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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, DECEMBER 20, 2018 
ALL TIMES ARE IN EASTERN STANDARD TIME

A WARMER THAN USUAL DAY WITH LIMITED VISIBILITY
AND INCREASING CLOUD COVER IN THE AFTERNOON....

Visibility has been limited due to a distant smoke 
layer since this morning, with only 20 miles being 
seen at 7 A.M. and 10 A.M. The smoke layer thinned 
out marginally by 1 P.M., when 40 miles could be 
seen. Cloud cover increased throughout the day, 
becoming nearly overcast following a pressure drop
that began around 10 A.M. Light warm air advection 
is occurring with a persistent 10 mph wind from the
SW. The high so far of 47F is 9 degrees above the 
daily normal of 38F. The low since midnight is 30F, 
8 degrees above the normal minimum of 22F.  


Today's Observations:

7 A.M.
Weather: Scattered cirrus
Temperature: 32F; Dew Point: 24F; Wind: SW at 14G16 kts   
Sea-level pressure: 30.09 ins. Hg, rising steadily       
Visibility: 25 miles, smoke layer 
6-hr Max temp: 32F
6-hr Min temp: 30F
24-hr Precip: 0.00 ins.
24-hr snowfall: 0.0 ins.
Snow depth: 0 ins.   
BHO SA 1155 250 SCT 25 190/32/24/2314G16/009/ K LYR ALQDS/ 
8/002 53003 10032 20030  

10 A.M.
Weather: Few cirrus  
Temperature: 41F; Dew Point: 26F; Wind: SW at 9G18 kts    
Sea-level pressure: 30.14 ins. Hg, rising steadily
Visibility: 25 miles, smoke layer
3-hr Precip: 0.00 ins. 
BHO SA 1455 CLR 25 206/41/26/2209G18/014/ FEW CI K LYR 
ALQDS/ 8/002 51016

1 P.M.
Weather: Broken cirrostratus, sun dimly visible   
Temperature: 46F; Dew Point: 29F; Wind: SW at 9G18 kts    
Sea-level pressure: 30.07 ins. Hg, falling, then more rapidly      
Visibility: 40 miles, thin smoke layer in all directions
6-hr Max temp: 47F
6-hr Min temp: 31F
6-hr Precip: 0.00 ins.
6-hr snowfall: 0.0 ins.
Snow depth: 0 ins.   
BHO SA 1755 E250 BKN 40 183/46/29/2109G18/007/ THN K LYR 
ALQDS SUN DMLY VSBL/ 8/007 58023 10047 20031
 
SUMMARY FOR WEDNESDAY, DECEMBER 19, 2018 

TEMPERATURE (DEGREES F)
MAX.....38   NORMAL.....38
MIN.....17   NORMAL.....23
MEAN....28   NORMAL.....30

DEPARTURE FROM 30-YEAR NORMAL........................-2
TOTAL DEPARTURE FOR THE MONTH.......................-29 [-1.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............37   DEPARTURE.........+2
TOTAL HEATING UNITS FOR THE MONTH.............630   DEPARTURE........+27
TOTAL HEATING UNITS FOR THE SEASON...........1950   DEPARTURE........+86
TOTAL HEATING UNITS LAST SEASON TO DATE......1577   DIFFERENCE......+373

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY....................23 WNW AT  1:40 A.M.
                   AERO.........................23 WNW AT  3:02 A.M. 
                   ASOS.........................23 WNW AT  1:45 A.M. 
                   DAVIS........................25 W   AT  3:06 A.M. RMY N/A
FASTEST MILE FOR YESTERDAY......................15 WNW AT  1:58 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE...................16 WNW AT  2:01 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE..................18 WNW AT 12:21 A.M.
AVERAGE WIND SPEED AND DIRECTION..............10.2 WNW
                   ASOS.......................10.3
                   DAVIS......................10.5 W [268 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..........1.95  DEPARTURE.......-1.13
                         ASOS..............2.68 *
TOTAL PRECIPITATION FOR THE YEAR..........65.32  DEPARTURE......+13.90
                         ASOS.............68.31 *
* ASOS MONTHLY AND ANNUAL PRECIPITATION IS SUSPECT

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE........-0.5
TOTAL SNOWFALL FOR THE MONTH................0.1  DEPARTURE........-7.1
TOTAL SNOWFALL FOR THE SEASON...............7.7  DEPARTURE........-2.1

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 41/28/35/-2/0.00/0.0/391/70          20 NNW AERO 18 NNW RMY N/A
12/02 52/35/44/+8/1.04/0.0/000/00          28 ESE AERO 25 ESE RMY 27
12/03 54/38/46/+10/0.00/0.0/178/32         35 W   AERO 35 W   RMY 38 
12/04 38/23/31/-4/0.00/0.0/516/93          30 WNW AERO 31 WNW RMY 33
12/05 33/18/26/-9/0.00/0.0/432/78          16 NNW AERO 15 NNW RMY N/A
12/06 37/24/31/-4/0.00/0.0/354/64          29 W   AERO 28 W   RMY 30
12/07 37/21/29/-5/0.00/0.0/.../..          29 NW  AERO 29 NW  RMY 32
12/08 27/15/21/-13/0.00/0.0/.../..         28 NW  AERO 27 NW  RMY 29
12/09 34/17/26/-8/0.00/0.0/.../..          23 SSW AERO 21 SSW RMY 22
12/10 36/22/29/-4/0.00/0.0/.../..          24 NNW AERO 23 NNW RMY 22
12/11 36/17/27/-6/0.00/0.0/.../..          16 WSW AERO 14 WSW RMY N/A
12/12 35/18/27/-6/0.00/0.0/.../..          30 NW  AERO 29 NW  RMY M
12/13 31/16/24/-8/0.00/0.0/.../..          16 NNE AERO 12 SE  RMY N/A
12/14 46/28/37/+5/0.00/0.0/.../..          28 SSW AERO 28 SSW RMY 29
12/15 49/33/43/+11/0.04/0.0/.../..         28 NE  AERO 27 NE  RMY 30
12/16 40/37/39/+8/..../0.0/.../..          38 NE  AERO 38 NE  RMY 40
12/17 37/32/35/+4/..../0.0/.../..          39 NNE AERO 37 NNE RMY N/A
12/18 34/20/27/-4/0.02/0.1/.../..          48 NW  AERO 55 NW  RMY 48
12/19 38/17/28/-2/0.00/0.0/.../..          23 WNW AERO 23 WNW RMY N/A

12/20 Low temp since midnight is 30F; normal low is 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: Benjamin Turner