Sunday, December 17, 2017

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

DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, DECEMBER 17, 2017
ALL TIMES ARE IN EASTERN STANDARD TIME

COLD TEMPERATURES AND CLEAR SKIES FOR THE DAY

It was a cold start to the morning with a temperature of 15 degrees
at the 7 AM observation.  Clear skies led to good cooling conditions
last night with only a few clouds around throughout the morning and
visibilities around 80 miles.

High cirrus clouds began to fill the sky by the 1 o’clock observation.
Winds had diminished from yesterdays gusty winds and were blowing
lightly this afternoon.  Dry conditions prevailed as the temperatures
rose into the upper 20s during this colder than normal day.

Today’s Observations:

7 A.M.
Weather: Clear, few altocumulus E and SW-W, few cirrus overhead and east
few cumulus distant and offshore
Temperature: 15F; Dew Point: 9F; Wind: NW at 9 kts
Sea-level pressure: 30.26 ins. Hg, rising, then less quickly
Visibility: 80 miles
6-hr Max temp: 19F
6-hr Min temp: 14F
24-hr precip: None
24-hr snowfall: 0.0 in.
Snow cover: 1 in.
BHO SA 1155 CLR 80 246/15/9/3109/026/ FEW AC E AND SW-W FEW CI E AND OVHD
FEW CU DSNT OFFSHR/ 8/181 51013 10019 20014

10 A.M.
Weather: Clear, few altostratus, few cirrostratus S-SW, few cumulus distant
offshore
Temperature: 21F; Dew Point: 7F; Wind: NW at 10G17 kts
Sea-level pressure: 30.28 ins. Hg, rising, then falling
Visibility: 80 miles
3-hr precip: 0.00 ins.
3-hr snowfall: 0.0 ins.
BHO SA 1455 CLR 80 253/21/7/3210G17/028/ FEW AS FEW CS S-SW FEW CU DSNT
OFFSHR/ 8/185 50007

1 P.M.
Weather: Scattered cirrus, few altostratus south
Temperature: 27F; Dew Point: 8F; Wind: WNW at 6 kts
Wind: Light
Sea-level pressure: 30.24 ins. Hg, decreasing then more rapidly
Visibility: 80 miles
6-hr Max temp: 27F
6-hr Min temp: 15F
6-hr precip: 0.00 ins.
6-hr snowfall: 0.0 ins.
Snow cover: 1 in.
BHO SA 1755 250 SCT 80 239/27/8/2906/024/ FEW AS S WND LGT/ 8/086 58014
10027 20015

SUMMARY FOR SATURDAY, DECEMBER 16, 2017

TEMPERATURE (DEGREES F)
MAX…..32   NORMAL…..39
MIN…..17   NORMAL…..24
MEAN….25   NORMAL…..31

DEPARTURE FROM 30-YEAR NORMAL………………………-6
TOTAL DEPARTURE FOR THE MONTH………………………-6 [-0.5 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY………….40  DEPARTURE……….+6
TOTAL HEATING UNITS FOR THE MONTH…………504  DEPARTURE……….+5
TOTAL HEATING UNITS FOR THE SEASON……….1473  DEPARTURE……..-280
TOTAL HEATING UNITS LAST SEASON TO DATE…..1562  DIFFERENCE……..-89

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….32 W AT 2:47 P.M.
AERO……………………35 W AT 2:45 P.M.
ASOS……………………35 W AT 2:47 P.M.
DAVIS…………………..34 W AT 2:46 P.M. RMY 36
FASTEST MILE FOR YESTERDAY…………………25 W AT 2:48 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………25 W AT 2:48 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..25 W AT 2:48 P.M.
AVERAGE WIND SPEED AND DIRECTION…………..13.1 W
ASOS…………………..12.8
DAVIS………………….12.7 WNW [285 DEG.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.00  DEPARTURE……-0.16
ASOS…………..0.00
TOTAL PRECIPITATION FOR THE MONTH……….1.54  DEPARTURE……-1.08
ASOS…………..1.63
TOTAL PRECIPITATION FOR THE YEAR……….51.38  DEPARTURE……+0.23
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…….-0.1
TOTAL SNOWFALL FOR THE SEASON……………5.7  DEPARTURE…….-2.7

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/+3/0.00/522/98          25 WSW AERO 24 WSW RMY 25
12/08 38/28/33/-1/0.00/…/..          21 W   AERO 18 W   RMY 20
12/09 34/28/31/-3./…./…/..         23 NNW AERO 23 NNW RMY 23
12/10 35/27/31/-2/…./…/..          30 W   AERO 30 W   RMY 27
12/11 38/29/34/+1/0.00/…/..          23 W   AERO 21 W   RMY 22
12/12 43/31/37/+4/0.06/…/..          35 W   AERO 31 W   RMY N/A
12/13 31/18/25/-7/0.00/…/..          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 Low temp since midnight is 14F; normal low is now 23F

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

RECORDS FOR DECEMBER 17
HIGH 63 IN 2000
LOW -10 IN 1942
PRECIP 3.03 INS. IN 1888
SNOWFALL 7.5 INS. IN 1988
PEAK GUST 78 MPH SSE IN 2000

RECORDS FOR DECEMBER 18
HIGH 59 IN 1928
LOW -11 IN 1919
PRECIP 1.44 INS. IN 1915
SNOWFALL 7.0 INS. IN 1904
PEAK GUST 76e W IN 1978

TODAY’S REPORT PREPARED BY: Robert Millette