Wednesday, December 20, 2023

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

WEDNESDAY, DECEMBER 20, 2023
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0709E
SUNSET:  1614E

ABUNDANT SUNSHINE, BUT SEASONABLY CHILLY TODAY AT BLUE HILL….

Wall to wall sunshine has been the theme today with only some
distant clouds offshore over the ocean. Interestingly, the cirrus
deck has been getting closer as a low pressure well offshore
intensifies. This system however will remain well offshore leaving
us with dry conditions under high pressure for the next few days.

A dry arctic boundary will slip through this evening with a
freshening northerly wind and dropping temperatures and dew points.

But for now, not a bad day ongoing with temperatures in the upper
30s to near 40. The dew point has been holding in the lower 20s
all day.

The wind has been on the light side today out of mainly the north-
northwest. The average speed for the day so far is around 9mph. The
highest gust occurred just before 8:30am this morning and was
measured at around 26mph.

Visibility has been excellent today, ranging between 70-80 miles.

The maximum temperature for today is 39F degrees, this is equal
to the normal high of 39F. The minimum temperature since midnight
is 26F degrees, this is 2 degrees above the normal low of 24F.

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Today’s Observations:

7 A.M.
Weather: Clear, few stratocumulus offshore distant NNE-S
Temperature: 27F; Dew Point: 21F; Relative Humidity: 79%
Wind: NNW @ 10G17 kts
Sea-level pressure: 1025.6 mb; 30.29 in. Hg: rising, then more slowly
Visibility: 70 miles
6-hr Max temp: 30F
6-hr Min temp: 27F
24-hr Precip:  0.00 inches
24-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1155 CLR 70 256/27/21/3410G17/029/ FEW SC OFFSHR DSNT NNE-S/
8/500 51021 10030 20027

10 A.M.
Weather: Clear, few stratocumulus offshore distant NE-S, few cirrus
distant NE-SE
Temperature: 33F; Dew Point: 20F; Relative Humidity: 59%
Wind: NNW @ 6 kts, wind light
Sea-level pressure: 1027.3 mb; 30.34 in. Hg: rising, then more rapidly
Visibility: 80 miles
3-hr Precip:  0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 CLR 80 273/33/20/3406/034/ FEW SC OFFSHR DSNT NE-S FEW CI
DSNT NE-SE WND LGT/ 8/502 53017

1 P.M.
Weather: Clear, few cirrus distant NE-SSE
Temperature: 38F; Dew Point: 20F; Relative Humidity: 47%
Wind: NW @ 6 kts, wind light
Sea-level pressure: 1025.3 mb; 30.28 in. Hg: falling, then more slowly
Visibility: 80 miles
6-hr Max temp: 39F
6-hr Min temp: 26F
6-hr Precip:  0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1755 CLR 80 253/38/20/3206/028/ FEW CI DSNT NE-SSE WND LGT/
8/002 56020 10039 20026

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SUMMARY FOR TUESDAY, DECEMBER 19, 2023

TEMPERATURE (DEGREES F)
MAX…….46   NORMAL…..39
MIN…….30   NORMAL…..24
MEAN……38   NORMAL…..32

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL………..+6
TOTAL DEPARTURE FOR THE MONTH…………………+107 [+5.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2023 THRU JUN 2024)
TOTAL HEATING UNITS FOR YESTERDAY……………27  DEPARTURE……..-6
TOTAL HEATING UNITS FOR THE MONTH…………..478  DEPARTURE……-108
TOTAL HEATING UNITS FOR THE SEASON…………1565  DEPARTURE……-225
TOTAL HEATING UNITS LAST SEASON TO DATE…….1519  DEPARTURE…….+46

