Wednesday, December 18, 2019

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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, DECEMBER 18, 2019
ALL TIMES ARE IN EASTERN STANDARD TIME

FAIR WEATHER WITH SOME DISTANT SNOW SHOWERS
FOLLOWING LAST NIGHT’S WINTRY MIX….

Snowfall since yesterday morning amounted to an inch
at the 7 A.M. observation, with the majority of
measurable snowfall occurring yesterday morning and
night. Rainfall/ liquid amounts equated to 0.76 inches
since 7 A.M. yesterday. Light snow continued early to
late morning, leaving only a trace between 7 A.M. and
10 A.M. Visibility increased since this morning, where
only 3 miles were seen due to the snow and fog. It reached
a max of 80 miles at 10 A.M., decreasing to the west before
1 P.M. as result of some distant virga. Since then, the
far-off snow showers are approaching at a good clip,
seemingly building in strength along the way.

The high so far today is 33F, which is 5 degrees below the
daily normal maximum of 38F. The low since midnight
is 26F, which is 3 degrees above the normal minimum of 23F.

PRELIMINARY STATS FOR NOVEMBER 2019

TEMPERATURE, Deg. F
Avg. Max. 46.0 [-4.0] Avg. Min. 30.3 [-3.2] Mean      38.2 [-3.5] 24-hour corrected mean: 38.0
Max. for month: 67F on the 1st
Min. for month: 15F on the 13th

HEATING DEGREE DAYS
Total heating units:    761 [+99] Total for the season:  1237 [-24] Total for last season: 1319

PRECIPITATION, Inches
Total: 3.74 [-1.02] Greatest in 24 hrs: 1.60 ins. on the 24th

SNOWFALL, Inches
Total: 0.1 [-2.2] Greatest in 24 hrs: 0.1 ins. on the 12th

WIND, mph
Avg. uncorrected wind speed: 12.5 mph
Avg. corrected wind speed:   12.9 mph
Prevailing wind direction:   W [16%] Peak gust and direction:     67 S on the 1st

SUNSHINE:
Campbell-Stokes card minutes: 8652 minutes of possible 17010 or 51%
Astronomical total minutes: 8985 minutes of possible 17640 or 51%

Today’s Observations:

7 A.M.
Weather: Overcast nimbostratus, light snow and fog
Temperature: 27F; Dew Point: 27F; Wind: NW at 7 kts
Sea-level pressure: 29.75 ins. Hg, rising steadily
Visibility: 3 miles, fog
24-hr Precip: 0.76 ins.
24-hr Snowfall: 1.0 ins.
Snow Depth: Trace
BHO SA 1155 E65 OVC 3S-F 073/27/27/3107/975/ S-CTD NEW SNOW
PAST 24 HRS 1.0 INS. / 8/02/ 70076 53020 10027 20026

10 A.M.
Weather: Broken stratus fractus, altocumulus
Temperature: 29F; Dew Point: 26F; Wind: WNW at 8G14 kts
Sea-level pressure: 29.97 ins. Hg, rising steadily
Visibility: 80 miles
3-hr Precip: Trace
3-hr Snowfall: Trace
BHO SA 1455 E20 BKN 110 BKN 80 080/29/26/2908G14/977/
NEW SNOW PAST 3 HRS TRACE/ 8/770 600// 53007

1 P.M.
Weather: Broken stratocumulus, distant virga SW-NW
Temperature: 33F; Dew Point: 30F; Wind: W at 8 kts
Sea-level pressure: 29.70 ins. Hg, falling steadily
Visibility: 65 miles
6-hr Max temp: 33F
6-hr Min temp: 27F
6-hr Precip:  Trace
6-hr Snowfall: Trace
Snow Depth: 0 ins.
BHO SA 1755 E40 BKN 65 060/33/30/2808/970/ DSNT VIRGA
SW-NW NEW SNOW PAST 6 HRS TRACE/ 8/400 600// 56020 10033
20027

