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BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
SATURDAY, DECEMBER 21, 2024
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0710E
SUNSET: 1615E
COLD AIR MOVES IN AFTER SNOW COMES TO AN END….
It is a winter wonderland up here on the summit of Great Blue Hill,
which is quite timely given that today is the winter solstice. The
snow came to an end overnight, leaving us with an accumulation of
9.4 inches! The liquid equivalent was 1.17″, giving us roughly an 8:1
snow to liquid ratio.
While virga has been observed to the south through west, potentially
indicating flurries falling out that way, no additional snow has fallen
here during the daylight hours. Skies have been mostly cloudy, though
clearing has been the trend during the early afternoon.
Temperatures are cold, which seems to be the norm for weekends around
here lately. We began at 20F before sunrise, and have only managed to
make it to the mid 20s since. The dew point has hovered within the
low 20s range all day.
Winds are picking up, primarily out of the northwest. The average for
the day so far is 12mph. Our peak gust to this point is about 31mph,
taking place around 12:30pm.
Visibility has improved from 30 miles this morning to 60 miles by
the afternoon.
The maximum temperature for today is 26F degrees, which is 13 degrees
below the normal high of 39F. The minimum temperature since midnight
is 20F degrees, which is 4 degrees below the normal low of 24F.
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Today’s Observations:
7 A.M.
Weather: Broken altostratus/altocumulus, broken cirrus,
few stratocumulus distant NE-S
Temperature: 20F; Dew Point: 20F; Relative Humidity: 96%
Wind: NNW @ 9 kts
Sea-level pressure: 1011.2 mb; 29.86 in. Hg: rising, then more rapidly
Visibility: 30 miles, virga distant SW-W-NNW
6-hr Max temp: 23F
6-hr Min temp: 20F
24-hr Precip: 1.17 inches
24-hr Snowfall: 9.4 inches
Snow Depth: 8 inches
BHO SA 1155 E100 BKN 250 BKN 30 112/20/20/3309/986/ FEW SC DSNT NE-S
VIRGA DSNT SW-W-NNW TOTAL NEW SNW PST 24 HRS 9.4 INS/ 8/571 4/008
53005 70117 10023 20020
10 A.M.
Weather: Scattered stratocumulus, overcast altostratus,
few breaks in overcast distant N-E, sun dimly visible
Temperature: 25F; Dew Point: 23F; Relative Humidity: 92%
Wind: NW @ 10G17 kts
Sea-level pressure: 1012.7 mb; 29.91 in. Hg: rising, then steady
Visibility: 60 miles, virga distant S-SW
3-hr Precip: 0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 55 SCT E70 OVC 60 127/25/23/3210G17/991/ FEW BINOVC DSNT N-E
SUN DMLY VSBL VIRGA DSNT S-SW/ 8/51/ 51015
1 P.M.
Weather: Scattered stratocumulus, scattered altostratus, broken cirrus
Temperature: 25F; Dew Point: 20F; Relative Humidity: 80%
Wind: NW @ 13G21 kts, peak wind NW 31mph @ 12:33pm
Sea-level pressure: 1011.9 mb; 29.88 in. Hg: falling, then rising
Visibility: 60 miles, virga distant SE-SSW
6-hr Max temp: 26F
6-hr Min temp: 20F
6-hr Precip: 0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 8 inches
BHO SA 1755 30 SCT 90 SCT E250 BKN 60 119/25/20/3113G21/988/ VIRGA DSNT SE-SSW
PK WND 3127/33/ 8/511 4/008 55008 10026 20020
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SUMMARY FOR FRIDAY, DECEMBER 20, 2024
TEMPERATURE (DEGREES F)
MAX…….32 NORMAL…..39
MIN…….24 NORMAL…..24
MEAN……28 NORMAL…..31
DEPARTURE FROM 30-YEAR (1991-2020) NORMAL………….-3
TOTAL DEPARTURE FOR THE MONTH…………………….+4 [+0.0 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON: JUL 2024 THRU JUN 2025)
TOTAL HEATING UNITS FOR YESTERDAY……………37 DEPARTURE……..+3
TOTAL HEATING UNITS FOR THE MONTH…………..615 DEPARTURE……..-4
TOTAL HEATING UNITS FOR THE SEASON…………1558 DEPARTURE……-265
TOTAL HEATING UNITS LAST SEASON TO DATE…….1596 DEPARTURE…….-38
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)………..28 NNE @ 06:45 P.M.
VECTOR #1 (1-Sec)……….29 N @ 10:56 P.M.
VECTOR #2 (1-Sec)……….28 N @ 10:31 P.M.
DAVIS #1……………….24 N @ 10:56 P.M.
DAVIS #2 ………………24 NNE @ 10:56 P.M.
RMY #1 (Instantaneous)…..29 N @ 10:56 P.M.
RMY #2 (Instantaneous)…..29 N @ 10:31 P.M.
MERLIN…………………26 NE
RICHARDS (C5C) (Inst)…..OTS
FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………18 NNW @ 10:58 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..18 @ 10:58 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..18 @ 11:54 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………16 ENE @ 05:37 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………16 E @ 07:06 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..18 NNW @ 10:58 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..18 NNW @ 11:55 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..10.8 N [259 total miles]
VECTOR #1………………10.9
VECTOR #2………………11.3
DAVIS #1……………….10.4 NNE
DAVIS #2……………….10.5 NNE
RMY #1…………………11.0 NNE
RMY #2…………………11.3 NNE
RICHARDS (C5C)…………..OTS
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..1.17 DEPARTURE…..+1.00
TOTAL PRECIPITATION FOR THE MONTH…………..6.66 DEPARTURE…..+3.10
TOTAL PRECIPITATION FOR THE YEAR (2024)…….54.13 DEPARTURE…..+2.10
SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..9.4 DEPARTURE……+8.9
TOTAL SNOWFALL FOR THE MONTH……………….12.4 DEPARTURE……+5.3
TOTAL SNOWFALL FOR THE SEASON (2024-2025)……12.4 DEPARTURE……+2.8
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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/…./…/…/.. 28 NNE VEC1 29 N RMY 29
12/21 The low since midnight is 20F, the daily normal low is 24F.
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DECEMBER DAILY RECORDS TO DATE
12/11 NEW PRECIPITATION RECORD OF 3.38″; OLD RECORD 2.36″ IN 1992
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DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)
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
RECORDS FOR DECEMBER 22
HIGH 63 IN 2013
LOW -5 IN 1921
PRECIP 1.52 INS. IN 1975
SNOWFALL 8.8 INS. IN 1975
PEAK GUST 62 MPH WNW IN 1998
TODAY’S REPORT PREPARED BY: Joshua Polen
