Thursday, December 7, 2017

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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, DECEMBER 7, 2017
ALL TIMES ARE IN EASTERN STANDARD TIME

PRESSURE DROPS AS COLD FRONT MOVES IN…

The sky was partially covered by altocumulus early this
morning, which cleared later in the morning. By 1 PM,
cumulus clouds stated to move in. The temperature
increased as the sky cleared, and the relative humidity
dropped from 65 to 38%. Winds increased from 10 AM to
mid-afternoon while the direction changed from SW to NW.

PRELIMINARY STATS FOR NOVEMBER 2017

TEMPERATURE, Deg. F
Avg. Max. 49.8 [-0.2] Avg. Min. 32.9 [-0.6] Mean 41.4 [-0.3] 24-hour corrected mean: 41.7
Max. for month: 74F on 3rd
Min. for month: 18F on 11th

HEATING DEGREE DAYS
Total heating units: 701 [+3] Total for the season: 969 [-292] Total for last season: 1030

PRECIPITATION, Inches
Total: 2.04 [-2.72] Greatest in 24 hrs: 0.87 in. on the 22nd

WIND, mph
Avg. uncorrected wind speed: 12.7
Avg. corrected wind speed: 13.0
Prevailing wind direction: WNW at 12%
Peak gust and direction: 50 W on 19th

SUNSHINE:
Campbell-Stokes card minutes: 9,108 minutes of possible 17,010 or 54%
Astronomical total minutes: 9,431 minutes of possible 17,610 or 54%

BHO Warmest Fall (Sep-Nov) 24-hour Corrected Mean Temperature, deg F (1885-2017):

1) 55.3 in 2017
2) 55.1 in 2011
3) 54.8 in 1931
54.8 in 2015
5) 54.3 in 1946
54.3 in 2001

Today’s Observations:

7 A.M.
Weather: Clear, few distant altocumulus at ENE-Sw, few
altocumulus W-N
Temperature: 30F; Dew Point: 20F; Wind: WSW at 12 kts
Sea-level pressure: 29.93 ins. Hg, falling, then rising
Visibility: 50 miles
6-hr Max temp: 32F
6-hr Min temp: 30F
24-hr precip: 0.00 ins.
BHO SA 1155 CLR 50 136/30/20/2512/993/ FEW AC DSNT ENE-SW
FEW AC W-N/ 8/090 53003 10032 20030

10 A.M.
Weather: Clear, few altocumulus E-SE and W-NE
Temperature: 38F; Dew Point: 23F; Wind: W at 8 kts
Sea-level pressure: 29.96 ins. Hg, rising, then more slowly
Visibility: 60 miles
3-hr precip: 0.00 ins.
BHO SA 1455 CLR 60 145/38/23/2608/996/ FEW AC E-SE
FEW AC W-NE/ 8/050 51009

1 P.M.
Weather: Scattered cumulus, few distant cirrus SE-SW
Temperature: 43F; Dew Point: 19F; Wind: W at 12G22 kts
Sea-level pressure: 29.90 ins. Hg, falling steadily
Visibility: 70 miles
6-hr Max temp: 43F
6-hr Min temp: 29F
6-hr precip: 0.00 ins.
BHO SA 1755 65 SCT 70 124/43/19/2612G22/990/
FEW DSNT CI SE-SW/ 8/101 58021 10043 20029

SUMMARY FOR WEDNESDAY, DECEMBER 6, 2017

TEMPERATURE (DEGREES F)
MAX…..56 NORMAL…..42
MIN…..32 NORMAL…..27
MEAN….44 NORMAL…..35

DEPARTURE FROM 30-YEAR NORMAL……………………..+9
TOTAL DEPARTURE FOR THE MONTH……………………..+30 [+4.8 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY………….21 DEPARTURE……….-9
TOTAL HEATING UNITS FOR THE MONTH…………146 DEPARTURE………-31
TOTAL HEATING UNITS FOR THE SEASON……….1115 DEPARTURE……..-323
TOTAL HEATING UNITS LAST SEASON TO DATE…..1193 DIFFERENCE……..-78

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….52 S AT 12:48 A.M.
AERO……………………55 S AT 12:22 A.M.
ASOS……………………55 SSW AT 12:21 A.M.
DAVIS…………………..57 SSW AT 12:20 A.M. RMY 29
FASTEST MILE FOR YESTERDAY…………………40 S AT 12:55 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………39 S AT 12:51 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..38 S AT 12:57 A.M.
AVERAGE WIND SPEED AND DIRECTION………….14.1 WSW
ASOS………………….13.8
DAVIS…………………13.4 WSW [256 DEG.] *** LAST OF MULTIPLE PEAK GUST

