BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, DECEMBER 15, 2013
ALL TIMES ARE IN EASTERN STANDARD TIME
 
MESSY STORM PULLS AWAY THIS MORNING
FLASH FREEZE OCCURS AS WIND SHIFTS
 
A low pressure area passed just to the east of the region this morning,
bringing stormy conditions.  Light snow began early yesterday afternoon
and intensified into the evening and overnight hours.  The temperature
rose steadily at a rate of about one degree per hour from 5PM yesterday
through 7AM this morning.  The temperature rose to the freezing mark by
3AM, and the snow changed to rain as warming continued in the following
hours.  By the 7AM observation, 5.9 inches of new snow remained on the
ground, but it is likely that some melting occurred after the temperature
climbed above freezing, which occurred after 4AM.  The total liquid
precipitation through 7AM was 1.33 inches, and an additional 0.10 inches
of rain fell after that time.   Winds became stronger out of the E and NE
last night and especially this morning.  A peak gust of 48mph occurred
around 7:37 A.M.  Winds have calmed considerably early this afternoon.
   
The other big story of today became the flash freeze which occurred around
9:30 this morning.  The temperature dove close to 10 degrees in 20 minutes,
freezing the leftover rainfall.  This created a glaze on all surfaces, and
made for treacherous conditions outside.  This freeze occurred as a result
of a wind shift to the N and NW as the storm pulled away.  The temperature
has steadied this afternoon, holding above 20F.  The high temperature for
today will likely end up as 36F, which occurred a couple hours before the
big temperature drop.  Today will be the 9th consecutive day of below
average temperatures here on the summit, and the month is now running close
to 3 degrees below average.
 
Today's Observations:
 
7 A.M.
Weather: Sky obscured by dense fog and light rain
Temperature: 36F; Dew Point: 36F; Wind: NE at 23G34 kts,
Wind: Peak wind 38 kts ENE at 6:28 A.M.
Wind: Direction variable N-E
Sea-level pressure: 29.51 ins. Hg, falling rapidly, then falling more slowly
Visibility: 1/8 mile, dense fog and light rain
24-hr snowfall: 5.9 inches
Snow depth: 7 inches
24-hr precip: 1.33 inches
6-hr precip (ASOS): 0.81 inches
6-hr. min temp: 29F
BHO SA 1155 W3 X 1/8R-F 993/36/36/0523G34/951/ TOTAL NEW SNOW
PAST 24 HRS 5.9 INS PK WND 0638/28 WND 00V09/ 8//// 4/007 56080
MANUAL 70133 ASOS 70135 ASOS 60081 10036 20029
 
10 A.M. 
Weather: Sky partially obscured by fog, overcast nimbostratus, stratus
fractus drifting below summit, thin glaze all surfaces, flash freeze
past hour
Temperature: 24F; Dew Point: 23F; Wind: NW at 18G25 kts,
Wind: Peak wind 26 kts NW at 9:30 A.M.
Sea-level pressure: 29.45 ins. Hg, falling then rising
Visibility: 3/4 miles, fog
3-hr precip: 0.10 inches
BHO SA 1455 –X E3 OVC 3/4F 973/24/23/3118G25/945/ F3 STFRA DRFTNG BLO SMT
THN GLZ ALL SFCS FLASH FREEZE PST HR PK WND 3226/30 8/72/ 55020
MANUAL 60010 ASOS 60011
 
1 P.M.
Weather: Overcast nimbostratus, thin fog all quadrants, thin glaze all
surfaces
Temperature: 22F; Dew Point: 20F; Wind: NW at 12 kts
Sea-level pressure: 29.46 ins. Hg, rising slightly
Visibility: 10 miles, thin fog
6-hr max. temp. 36F
6-hr precip: 0.10 inches
BHO SA 1755 E8 OVC 10 977/22/20/3112/946/ TF ALQDS THN GLZ ALL SFCS/
8/72/ 53004 MANUAL 60010 ASOS 60011 10036 20021
 
