BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, DECEMBER 9, 2009
ALL TIMES ARE IN EASTERN STANDARD TIME
 
SNOW BEGINS BY 5 A.M. BECOMES MODERATE TO
HEAVY ACCUMULATING AN INCH OR MORE PER HOUR
FROM 6 TO 10 A.M. BEFORE CHANGING TO RAIN
 
The final snowfall accumulation was 5.7 inches
measured just after 10 a.m. as snow was changing
to rain with some light sleet mixed in. Temperatures
were just below 32F at 31.5 for three hours from
7 a.m. to 10 a.m. allowing the heavy precipitation
to quickly add up as snowfall. Close to one inch of
precipitation has fallen thru 1 p.m. The temperature
reached 39F just after the hour. The peak wind has
reached 46 MPH from the ENE.
 
Today's observations:
 
7 A.M.
Weather: Obscurement with moderate snow and heavy fog,
snow occasionally heavy snow, snow wet, snow increase
one inch past hour  
Temperature: 32F, Dew point: 32F, Wind: E at 18G25 kts,
Wind: Peak gust 26 kts from east at 6:29 a.m.
Sea-level pressure: 30.03 inches Hg, falling
Visibility: 1/16 mile moderate snow and heavy fog 
6-hour minimum temp: 29F
24-hour precipitation: 0.13 inch
24-hour snowfall: 1.7 inches
Total snow depth: 5 inches
BHO SA 1155 W2 X 1/16SF 170/32/32/0818G25/003/ OCNL S+ PK WND 
0926/29/ SNOINC ONE TOTAL NEW SNW PST 24 HRS 1.7 INS/ 8//// 
4/005 58042 MANUAL 6013/ ASOS 60014 MANUAL 70013 ASOS 70014 
10034 20029
 
10 A.M.
Weather: Partial obscurement with 5/10 of sky covered by
snow and fog and an overcast of stratus fractus
light snow occurring, occasionally moderate,
snow increased one inch past hour 
Temperature: 32F, Dew point: 32F, Wind: ENE at 22G34 kts
Wind: Peak gust to 34 kts ENE at 9:47 a.m.
Sea-level pressure: 29.80 inches Hg, falling rapidly 
Visibility: 1/2 mile variable from 1/8 to 1 mile
3-hourly snowfall: 3.8 inches
3-hourly melted precipitation: 0.52 inch 
BHO SA 1455 –X E3 OVC 1/2VS-F 092/32/32/0722G34/980/
SF5 S- OCNL S SNW WET SNOINC ONE PK WND 0734/47/ PRESFR 
TOTAL NEW SNW PST 3 HRS 3.8 INS/ 8/7// 58078 ASOS 60041 
MANUAL 6052/
 
1 P.M.
Weather: Low overcast, light rain and fog  
Temperature: 38F, Dew point: 37F, Wind: ENE at 22G34 kts,
Wind Peak wind gust 40 kts from ENE at 12:34 p.m.
Wind: Direction variable NE to E 
Sea-level pressure: 29.53 inches Hg, falling rapidly 
Visibility: 4 miles, light rain and fog 
6-hour maximum temp: 38F
6-hour snowfall: 4.0 inches
6-hour precipitation: 0.85 inches 
BHO SA 1755 E6 BKN 10 OVC 4R-F 000/38/37/0722G34/953/
PK WND 0740/34/ WND 04V10 PRESFR TOTAL NEW SNOW PST
6 HRS 4.0 INS/ 8/72/ 58092 ASOS 60078 MANUAL 6085/ 
10038 20032
 
WEATHER SUMMARY FOR TUESDAY, DECEMBER 8
 
TEMPERATURE (DEGREES F)
MAX.....39     NORMAL.....41
MIN.....25     NORMAL.....26
MEAN....32     NORMAL.....33
 
DEPARTURE FROM 30-YEAR AVERAGE.............-1
TOTAL DEPARTURE FOR THE MONTH.............+30  [+3.6 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............33    DEPARTURE........+2
TOTAL HEATING UNITS FOR THE MONTH...........212    DEPARTURE.......-29
TOTAL HEATING UNITS FOR THE SEASON.........1372    DEPARTURE......-158
TOTAL HEATING UNITS LAST SEASON TO DATE....1495    DIFFERENCE.....-123
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............27 WNW AT  7:24 A.M.    
                   AEROVANE..............24 WNW AT  7:12 A.M.  
                   ASOS..................25 WNW AT  7:25 A.M.     
                   DAVIS.................27 WNW AT  7:08 A.M.   
THE FASTEST MILE FOR YESTERDAY...........18 WNW AT  7:13 A.M.  
MAXIMUM 2-MINUTE ASOS AVERAGE............20 WNW AT  7:12 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE...........21 WNW AT  7:12 A.M.   
AVERAGE WIND SPEED AND DIRECTION.......11.0 W    
                   ASOS................10.9
                   DAVIS...............11.3 WNW [290 DEG]
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.13   DEPARTURE....-0.02
                         ASOS..............0.14
TOTAL PRECIPITATION FOR THE MONTH..........2.10   DEPARTURE....+0.90
                         ASOS..............2.21
TOTAL PRECIPITATION FOR THE YEAR..........51.67   DEPARTURE....+3.81
                         ASOS.............52.97
                 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........1.7  DEPARTURE.....+1.4
TOTAL SNOWFALL FOR THE MONTH................7.0  DEPARTURE.....+4.7
TOTAL SNOWFALL FOR THE SEASON..............10.0  DEPARTURE.....+5.1
                                               
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 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/.../..  36 NW
12/7  36/25/31/-3/0/0/.../..       22 WSW
12/8  39/25/32/-1/0/0/.../..       27 WNW
 
12/9  our morning low temp: 29F; the normal low is now 26F
 
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 9
HIGH 68 IN 1966
LOW -14 IN 1902
PRECIP 1.52 INS. IN 1956
SNOWFALL 10.8 INS. IN 2005
PEAK GUST 66 SE IN 1973
 
RECORDS FOR DECEMBER 10
HIGH 62 IN 1946
LOW -6 IN 1902
PRECIP 1.67 INS. IN 1907
SNOWFALL 6.0 INS. IN 1905
PEAK GUST 66e SW IN 1940
 
TODAY'S REPORT PREPARED BY: Robert Skilling