Monday, December 20, 2021

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

MONDAY, DECEMBER 20, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0710E
SUNSET:  1614E

COLD AND DRY WITH AN ABUNDANCE OF SUNSHINE….

An arctic air mass is over the region today as temperatures and
dew points are running well below normal for the day. Even with
plenty of sunshine today, the mercury has been hard pressed to
reach 30 so far here on the summit.

The dew point has definitely been indicative of the air mass in
place with single digits being measured early this morning. It has
recovered a tad bit to the mid teens by early this afternoon.

Visibility hasn’t been as great as one would expect with the dry air
in place. Maximum visibility has only been 60 miles today, up from
40 miles early this morning.

The Blue Hill Ski area was making snow overnight for the first time
this season. Quite late of course. Also of note, the two ponds we
observe from the summit, Houghton’s and Ponkapoag, have yet to have
much ice cover on them. Again, this is quite late as well.

The high so far today is 30F, which is 9 degrees below the normal
max of 39F. The low since midnight is 15F, which 9 degrees below
the normal low of 24F.

————————————————————–

Today’s Observations:

7 A.M.
Weather: Clear, few stratocumulus offshore distant NNE-SSE
Temperature: 16F; Dew Point: 9F; Relative Humidity: 75%
Wind: NW @ 10 kts
Sea-level pressure: 1026.6 mb; 30.32 in. Hg: rising then steady
Visibility: 40 miles, hazy
6-hr Max temp: 19F
6-hr Min temp: 15F
24-hr Precip:  Trace
24-hr Snowfall: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1155 CLR 40 266/16/9/3310/032/ FEW SC OFFSHR DSNT NNE-SSE HAZY/
8/500 51015 70000 10019 20015

10 A.M.
Weather: Thin scattered cirrus, few stratocumulus offshore distant NNE-SE
Temperature: 22F; Dew Point: 14F; Relative Humidity: 70%
Wind: WNW @ 3 kts, wind light
Sea-level pressure: 1028.4 mb; 30.37 in Hg; rising, then more slowly
Visibility: 50 miles
3-hr Precip: 0.00 ins.
3-hr Snowfall: 0.0 ins.
BHO SA 1455 250 -SCT 50 284/22/14/2903/037/ FEW SC OFFSHR DSNT NNE-SE
WND LGT/ 8/501 51018

1 P.M.
Weather: Scattered altocumulus, thin scattered cirrus, few stratocumulus
offshore distant NE-SE
Temperature: 30F, Dew point: 14F; Relative Humidity: 51%
Wind: SSW @ 5 kts, wind light
Sea-level pressure: 1025.9 mb; 30.29 in Hg; falling, then more rapidly
Visibility: 60 miles
6-hr Max temp: 30F
6-hr Min temp: 16F
6-hr Precip:   0.00 ins.
6-hr Snowfall: 0.0 ins.
Snow Depth: 0.0 ins.
BHO SA 1755 130 SCT 250 -SCT 60 259/30/14/2105/029/ FEW SC OFFSHR DSNT NE-SE
WND LGT/ 8/551 58025 10030 20016

SUMMARY FOR SUNDAY, DECEMBER 19, 2021

TEMPERATURE (DEGREES F)
MAX…….39     NORMAL…..39
MIN…….20     NORMAL…..24
MEAN……30     NORMAL…..32

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL……………-2
TOTAL DEPARTURE FOR THE MONTH………………………+96 [+4.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2021 THRU JUN 2022)
TOTAL HEATING UNITS FOR YESTERDAY……………35  DEPARTURE……..+2
TOTAL HEATING UNITS FOR THE MONTH…………..489  DEPARTURE…….-97
TOTAL HEATING UNITS FOR THE SEASON…………1496  DEPARTURE……-294
TOTAL HEATING UNITS LAST SEASON TO DATE…….1565  DEPARTURE…….-69

PEAK WIND GUST (MPH):
Official (1-Sec AVG)…….35 NNW @  7:36 P.M.
AEROVANE……………….37 NNW @  4:24 P.M.
VECTOR #2 (Instantaneous)..37     @  5:08 P.M.
DAVIS #2 ………………32 N   @  4:48 P.M.
RMY #2 (Instantaneous)…..36 NNW @  5:08 P.M.
ASOS………..OUT OF SERVICE D/T RENOVATIONS
VECTOR #1……OUT OF SERVICE D/T RENOVATIONS
DAVIS #1…….OUT OF SERVICE D/T RENOVATIONS
RMY #1………OUT OF SERVICE D/T RENOVATIONS
MERLIN………OUT OF SERVICE D/T RENOVATIONS

