 37 
4/27 60/45/53/+2/0.55/0.0/192/23   18 W   AERO 15 W   RMY N/A
4/28 73/47/60/+8/0.00/0.0/711/85   25 S   AERO 21 S   RMY 25
4/29 59/38/49/-3/0.04/0.0/227/27   32 SW  AERO 26 SW  RMY 31
4/30 46/36/41/-11/0.37/0.0/017/02  23 WSW AERO 16 WSW RMY N/A

DAILY RECORDS FOR APRIL 2018

4/16/18: NEW DAILY RECORD MAXIMUM PRECIPITATION OF 2.63 INS.
         PREVIOUS RECORD WAS 2.45 INS. SET IN 1929

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/.../..    25 WNW AERO 21 WNW RMY 25
5/02 88/59/74/+21/0.00/0.0/.../..   37 WSW AERO 29 WSW RMY 35 
5/03 90/67/70/+26/..../0.0/.../..   36 SW  AERO 32 WSW RMY 36  
5/04 84/67/74/+20/..../0.0/.../..   39 SSW AERO 37 SSW RMY N/A
5/05 73/54/64/+10/0.00/0.0/.../..   56 W   AERO 55 W   RMY N/A
5/06 65/48/57/+3/0.21/0.0/.../..    24 NE  AERO 18 NE  RMY 21
5/07 62/49/56/+1/0.00/0.0/.../..    26 ENE AERO 22 NE  RMY 24
5/08 73/46/60/+5/0.00/0.0/.../..    25 SSE AERO 21 ESE RMY 23 

5/09 Low temp since midnight is 49F; normal low is now 46F

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 9
HIGH 93F IN 2000
LOW 31F IN 1947
PRECIP 2.72 INCHES IN 1954
SNOWFALL 5.0 INS IN 1977 (RECORD FOR MAY)
PEAK GUST 70e MPH NE IN 1977

RECORDS FOR MAY 10
HIGH 93F IN 1896
LOW 29F  IN 1900
PRE 1.85 INS IN 1998
SNOW 2.8 INS 1977 (7.8 INS TOTAL 5/9-5/10 1977)
PEAK GUST 64 MPH S IN 1990

TODAY'S REPORT PREPARED BY: K. Geagan