Monday, May 18, 2015

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

DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, MAY 18, 2015
ALL TIMES ARE IN EASTERN STANDARD TIME

DENSE FOG THIS MORNING CLEARS FOR A SUNNY BUT COOL AFTERNOON

A backdoor cold front moved through the region last night, cooling us down
from the upper 70s yesterday to the low 60s today.  Some low clouds, fog,
and light drizzle made for murky conditions early this morning, with very
low visibility at times.  By mid-morning, the overcast began to lift and
break, and partly to mostly sunny conditions have been observed for the rest
of the day.  The NE wind in the wake of the backdoor front has kept
temperatures lower today, with 61F being the high so far, and the marine
influence has been very noticeable at the summit.  This morning’s drizzle
provided just a trace of precipitation, and our monthly and yearly deficits
continue to grow.  Tomorrow appears to be our only chance at significant
precipitation for the next several days.

Today’s Observations:

7 A.M.
Weather: Sky obscured by dense fog, stratus fractus drifting above and
below summit
Temperature: 48F; Dew Point: 48F; Wind: NE at 8 kts
Sea-level pressure: 30.29 ins. Hg, rising then rising more slowly
Visibility: 1/8 miles, dense fog
6-hr Max temp: 50F
6-hr Min temp: 48F
24-hr precip: Trace
BHO SA 1155 W3 X 1/8F 258/48/48/0408/029/ STFRA DRFTNG ABV AND BLO SMT/
8//// 51022 MANUAL 6000/ 7000/ 10050 20048

10 A.M.
Weather: Scattered stratocumulus
Temperature: 56F; Dew Point: 49F; Wind: ENE at 10 kts
Sea-level pressure: 30.27 ins. Hg, rising then falling
Visibility: 20 miles, hazy
BHO SA 1455 15 SCT 20 249/56/49/0710/027/ HZY/ 8/500 58009

1 P.M.
Weather: Thin broken cirrus, few cumulus distant N-NNE
Temperature: 60F; Dew Point: 46F; Wind: NE at 10 kts
Sea-level pressure: 30.25 ins. Hg, falling then falling more rapidly
Visibility: 35 miles, distant haze
6-Hr Max temp: 61F
6-Hr Min temp: 48F
BHO SA 1755 E250 –BKN 35 243/60/46/0510/025/ FEW CU DSNT N-NNE DSNT HZ/
8/101 58006 10061 20048

SUMMARY FOR SUNDAY, MAY 17, 2015

TEMPERATURE (DEGREES F)
MAX…..79   NORMAL…..67
MIN…..50   NORMAL…..48
MEAN….65   NORMAL…..57

DEPARTURE FROM 30-YEAR NORMAL…………………..+8
TOTAL DEPARTURE FOR THE MONTH………………….+108 [+6.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………0  DEPARTURE………..-8
TOTAL HEATING UNITS FOR THE MONTH…………..76  DEPARTURE………-101
TOTAL HEATING UNITS FOR THE SEASON………..6347  DEPARTURE………+135
TOTAL HEATING UNITS LAST SEASON TO DATE……6281  DIFFERENCE………+66

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………..0   DEPARTURE……….-1
TOTAL COOLING UNITS FOR THE MONTH………….16   DEPARTURE………+10
TOTAL COOLING UNITS FOR THE SEASON…………16   DEPARTURE……….+8
TOTAL COOLING UNITS LAST SEASON TO DATE…….13   DIFFERENCE………+3

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………21 NE  AT  10:34 P.M.
ASOS…………………..20 NE  AT  10:34 P.M.
DAVIS………………….19 NE  AT  10:33 P.M. RMY N/A
FASTEST MILE FOR YESTERDAY………………..16 NE  AT  10:53 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE……………..16 NE  AT  10:34 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….15 NE  AT  10:34 P.M.
AVERAGE WIND SPEED AND DIRECTION………….8.3 NE
ASOS………………….8.7
DAVIS…………………7.4 ENE [71 deg.] * Last of several occurrences…

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…..Trace DEPARTURE…..-0.13
ASOS……………0.00
TOTAL PRECIPITATION FOR THE MONTH………..0.27  DEPARTURE…..-1.81
ASOS……………0.26
TOTAL PRECIPITATION FOR THE YEAR………..18.19  DEPARTURE…..-2.31
ASOS…………….N/A ***
*** ASOS annual totals not available due to erroneous readings

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M………..0.0  DEPARTURE……0.0
TOTAL SNOWFALL FOR THE MONTH……………..0.0  DEPARTURE……0.0
TOTAL SNOWFALL FOR THE SEASON…………..150.8  DEPARTURE….+88.1

PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/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

5/1  52/37/45/-8/0.00/0.0/354/42               21 NE  RMY 20
5/2  63/35/49/-4/0.00/0.0/668/79               20 S   RMY 20
5/3  74/44/59/+6/0.00/0.0/509/60               22 S   RMY 22
5/4  83/47/65/+11/0.00/0.0/783/92              39 SSW RMY 45
5/5  77/56/67/+13/0.03/0.0/222/26              29 SW  RMY N/A
5/6  74/54/64/+10/0.00/0.0/574/67              24 SSW RMY 25
5/7  84/52/68/+13/0.00/0.0/824/96              29 S   RMY 32
5/8  74/44/59/+4/0.00/0.0/809/94               27 NNE RMY 26
5/9  77/44/61/+6/0.00/0.0/509/59               30 S   RMY 32
5/10 88/60/74/+19/0.00/0.0/692/80              28 SSW RMY 30
5/11 84/48/66/+10/0.00/0.0/529/61              30 NE  RMY 31
5/12 84/47/66/+10/0.24/0.0/287/33              33 WNW RMY 37
5/13 67/47/57/+1/0.00/0.0/820/94               31 WNW RMY N/A
5/14 70/44/57/+0/0.00/0.0/…/..               22 NW  RMY 22
5/15 73/51/62/+5/0.00/0.0/…/..               20 WSW RMY 21
5/16 68/53/61/+4/T/0.0/…/..                  23 S   RMY 24
5/17 79/50/65/+8/T/0.0/…/..                  21 NE  RMY N/A

5/18 low since midnight is 48F; normal low is now 49F

DAILY RECORDS FOR MAY 2015

NONE SO FAR.

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

RECORDS FOR MAY 18
HIGH 88F IN 1906, 1936, 1986
LOW 35F IN 2002
PRECIP 1.93 INS IN 2007
SNOW TRACE IN 2002 (Ice pellets)
PEAK GUST 64 MPH SSW IN 2000

RECORDS FOR MAY 19
HIGH 91F IN 1962
LOW 34F IN 2002
PRECIP 1.54 INCHES IN 1900
PEAK GUST 58 MPH NW IN 1964

TODAY’S REPORT PREPARED BY: Jonathan O’Brien