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

WEDNESDAY, DECEMBER 25, 2024
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0712E
SUNSET: 1617E

SUNNY AND COLD ON THIS CHRISTMAS DAY….

We have a White Christmas this year as there is still 7″ of snow on
the ground today. The last official White Christmas here on the summit
was in 2012 when there was 1″ reported on the ground at 7am. Today’s
depth is the highest on Christmas Day since 2009 when 9″ was reported.
While we did get a 3.2″ snowfall on Christmas in 2017, it all fell
after 7am, thus didn’t officially count as a White Christmas.

Per our Chief Scientist Mike Iacono, here are some statistics about
White Christmases here at Blue Hill.

Measurements of snow depth on the ground began regularly in 1895. For
the 130 years since then, 57 years (including this year) had one inch
or more of snow on the ground on Christmas Day. That’s an average chance
of 44%.

Looking at the first 65 years (1895-1959) and the last 65 years
(1960-2024) separately, there were 28 such days in the earlier period
and 29 days in the latter period, so the chance hasn’t changed much
during the period of record. The average snow depth on white Christmas
days was 4.3 inches during 1895-1959 and 5.5 inches for 1960-2024.

Getting back to today, after some cloud cover very early this morning,
sunshine has been the rule for today giving us a spectacular day
weatherwise, despite it being on the chilly side.

Temperature has gradually risen through the 20s, after starting the
day right at 20F. We have reached 30F as of the 1pm observation. The
dew point has been holding in the teens, so the air is on the dry side.

Thankfully, the wind has been mostly on the light side today, mainly out
of the north and north-northwest. The average speed for the day so far
is around 9mph. The peak gust for the day so far is 18mph, which
occurred at 5:33am this morning.

Visibility has been somewhat limited today, but gradually improving.
Hazy conditions have been the theme thanks to pollution getting trapped
under an inversion. The view has improved some as the inversion lifts.
We started the day being able to see only 25-30 miles, but its up to
around 50 miles early this afternoon.

The maximum temperature for today is 31F degrees, which is 7 degrees
below the normal high of 38F. The minimum temperature since midnight
is 20F degrees, which is 2 degrees below the normal low of 22F.
————————————————————–

Today’s Observations:

7 A.M.
Weather: Broken stratocumulus, broken cirrus, few lower stratocumulus
along shore distant NNE-SE
Temperature: 22F; Dew Point: 17F; Relative Humidity: 82%
Wind: N @ 6 kts, wind light
Sea-level pressure: 1028.2 mb; 30.36 in. Hg: rising unsteadily
Visibility: 30 miles, hazy
6-hr Max temp: 23F
6-hr Min temp: 21F
24-hr Precip: 0.02 inches
24-hr Snowfall: 0.2 inches
Snow Depth: 7 inches
BHO SA 1155 E23 BKN 250 BKN 30 282/22/17/3506/036/ FEW LWR SC ALNG
SHR DSNT NNE-SE HAZY WND LGT TOTAL NEW SNW PST 24 HRS 0.2 INS/ 8/501
4/007 52009 70002 10023 20021

10 A.M.
Weather: Clear, few stratocumulus distant all quadrants
Temperature: 26F; Dew Point: 18F; Relative Humidity: 73%
Wind: NNW @ 5 kts, wind light
Sea-level pressure: 1029.1 mb; 30.39 in. Hg: rising, then more slowly
Visibility: 40 miles, hazy
3-hr Precip: 0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 CLR 40 291/26/18/3405/039/ FEW SC DSNT ALQDS HAZY WND LGT/
8/500 51009

1 P.M.
Weather: Clear, few stratocumulus offshore distant NE-SSE
Temperature: 30F; Dew Point: 19F; Relative Humidity: 63%
Wind: NNW @ 6 kts, wind light
Sea-level pressure: 1028.0 mb; 30.36 in. Hg: falling, then more slowly
Visibility: 50 miles, hazy
6-hr Max temp: 31F
6-hr Min temp: 20F
6-hr Precip: 0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 7 inches
BHO SA 1755 CLR 50 280/30/19/3406/036/ FEW SC OFFSHR DSNT NE-SSE HAZY
WND LGT/ 8/500 4/007 56011 10031 20020

————————————————————–

SUMMARY FOR TUESDAY, DECEMBER 24, 2024

TEMPERATURE (DEGREES F)
MAX…….31 NORMAL…..38
MIN…….19 NORMAL…..23
MEAN……25 NORMAL…..30

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL………….-5
TOTAL DEPARTURE FOR THE MONTH……………………-48 [-2.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2024 THRU JUN 2025)
TOTAL HEATING UNITS FOR YESTERDAY……………40 DEPARTURE……..+5
TOTAL HEATING UNITS FOR THE MONTH…………..804 DEPARTURE…….+47
TOTAL HEATING UNITS FOR THE SEASON…………1747 DEPARTURE……-214
TOTAL HEATING UNITS LAST SEASON TO DATE…….1729 DEPARTURE…….+18