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

F420C (Official)……….E28 NW   @  08:57 P.M.
VECTOR #1 (1-Sec)……….28 NW   @  08:57 P.M.
VECTOR #2 (1-Sec)……….28 NW   @  08:43 P.M.
DAVIS #1……………….24 NW   @  08:57 P.M.
DAVIS #2 ………………25 NW   @  08:43 P.M.
RMY #1 (Instantaneous)…..26 NW   @  08:57 P.M.
RMY #2 (Instantaneous)…..28 NW   @  08:43 P.M.
MERLIN…………………24 NW
RICHARDS (C5C) (Inst)……25      @  08:42 P.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………17 NW   @  09:01 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..17      @  12:12 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..18      @  12:02 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………17 NW   @  08:59 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………18 SW   @  12:02 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..17 SW   @  12:12 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..19 SW   @  12:02 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………17      @  08:59 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……10.5 WNW [253 total miles] VECTOR #1…………….10.6
VECTOR #2…………….11.3
DAVIS #1……………..10.8 W
DAVIS #2……………..11.1 W
RMY #1……………….10.4 W
RMY #2……………….11.2 W
RICHARDS (C5C)………..10.7

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.18
TOTAL PRECIPITATION FOR THE MONTH…………..6.44 DEPARTURE…..+3.05
TOTAL PRECIPITATION FOR THE YEAR…………..57.81 DEPARTURE…..+5.95

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE……-0.5
TOTAL SNOWFALL FOR THE MONTH………………..0.3 DEPARTURE……-6.3
TOTAL SNOWFALL FOR THE SEASON (2023-2024)…….0.3 DEPARTURE……-8.8

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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  51/38/45/+8/0.04/0.0/213/38         29 SW  VEC1 28 SW  RMY 29
12/2  48/43/46/+9/T/0.0/000/00            18 SSW VEC1 19 SSW RMY 19
12/3  44/41/43/+7/0.76/0.0/000/00         31 ENE VEC1 32 ENE RMY 33
12/4  49/37/43/+7/0.07/0.0/155/28         23 W   VEC1 22 W   RMY 23
12/5  38/28/33/-3/0.00/0.0/144/26         23 NNW VEC1 24 NW  RMY 24
12/6  34/22/28/-7/0.01/0.3/100/18         21 N   VEC1 21 N   RMY 20
12/7  28/17/56/-12/0.00/0.0/121/22        18 NNW VEC1 18 NW  RMY 19
12/8  42/24/33/-2/0.00/0.0/530/96         20 S   VEC1 18 S   RMY 18
12/9  52/33/43/+9/0.00/0.0/264/48         24 S   VEC1 24 S   RMY 24
12/10 60/43/52/+18/0.66/0.0/033/06        55 SSW VEC1 54 SSW RMY 53
12/11 61/33/47/+13/1.96/0.0/038/07        69 SSW VEC1 69 SSW RMY 71
12/12 42/29/36/+2/0.00/0.0/543/99         33 WNW VEC1 32 WNW RMY 34
12/13 43/28/36/+3/0.00/0.0/470/86         36 WNW VEC1 34 WNW RMY 36
12/14 34/22/28/-5/0.00/0.0/…/..         31 SW  VEC1 31 SW  RMY 32
12/15 53/30/42/+9/0.00/0.0/…/..         31 WNW VEC1 30 WNW RMY 28
12/16 50/36/43/+11/0.00/0.0/…/..        21 ESE VEC1 22 ESE RMY 22
12/17 55/37/46/+14/0.47/0.0/…/..        40 SSE VEC1 41 SSE RMY 41
12/18 61/42/52/+20/2.47/0.0/…/..        90 SSE VEC1 95 SSE RMY 101
12/19 46/30/38/+6/0.00/0.0/…/..         28 NW  VEC1 28 NW  RMY 26

12/20 The low since midnight is 26F, the daily normal low is 24F

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DECEMBER DAILY RECORDS TO DATE

12/18: RECORD MAXIMUM TEMPERATURE OF 61F;
BEATS OLD RECORD OF 59F SET IN 1928

12/18: RECORD PRECIPITATION OF 2.47 INS;
BEATS OLD RECORD OF 1.44 INS SET IN 1915

12/18: RECORD PEAK WIND GUST OF 90 MPH;
BEATS OLD RECORD OF 76e MPH SET IN 1978

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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