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

DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, DECEMBER 19, 2017  
ALL TIMES ARE IN EASTERN STANDARD TIME

SOUTHERN WIND BRINGS THE RETURN OF ABOVE SEASONABLE
TEMPERATURES AFTER LAST WEEK'S COLD SNAP....

Wind from the south has been moderate today gusting
up to 20 kts (23 MPH). The southern wind allowed
temperatures to reach 47F by 1:00 P.M. EST. This 
is 9 degrees above the normal of 38F. The low since
midnight is 34F which is 11 degrees above the normal
daily minimum of 23F. The morning began overcast
by the sky cleared throughout the day. Visibility
only reached a maximum of 40 miles by 1:00 P.M. due 
to a lingering distant haze in the region. 

Today's Observations:

7 A.M.
Weather: Scattered altocumulus, broken cirrostratus 
Temperature: 36F; Dew Point: 32F; Wind: WSW at 11 kts
Sea-level pressure: 29.84 ins. Hg, steady 
Visibility: 20 miles, distant fog in all directions
6-hr Max temp: 36F
6-hr Min temp: 34F
24-hr precip: Trace
24-hr snowfall: Trace
Snow cover: 1 in.
BHO SA 1155 70 SCT E250 BKN 20 106/36/32/2411/984/ NEW SNW
PST 24 HRS TRACE DSNT FG ALQDS/ 8/038 4/001 54000 10036 20034 

10 A.M.
Weather: Overcast altostratus 
Temperature: 39F; Dew Point: 33F; Wind: WSW at 10 kts
Sea-level pressure: 30.14 ins. Hg, falling, then more slowly 
Visibility: 35 miles, distant fog in all directions
3-hr precip: 0.00 ins. 
3-hr snowfall: 0.0 ins.
BHO SA 1455 E70 OVC 35 100/39/33/2410/983/ DSNT FG ALQDS/ 
8/02/ 58006 

1 P.M.
Weather: Broken altocumulus 
Temperature: 47F; Dew Point: 35F; Wind: WSW at 12G18 kts
Sea-level pressure: 29.74 ins. Hg, falling, then more quickly
Visibility: 40 miles, distant haze 
6-hr Max temp: 47F
6-hr Min temp: 36F
6-hr precip: 0.00 ins.
6-hr snowfall: 0.0 ins. 
Snow cover: 0 ins.
BHO SA 1755 E65 BKN 40 070/47/35/2412G18/974/ DSNT HZ/ 8/070 
58030 10047 20036

SUMMARY FOR MONDAY, DECEMBER 18, 2017

TEMPERATURE (DEGREES F)
MAX.....35   NORMAL.....38
MIN.....20   NORMAL.....23
MEAN....28   NORMAL.....31

DEPARTURE FROM 30-YEAR NORMAL...........................-3
TOTAL DEPARTURE FOR THE MONTH..........................-18 [-1.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY.............37  DEPARTURE..........+3
TOTAL HEATING UNITS FOR THE MONTH............585  DEPARTURE.........+17
TOTAL HEATING UNITS FOR THE SEASON..........1554  DEPARTURE........-276
TOTAL HEATING UNITS LAST SEASON TO DATE.....1622  DIFFERENCE........-68

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................20 SSE AT 7:13 P.M. 
                   AERO........................16 SSE AT 7:13 P.M.
                   ASOS........................19 S   AT 7:13 P.M.
                   DAVIS.......................17 SSE AT 4:38 P.M. RMY 20
FASTEST MILE FOR YESTERDAY.....................16 SSE AT 7:12 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................15 S   AT 7:51 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE.................14 SSE AT 4:39 P.M.
AVERAGE WIND SPEED AND DIRECTION..............6.5 SSE 
                   ASOS.......................6.9
                   DAVIS......................6.3 S [176 DEG.]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.16
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........1.54  DEPARTURE......-1.39
                         ASOS..............1.63
TOTAL PRECIPITATION FOR THE YEAR..........51.38  DEPARTURE......-0.08
                         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.......-0.4
TOTAL SNOWFALL FOR THE MONTH................5.7  DEPARTURE.......-1.0
TOTAL SNOWFALL FOR THE SEASON...............5.7  DEPARTURE.......-3.6 


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/+3/0.00/522/98          25 WSW AERO 24 WSW RMY 25
12/08 38/28/33/-1/0.00/.../..          21 W   AERO 18 W   RMY 20
12/09 34/28/31/-3./..../.../..         23 NNW AERO 23 NNW RMY 23 
12/10 35/27/31/-2/..../.../..          30 W   AERO 30 W   RMY 27 
12/11 38/29/34/+1/0.00/.../..          23 W   AERO 21 W   RMY 22
12/12 43/31/37/+4/0.06/.../..          35 W   AERO 31 W   RMY N/A
12/13 31/18/25/-7/0.00/.../..          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/-10/0.00/.../..            21 NW  AERO 21 NW  RMY 20
12/18 35/20/28/T/.../..                20 SSE AERO 16 SSE RMY 20
 
12/19 Low temp since midnight is 34F; normal low is now 23F

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

RECORDS FOR DECEMBER 19
HIGH 59 IN 1899
LOW -1 IN 1919
PRECIP 2.06 INS. IN 1986
SNOWFALL 14.1 INS. IN 1945
PEAK GUST 68 NE IN 1986

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

TODAY'S REPORT PREPARED BY: Kaitlin Geagan