Sunday, December 20, 2015

| December 20, 2015 | Reply

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

DAILY DISCUSSION AND CLIMATE SUMMARY
SUNDAY, DECEMBER 20, 2015
ALL TIMES ARE IN EASTERN STANDARD TIME

COOLER, DRIER AIR STICKS AROUND, BUT VERY MILD WEATHER SET TO RETURN

The low temperature dropped to 28F this morning, the coldest reading so
far this month.  Yesterday’s high of 38F also marked the coldest high
temperature of the month so far.  Despite these cooler conditions, yesterday
still averaged four degrees above normal, the 18th above average day in a
row, and that streak will continue today and well into the coming days.
December so far is averaging 11 degrees above normal.

The day began mostly cloudy with stratocumulus clouds present.  They have
decreased in coverage during the day, allowing for plenty of sunshine.
Winds have remained mainly out of the west, but not as strong as yesterday
when gusts approached 40mph.  Visibility has been excellent today, up to
85 miles this afternoon.

So far this season, there has been no measurable snow on Blue Hill.
This season is now the fifth latest on record for the first occurrence
of measurable snowfall with no snow likely over the next week.

BHO Latest First Measurable Snowfall, (1885-2014)

1) January 13, 2000   (7.0 inches)
2) January 1, 1954    (0.8 inches)
3) December 29, 1941  (0.4 inches)
4) December 22, 1998  (0.6 inches)
5) December 16, 1973  (0.4 inches)
6) December 15, 1891  (0.3 inches)

Today’s Observations:

7 A.M.
Weather: Broken stratocumulus
Temperature: 29F; Dew Point: 19F; Wind: W at 8 kts
Sea-level pressure: 30.33 ins. Hg, rising
Visibility: 75 miles
6-hr Max temp: 29F
6-hr Min temp: 27F
24-hr precip: 0.00 ins
BHO SA 1155 E45 BKN 75 270/29/19/2708/033/ 8/5// 52034 10029 20027

10 A.M.
Weather: Scattered stratocumulus
Temperature: 34F; Dew Point: 20F; Wind: W at 7 kts
Sea-level pressure: 30.40 ins. Hg, rising then rising more slowly
Visibility: 80 miles
BHO SA 1455 45 SCT 80 296/34/20/2807/040/ 8/500 51026

1 P.M.
Weather: Clear, few small stratocumulus all quadrants, few cirrus mostly
distant SSE-NW, few cirrocumulus mostly NE
Temperature: 38F; Dew Point: 19F; Wind: W at 11 kts
Sea-level pressure: 30.40 ins. Hg, rising slightly
Visibility: 85 miles
6-hr Max Temp: 39F
6-hr Min Temp: 29F
BHO SA 1755 CLR 85 297/38/19/2711/041/ FEW SML SC ALQDS
FEW CI MSTLY DSNT SSE-NW FEW CC MSTLY NE/ 8/501 51001 10039 20029

SUMMARY FOR SATURDAY, DECEMBER 19, 2015

TEMPERATURE (DEGREES F)
MAX…..38   NORMAL…..38
MIN…..30   NORMAL…..23
MEAN….34   NORMAL…..30

DEPARTURE FROM 30-YEAR NORMAL………………..+4
TOTAL DEPARTURE FOR THE MONTH………………..+212  [+11.0 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………..31   DEPARTURE……….-4
TOTAL HEATING UNITS FOR THE MONTH………….389   DEPARTURE……..-214
TOTAL HEATING UNITS FOR THE SEASON………..1391   DEPARTURE……..-473
TOTAL HEATING UNITS LAST SEASON TO DATE……1721   DIFFERENCE…….-330

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….39  W   AT  4:36 P.M.*
ASOS……………………39  W   AT  7:19 P.M.
DAVIS…………………..39  WNW AT  9:45 A.M. RMY 40
FASTEST MILE FOR YESTERDAY…………………30  WNW AT 11:17 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………30  NW  AT 11:19 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..26  NW  AT 11:19 A.M.
AVERAGE WIND SPEED AND DIRECTION………….17.4  W
ASOS………………….15.8
DAVIS…………………14.9  WNW [289 Deg.]
* Last of several occurrences…

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…..0.00  DEPARTURE……-0.15
ASOS……………0.00
TOTAL PRECIPITATION FOR THE MONTH………..1.60  DEPARTURE……-1.48
ASOS……………1.61
TOTAL PRECIPITATION FOR THE YEAR………..41.02  DEPARTURE…..-10.60
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……-0.5
TOTAL SNOWFALL FOR THE MONTH…………….0.0  DEPARTURE……-7.2
TOTAL SNOWFALL FOR THE SEASON………….TRACE  DEPARTURE……-9.8

PRELIMINARY CLIMATE SUMMARY FOR DECEMBER CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/RMY 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

12/1  42/30/36/-1/…./0.0/000/00           19 NNE RMY 19
12/2  53/37/45/+9/…./0.0/000/00           25 SSE RMY 25
12/3  53/37/45/+9/…./0.0/162/29           43 WNW RMY 42
12/4  47/32/40/+5/0.00/0.0/444/80           32 NW  RMY 32
12/5  50/33/42/+7/0.00/0.0/548/99           21 W   RMY N/A
12/6  57/35/46/+11/0.00/0.0/531/96          22 SW  RMY N/A
12/7  54/37/46/+12/0.00/0.0/353/64          31 NE  RMY N/A
12/8  42/35/39/+5/0.01/0.0/000/00           32 NE  RMY 31
12/9  44/34/39/+5/…./0.0/044/08           28 SSE RMY N/A
12/10 57/41/49/+16/T/0.0/209/38             29 SE  RMY N/A
12/11 56/44/50/+17/0.00/0.0/049/09          28 SSW RMY 28
12/12 59/46/53/+20/0.00/0.0/367/67          23 W   RMY N/A
12/13 54/44/49/+17/0.00/0.0/000/00          18 ESE RMY 19
12/14 60/43/52/+20/…./0.0/000/00          32 S   RMY N/A
12/15 61/45/53/+21/…./0.0/371/68          48 W   RMY 51
12/16 45/34/40/+9/0.00/0.0/415/76           25 N   RMY N/A
12/17 53/36/45/+14/…./0.0/000/00          29 SE  RMY 28
12/18 50/35/43/+12/…./0.0/000/00          29 NW  RMY 30
12/19 38/30/34/+4/0.00/0.0/…/..           39 W   RMY 40

12/20 low since midnight is 28F; normal low is now 22F

DAILY RECORDS FOR DECEMBER 2015

**12/13/2015- NEW DAILY RECORD HIGH MINIMUM TEMPERATURE OF 44F,
BREAKS PREVIOUS RECORD OF 43F SET IN 1919, TIED 1983**

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

RECORDS FOR DECEMBER 20
HIGH 61 IN 1957
LOW -16 IN 1942
PRECIP 1.69 INS. IN 1936
SNOWFALL 13.7 INS. IN 2009
PEAK GUST 75 MPH S IN 2002

RECORDS FOR DECEMBER 21
HIGH 60 IN 1957
LOW -10 IN 1942
PRECIP 2.01 INS. IN 1946
SNOWFALL 11.4 INS. IN 1954
PEAK GUST 77 MPH SSE IN 1957

TODAY’S REPORT PREPARED BY: Jonathan O’Brien

Category: Daily Discussions

Leave a Reply