Saturday, May 15, 2021
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
SATURDAY, MAY 15, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0423E
SUNSET: 1859E
MORNING SUNSHINE GIVING WAY TO DEVELOPING CLOUDS AND EVEN SOME
BRIEF RAIN SHOWERS…
Plenty of sun this morning allowed for rapidly rising
temperatures. As a matter of fact, the temperature spiked
11 degrees in 1 hour between 6 and 7 A.M. The wind during
the morning was very light, even going calm for a time
during mid morning.
However, a sea-breeze developed late morning. This sea-
breeze has created a boundary in which clouds have developed
and even some showers. A couple of these showers have passed
over the hill bringing 0.01″ of rain.
The temperature has of course responded to the sea-breeze
and has dropped from the mid 70s to the upper 60s.
The high so far today is 75F, which is 9 degrees
above the normal high of 66F. The low since midnight
is 55F, which is 7 degrees above the daily normal low
of 48F.
PRELIMINARY STATS FOR APRIL 2021
TEMPERATURE, Deg. F
Avg. Max. 57.2 [+1.5]
Avg. Min. 37.8 [+0.1]
Mean 47.5 [+0.8]
24-hour corrected mean: 47.0
Max. for month: 75F on the 10th
Min. for month: 23F on the 3rd
HEATING DEGREE DAYS
Total heating units: 519 [-32]
Total for the season: 5341 [-694]
Total for last season: 5521
PRECIPITATION, Inches
Total: 4.89 [+0.45]
Greatest in 24 hrs: 2.45 ins. on the 15-16th
SNOWFALL, Inches
Total: 3.6 [+0.6]
Greatest in 24 hrs: 3.6 ins. on the 16th
WIND, mph
Avg. uncorrected wind speed: 12.1 mph
Avg. corrected wind speed: 12.5 mph
Prevailing wind direction: WNW [16%]
Peak gust and direction: 58 WNW on the 30th
SUNSHINE:
Campbell-Stokes card minutes: 12444 minutes of a possible 23250 or 54%
Astronomical total minutes: 12904 minutes of a possible 24128 or 53%
Today’s Observations:
7 A.M.
Weather: Scattered altocumulus/altocumulus castellanus,
thin scattered cirrus
Temperature: 68F; Dew Point: 33F; Relative Humidity: 27%
Wind: ENE at 4 kts, wind light
Sea-level pressure: 30.21 in. Hg; rising, then more slowly
Visibility: 65 miles
6-hr Max temp: 68F
6-hr Min temp: 55F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0.0 ins.
BHO SA 1755 85 SCT 250 -SCT 65 230/68/33/0604/021/ VIRGA ALQDS
THN K LYR ALNG HRZN SSW-WSW WND LGT/ 8/081 51013 10068 20055
10 A.M.
Weather: Scattered cumulus, scattered altocumulus,
thin scattered cirrus
Temperature: 73F; Dew Point: 33F; Relative Humidity: 22%
Wind: S @ 3 kts, wind light and variable
Sea-level pressure: 30.22 in Hg; rising, then falling
Visibility: 60 miles
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 55 SCT 100 SCT 250 -SCT 60 233/73/33/1803/022/
WND L/V/ 8/261 50003
1 P.M.
Weather: Broken cumulus, broken altocumulus, thin broken cirrus,
cumulonimbus SSE-S, virga all quadrants
Temperature: 71F, Dew point: 38F; Relative Humidity: 30%
Wind: ESE @ 9G15 kts
Sea-level pressure: 30.19 in Hg; falling, then more rapidly
Visibility: 60 miles
6-hr Max temp: 75F
6-hr Min temp: 65F
6-hr Precip: 0.01 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1755 E60 BKN 120 BKN 250 -BKN 60 223/71/38/1109G15/019/
CB SSE-S VIRGA ALQDS RW-B05E30/ 8/361 58010 6001/ 10075 20065
SUMMARY FOR FRIDAY, MAY 14, 2021
TEMPERATURE (DEGREES F)
MAX…….76 NORMAL…..66
MIN…….49 NORMAL…..47
MEAN……63 NORMAL…..57
DEPARTURE FROM 30-YEAR (1981-2010) NORMAL……. +6
TOTAL DEPARTURE FOR THE MONTH……………….-15 [-1.3 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON JUL THRU JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………… 2 DEPARTURE…….-7
TOTAL HEATING UNITS FOR THE MONTH…………..159 DEPARTURE…… +8
TOTAL HEATING UNITS FOR THE SEASON…………5500 DEPARTURE…..-686
TOTAL HEATING UNITS LAST SEASON TO DATE…….5712 DEPARTURE…..-212
COOLING DEGREE DAYS (SEASON JAN THRU DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………… 0 DEPARTURE…….-1
TOTAL COOLING UNITS FOR THE MONTH…………… 0 DEPARTURE…….-5
TOTAL COOLING UNITS FOR THE SEASON………….. 0 DEPARTURE…….-7
TOTAL COOLING UNITS LAST SEASON TO DATE……… 2 DEPARTURE…….-2
PEAK WIND GUST (MPH):
420C/Official…………..23 WNW @ 1:17 P.M.
