Sunday, December 15, 2024

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

SUNDAY, DECEMBER 15, 2024
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0707E
SUNSET:  1613E

STRONG HIGH PRESSURE STILL IN CONTROL FOR NOW; COLD WITH INCREASING
CLOUDS….

An area of strong high pressure has been working its way across the
region over the past couple of days. The axis of this high has finally
passed by and pressure levels are beginning to fall off from its peak
yesterday. The highest sea-level pressure observed here was 1047.6mb,
or 30.94 in/hg between 10-11am yesterday morning!

As the high pressure system departs, a weather system is approaching
from the west, and thus the increasing clouds today. So far, it’s just
high thin cirrus clouds overtaking the sky, as such, there is still a
decent amount of sunshine being observed today, at least for now.

Temperatures once again started the day in the mid to upper teens here
on the summit, but quickly rose through the 20s this morning, and into
the low to mid 30s by early this afternoon. Dew points are still quite
low, but finally on their way upwards with values rising through the
teens. The air mass is still on the very dry side.

Winds have been on the light side today with an average speed so far of
only around 8mph. The peak gust so far occurred just after midnight,
with a speed of 17mph.

Visibility has been holding at around 60-70 miles all day.

The maximum temperature for today is 34F degrees, which is 6 degrees
below the normal high of 40F. The minimum temperature since midnight
is 17F degrees, which is 8 degrees below the normal low of 25F.

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Today’s Observations:

7 A.M.
Weather: Thin scattered cirrus,  few stratocumulus distant N-E-S
Temperature: 17F; Dew Point: 11F; Relative Humidity: 75%
Wind: N @ 7 kts
Sea-level pressure: 1045.9 mb; 30.89 in. Hg: steady, then falling
Visibility: 60 miles
6-hr Max temp: 21F
6-hr Min temp: 17F
24-hr Precip:  0.00 inches
24-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1155 250 -SCT 60 459/17/11/3507/089/ FEW SC DSNT N-E-S/ 8/501
58002 10021 20017

10 A.M.
Weather: Thin broken cirrus, few stratocumulus distant N-E-S
Temperature: 27F; Dew Point: 13F; Relative Humidity: 55%
Wind: NNW @ 4 kts, wind light
Sea-level pressure: 1046.1 mb; 30.89 in. Hg: rising, then falling
Visibility: 60 miles
3-hr Precip:  0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 E250 -BKN 60 461/27/13/3404/089/ FEW SC DSNT N-E-S WND LGT/
8/551 50002

1 P.M.
Weather: Thin broken cirrus, few stratocumulus distant NNE-E-S
Temperature: 33F; Dew Point: 19F; Relative Humidity: 56%
Wind: SSW @ 4 kts, wind light
Sea-level pressure: 1043.6 mb; 30.82 in. Hg: falling, then more slowly
Visibility: 70 miles
6-hr Max temp: 34F
6-hr Min temp: 17F
6-hr Precip:  0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1755 E250 -BKN 70 436/33/19/2104/082/ FEW SC DSNT NNE-E-S
WND LGT/ 8/504 56025 10034 20017

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SUMMARY FOR SATURDAY, DECEMBER 14, 2024

TEMPERATURE (DEGREES F)
MAX…….33  NORMAL…..41
MIN…….17  NORMAL…..25
MEAN……25  NORMAL…..33

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL………….-8
TOTAL DEPARTURE FOR THE MONTH……………………-25 [-2.0 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2024 THRU JUN 2025)
TOTAL HEATING UNITS FOR YESTERDAY……………40  DEPARTURE……..+8
TOTAL HEATING UNITS FOR THE MONTH…………..446  DEPARTURE…….+24
TOTAL HEATING UNITS FOR THE SEASON…………1389  DEPARTURE……-237
TOTAL HEATING UNITS LAST SEASON TO DATE…….1461  DEPARTURE…….-72

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)………..20 NW   @   07:27 A.M.
VECTOR #1 (1-Sec)……….19 NNW  @   09:30 A.M.
VECTOR #2 (1-Sec)……….21 NW   @   06:36 A.M.
DAVIS #1……………….19 NW   @   05:03 A.M.
DAVIS #2 ………………19 NNW  @   05:02 A.M.
RMY #1 (Instantaneous)…..20 NNW  @   06:20 A.M.
RMY #2 (Instantaneous)…..21 NW   @   05:02 A.M.
MERLIN………………….M
RICHARDS (C5C) (Inst)…..OTS

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………16 NNW  @   06:17 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..15      @   05:02 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..16      @   06:12 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………15 NW   @   05:02 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………15 NNW  @   05:09 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..15 NNW  @   05:02 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..15 NNW  @   06:12 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………7.4 NNW [178 total miles] VECTOR #1……………….8.2
VECTOR #2……………….8.5
DAVIS #1………………..8.1 NNW
DAVIS #2………………..7.9 NNW
RMY #1………………….8.1 NNW
RMY #2………………….8.4 NNW
RICHARDS (C5C)…………..OTS

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.18
TOTAL PRECIPITATION FOR THE MONTH…………..4.54 DEPARTURE…..+2.03
TOTAL PRECIPITATION FOR THE YEAR (2024)…….52.01 DEPARTURE…..+1.03

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE……-0.4
TOTAL SNOWFALL FOR THE MONTH………………..3.0 DEPARTURE……-1.5
TOTAL SNOWFALL FOR THE SEASON (2024-2025)…….3.0 DEPARTURE……-4.0

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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/…/..        51 WNW VEC1 49 WNW RMY 51
12/13  31/19/25/-8/0.00/0.0/…/..        30 WNW VEC1 30 W   RMY 30
12/14  33/17/25/-8/0.00/0.0/…/..        20 NW  VEC1 19 NNW RMY 20

12/15 The low since midnight is 17F, the daily normal low is 25F.

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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 15
HIGH 64 IN 1975
LOW 4 IN 1900, 1905, 1933
PRECIP 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
PRECIP 1.88 INS. IN 2022
SNOW 8.5 INS. IN 2007
WIND 73 MPH SSE IN 1982

TODAY’S REPORT PREPARED BY: Matt Douglas