Thursday, December 31, 2020

BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

THURSDAY DECEMBER 31, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

RAIN EARLY THIS MORNING; REMAINING OVERCAST INTO THIS AFTERNOON…

Some light rain moved through the region during the wee hours
of the morning ending just after 7 A.M. A total of 0.14″ was
measured in our gauge, brining the monthly total to 7.32″.
This is 2.57″ above normal, and for the year we continue to
have a surplus of 0.44″. We are among only a few stations
across the region to actually have a precipitation surplus
for the year. Many surrounding stations are around 2 inches
below normal for the year.

Clouds have hung around following the depature of the rain.
Temperatures have also been very gradually falling through
the day. The max so far for today actually occured just before
6 A.M. with 44F degrees.

In addition to the slipping temperatures, the dew point has been
on the decline as well dropping from the low 40s early this
morning to 30F at the 1 P.M. observation. This is indicative of
cold air advection taking place.

Winds were gusty overnight into this morning with a peak gust
of 39 MPH occuring around 8 P.M. last night. Gusts of around
30 MPH where common very early this morning, but diminished a
bit from mid morning to early afternoon, however, with cold air
advection taking over, winds have increased again this afternoon.

The high so far today is 44 degrees, which is 9 degrees
above the daily normal high of 35. The low since midnight
is 40F, which is 21 degrees above the daily normal low of 19F.

Today’s Observations:

7 A.M.
Weather: Broken stratus fractus, overcast nimbostratus, light rain
Temperature: 42F; Dew Point: 41F; Relative Humidity: 96%
Wind: W at 14G23 kts, peak wind 30 MPH SW at 5:57 A.M.
Sea-level pressure: 29.94 in Hg; falling, then rising
Visibility: 20 miles
6-hr Max temp: 44F
6-hr Min temp: 41F
24-hr Precip: 0.14 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1155 E9 BKN 35 OVC 20R- 137/42/41/2614G23/994/ PCPN VRY LGT PK WND 2226/1057/ 8/6// 53008 6014/ 70014 10044 20041

10 A.M.
Weather: Broken altostratus, overcast altostratus, few stratus-
fractus all quadrants, few stratocumulus distant WNW-NNW
Temperature: 42F; Dew Point: 39F; Relative Humidity: 89%
Wind: W at 11G17 kts
Sea-level pressure: 30.03 in Hg; rising, then more slowly
Visibility: 50 miles
3-hr Precip: Trace
3-hr Snow: 0.0 ins.
BHO SA 1455 E60 BKN 100 OVC 50 169/42/39/2611G17/003/ FEW STFRA ALQDS FEW SC DSNT WNW-NNW/ 8/62/ 51032 6000/

1 P.M.
Weather: Scattered stratocumulus, broken altostratus, overcast
cirrostratus
Temperature: 40F, Dew point: 30F; Relative Humidity: 67%
Wind: WNW at 15G26 kts, peak wind 30 MPH WNW at 12:54 P.M.
Sea-level pressure: 30.03 inches Hg, rising, then falling
Visibility: 40 miles
6-hr Max temp: 42F
6-hr Min temp: 40F
6-hr Precip: Trace
6-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1755 25 SCT 120 BKN 180 OVC 40 168/40/30/2915G26/003/ PK WND 2926/54/ 8/517 58001 6000/ 10042 20040

SUMMARY FOR WEDNESDAY, DECEMBER 30, 2020

TEMPERATURE (DEGREES F)
MAX…….40   NORMAL…..35
MIN…….19   NORMAL…..19
MEAN……30   NORMAL…..27

DEPARTURE FROM 30-YEAR NORMAL………………… +3
TOTAL DEPARTURE FOR THE MONTH…………………+75 [+2.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………35  DEPARTURE…… -3
TOTAL HEATING UNITS FOR THE MONTH…………..928  DEPARTURE……-77
TOTAL HEATING UNITS FOR THE SEASON…………1901  DEPARTURE…..-366
TOTAL HEATING UNITS LAST SEASON TO DATE…….2222  DEPARTURE…..-321

PEAK WIND GUST FOR YESTERDAY (MPH):
420C/Official…………..39 SW  @  8:04 P.M.
AEROVANE (south tower)…..41 SW  @  8:05 P.M
ASOS…………………..42 S   @  8:05 P.M
DAVIS #1……………….45 SW  @  8:04 P.M
DAVIS #2 (south tower)…..38 SSW @  8:09 P.M
RMY……………………45     @  8:03 P.M.
VECTOR…………………46     @  8:04 P.M
MERLIN…………………42

FASTEST MILE FOR YESTERDAY:
CONTACTING/OFFICIAL………………………..30 SSW @  8:12 P.M
MAXIMUM 2-MINUTE ASOS AVERAGE……………….29 S   @  8:06 P.M
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………30 SW  @  8:00 P.M
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………29 SSW @  8:00 P.M
MAXIMUM 2-MINUTE RMY AVERAGE………………..29 SSW @  8:03 P.M
MAXIMUM 2-MINUTE VECTOR AVERAGE……………..30     @  7:57 P.M