AEROVANE (south tower)…..23 WNW @ 1:23 P.M.
ASOS…………………..23 W @ 1:17 P.M.
DAVIS #1……………….24 W @ 1:16 P.M.
DAVIS #2 (south tower)…..24 SSE @ 5:05 P.M.
RMY……………………25 @ 1:16 P.M.
VECTOR…………………24 @ 1:16 P.M.
MERLIN…………………23
FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………14 WNW @ 5:27 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….16 W @ 1:18 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………18 W @ 1:18 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………17 SSE @ 5:16 A.M.
MAXIMUM 2-MINUTE RMY AVERAGE………………..15 W @ 1:15 P.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE……………..15 @ 1:15 P.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL…… 9.0 WNW [217 total miles]
ASOS………………… 9.0
DAVIS #1…………….. 9.3 WNW
DAVIS #2…………….. 9.8 WNW
RMY…………………. 8.8 WNW
VECTOR………………. 9.4
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….0.00 DEPARTURE….-0.12
ASOS………….0.00
TOTAL PRECIPITATION FOR THE MONTH………….1.78 DEPARTURE….+0.07
ASOS………….1.73
TOTAL PRECIPITATION FOR THE YEAR………….16.84 DEPARTURE….-3.42
ASOS………..17.01
PRELIMINARY CLIMATE SUMMARY FOR MAY 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
05/01 62/38/50/-3/0.06/0.0/659/78 31 WNW AERO 35 WNW RMY 40
05/02 76/48/62/+9/0.01/0.0/220/26 41 SW AERO 41 SW RMY 46
05/03 67/48/58/+5/0.07/0.0/400/47 21 E AERO 20 E RMY 20
05/04 50/44/47/-7/0.78/0.0/000/00 36 NNE AERO 32 NNE RMY 37
05/05 48/44/46/-8/0.45/0.0/000/00 18 ESE AERO 14 ESE RMY 17
05/06 64/45/55/+1/0.00/0.0/780/91 33 NW AERO 38 NNW RMY 39
05/07 61/43/52/-3/0.00/0.0/516/60 28 ESE AERO 22 ESE RMY 26
05/08 54/40/47/-8/0.00/0.0/069/08 24 SSW AERO 23 SSW RMY 25
05/09 66/42/54/-1/T/0.0/579/67 30 SW AERO 29 SW RMY 34
05/10 60/45/53/-2/0.39/0.0/…/.. 21 W AERO 20 W RMY 20
05/11 63/45/54/-2/0.00/0.0/…/.. 38 WNW AERO 41 WNW RMY 41
05/12 65/41/53/-3/0.00/0.0/…/.. 28 NW AERO M M RMY 31
05/13 69/45/57/+1/0.00/0.0/…/.. 22 WNW AERO 21 WNW RMY 21
05/14 76/49/63/+8/0.00/0.0/…/.. 23 WNW AERO 23 WNW RMY 25
05/15 The low since midnight is 55F, the daily normal low is 48F
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)
RECORDS FOR MAY 15
HIGH 93F IN 1900
LOW 36F IN 1947,1985
PRECIP 1.63 INCHES IN 1978
PEAK GUST 53e MPH NE IN 1978, W 2002
RECORDS FOR MAY 16
HIGH 90F IN 1951
LOW 30F IN 1936
PRECIP 2.63 INCHES IN 1954
PEAK GUST 56e MPH NW IN 1952
TODAY’S REPORT PREPARED BY: Matt Douglas
