Sunday, December 24, 2017

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

DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, DECEMBER 24, 2017
ALL TIMES ARE IN EASTERN STANDARD TIME

ANOTHER CLOUDY DAY WITH TEMPERATURES HOVERING
AROUND FREEZING

The rain and freezing rain that came yesterday has left drier but cold conditions
in it’s wake, with the humidity dropping throughout the day.  The barometric
pressure made a dramatic recovery from yesterday, rising by nearly 20 millibars
before the 10 AM observation.

Winds, which had become stronger during the overnight, have become lighter
with a few stronger gusts. Visibility has improved throughout the morning and
is now 70 miles.

Today’s Observations:

7 A.M.
Weather: Scattered Altocumulus, Broken cirrostratus, few cumulus NNE-SE,
light distant haze
Temperature: 32F; Dew Point: 28F; Wind: NNW at 10 kts,
Sea-level pressure: 30.11 ins. Hg, rising then more slowly
Visibility: 50 miles, light distant haze
6-hr Max temp: 34F
6-hr Min temp: 31F
24-hr precip: 0.57 ins.
24-hr snowfall: 0.0 ins.
Snow cover: 0 ins.
BHO SA 1155 110 SCT E250 BKN 50 195/32/28/3310/011/ FEW CU NNE-SE
LGT DSNT HZ PRESRR/ 8/188 51037 MANUAL 70057 ASOS 70057 10034 20031

10 A.M.
Weather: Broken Altostratus, Few cumulus
Temperature: 33F; Dew Point: 25F; Wind: NNW at 11 kts Gust to 18 kts,
Sea-level pressure: 30.06 ins. Hg, falling, then more quickly
Visibility: 70 miles
3-hr precip: 0.00 ins.
3-hr snowfall: 0.0 ins.
BHO SA 1455 E220 BKN 70 238/33/25/3311G18/023/ FEW CU ALQDS PRESRR/
8/12/ 51043

1 P.M.
Weather: Overcast Altostratus, Few Altocumulus NNE-N, Few Cumulus,
Sun dimly visible
Temperature: 33F; Dew Point: 26F; Wind: N at 7 kts
Sea-level pressure: 30.19 ins. Hg, steady then falling
Visibility:  70 miles
6-hr Max temp: 33F
6-hr Min temp: 31F
6-hr precip: 0.00 ins.
6-hr snowfall: 0.0 ins.
Snow cover: 0 ins.
BHO SA 1755 E220 OVC 70 225/33/26/3507/019/ FEW CU ALQDS FEW AC
NNW-N THN GLZ IN SPTS SUN DMLY VSBL/ 8/11/ 56013 10033 20031

SUMMARY FOR SATURDAY, DECEMBER 23, 2017

TEMPERATURE (DEGREES F)
MAX…..36   NORMAL…..37
MIN…..24   NORMAL…..22
MEAN….30   NORMAL…..29

DEPARTURE FROM 30-YEAR NORMAL………………………+1
TOTAL DEPARTURE FOR THE MONTH………………………-5 [-0.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY………….35  DEPARTURE……….-1
TOTAL HEATING UNITS FOR THE MONTH…………749  DEPARTURE……….+4
TOTAL HEATING UNITS FOR THE SEASON……….1718  DEPARTURE……..-289
TOTAL HEATING UNITS LAST SEASON TO DATE…..1796  DIFFERENCE……..-78

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….31 WSW AT 8:51 P.M.
AERO……………………28 WSW AT 8:51 P.M.*
ASOS……………………30 W   AT 8:51 P.M.
DAVIS…………………..29 W   AT 8:51 P.M. RMY 31
FASTEST MILE FOR YESTERDAY…………………23 WSW AT 8:16 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………24 W   AT 8:17 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..23 W   AT 8:16 P.M.
AVERAGE WIND SPEED AND DIRECTION…….. …..10.7*   *potentially erroneus due
ASOS……………….. ..10.9*    to ice accretion
DAVIS………………. ..7.1* WNW [292 DEG.]

*Last of several occurances

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.57  DEPARTURE……+0.41
ASOS…………..0.57
TOTAL PRECIPITATION FOR THE MONTH……….2.22  DEPARTURE……-1.49
ASOS…………..2.29
TOTAL PRECIPITATION FOR THE YEAR……….52.06  DEPARTURE……-0.18
ASOS……………N/A **
** ASOS annual total not available due to erroneous readings

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….0.0  DEPARTURE…….-0.5
TOTAL SNOWFALL FOR THE MONTH…………….5.7  DEPARTURE…….-3.5
TOTAL SNOWFALL FOR THE SEASON……………5.7  DEPARTURE…….-6.1

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 50/35/43/+6/0.04/262/47          28 NW  AERO 29 NW  RMY 30
12/02 42/29/36/0/0.00/033/06           20 NNW AERO 18 NNW RMY N/A
12/03 42/32/37/+1/0.00/172/31          14 N   AERO 10 N   RMY N/A
12/04 43/32/38/+3/0.00/522/94          16 E   AERO 14 E   RMY N/A
12/05 58/34/46/+11/0.18/000/00         62 S   AERO 66 S   RMY 65
12/06 56/32/44/+9/0.54/160/29          52 S   AERO 55 S   RMY N/A
12/07 44/30/37/+3/0.00/540/98          25 WSW AERO 24 WSW RMY 25
12/08 38/28/33/-1/0.00/116/21          21 W   AERO 18 W   RMY 20
12/09 34/28/31/-3./0.70/000/00         23 NNW AERO 23 NNW RMY 23
12/10 35/27/31/-2/0.02/384/70          30 W   AERO 30 W   RMY 27
12/11 38/29/34/+1/0.00/301/55          23 W   AERO 21 W   RMY 22
12/12 43/31/37/+4/0.06/000/00          35 W   AERO 31 W   RMY N/A
12/13 31/18/25/-7/0.00/312/57          44 W   AERO 44 W   RMY 44
12/14 27/14/21/-11/T/…/..            35 WSW AERO 33 W   RMY 34
12/15 24/12/18/-14/T/…/..            25 W   AERO 23 W   RMY N/A
12/16 32/17/25/-6/0.00/…/..          33 W   AERO 35 W   RMY 36
12/17 27/14/21/-10/0.00/…/..         21 NW  AERO 21 NW  RMY 20
12/18 35/20/28/-3/T/…/..             20 SSE AERO 16 SSE RMY 20
12/19 49/34/42/+12/T/…/..            36 WNW AERO 35 SW  RMY 38
12/20 42/26/34/+4/T/…/..             41 W   AERO 40 W   RMY 45
12/21 32/23/28/-2/0.00/…/..          26 NW  AERO 24 NW  RMY 27
12/22 32/21/27/-2/…./…/..          18 E   AERO 17 E   RMY N/A
12/23 36/24/30/+1/…./…/..          31 WSW AERO 28 WSW RMY 31

12/24 Low temp since midnight is 31F; normal low is now 21F

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

RECORDS FOR DECEMBER 24
HIGH 67 IN 2015
LOW -6 IN 1943
PRECIP 2.21 INS. IN 1994
SNOWFALL 12.3 INS. IN 1961
PEAK GUST 79e MPH SE IN 1941

RECORDS FOR DECEMBER 25
HIGH 64 IN 2015
LOW -11 IN 1980
PRECIP 1.37 INS. IN 2002
SNOWFALL 8.5 INS. IN 2002
PEAK GUST 80 MPH NW IN 1971

TODAY’S REPORT PREPARED BY: Robert Millette