PEAK WIND GUST (MPH):
Note: Instruments designated #1 = Main Tower, #2 = South Tower,
F420C, Contacting, Merlin, and Richards are all on Main Tower.
E=Estimated

F420C (Official)………..29 WSW @ 08:37 A.M.
VECTOR #1 (1-Sec)……….29 WSW @ 08:37 A.M.
VECTOR #2 (1-Sec)……….30 WSW @ 08:35 A.M.
DAVIS #1……………….29 WSW @ 08:37 A.M.
DAVIS #2 ………………30 W @ 08:35 A.M.
RMY #1 (Instantaneous)…..30 WSW @ 08:37 A.M.
RMY #2 (Instantaneous)…..30 WSW @ 08:37 A.M.
MERLIN…………………28 W
RICHARDS (C5C) (Inst)…..OTS

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………19 SW @ 07:30 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..19 @ 07:22 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..20 @ 07:23 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………18 SSW @ 07:22 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………21 SSW @ 07:23 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..20 SSW @ 07:22 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..21 SSW @ 07:23 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..10.6 SW [254 total miles] VECTOR #1………………11.0
VECTOR #2………………11.4
DAVIS #1……………….10.9 W
DAVIS #2……………….11.3 W
RMY #1…………………10.8 W
RMY #2…………………11.4 W
RICHARDS (C5C)…………..OTS

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.02 DEPARTURE…..-0.15
TOTAL PRECIPITATION FOR THE MONTH…………..6.68 DEPARTURE…..+2.42
TOTAL PRECIPITATION FOR THE YEAR (2024)…….54.15 DEPARTURE…..+1.42

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.2 DEPARTURE……-0.3
TOTAL SNOWFALL FOR THE MONTH……………….12.6 DEPARTURE……+3.6
TOTAL SNOWFALL FOR THE SEASON (2024-2025)……12.6 DEPARTURE……+1.1

————————————————————–

PRELIMINARY CLIMATE SUMMARY FOR DECEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN)/SUN(%)/PEAK GUST/VEC1/RMY GUST
PEAK GUST: F420C (Official)
VEC1: Vector #1 1-second gust
RMY: R.M. Young #1 wind gust recording system (Instantaneous)
TSTM: Thunderstorm day (thunder heard some time during day)
….: Data not yet available, records not finalized
M: Missing data

12/1 37/23/30/-7/0.00/0.0/452/81 21 WSW VEC1 21 WSW RMY 21
12/2 38/22/30/-7/0.00/0.0/551/99 18 W VEC1 18 W RMY 18
12/3 36/20/28/-8/0.00/0.0/411/74 21 NW VEC1 21 WNW RMY 21
12/4 39/22/31/-5/0.13/T/394/71 30 S VEC1 31 S RMY 33
12/5 37/31/34/-2/0.40/3.0/072/13 43 WNW VEC1 43 WNW RMY 47
12/6 31/23/27/-8/0.00/0.0/514/93 39 NW VEC1 39 W RMY 42
12/7 37/22/30/-5/T/T/408/74 25 S VEC1 25 S RMY 26
12/8 47/28/38/+3/0.02/T/198/36 37 SSW VEC1 37 SSW RMY 40
12/9 47/34/41/+7/0.41/0.0/187/34 28 ENE VEC1 28 E RMY 29
12/10 42/31/37/+3/0.15/0.0/000/00 31 NE VEC1 32 NE RMY 34
12/11 62/36/49/+15/3.38/0.0/000/00 65 SSW VEC1 67 SSW RMY 70 TSTM
12/12 53/25/39/+5/0.05/0.0/460/84 51 WNW VEC1 49 WNW RMY 51
12/13 31/19/25/-8/0.00/0.0/514/94 30 WNW VEC1 30 W RMY 30
12/14 33/17/25/-8/0.00/0.0/546/100 20 NW VEC1 19 NNW RMY 20
12/15 34/17/26/-7/0.00/0.0/377/69 17 N VEC1 17 N RMY 16
12/16 45/29/37/+5/T/0.0/005/01 35 SSE VEC1 35 SSE RMY 35
12/17 59/41/50/+18/0.25/0.0/360/66 48 SSW VEC1 50 SSW RMY 50
12/18 50/36/43/+11/0.57/0.0/507/93 21 S VEC1 21 S RMY 21
12/19 44/30/37/+5/0.13/0.0/…/.. 31 NW VEC1 31 NW RMY 32
12/20 32/24/28/-3/1.17/9.4/000/00 28 NNE VEC1 29 N RMY 29
12/21 26/12/19/-12/0.00/0.0/…/.. 38 NW VEC1 38 NW RMY 41
12/22 17/6/12/-19/0.00/0.0/…/.. 33 NW VEC1 33 NW RMY 35
12/23 26/4/15/-16/0.00/0.0/…/.. 21 S VEC1 21 SSW RMY 20
12/24 31/19/25/-5/0.02/0.2/…/.. 29 WSW VEC1 29 WSW RMY 30