WEATHER SUMMARY FOR SATURDAY, DECEMBER 14, 2013
 
TEMPERATURE (DEGREES F)
MAX.....28    NORMAL.....40
MIN......9    NORMAL.....24
MEAN....19    NORMAL.....32
 
DEPARTURE FROM 30-YEAR NORMAL.....................-13
TOTAL DEPARTURE FOR THE MONTH.....................-38 [-2.9 DEGREE/DAY]
 
HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............46  DEPARTURE........+13
TOTAL HEATING UNITS FOR THE MONTH.............469  DEPARTURE........+27
TOTAL HEATING UNITS FOR THE SEASON...........1693  DEPARTURE..........0
TOTAL HEATING UNITS LAST SEASON TO DATE......1496  DIFFERENCE......+197
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY..................30 E   AT 10:53 P.M.
                   AERO.......................26 E   AT 1O:53 P.M. *
                   ASOS.......................29 E   AT 10:29 P.M.
                   DAVIS......................27 E   AT 10:53 P.M. RMY N/A
FASTEST MILE FOR YESTERDAY....................22 E   AT 1O:27 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE.................21 E   AT 11:04 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE................21 E   AT 10:54 P.M.
AVERAGE WIND SPEED AND DIRECTION.............9.7 NNW
                   ASOS.....................10.2
                   DAVIS.....................8.5 NE [37 degrees]
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....1.33  DEPARTURE.............+1.17
                         ASOS..............1.35
TOTAL PRECIPITATION FOR THE MONTH..........2.62  DEPARTURE.............+0.32
                         ASOS..............2.61
TOTAL PRECIPITATION FOR THE YEAR..........49.22  DEPARTURE.............-1.61
                         ASOS..............N/A**
** ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals
 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M.......5.9     DEPARTURE.............+5.5
TOTAL SNOWFALL FOR THE MONTH.............8.6     DEPARTURE.............+3.7
TOTAL SNOWFALL FOR THE SEASON............8.8     DEPARTURE.............+1.3
 
PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 2013 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
RMY:  RMY = R.M. Young wind gust recording system added 8/9/2011
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
12/1  45/30/38/+1/0.28/T/000/00           22 SSE AERO 23 MPH SSE RMY 23
12/2  38/34/36/0/T/0.0/000/00             15 NW  AERO 15 MPH NW  RMY 16
12/3  45/32/39/+3/0.00/0.0/284/51         18 NNW AERO 18 MPH NNW RMY 20
12/4  43/29/36/+1/0.00/0.0/389/70         21 WNW AERO 21 MPH WNW RMY 21
12/5  53/38/46/+11/0.02/0.0/000/00        36 S   AERO 40 MPH S   RMY 39
12/6  55/33/44/+9/0.38/T/000/00           25 SSW AERO 28 MPH SSW RMY N/A
12/7  40/26/33/-1/0.12/T/287/52           23 NW  AERO 25 MPH NW  RMY N/A
12/8  30/22/26/-8/T/T/039/07              25 NW  AERO 27 MPH NW  RMY N/A
12/9  41/25/33/-1/0.35/0.6/000/00         28 E   AERO 28 MPH E   RMY 24
12/10 33/21/27/-6/0.14/2.1/000/00         28 W   AERO 28 MPH W   RMY 28
12/11 28/19/24/-9/0.00/0.0/345/63         27 SW  AERO 28 MPH SW  RMY 27
12/12 23/14/19/-14/0.00/0.0/.../..        28 WNW AERO 31 MPH NW  RMY 30
12/13 28/14/21/-11/0.00/0.0/.../..        31 W   AERO 32 MPH W   RMY 33
12/14 28/9/19/-13/..../../000/00          30 E   AERO 26 MPH E   RMY N/A
 
12/15 morning low temp: 28F; the normal low is now 24F
 
DAILY RECORDS FOR DECEMBER 2013
None so far.                                   
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR DECEMBER 15
HIGH 64 IN 1975
LOW 4 IN 1900, 1905, 1933
PRE 1.80 INS. IN 1981
SNOW 7.5 INS. IN 1951
PEAK GUST 65 MPH NW IN 1991
 
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
 
TODAY'S REPORT PREPARED BY: Jonathan O'Brien