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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, DECEMBER 20, 2017  
ALL TIMES ARE IN EASTERN STANDARD TIME

STRONG WEST WIND LEAVES CLOSE TO SEASONABLE
TEMPERATURES...

Today winds from the west were strong frequently
gusting over 29 kts (33 MPH). So far today we 
have had a peak gust of 36 kts (41 MPH). 
Yesterday temperatures were well above seasonable 
with a max of 49F, this is 11 degrees above the 
daily normal of 38F. Since midnight the low is 36F 
which is 14 degrees above the normal daily minimum 
of 22F. Today temperatures returned to more seasonable
conditions with a high maximum of 41F by 1:00 PM, 
which is 3 degrees above the normal of 38F. Overnight 
a rain shower left a trace of precip. on top of Great 
Blue Hill. 
Humidity dropped throughout the day from 54 to 32%.
This made for excellent visibility at 80 miles 
during the 10:00 AM and 1:00 PM observations. 

Today's Observations:

7 A.M.
Weather: Broken altocumulus, few cumulus distant along
horizon ENE-E 
Temperature: 37F; Dew Point: 22F; Wind: W at 11 kts
Sea-level pressure: 29.72 ins. Hg, rising, then more quickly 
Visibility: 60 miles
6-hr Max temp: 42F
6-hr Min temp: 36F
24-hr precip: Trace
24-hr snowfall: 0.0 ins. 
Snow cover: 0 ins.
BHO SA 1155 E70 BKN 60 066/37/22/2711/972/ FEW CU DSNT ALG 
HRZN ENE-E/ 8/130 53021 10042 20036 

10 A.M.
Weather: Broken cumulus  
Temperature: 38F; Dew Point: 18F; Wind: W at 25G32 kts,
Peak Wind: 32 kts W at 9:54 A.M. 
Sea-level pressure: 29.77 ins. Hg, falling, then more slowly 
Visibility: 80 miles
3-hr precip: 0.00 ins. 
3-hr snowfall: 0.0 ins.
BHO SA 1455 E60 BKN 80 082/38/18/2725G32/977/ PK WND 2732/54/ 
8/030 53016

1 P.M.
Weather: Scattered cumulus, scattered cirrostratus 
Temperature: 41F; Dew Point: 14F; Wind: W at 13G28 kts,
Peak Wind: 28 kts W at 12:47 P.M.
Sea-level pressure: 29.74 ins. Hg, falling, steadily 
Visibility: 80 miles
6-hr Max temp: 41F
6-hr Min temp: 37F
6-hr precip: 0.00 ins.
6-hr snowfall: 0.0 ins. 
Snow cover: 0 ins.
BHO SA 1755 60 SCT 250 SCT 80 076/41/14/2813G28/975/ PK WND 2728/47/ 
8/105 58006 10041 20037 

SUMMARY FOR TUESDAY, DECEMBER 19, 2017

TEMPERATURE (DEGREES F)
MAX.....49   NORMAL.....38
MIN.....34   NORMAL.....23
MEAN....42   NORMAL.....30

DEPARTURE FROM 30-YEAR NORMAL..........................+12
TOTAL DEPARTURE FOR THE MONTH...........................-6 [-0.5 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY.............23  DEPARTURE.........-12
TOTAL HEATING UNITS FOR THE MONTH............608  DEPARTURE..........+5
TOTAL HEATING UNITS FOR THE SEASON..........1577  DEPARTURE........-287
TOTAL HEATING UNITS LAST SEASON TO DATE.....1663  DIFFERENCE........-86

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................36 WNW AT 10:59 P.M. 
                   AERO........................35 SW  AT  8:39 P.M.
                   ASOS........................36 SW  AT  8:10 P.M.
                   DAVIS.......................37 SW  AT  8:09 P.M. RMY 38
FASTEST MILE FOR YESTERDAY.....................25 WNW AT 11:00 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................25 W   AT 11:01 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE.................25 WNW AT 11:01 P.M.
AVERAGE WIND SPEED AND DIRECTION.............14.6 SW 
                   ASOS......................14.1
                   DAVIS.....................14.0 WSW [248 DEG.]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.15
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........1.54  DEPARTURE......-1.54
                         ASOS..............1.63
TOTAL PRECIPITATION FOR THE YEAR..........51.38  DEPARTURE......-0.23
                         ASOS...............N/A **
** ASOS annual total not available due to erroneous readings

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.......-0.5
TOTAL SNOWFALL FOR THE MONTH................5.7  DEPARTURE.......-1.5
TOTAL SNOWFALL FOR THE SEASON...............5.7  DEPARTURE.......-4.1 


PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 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

12/01 50/35/43/+6/0.04/262/47          28 NW  AERO 29 NW  RMY 30
12/02 42/29/36/0/0.00/033/06           20 NNW AERO 18 NNW RMY N/A
12/03 42/32/37/+1/0.00/172/31          14 N   AERO 10 N   RMY N/A 
12/04 43/32/38/+3/0.00/522/94          16 E   AERO 14 E   RMY N/A 
12/05 58/34/46/+11/0.18/000/00         62 S   AERO 66 S   RMY 65
12/06 56/32/44/+9/0.54/160/29          52 S   AERO 55 S   RMY N/A
12/07 44/30/37/+3/0.00/540/98          25 WSW AERO 24 WSW RMY 25
12/08 38/28/33/-1/0.00/116/21          21 W   AERO 18 W   RMY 20
12/09 34/28/31/-3./..../000/00         23 NNW AERO 23 NNW RMY 23 
12/10 35/27/31/-2/..../384/70          30 W   AERO 30 W   RMY 27 
12/11 38/29/34/+1/0.00/301/55          23 W   AERO 21 W   RMY 22
12/12 43/31/37/+4/0.06/000/00          35 W   AERO 31 W   RMY N/A
12/13 31/18/25/-7/0.00/312/57          44 W   AERO 44 W   RMY 44
12/14 27/14/21/-11/T/.../..            35 WSW AERO 33 W   RMY 34 
12/15 24/12/18/-14/T/.../..            25 W   AERO 23 W   RMY N/A
12/16 32/17/25/-6/0.00/.../..          33 W   AERO 35 W   RMY 36
12/17 27/14/21/-10/0.00/.../..         21 NW  AERO 21 NW  RMY 20
12/18 35/20/28/-3/T/.../..             20 SSE AERO 16 SSE RMY 20
12/19 49/34/42/+12/..../.../..         36 WNW AERO 35 SW  RMY 38  

12/20 Low temp since midnight is 36F; normal low is now 22F

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

RECORDS FOR DECEMBER 20
HIGH 61 IN 1957
LOW -16 IN 1942
PRECIP 1.69 INS. IN 1936
SNOWFALL 13.7 INS. IN 2009
PEAK GUST 75 MPH S IN 2002

RECORDS FOR DECEMBER 21
HIGH 60 IN 1957
LOW -10 IN 1942
PRECIP 2.01 INS. IN 1946
SNOWFALL 11.4 INS. IN 1954
PEAK GUST 77 MPH SSE IN 1957

TODAY'S REPORT PREPARED BY: Kaitlin Geagan<