BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, DECEMBER 22, 2009
ALL TIMES ARE IN EASTERN STANDARD TIME
 
SUNNY COLD AND DRY WITH GUSTY WEST WINDS
SUB-FREEZING TEMPS. CONTINUE FOR A 6TH DAY
SNOW DEPTH ON GROUND SLOWLY SUBLIMATING
 
Today will make the 6th consecutive day with
sub-freezing temperatures.  Temperatures have
averaged 10.6 degrees colder than normal for the
past five days. The depth of Sunday's heavy snow-
fall which totaled nearly 14 inches had decreased
to an average of just over 11 inches on the ground
as of early today. Strong winds are combining with
with dry air and resulting in sublimation of the
snow cover.
 
Today's observations:
 
7 A.M.
Weather: Clear, stratocumulus offshore distant ENE-ESE,
few altocumulus distant NE-ENE 
Temperature: 16F, Dew point: 3F, Wind: W at 17G28 kts,
Wind: Peak wind gust 28 kts @ 6:49 a.m.
Sea-level pressure: 29.90 inches Hg, rising
Visibility: 60 miles
6-hour minimum temp: 16F
24-hour precipitation: 0.00 in.
24-hour snowfall: 0.0
Average snow depth: 11 ins.
BHO SA 1155 CLR 60 125/16/3/2817G28/990/ SC DSNT OFFSHR ENE-ESE 
FEW AC DSNT NE-ENE PK WND 2728/49/ 8/540 4/011 53016 10018 20016
 
10 A.M.
Weather: Clear, stratocumulus distant offshore ENE-E 
Temperature: 21F, Dew point: 2F, Wind: WNW at 16G26 kts,
Wind: Direction variable WSW to NW
Sea-level pressure: 29.94 inches Hg, rising
Visibility: 75 miles
BHO SA 1455 CLR 75 140/21/2/2916G26/994/ SC DSNT OFFSHR ENE-E
WND 24V31/ 8/500 51015 
 
1 P.M.
Weather: Clear, few stratocumulus distant offshore ENE-ESE,
few cirrus distant S-SW  
Temperature: 27F, Dew point: 2F, Wind: W at 13G25 kts,
Wind: Peak wind 28 kts from the west at 12:22 P.M.
Wind: Direction variable WSW to WNW
Sea-level pressure: 29.91 inches Hg, falling  
Visibility: 75 miles
6-hour max. temp: 27F
BHO SA 1755 CLR 75 128/27/2/2813G25/991/ SC OFFSHR DSNT ENE-ESE 
FEW CI DSNT S-SW PK WND 2827/22/ WND 24V30/ 8/501 56012 10027 20016
 
WEATHER SUMMARY FOR MONDAY, DECEMBER 21
 
TEMPERATURE (DEGREES F)
MAX.....30     NORMAL.....37
MIN.....15     NORMAL.....22
MEAN....23     NORMAL.....30
 
DEPARTURE FROM 30-YEAR AVERAGE.............-7
TOTAL DEPARTURE FOR THE MONTH.............-21  [-1.2 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............42    DEPARTURE........+7
TOTAL HEATING UNITS FOR THE MONTH...........702    DEPARTURE.......+26
TOTAL HEATING UNITS FOR THE SEASON.........1862    DEPARTURE......-103
TOTAL HEATING UNITS LAST SEASON TO DATE....1902    DIFFERENCE......-40
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............45 WNW AT  6:07 P.M.
                   AEROVANE..............45 WNW AT  6:07 P.M. 
                   ASOS..................44 WNW AT  6:07 P.M.         
                   DAVIS.................44 W   AT  6:06 P.M.     
THE FASTEST MILE FOR YESTERDAY...........31 WNW AT  4:34 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE............29 WNW AT  4:22 P.M.    
MAXIMUM 2-MINUTE DAVIS AVERAGE...........31 W   AT  2:34 P.M.   
AVERAGE WIND SPEED AND DIRECTION.......21.0 W 
                   ASOS................19.2
                   DAVIS...............20.9 W [280 DEG]
* last of several occurrences....
 
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..........4.99   DEPARTURE....+1.93
                         ASOS..............5.14
TOTAL PRECIPITATION FOR THE YEAR..........54.56   DEPARTURE....+4.84
                         ASOS.............55.90
                 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.....-0.4
TOTAL SNOWFALL FOR THE MONTH...............24.8  DEPARTURE....+18.1
TOTAL SNOWFALL FOR THE SEASON..............27.8  DEPARTURE....+18.2
                                               
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 30/15/23/-7/0/0/.../..       45 WNW  AERO 45 MPH WNW
 
12/22 morning low temp: 16F; 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 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
 
RECORDS FOR DECEMBER 23
HIGH 62 IN 1990
LOW -1 IN 1989
PRECIP 1.70 INS. IN 1947
SNOWFALL 11.9 INS. IN 1947
PEAK GUST 67 SSE IN 2004
 
TODAY'S REPORT PREPARED BY: Robert Skilling