SUMMARY FOR TUESDAY, DECEMBER 17, 2019

TEMPERATURE (DEGREES F)
MAX…..35   NORMAL…..39
MIN…..23   NORMAL…..23
MEAN….29   NORMAL…..31

DEPARTURE FROM 30-YEAR NORMAL………………… -2
TOTAL DEPARTURE FOR THE MONTH…………………-21 [-1.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………36  DEPARTURE……..+2
TOTAL HEATING UNITS FOR THE MONTH…………..553  DEPARTURE…….+20
TOTAL HEATING UNITS FOR THE SEASON…………1790  DEPARTURE……..-5
TOTAL HEATING UNITS LAST SEASON TO DATE…….1874  DEPARTURE…….-84

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………..22 NNW AT 10:17 P.M.
AERO…………………….21 NE  AT  5:34 P.M.
ASOS…………………….24 NNW AT 11:22 P.M.
DAVIS……………………22 E   AT  5:29 P.M. RMY 23
FASTEST MILE FOR YESTERDAY………………….19 NNW AT 10:32 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….17 NNW AT 11:34 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………16 ENE AT  5:32 P.M.
AVERAGE WIND SPEED AND DIRECTION…………….7.6 NNE
ASOS…………………….7.8
DAVIS……………………7.3 NNE [19 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.76  DEPARTURE……+0.61
ASOS…………..0.74
TOTAL PRECIPITATION FOR THE MONTH……….6.06  DEPARTURE……+3.29
ASOS…………..6.51
TOTAL PRECIPITATION FOR THE YEAR……….55.14  DEPARTURE……+3.29
ASOS………….55.91

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….1.0  DEPARTURE…….+0.5
TOTAL SNOWFALL FOR THE MONTH……………19.1  DEPARTURE……+12.8
TOTAL SNOWFALL FOR THE SEASON…………..19.2  DEPARTURE……+10.8

PRELIMINARY CLIMATE SUMMARY FOR NOVEMBER 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

11/01  67/35/51/+5/0.12/0.0/534/86            67 S   AERO M  M   RMY N/A
11/02  50/31/41/-5/0.00/0.0/612/99            17 WNW AERO 14 W   RMY N/A
11/03  53/35/44/-2/0.00/0.0/567/92            25 WSW AERO 23 W   RMY 26
11/04  53/33/43/-2/0.00/0.0/546/89            24 S   AERO 20 S   RMY 24
11/05  54/44/49/+4/0.33/0.0/000/00            22 S   AERO 18 WNW RMY 28
11/06  51/36/44/-1/0.00/0.0/596/98            28 WSW AERO 23 W   RMY 27
11/07  55/38/47/+2/0.27/0.0/000/00            30 S   AERO 26 SSW RMY 32
11/08  38/23/31/-13/0.00/0.0/555/92           38 NW  AERO 37 WNW RMY 44
11/09  39/20/30/-14/0.00/0.0/583/97           22 S   AERO 18 S   RMY N/A
11/10  51/30/41/-3/0.00/0.0/174/29            30 SW  AERO 30 SW  RMY 31
11/11  52/39/46/+3/T/0.0/000/00               23 NE  AERO 22 NE  RMY 23
11/12  42/20/31/-12/0.08/0.1/000/00           37 WNW AERO 37 WNW RMY 41
11/13  28/15/22/-21/0.00/0.0/592/100          32 WNW AERO 32 WNW RMY 35
11/14  36/17/28/-14/0.00/0.0/136/23           18 SW  AERO 17 SW  RMY 20
11/15  51/32/42/0/0.00/0.0/553/94             25 WNW AERO 25 WNW RMY N/A
11/16  35/22/29/-13/0.00/0.0/580/99           35 NNW AERO 35 NNW RMY N/A
11/17  40/21/31/-10/T/T/000/00                28 ENE AERO 27 ENE RMY 29
11/18  36/32/34/-7/0.45/0.0/000/00            28 NNE AERO 29 N   RMY 31
11/19  42/36/39/-2/0.22/0.0/000/00            12 SSW AERO  9 NNW RMY N/A
11/20  38/33/36/-4/0.23/T/000/00              20 NW  AERO 18 NW  RMY 21
11/21  46/30/38/-2/0.00/0.0/536/93            21 NW  AERO 21 NW  RMY N/A
11/22  52/32/42/+2/0.13/0.0/000/00            46 W   AERO 47 W   RMY 47
11/23  44/27/36/-3/0.00/0.0/503/88            29 WNW AERO 29 WNW RMY N/A
11/24  44/35/40/+1/1.60/0.0/000/00            45 N   AERO 44 NE  RMY 46 TSTM
11/25  50/34/42/+3/0.00/0.0/329/58            32 WNW AERO 35 WNW RMY 23
11/26  59/39/49/+11/0.00/0.0/544/96           28 SSW AERO 27 SSW RMY 29
11/27  50/42/46/+8/0.24/0.0/011/02            30 W   AERO 32 W   RMY N/A TSTM
11/28  48/30/39/+1/0.07/T/062/11              42 NW  AERO 44 NW  RMY 44
11/29  39/27/33/-4/0.00/0.0/433/77            35 NW  AERO 36 NW  RMY 39
11/30  35/22/29/-8/0.00/0.0/539/96            30 NW  AERO 28 WNW RMY 31

