Sunday, December 30, 2018

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

DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, DECEMBER 30, 2018
ALL TIMES ARE IN EASTERN STANDARD TIME

ALTOCUMULUS CLEARS AS TEMPERATURES RETURN TO SEASONAL NORMS….

Despite a near overcast layer of altocumulus at the time of the 10 A.M.
observation, skies have cleared significantly, baring excellent visibility
of up to 70 miles for the 10 A.M. and 1 P.M. observations.  Temperatures
have dropped substantially following two days of exceptionally warm
December days.  This plunge has returned readings to the proximity of
what we expect this time of year.  The past two days have led to complete
thawing of both Houghton’s and Ponkapoag Ponds, with no signs of refreezing
so far today.  With small chances of snow in today’s forecast, no snowfall
was observed on the hill, but a small shower was observed to the SE in the
form of virga during the 10 A.M. observation. Winds have been noticeably
very calm, especially towards the end of the morning and into the early
afternoon, where wind speeds reached zero at different points.  Coupled
with the lack of wind today, there has been a marked shift in wind
direction, with the late morning hours seeing the end of the prevailing
north-westerlies that dominated yesterday’s wind charts.

Today’s Observations:

7 A.M.
Weather: Scattered altocumulus, scattered altostratus
Temperature: 23F; Dew Point: 11F; Wind: NNW at 4 kts
Sea-level pressure: 30.21 ins. Hg, steady, then increasing more rapidly
Visibility: 40 miles
6-hr Max temp: 27F
6-hr Min temp: 23F
24-hr Precip: 0.00 ins.
24-hr snowfall: 0.0 ins.
Snow depth: 0 ins.
BHO SA 1155 E140 SCT 40 230/23/11/3404/021/ WND LGT/ 8/070 53020 10027
20023

10 A.M.
Weather: Broken altocumulus, few lower altocumulus, virga SE
Temperature: 26F; Dew Point: 14F; Wind: WSW at 2 kts (estimated)
Sea-level pressure: 30.23 ins. Hg, increasing, then decreasing
Visibility: 70 miles
3-hr Precip: 0.00 ins.
BHO SA 1455 E100 BKN 70 238/26/14/E2802/023/ WND LGT FEW AC VIRGA SE/
8/070 50008

1 P.M.
Weather: Few distant altocumulus in all directions
Temperature: 31F; Dew Point: 10F; Wind: WNW at 4 kts
Sea-level pressure: 30.17 ins. Hg, decreasing then decreasing more slowly
Visibility: 70 mileS
6-hr Max temp: 32F
6-hr Min temp: 22F
6-hr Precip: 0.00 ins.
6-hr snowfall: 0.0 ins.
Snow depth: 0 ins.
BHO SA 1755 CLR 70 217/31/10/2904/017/ WND LGT FEW DSNT AC ALQDS/ 8/050
56021 10032 20022

SUMMARY FOR SATURDAY, DECEMBER 29, 2018

TEMPERATURE (DEGREES F)
MAX…..54   NORMAL…..35
MIN…..30   NORMAL…..20
MEAN….42   NORMAL…..27

DEPARTURE FROM 30-YEAR NORMAL…………………..+15
TOTAL DEPARTURE FOR THE MONTH…………………..+56 [+1.8 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………..23   DEPARTURE……..-15
TOTAL HEATING UNITS FOR THE MONTH………….909   DEPARTURE……..-58
TOTAL HEATING UNITS FOR THE SEASON………..2229   DEPARTURE……….0
TOTAL HEATING UNITS LAST SEASON TO DATE……2005   DIFFERENCE……+224

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………..38 WNW AT 3:26 P.M.
AERO…………………….38 WNW AT 3:24 P.M.
ASOS…………………….40 W   AT 3:27 P.M.
DAVIS……………………40 WNW AT 3:27 P.M. RMY 38
FASTEST MILE FOR YESTERDAY………………….30 WNW AT 2:02 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….28 W   AT 1:34 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………30 W   AT 1:34 P.M.
AVERAGE WIND SPEED AND DIRECTION…………..16.2 WNW
ASOS…………………..15.4
DAVIS………………….16.2 WNW [286 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.00  DEPARTURE…….-0.14
ASOS…………..0.00
TOTAL PRECIPITATION FOR THE MONTH……….3.55  DEPARTURE…….-1.06
ASOS…………..4.22 *
TOTAL PRECIPITATION FOR THE YEAR……….66.92  DEPARTURE……+13.97
ASOS………….69.85 *
* ASOS MONTHLY AND ANNUAL PRECIPITATION IS SUSPECT