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL…14.6 SSW [351 total miles] ASOS………………14.6     [351 total miles] DAVIS #1…………..14.7 WSW [353 total miles] DAVIS #2…………..15.2 SW  [365 total miles] RMY……………….14.6 SW  [351 total miles] VECTOR…………….15.0     [360 total miles]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.14  DEPARTURE…. 0.00
ASOS………….0.16
TOTAL PRECIPITATION FOR THE MONTH………….7.32  DEPARTURE….+2.57
ASOS………….7.93
TOTAL PRECIPITATION FOR THE YEAR………….53.72  DEPARTURE….+0.44
ASOS………..55.26

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..0.0  DEPARTURE…..-0.6
TOTAL SNOWFALL FOR THE MONTH………………19.7  DEPARTURE…..+6.8
TOTAL SNOWFALL FOR THE SEASON……………..26.2  DEPARTURE….+10.7

PRELIMINARY CLIMATE SUMMARY FOR DECEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST
AERO: Aerovane wind recording system gust
RMY:  R.M. Young wind gust recording system
TSTM: Thunderstorm day (thunder heard some time during day)
….: Data not yet available, records not finalized
M:    Missing data

12/01   62/40/51/+14/0.61/0.0/112/20      60 S    AERO 67 W    RMY 64
12/02   42/32/37/+1/0.00/0.0/301/54       32 SW   AERO 32 SW   RMY 35
12/03   49/30/40/+4/0.00/0.0/512/92       25 SSW  AERO 25 SSW  RMY 28
12/04   58/40/49/+14/0.06/0.0/332/60      35 SSW  AERO 35 SSW  RMY 37
12/05   42/32/37/+2/2.13/2.8/000/00       58 NNW  AERO 58 NNW  RMY 67
12/06   34/26/30/-5/0.01/T/403/73        E44 WNW  AERO 44 WNW  RMY 49
12/07   33/22/28/-6/T/T/…/..            24 NW   AERO 26 NW   RMY 26
12/08   29/22/26/-8/T/T/…/..            24 NW   AERO 25 NW   RMY 28
12/09   34/19/27/-7/T/T/…/..            16 W    AERO 17 W    RMY 19
12/10   42/30/36/+3/0.00/0.0/…/..       30 WNW  AERO 31 WNW  RMY 29
12/11   50/31/41/+8/0.00/0.0/…/..       32 SW   AERO 35 SW   RMY 34
12/12   48/40/44/+11/0.38/0.0/…/..      25 E    AERO 21 E    RMY 25
12/13   58/35/47/+15/0.00/0.0…/..       28 W    AERO 31 WSW  RMY 31
12/14   35/30/33/+1/0.10/0.4/…/..       25 N    AERO 25 N    RMY 29
12/15   34/21/28/-4/0.00/0.0/…/..       32 WNW  AERO 33 WNW  RMY 38
12/16   27/13/20/-11/0.14/1.4/…/..      38 E    AERO 37 E    RMY 39
12/17   31/19/25/-6/1.58/15.1/…/..      55 ENE  AERO 56 ENE  RMY 59
12/18   27/18/23/-8/0.00/0.0/…/..       28 N    AERO 26 N    RMY 27
12/19   29/13/21/-9/0.00/0.0/…/..       16 SW   AERO 16 S    RMY 16
12/20   36/24/30/0/0.02/T/…/..          14 S    AERO 16 SW   RMY 14
12/21   34/29/32/+2/0.00/0.0/…/..       22 WNW  AERO 24 WNW  RMY 23
12/22   42/30/36/+7/0.00/0.0/…/…      34 WNW  AERO 35 WNW  RMY 38
12/23   37/26/32/+3/0.00/0.0/…/..       30 WNW  AERO 28 WNW  RMY 31
12/24   53/30/42/+13/T/0.0/…/..         46 SSE  AERO 50 SSE  RMY 55
12/25   61/37/49/+21/2.15/0.0/…/..      68 SSE  AERO 77 SSE  RMY 84
12/26   37/25/31/+3/0.00/0.0/…/..       38 SW   AERO 44 SW   RMY 43
12/27   38/22/30/+2/0.00/0.0/…/..       18 W    AERO 18 W    RMY 20
12/28   49/27/38/+10/T/0.0/…/..         35 SSW  AERO 36 –    RMY 37
12/29   38/20/29/+2/0.00/0.0/…/..       48 WNW  AERO 50 WNW  RMY 56
12/30   40/19/30/+3/0.00/0.0/…/..       39 SW   AERO 41 SW   RMY 45

12/31 The low since midnight is 40F, the daily normal low is 19F

DAILY RECORDS FOR DECEMBER 2020
12/17/20: DAILY RECORD SNOWFALL OF 15.1 INCHES,
BREAKS PREVIOUS RECORD OF 7.5 INCHES SET IN 1988

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):

RECORDS FOR DECEMBER 31
HIGH 62 IN 1965
LOW -12 IN 1917
PRECIP 0.96 INS. IN 1906
SNOWFALL 7.5 INS. IN 2008
PEAK GUST 78 MPH NW IN 1990

RECORDS FOR JANUARY 1
HIGH 58F IN 1966
LOW -6F IN 1918
PRECIP 1.45 INS. IN 1982
SNOWFALL 7.2 INS. IN 1938
PEAK GUST 90e MPH S IN 1945

TODAY’S REPORT PREPARED BY: Matt Douglas