BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, DECEMBER 21, 2009
ALL TIMES ARE IN EASTERN STANDARD TIME
 
STORM TOTAL SNOWFALL 13.8 INCHES
RECORD DAILY SNOWFALL 13.7 INCHES ON DECEMBER 20
WINTER SOLSTICE OCCURS TODAY AT 12:47 P.M. EST
 
The total snowfall was 13.8 inches for the storm
which began before midnight on December 19th. 
Only 0.1 inch of snow fell on the 19th with the
rest of the snow falling yesterday, December 20
between midnight and about 2:30 P.M.
 
The daily snowfall amount of 13.7 inches is a new
record for yesterday's date, surpassing the previous
record of 8.3 inches in 1995.  This is the 7th highest
calendar day snowfall amount for any day in the month
of December on record.
 
Highest December Calendar Day Snowfalls, 1885-2009 (inches):
 
1) 20.3 on 12 Dec, 1960
2) 18.4 on 29 Dec, 1945
3) 17.5 on 26 Dec, 1909
4) 17.0 on  6 Dec, 2003
5) 15.0 on 12 Dec, 1992
6) 14.1 on 19 Dec, 1945
7) 13.7 on 20 Dec, 2009  
8) 13.1 on 29 Dec, 1976
9) 12.3 on 24 Dec, 1961
 
The snow on the ground today measures 13 inches,
with significant drifting due to high winds. 
 
The winter solstice occurs today at 12:47 P.M.
 
Today's observations:
 
7 A.M.
Weather: Scattered altocumulus, broken cirrus, drifting snow
Temperature: 17F, Dew point: 8F, Wind: W at 15G22 kts
Sea-level pressure: 29.67 inches Hg, falling slightly
Visibility: 75 miles
6-hour minimum temp: 15F
24-hour precipitation: 0.46 in.
24-hour snowfall: N/A
Average snow depth: 13 in.
BHO SA 1155 140 SCT E200 BKN 75 046/17/8/2815G22/967/ TOTAL NEW 
SNW PST 24 HRS X.X INS STRM TOTAL 13.8 INS DRFTG SNW/ 8/037 4/013 
55001 MANUAL 70046 ASOS 70063 10017 20015
 
10 A.M.
Weather: Scattered cirrostratus, broken cirrus, drifting snow
Temperature: 25F, Dew point: 8F, Wind: W at 21G29 kts,
Wind: Peak gust 31 kts from the west at 9:43 A.M.
Wind: Direction variable SW to NW
Sea-level pressure: 29.67 inches Hg, rising slightly
Visibility: 75 miles
BHO SA 1455 200 SCT E250 BKN 75 047/25/8/2821G29/967/ DRFTG SNW
PK WND 2831/43 WND 23V32/ 8/007 50001
 
1 P.M.
Weather: Scattered cirrostratus, broken cirrus, drifting snow
Temperature: 30F, Dew point: 9F, Wind: W at 20G25 kts,
Wind: Peak gust 30 kts from the west at 12:16 P.M.
Wind: Direction variable SW to NW
Sea-level pressure: 29.64 inches Hg, falling  
Visibility: 75 miles
6-hour max. temp: 30F  
BHO SA 1755 200 SCT E250 BKN 75 037/30/9/2820G25/964/ DRFTG SNW
PK WND 2730/16 WND 23V32/ 8/007 55010 10030 20017
 