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….0.0  DEPARTURE……..-0.5
TOTAL SNOWFALL FOR THE MONTH…………….0.1  DEPARTURE…….-12.2
TOTAL SNOWFALL FOR THE SEASON……………7.7  DEPARTURE……..-7.2

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 41/28/35/-2/0.00/0.0/391/70          20 NNW AERO 18 NNW RMY N/A
12/02 52/35/44/+8/1.04/0.0/000/00          28 ESE AERO 25 ESE RMY 27
12/03 54/38/46/+10/0.00/0.0/178/32         35 W   AERO 35 W   RMY 38
12/04 38/23/31/-4/0.00/0.0/516/93          30 WNW AERO 31 WNW RMY 33
12/05 33/18/26/-9/0.00/0.0/432/78          16 NNW AERO 15 NNW RMY N/A
12/06 37/24/31/-4/0.00/0.0/354/64          29 W   AERO 28 W   RMY 30
12/07 37/21/29/-5/0.00/0.0/546/99          29 NW  AERO 29 NW  RMY 32
12/08 27/15/21/-13/0.00/0.0/518/94         28 NW  AERO 27 NW  RMY 29
12/09 34/17/26/-8/0.00/0.0/391/71          23 SSW AERO 21 SSW RMY 22
12/10 36/22/29/-4/0.00/0.0/544/99          24 NNW AERO 23 NNW RMY 22
12/11 36/17/27/-6/0.00/0.0/543/99          16 WSW AERO 14 WSW RMY N/A
12/12 35/18/27/-6/0.00/0.0/471/86          30 NW  AERO 29 NW  RMY M
12/13 31/16/24/-8/0.00/0.0/088/16          16 NNE AERO 12 SE  RMY N/A
12/14 46/28/37/+5/0.00/0.0/399/73          28 SSW AERO 28 SSW RMY 29
12/15 49/33/43/+11/0.04/0.0/000/00         28 NE  AERO 27 NE  RMY 30
12/16 40/37/39/+8/…./0.0/…/..          38 NE  AERO 38 NE  RMY 40
12/17 37/32/35/+4/…./0.0/…/..          39 NNE AERO 37 NNE RMY N/A
12/18 34/20/27/-4/0.02/0.1/…/..          48 NW  AERO 55 NW  RMY 48
12/19 38/17/28/-2/0.00/0.0/…/..          23 WNW AERO 23 WNW RMY N/A
12/20 47/30/39/+9/0.00/0.0/…/..          23 SW  AERO 22 SW  RMY N/A
12/21 62/43/53/+23/…./0.0/…/..         60 SSE AERO 62 SSE RMY 63
12/22 54/31/43/+14/…./0.0/…/..         41 W   AERO 45 W   RMY 43
12/23 38/27/33/+4/0.00/0.0/…/..          30 WNW AERO 32 WNW RMY N/A
12/24 34/27/31/+2/0.01/T/…/..            21 W   AERO 21 W   RMY N/A
12/25 35/23/29/+1/0.00/0.0/…/..          28 NW  AERO 28 NW  RMY 29
12/26 36/20/28/0/0.00/0.0/…/..           24 NW  AERO 24 NW  RMY 25
12/27 35/26/31/+3/0.00/0.0/…/..          23 NW  AERO 22 NW  RMY N/A
12/28 54/30/42/+14/…./0.0/…/.. 44 SSW AERO M  M   RMY 47
12/29 54/30/42/+15/…./0.0/…/..         38 WNW AERO 38 WNW RMY 38

12/30 Low temp since midnight is 23F; normal low is 19F

DAILY RECORDS FOR DECEMBER 2018

12/21/18: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 62F,
BREAKS PREVIOUS RECORD OF 60F SET IN 1957

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

RECORDS FOR DECEMBER 30
HIGH 60 IN 1984
LOW -18 IN 1933
PRECIP 1.48 INS. IN 1891
SNOWFALL 7.5 INS. IN 1956
PEAK GUST 81 MPH WNW IN 1962

RECORDS FOR DECEMBER 31
HIGH 62 IN 1965
LOW -12 IN 1917
PRECIP 0.96 INS. IN 1906
SNOWFALL 7.5 INS. IN 2008
PEAK GUST 78 MPH NW IN 1990

TODAY’S REPORT PREPARED BY: Nate Iannuccillo