BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, DECEMBER 16, 2009
ALL TIMES ARE IN EASTERN STANDARD TIME
 
ARCTIC AIR MASS RUSHES IN DURING EARLY MORNING
WEST WIND GUSTS GO OVER 40 MPH
ICE HAS MELTED OFF NEARBY PONDS
 
The arrival of an Arctic air mass early this
morning brought a few very light rain and snow
showers throughout the local area.  Peak wind
gusts for the day were 41 to 44 MPH from the
west between 5 and 6 a.m. Temperatures dropped
from 35F at midnight to 25F between 8 and 9 a.m.
The above freezing temperatures over the past
several days have resulted in the melting of
the ice cover on our nearby ponds.  Ponkapoag
had completely frozen over and Houghtons Pond
was nearly frozen with 9/10 cover when both were
observed on December 13th. 
 
Today's observations:
 
7 A.M.
Weather: Clear, cumulus, stratocumulus distant NE-S
offshore
Temperature: 26F, Dew point: 7F, Wind: W at 19G31 kts,
Wind: Peak wind gust 35 kts from WNW at 6:14 a.m.,
Wind: Direction variable WSW to NW
Sea-level pressure: 30.06 inches Hg, rising
Visibility: 50 miles
6-hour minimum temp: 26F
24-hour precipitation: trace
24-hour snowfall: trace
Average snow depth: none
BHO SA 1155 CLR 50 181/26/7/2819G31/006/ CU/SC DSNT NE-S 
ALG/OFFSHR FEW SC DSNT SW-WSW PK WND 2935/14/ WND 25V31/
8/800 53024 MANUAL 6000/ 10034 20026
 
10 A.M.
Weather: Clear few cumulus and stratocumulus
Temperature: 26F, Dew point: 5F, Wind: WNW at 20G29 kts,
Wind: Peak wind gust 30 kts WNW at 9:16 a.m.,
Wind; Direction variable W to NNW
Sea-level pressure: 30.15 inches Hg, rising 
Visibility: 65 miles 
BHO SA 1455 CLR 65 210/26/5/2920G29/015/
FEW CU/SC ALQDS PK WND 2930/16/ WND 26V33/ 8/800 51029
 
1 P.M.
Weather: Scattered cumulus and stratocumulus, cirrus
east thru south-southeast
Temperature: 30F, Dew point: 7F, Wind: WNW at 14G30 kts,
Wind: Peak wind gust 34 kts W @ 12:41 p.m.,
Wind: Direction variable WSW to NW 
Sea-level pressure: 30.08 inches Hg, falling  
Visibility: 65 miles, 70 miles northwest
6-hour max. temp: 30F  
BHO SA 1755 55 SCT 220 SCT 65 186/30/7/2914G30/008/
CU/SC FEW CI E-SSE  VSBY NW 70 PK WND 2834/41/
WND 24V32/ 8/801 86024 10030 20025
 
WEATHER SUMMARY FOR TUESDAY, DECEMBER 15
 
TEMPERATURE (DEGREES F)
MAX.....46     NORMAL.....39
MIN.....34     NORMAL.....24
MEAN....40     NORMAL.....31
 
DEPARTURE FROM 30-YEAR AVERAGE.............+9
TOTAL DEPARTURE FOR THE MONTH.............+35  [+2.1 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............25    DEPARTURE........-8
TOTAL HEATING UNITS FOR THE MONTH...........438    DEPARTURE.......-31
TOTAL HEATING UNITS FOR THE SEASON.........1598    DEPARTURE......-160
TOTAL HEATING UNITS LAST SEASON TO DATE....1682    DIFFERENCE......-84
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............35 W   AT  7:44 P.M.  
                   AEROVANE..............32 W   AT  7:44 P.M. *  
                   ASOS..................32 W   AT  7:44 P.M.  
                   DAVIS.................35 W   AT  7:43 P.M.  
THE FASTEST MILE FOR YESTERDAY...........24 W   AT  7:44 P.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE............23 W   AT  7:45 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE...........25 W   AT  7:45 P.M.  
AVERAGE WIND SPEED AND DIRECTION.......13.0 W  
                   ASOS................12.5 
                   DAVIS...............12.3 SW [230 DEG]
 
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....trace   DEPARTURE...-0.14
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........3.94   DEPARTURE....+1.73
                         ASOS..............4.01
TOTAL PRECIPITATION FOR THE YEAR..........53.51   DEPARTURE....+4.64
                         ASOS.............54.77
                 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........trace DEPARTURE.....-0.4
TOTAL SNOWFALL FOR THE MONTH...............11.0  DEPARTURE.....+6.7
TOTAL SNOWFALL FOR THE SEASON..............14.0  DEPARTURE.....+6.8
                                               
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/.../..       36 W    AERO 33 MPH W 
12/13 46/23/35/+3/0.74/0/.../..    35 SSE  AERO 31 MPH SSE
12/14 41/33/37/+6/0/0/.../..       29 NW
12/15 46/34/40/+9/0/0/006/01       35 W    AERO 32 MPH W
 
12/16 our morning low temp: 26F; our normal low is now 24F
 
NEW DAILY RECORD FOR DECEMBER 2009
12/3 NEW RECORD HIGH MAXIMUM TEMPERATURE of 67F;
     surpasses previous record of 61F in 1932, 1950.
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR DECEMBER 16
HIGH 61 IN 1971
LOW -2 IN 1930
PRE 1.67 INS. IN 1960
SNOW 8.5 INS. IN 2007
WIND 73 MPH SSE IN 1982
 
RECORDS FOR DECEMBER 17
HIGH 63 IN 2000
LOW -10 IN 1942
PRECIP 3.03 INS. IN 1888
SNOWFALL 7.5 INS. IN 1988
PEAK GUST 78 MPH SSE IN 2000
 
TODAY'S REPORT PREPARED BY: Robert Skilling