Saturday, December 19, 2015

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

DAILY DISCUSSION AND CLIMATE SUMMARY
SATURDAY, DECEMBER 19, 2015
ALL TIMES ARE IN EASTERN STANDARD TIME

COLDER AND DRIER AIR BRIEFLY MOVING IN THIS WEEKEND…
CLOUDS EARLY THIS MORNING LEAVE BY MID-MORNING…

The low temperature this morning of 30F matches the lowest
temperature observed so far this month back on December 1st.
The higher minimum temperature of 32F at nearby Norwood Airport
this morning and the absence of a temperature inversion is evidence
that the cold air is advecting into the region this morning. If
winds diminish by tonight, then radiational cooling is more likely
to dominate the morning low temperatures tomorrow with colder
readings in the lower terrain than on the summit.

Skies were mostly cloudy this morning, though the sun was visible
at sunrise and added beautiful colors to the few low and mostly
middle level clouds.  Most of the cloudiness moved eastward by
mid-morning, leaving a bright and sunny sky with increasing winds.
The winds have been very gusty since mid-morning, with a peak gust
of 35 kts, 40 mph, WNW at 1:13 PM EST.

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: Scattered stratocumulus, broken altocumulus,
overcast cirrus, few lower stratocumulus distant ENE-S,
few breaks in overcast distant E-SSE, light distant haze
Temperature: 32F; Dew Point: 23F; Wind: W at 13G20 kts
Sea-level pressure: 29.83 ins. Hg, rising, then more rapidly
Visibility: 55 miles, visiblity WNW-NW 45
6-hr Max temp: 35F
6-hr Min temp: 30F
24-hr precip: 0.10 ins
BHO SA 1155 60 SCT E110 BKN 200 OVC 55 102/32/23/2713G20/983/
FEW LWR SC DSNT ENE-S FEW BINOVC DSNT E-SSE VSBY WNW-NW 45
LGT DSNT HZ/ 8/571 53027 70010 10035 20030

10 A.M.
Weather: Scattered stratocumlus, few cumulus fractus vicinity
station, few altocumulus distant ESE-SSE
Temperature: 35F; Dew Point: 16F; Wind: WNW at 17G32 kts,
Wind: Peak gust 32 knots, WNW at 9:48 AM
Sea-level pressure: 29.89 ins. Hg, rising, then more slowly
Visibility: 65 miles
BHO SA 1455 60 SCT 65 121/35/16/3017G32/989/ FEW CUFRA VCNTY
STN FEW AC DSNT ESE-SSE PK WND 3032/48/ 8/570 51019

1 P.M.
Weather: Scattered cumulus, few cumulus fractus
Temperature: 36F; Dew Point: 13F; Wind: W at 17G26 kts,
Wind: Peak gust 32 knots W at 12:42 PM
Sea-level pressure: 29.89 ins. Hg, rising,
Visibility: 75 miles, visibility NW-NNW 60
6-hr max. temp: 37F
6-hr min. temp: 32F
BHO SA 1755 55 SCT 75 121/36/13/2817G26/989/ FEW CUFRA VSBY
NW-NNW 60 PK WND 2732/42/ 8/100 55000 10037 20032

SUMMARY FOR FRIDAY, DECEMBER 18, 2015

TEMPERATURE (DEGREES F)
MAX…..50   NORMAL…..38
MIN…..35   NORMAL…..23
MEAN….43   NORMAL…..31

DEPARTURE FROM 30-YEAR NORMAL…………………+12
TOTAL DEPARTURE FOR THE MONTH………………..+208  [+11.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………..22   DEPARTURE………-13
TOTAL HEATING UNITS FOR THE MONTH………….358   DEPARTURE……..-210
TOTAL HEATING UNITS FOR THE SEASON………..1360   DEPARTURE……..-470
TOTAL HEATING UNITS LAST SEASON TO DATE……1686   DIFFERENCE…….-326

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….29  NW AT 11;03 P.M.
ASOS……………………30  NW AT 11:02 P.M.
DAVIS…………………..29  NW AT 11:00 P.M. RMY 30
FASTEST MILE FOR YESTERDAY…………………20  NW AT 11:03 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………21  NW AT 10:52 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..19  NW AT 10:51 P.M.
AVERAGE WIND SPEED AND DIRECTION………….11.5  NW
ASOS………………….11.4
DAVIS………………….9.8  NW [320 Deg.] * Last of several occurrences

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…..0.10  DEPARTURE……-0.06
ASOS……………0.09
TOTAL PRECIPITATION FOR THE MONTH………..1.60  DEPARTURE……-1.33
ASOS……………1.61
TOTAL PRECIPITATION FOR THE YEAR………..41.02  DEPARTURE…..-10.45
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……-0.4
TOTAL SNOWFALL FOR THE MONTH…………….0.0  DEPARTURE……-6.7
TOTAL SNOWFALL FOR THE SEASON………….TRACE  DEPARTURE……-9.3

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 since midnight is 30F; normal low is now 23F

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 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

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

TODAY’S REPORT PREPARED BY: Mike Iacono