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………24 NNW @  5:07 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..22     @  5:09 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………22 N   @  5:09 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..23 NNW @  5:09 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE…….OUT OF SERVICE D/T RENOVATIONS
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE…OUT OF SERVICE D/T RENOVATIONS
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE..OUT OF SERVICE D/T RENOVATIONS
MAXIMUM 2-MINUTE RMY #1 AVERAGE…..OUT OF SERVICE D/T RENOVATIONS

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL…..13.5 NNW  [325 total miles] VECTOR #2…………… N/A
DAVIS #2…………….12.8 N
RMY #2………………12.5 NNW
RMY #1…………..OUT OF SERVICE D/T RENOVATIONS
ASOS…………….OUT OF SERVICE D/T RENOVATIONS
VECTOR #1………..OUT OF SERVICE D/T RENOVATIONS
DAVIS #1…………OUT OF SERVICE D/T RENOVATIONS

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……TRACE  DEPARTURE…..-0.18
TOTAL PRECIPITATION FOR THE MONTH………….1.95  DEPARTURE…..-1.44
TOTAL PRECIPITATION FOR THE YEAR………….58.72  DEPARTURE…..+7.12

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M………….0.0  DEPARTURE……-0.5
TOTAL SNOWFALL FOR THE MONTH……………….1.4  DEPARTURE……-5.2
TOTAL SNOWFALL FOR THE SEASON (2021-2022)……2.4  DEPARTURE……-6.7

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   44/30/37/0.00/0.0/263/47          35 W   AERO 35 W   RMY 34
12/02   58/35/47/10/T/0.0/106/19          56 WNW AERO 59 WNW RMY 62 TSTM
12/03   41/28/35/-1/0.00/0.0/512/92       46 NW  AERO 44 NW  RMY 46
12/04   39/25/32/-4/0.00/0.0/233/42       25 SW  AERO 23 SW  RMY 26
12/05   45/32/39/+3/0.00/0.0/460/83       25 SE  AERO 25 SE  RMY 25
12/06   59/37/48/+13/0.34/0.0/077/14      59 WNW AERO 59 NW  RMY 60
12/07   40/29/35/0/T/0.0/436/79           47 WNW AERO 36 WNW RMY 48
12/08   34/25/30/-5/0.05/0.6/000/00       26 NNE AERO 25 NE  RMY 26
12/09   35/20/28/-6/0.05/0.6/319/58       32 NW  AERO 30 NW  RMY 33
12/10   43/27/35/+1/0.00/0.0/000/00       21 SE  AERO 20 SE  RMY 21
12/11   62/37/50/+16/0.34/0.0/000/00      57 SSW AERO 59 SSW RMY 58
12/12   58/36/47/+13/0.05/0.0/416/76      55 WNW AERO 55 WNW RMY 58
12/13   50/35/43/+10/0.00/0.0/224/41      32 WSW AERO 33 WSW RMY 33
12/14   50/33/42/+9/0.00/0.0/442/81       31 WSW AERO 30 WSW RMY 32
12/15   42/28/35/+2/T/0.0/153/28          35 SSE AERO 35 SSE RMY 36
12/16   58/42/50/+18/0.21/0.0/016/03      35 SW  AERO 37 SW  RMY 38
12/17   56/39/48/+16/0.00/0.0/518/95      43 WNW AERO 41 WNW RMY 46
12/18   39/31/35/+3/0.52/0.2/000/00       21 NNW AERO 20 NNW RMY 20
12/19   39/20/30/-2/0.39/0.0/…/..       35 NNW AERO 37 NNW RMY 36

12/20 The low since midnight is 15F, the daily normal low is 24F

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

RECORDS FOR DECEMBER 20
HIGH 61 IN 1957
LOW -16 IN 1942
PRECIP 1.69 INS. IN 1936
SNOWFALL 13.7 INS. IN 2009
PEAK GUST 75 MPH S IN 2002

RECORDS FOR DECEMBER 21
HIGH 62 IN 2018
LOW -10 IN 1942
PRECIP 2.37 INS. IN 1946
SNOWFALL 11.4 INS. IN 1954
PEAK GUST 77 MPH SSE IN 1957

TODAY’S REPORT PREPARED BY: Matt Douglas