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……….0.76 DEPARTURE……-0.22
ASOS…………..0.83
TOTAL PRECIPITATION FOR THE YEAR……….50.60 DEPARTURE……+1.09
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…….-0.3
TOTAL SNOWFALL FOR THE MONTH…………….0.0 DEPARTURE…….-1.7
TOTAL SNOWFALL FOR THE SEASON……………0.0 DEPARTURE…….-4.3

PRELIMINARY CLIMATE SUMMARY FOR NOVEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/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

11/01 53/39/46/0/0.00/167/27 25 SE AERO 24 SE RMY 25
11/02 71/49/60/+14/0.00/000/00 28 SSE AERO 25 SSE RMY 27
11/03 74/47/61/+15/T/350/57 35 WNW AERO 35 WNW RMY 38
11/04 54/39/47/+2/0.00/545/89 31 NW AERO 31 NW RMY N/A
11/05 61/46/54/+9/0.01/006/01 26 S AERO 24 S RMY N/A
11/06 64/47/56/+11/0.05/000/00 32 S AERO 28 SSW RMY 35
11/07 46/35/41/-4/0.11/145/24 26 NNW AERO 23 N RMY 26
11/08 3/34/39/-5/0.08/295/49 26 N AERO 23 N RMY 27
11/09 50/31/41/-3/0.01/480/80 25 S AERO 23 S RMY N/A
11/10 45/20/33/-11/0.00/586/98 46 WNW AER0 44 WNW RMY 46
11/11 36/18/27/-16/0.00/589/99 28 WNW AERO 26 WNW RMY 28
11/12 44/27/36/-7/0.00/302/51 13 E AERO 9 S RMY 14
11/13 40/35/38/-5/0.26/000/00 20 NNW AERO 17 NNW RMY 20
11/14 40/33/37/-5/T/000/00 18 N AERO 15 N RMY 18
11/15 43/31/37/-5/0.00/417/71 20 NE AERO 15 NE RMY N/A
11/16 51/37/44/+2/0.21/012/02 32 SE AERO 32 SE RMY N/A TSTM
11/17 42/30/36/-5/0.00/565/97 41 WNW AERO 43 WNW RMY 47
11/18 49/26/38/-3/0.08/168/29 35 SSW AERO 35 SSW RMY 39
11/19 58/34/46/+5/0.36/231/40 50 W AERO 50 W RMY 54
11/20 39/31/35/-5/0.00/462/80 48 WNW AERO 50 WNW RMY 44
11/21 57/35/46/+6/0.00/506/88 46 SSW AERO 46 SSW RMY 48
11/22 53/35/44/+4/0.87/000/00 37 NW AERO 38 NW RMY 41
11/23 40/26/33/-6/0.00/571/100 26 NW AERO 25 NW RMY N/A
11/24 49/29/39/0/0.00/558/98 28 SSW AERO 26 SSW RMY 29
11/25 57/38/48/+9/0.00/523/92 29 SSW AERO 28 SSW RMY 31
11/26 46/33/40/+2/0.00/509/90 39 WNW AERO 41 WNW RMY 41
11/27 44/24/34/-4/0.00/254/45 37 W AERO 39 W RMY 36
11/28 45/19/32/-6/0.00/557/99 35 S AERO 37 S RMY N/A
11/29 58/34/46/+9/0.00/370/66 46 W AERO 47 W RMY 46
11/30 43/26/35/-2/0.00/263/47 25 SSE AERO 25 NNW RMY 25

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/…/.. 28 NW AERO 29 NW RMY 30
12/02 42/29/36/0/0.00/…/.. 20 NNW AERO 18 NNW RMY N/A
12/03 42/32/37/+1/0.00/…/.. 14 N AERO 10 N RMY N/A
12/04 43/32/38/+3/0.00/…/.. 16 E AERO 14 E RMY N/A
12/05 58/34/46/+11/0.00/…/.. 62 S AERO 66 S RMY 65
12/06 56/32/44/+9/0.00/…/.. 52 S AERO 55 S RMY 29

12/07 Low temp since midnight is 30F; normal low is now 27F

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

RECORDS FOR DECEMBER 7
HIGH 74 IN 1998
LOW 6 IN 1906
PRECIP 1.67 INS. IN 1953
SNOWFALL 6.3 INS. IN 2003
PEAK GUST 76e SE IN 1976

RECORDS FOR DECEMBER 8
HIGH 62 IN 1966
LOW -4 IN 1906
PRECIP 1.54 INS. IN 1969
SNOWFALL 2.5 INS. IN 2001
PEAK GUST 78e W IN 1979

TODAY’S REPORT PREPARED BY: Afshin Pourmokhtarian