Tuesday, December 17, 2019

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

DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, DECEMBER 17, 2019
ALL TIMES ARE IN EASTERN STANDARD TIME

WINTRY MIX BRINGS SNOW AND ICE TO BLUE HILL….

Snow began falling between 6-7am this morning bringing
0.1″ of accumulation by the 7am observation. Sleet began
mixing in before 8am, then freezing rain began mixing in
by 9am. Snow ended between 9-10am with a mix of sleet and
freezing rain continuing through the 1pm observation.
Including what fell before 7am, the total snow/sleet
accumulation is 0.9″.

As of mid afternoon, sleet had ended and light freezing
rain is falling. Accretion is finally starting to take
hold with 0.1″ of ice now on most surfaces as of 3pm.

The storm total liquid equivalent through 1pm is 0.34″.

The high so far today as of 3pm is 30F, which is 9 degrees
below the daily normal maximum of 39F. The low since midnight
is 23F, which is 1 degree below the normal minimum of 24F.

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 stratus, light snow and fog
Temperature: 23F; Dew Point: 21F; Wind: NNE at 5 kts
Sea-level pressure: 30.06 ins. Hg, falling, then more rapidly
Visibility: 2 miles, fog
24-hr Precip: 0.03 ins.
24-hr Snowfall: 0.1 ins.
Snow Depth: Trace.
BHO SA 1155 E15 OVC 2S-F 181/23/21/0305/006/ WND LGT TOTAL NEW SNOW
LAST 24 HRS 0.1 INS/ 8/7// 4/000 58014 6003 70003 10027 2002

10 A.M.
Weather: Overcast stratus, light sleet and freezing rain
Temperature: 26F; Dew Point: 25F; Wind: NNE at 4 kts
Sea-level pressure: 29.95 ins. Hg, falling, unsteadily
Visibility: 2 miles, fog
3-hr Precip: 0.12 ins.
3-hr Snowfall: 0.3 ins.
BHO SA 1455 E5 OVC 2IPZR-F 141/26/25/0304/995/ WND LGT TOTAL NEW
SNOW/SLEET LAST 3 HRS 0.3 INS/ 8/7// 56040 6012

1 P.M.
Weather: Overcast stratus, light sleet and freezing rain
Temperature: 26F; Dew Point: 25F; Wind: N at 9 kts
Sea-level pressure: 29.80 ins. Hg, falling, unsteadily
Visibility: 1.5 miles, fog
6-hr Max temp: 28F
6-hr Min temp: 23F
6-hr Precip:  0.31 ins.
6-hr Snowfall: 0.8 ins.
Snow Depth: 1 ins.
BHO SA 1755 E10 OVC 11/2IPZR-F 090/26/25/3609/980/ TOTAL NEW
SNOW/SLEET LAST 6 HRS 0.8 INS/ 8/7// 4/001 56051 6031 10028 20023

SUMMARY FOR MONDAY, DECEMBER 16, 2019

TEMPERATURE (DEGREES F)
MAX…..30   NORMAL…..39
MIN…..25   NORMAL…..24
MEAN….28   NORMAL…..31

DEPARTURE FROM 30-YEAR NORMAL………………… -3
TOTAL DEPARTURE FOR THE MONTH…………………-19 [-1.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………37  DEPARTURE……. +3
TOTAL HEATING UNITS FOR THE MONTH…………..517  DEPARTURE…….+18
TOTAL HEATING UNITS FOR THE SEASON…………1754  DEPARTURE……..-7
TOTAL HEATING UNITS LAST SEASON TO DATE…….1844  DEPARTURE…….-90

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………..36 W   AT  1:18 A.M.
AERO…………………….36 W   AT 12:15 A.M.
ASOS…………………….35 WNW AT  1:18 A.M.
DAVIS……………………36 W   AT  1:16 A.M. RMY N/A
FASTEST MILE FOR YESTERDAY………………….31 W   AT 12:02 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….26 WNW AT 12:02 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………29 W   AT 12:00 A.M.
AVERAGE WIND SPEED AND DIRECTION……………11.4 W
ASOS……………………11.3
DAVIS…………………..11.9 WNW [285 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.03  DEPARTURE……-0.12
ASOS…………..0.02
TOTAL PRECIPITATION FOR THE MONTH……….5.30  DEPARTURE……+2.69
ASOS…………..5.77
TOTAL PRECIPITATION FOR THE YEAR……….54.38  DEPARTURE……+3.23
ASOS………….55.17

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….0.1  DEPARTURE…….-0.4
TOTAL SNOWFALL FOR THE MONTH……………18.1  DEPARTURE……+12.2
TOTAL SNOWFALL FOR THE SEASON…………..18.2  DEPARTURE…….+9.7

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 The low since midnight is 23F, daily normal minimum is 24F

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 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: Matt Douglas