WEATHER SUMMARY FOR SUNDAY, DECEMBER 20
 
TEMPERATURE (DEGREES F)
MAX.....26     NORMAL.....37
MIN.....16     NORMAL.....22
MEAN....21     NORMAL.....30
 
DEPARTURE FROM 30-YEAR AVERAGE.............-9
TOTAL DEPARTURE FOR THE MONTH.............-14  [-0.9 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............44    DEPARTURE........+9
TOTAL HEATING UNITS FOR THE MONTH...........660    DEPARTURE.......+19
TOTAL HEATING UNITS FOR THE SEASON.........1820    DEPARTURE......-110
TOTAL HEATING UNITS LAST SEASON TO DATE....1862    DIFFERENCE......-42
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............42 NNW AT  4:18 A.M.
                   AEROVANE..............44 NNW AT  4:18 A.M. *
                   ASOS..................44 N   AT  4:19 A.M.    
                   DAVIS.................44 N   AT  2:32 A.M.    
THE FASTEST MILE FOR YESTERDAY...........31 WNW AT  4:05 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE............29 N   AT  4:20 A.M.   
MAXIMUM 2-MINUTE DAVIS AVERAGE...........30 WNW AT  4:07 P.M.   
AVERAGE WIND SPEED AND DIRECTION.......21.8 WNW
                   ASOS................19.8
                   DAVIS...............20.7 NW [307 DEG]
* Last of several occurrences
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.46   DEPARTURE....+0.32
                         ASOS..............0.63
TOTAL PRECIPITATION FOR THE MONTH..........4.99   DEPARTURE....+2.08
                         ASOS..............5.14
TOTAL PRECIPITATION FOR THE YEAR..........54.56   DEPARTURE....+4.99
                         ASOS.............55.90
                 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........N/A  DEPARTURE......N/A
TOTAL SNOWFALL FOR THE MONTH...............24.8  DEPARTURE....+18.5
TOTAL SNOWFALL FOR THE SEASON..............27.8  DEPARTURE....+18.6
                                               
PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane wind recording system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
12/1  41/28/35/-1/0/0/497/89       29 NW 
12/2  51/33/42/+6/0.08/0/345/62    30 SSE
12/3  67/47/57/+22/1.01/0/428/77   69 SSE  AERO 73 MPH SSE
12/4  52/40/46/+11/0/0/488/88      26 W
12/5  42/30/36/+1/0.79/4.7/000/00  36 N
12/6  33/25/29/-5/0.09/0.6/513/93  36 NW
12/7  36/25/31/-3/0/0/050/09       22 WSW
12/8  39/25/32/-3/0/0/512/93       27 WNW
12/9  45/29/37/+4/1.23/5.7/000/00  52 ENE  AERO 46 MPH ENE
12/10 40/26/33/0/0/0/351/64        46 WSW  AERO 39 MPH W
12/11 26/20/23/-9/0/0/395/72       46 WSW  AERO 41 MPH WSW
12/12 30/18/24/-8/0/0/548/100      36 W    AERO 33 MPH W 
12/13 46/23/35/+3/0.74/0/274/50    35 SSE  AERO 31 MPH SSE
12/14 41/33/37/+6/0/0/186/34       29 NW
12/15 46/34/40/+9/0/0/006/01       35 W    AERO 32 MPH W
12/16 35/22/29/-2/T/T/459/84       43 W    AERO 44 MPH W
12/17 22/7/15/-16/0/0/545/100      52 WNW  AERO 52 MPH WNW
12/18 26/6/16/-14/0/0/.../..       37 W    AERO 37 MPH W
12/19 30/14/22/-8/0.01/0.1/..../.. 38 N
12/20 26/16/21/-9/1.04/13.7/000/00 42 NNW
 
12/21 morning low temp: 15F; the normal low is now 22F 
 
NEW DAILY RECORD FOR DECEMBER 2009
12/3 NEW RECORD HIGH MAXIMUM TEMPERATURE of 67F;
     surpasses previous record of 61F in 1932, 1950.
12/20 NEW RECORD DAILY SNOWFALL 13.7 INCHES;
      surpasses previous record of 8.3 inches in 1995
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
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
 
RECORDS FOR DECEMBER 22
HIGH 62 IN 1994
LOW -5 IN 1921
PRECIP 1.52 INS. IN 1975
SNOWFALL 8.8 INS. IN 1975
PEAK GUST 62 MPH WNW IN 1998
 
TODAY'S REPORT PREPARED BY: Stephanie Radner