Tuesday, December 26, 2017

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

DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, DECEMBER 26, 2017
ALL TIMES ARE IN EASTERN STANDARD TIME

CLEAR BUT COLD AND WINDY TODAY AFTER CHRISTMAS SNOWFALL

It was a true white Christmas at Blue Hill and across much of New England
this year. A rapidly developing low pressure system just offshore produced
a total of 3.2 inches of snow at the Observatory.  Some rain and mixed
precipitation were also observed during this storm, for a liquid equivalent
total of 0.73 inches.  Winds became strong as the low passed by and departed
to our northwest.  A peak gust of 50mph was observed, with the average wind
speed for the day an impressive 20mph.

Since 1885, this was the fifth greatest snowfall on Christmas Day at the
Observatory, and over that time there is a 44 percent chance of having a
“white” Christmas on Blue Hill.

Dry weather has returned today, but cold air is also in place.  After a
morning low of 18F, the temperature has only risen slightly today to a high
so far of 24F, well below normal even for this time of year.  Windy conditions
have also persisted, with a west wind gusting to near 40mph.  Excellent
visibility has been observed today, around 80 miles for most of the day.

Today’s Observations:

7 A.M.
Weather: Scattered altocumulus, broken cirrus, few stratocumulus distant NE-S
Temperature: 19F; Dew Point: 8F; Wind: WSW at 14 kts
Sea-level pressure: 30.22 ins. Hg, rising then rising more rapidly
Visibility: 50 miles
6-hr Max temp: 21F
6-hr Min temp: 18F
24-hr precip: 0.42 ins.
24-hr snowfall: 3.0 ins.
Snow depth: 3 ins.
BHO SA 1155 120 SCT E250 BKN 50 235/19/8/2514/022/ FEW SC DSNT NE-S
NEW SNW PST 24 HRS 3.0 INS STORM TOTAL 3.2 INS/ 8/531 4/003 53021
MANUAL 70042 ASOS 70060 10021 20018

10 A.M.
Weather: Clear, few small cumulus all quadrants, patches of dense cirrus
distant NE and distant SE-SW
Temperature: 21F; Dew Point: 5F; Wind: W at 21G29 kts,
Peak wind: 29 kts (33 MPH) from the W at 09:49 A.M.
Sea-level pressure: 30.29 ins. Hg, rising then falling
Visibility: 80 miles
3-hr precip: 0.00 ins.
BHO SA 1455 CLR 80 256/21/5/2621G29/029/ FEW SML CU ALQDS
PTCHS DNS CI DSNT NE AND DSNT SE-SW PK WND 2629/49/ 8/102 50021

1 P.M.
Weather: Scattered stratocumulus, scattered dense cirrus
Temperature: 24F; Dew Point: 2F; Wind: W at 17G28 kts,
Peak wind: 32 kts (37MPH) from the W at 1:22 P.M.
Sea-level pressure: 30.26 ins. Hg, falling then falling more rapidly
Visibility: 80 miles
6-hr Max temp: 24F
6-hr Min temp: 18F
6-hr precip: 0.00 ins.
Snow depth: 3 ins.
BHO SA 1755 50 SCT 220 SCT 80 246/24/2/2617G28/026/ PK WND 2632/22/
8/502 4/003 58010 10024 20018

SUMMARY FOR MONDAY, DECEMBER 25, 2017

TEMPERATURE (DEGREES F)
MAX…..35   NORMAL…..36
MIN…..21   NORMAL…..21
MEAN….28   NORMAL…..28

DEPARTURE FROM 30-YEAR NORMAL……………………….0
TOTAL DEPARTURE FOR THE MONTH………………………-2 [-0.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY………….37  DEPARTURE………..0
TOTAL HEATING UNITS FOR THE MONTH…………819  DEPARTURE……….+1
TOTAL HEATING UNITS FOR THE SEASON……….1788  DEPARTURE……..-292
TOTAL HEATING UNITS LAST SEASON TO DATE…..1854  DIFFERENCE……..-66

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….50 W  AT 2:51 P.M.
AERO……………………54 W  AT 2:51 P.M.
ASOS……………………N/A*
DAVIS…………………..48 W  AT 2:51 P.M. RMY 47
FASTEST MILE FOR YESTERDAY…………………35 W  AT 2:51 P.M. **
MAXIMUM 2-MINUTE ASOS AVERAGE………………N/A
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..36 W  AT 2:20 P.M.
AVERAGE WIND SPEED AND DIRECTION………….20.5 W
ASOS………………….N/A
DAVIS…………………19.1 NW [305 DEG.] *ASOS wind data likely erroneous due to ice
**Last of several occurrences

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.42  DEPARTURE……+0.26
ASOS…………..0.60
TOTAL PRECIPITATION FOR THE MONTH……….2.95  DEPARTURE……-1.07
ASOS…………..3.20
TOTAL PRECIPITATION FOR THE YEAR……….52.79  DEPARTURE……+0.24
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……….3.0  DEPARTURE…….+2.5
TOTAL SNOWFALL FOR THE MONTH…………….8.9  DEPARTURE…….-1.3
TOTAL SNOWFALL FOR THE SEASON……………8.9  DEPARTURE…….-3.9

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/+6/0.04/0.0/262/47          28 NW  AERO 29 NW  RMY 30
12/02 42/29/36/0/0.00/0.0/033/06           20 NNW AERO 18 NNW RMY N/A
12/03 42/32/37/+1/0.00/0.0/172/31          14 N   AERO 10 N   RMY N/A
12/04 43/32/38/+3/0.00/0.0/522/94          16 E   AERO 14 E   RMY N/A
12/05 58/34/46/+11/0.18/0.0/000/00         62 S   AERO 66 S   RMY 65
12/06 56/32/44/+9/0.54/0.0/160/29          52 S   AERO 55 S   RMY N/A
12/07 44/30/37/+3/0.00/0.0/540/98          25 WSW AERO 24 WSW RMY 25
12/08 38/28/33/-1/0.00/0.0/116/21          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/+1/0.00/0.0/301/55          23 W   AERO 21 W   RMY 22
12/12 43/31/37/+4/0.06/0.0/000/00          35 W   AERO 31 W   RMY N/A
12/13 31/18/25/-7/0.00/0.0/312/57          44 W   AERO 44 W   RMY 44
12/14 27/14/21/-11/T/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/-6/0.00/0.0/…/..          33 W   AERO 35 W   RMY 36
12/17 27/14/21/-10/0.00/0.0/…/..         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/-2/0.00/0.0/…/..          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 35/29/32/+3/…./…/…/..          30 ENE AERO 25 ENE RMY N/A
12/25 35/21/28/0/…./…/…/..           50 W   AERO 54 W   RMY 47

12/26 Low temp since midnight is 18F; normal low is now 20F

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

RECORDS FOR DECEMBER 26
HIGH 58 IN 1973,1982
LOW -12 IN 1980
PRECIP 3.64 INS. IN 1969
SNOWFALL 17.5 INS. IN 1909
PEAK GUST 84 MPH SSE IN 1957

RECORDS FOR DECEMBER 27
HIGH 57 IN 1895,1949
LOW -4 IN 1903
PRECIP 2.43 INS. IN 1969
SNOWFALL 11.2 INS. IN 1947
PEAK GUST 73 S IN 2011

TODAY’S REPORT PREPARED BY: Jonathan O’Brien