DAILY RECORDS FOR NOVEMBER

11/13/19: DAILY RECORD LOW MAXIMUM TEMPERATURE OF 28F,
BREAKS PREVIOUS RECORD OF 30F SET IN 1920.
It was also the third earliest maximum temperature
colder than 30F on record, behind only 28F on 11/8/1894
and 29F on 11/12/1894.

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  32/16/24/-13/…./5.8/…/..           33 ENE AERO 32 ENE RMY N/A
12/02  37/25/31/-5/…./2.7/…/..            52 NE  AERO 47 NE  RMY 53
12/03  30/23/27/-9/…./4.6/…/..            32 N   AERO 35 N   RMY 36
12/04  34/22/28/-7/…./0.0/…/..            23 WNW AERO 23 NNW RMY N/A
12/05  41/26/34/-1/…./0.0/…/..            33 NW  AERO 35 NW  RMY 37
12/06  33/23/28/-7/0.02/0.1/…/..            25 NW  AERO 23 NW  RMY 29
12/07  31/18/25/-9/0.00/0.0/…/..            25 NW  AERO 23 NW  RMY N/A
12/08  36/15/26/-8/0.00/0.0/…/..            31 SSW AERO 32 SSW RMY N/A
12/09  57/36/47/+13/…./0.0/…/..           53 S   AERO 52 S   RMY 54
12/10  58/37/48/+15/…./0.0/…/..           35 SW  AERO 39 SW  RMY N/A
12/11  36/23/30/-3/…./3.0/…/..            25 NW  AERO 25 NW  RMY N/A
12/12  29/17/23/-10/…./1.8/…/..           29 W   AERO 30 W   RMY 25
12/13  46/22/34/+2/…./0.0/…/..            25 SSE AERO 25 SSE RMY N/A
12/14  58/46/52/+20/…./0.0/…/..           45 S   AERO 41 S   RMY N/A
12/15  48/28/38/+6/0.00/0.0/…/..            53 W   AERO 53 W   RMY 50
12/16  30/25/28/-3/0.00/0.0/…/..            36 W   AERO 36 W   RMY N/A
12/17  35/23/29/-2/…./1.0/…/..            22 NNW AERO 21 NE  RMY 23

12/18 The low since midnight is 26F, daily normal minimum is 23F

DAILY RECORDS FOR DECEMBER

12/01/19: DAILY RECORD SNOWFALL OF 5.8 INS.,
BREAKS PREVIOUS RECORD OF 2.0 INS. SET IN 1902.

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

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

RECORDS FOR DECEMBER 19
HIGH 59 IN 1899
LOW -1 IN 1919
PRECIP 2.06 INS. IN 1986
SNOWFALL 14.1 INS. IN 1945
PEAK GUST 68 NE IN 1986

TODAY’S REPORT PREPARED BY: Benjamin Turner and Greg White