Thursday, May 21, 2020

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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, MAY 21, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

DRY WITH LOW HUMIDITY AND A LIGHT WIND
ATOP GREAT BLUE HILL….

We observed almost clear conditions this morning,
with some extra clouds in the afternoon with a
steady pressure fall. Visibility was great at
75 miles on average, with the best of 80 being
seen at the 7 A.M. observation. Today was warm,
with some light warm air advection from the
southwest. Despite an average speed below 10 mph,
the peak gust so far today has reached 20 mph.
Humidity is very low, reaching 18% following
the 1 P.M. observation.

The high so far today is 74F, this is 6 degrees above the
daily normal high of 68F. The low since midnight is 42F,
which is 7 degrees below the daily normal low of 49F.

Today’s Observations:

7 A.M.
Weather: Few cirrus
Temperature: 50F; Dew Point: 34F; Relative Humidity: 54%
Wind: WSW at 7 kts
Sea-level pressure: 30.42 ins. Hg: steady, then rising
Visibility: 80 miles
6-hr Max temp: 50F
6-hr Min temp: 42F
24-hr Precip:  0.00 ins.
24-hr Snowfall: 0.0 ins.
BHO SA 1155 CLR 80 303/50/34/2507/042/ FEW CI ALQDS/ 8/002
52004 10050 20042

10 A.M.
Weather: Few cirrus
Temperature: 65F; Dew Point: 25F; Relative Humidity: 21%
Wind: SSW at 6 kts, light
Sea-level pressure: 30.39 ins. Hg: falling, then more slowly
Visibility: 70 miles
3-hr Precip:  0.00 ins.
3-hr Snowfall: 0.0 ins.
BHO SA 1455 CLR 70 293/65/25/2106/039/ FEW CI ALQDS WND LGT/
8/002 58010

1 P.M.
Weather: Broken cirrus
Temperature: 74F; Dew Point: 30F; Relative Humidity: 19%
Wind: SSW at 7 kts
Sea-level pressure: 30.33 ins. Hg: falling steadily
Visibility: 80 miles
6-hr Max temp: 74F
6-hr Min temp: 50F
6-hr Precip:  0.00 ins.
6-hr Snowfall: 0.0 ins.
BHO SA 1755 E250 BKN 80 273/74/30/2107/033/ 8/002 58020
10074 20050

SUMMARY FOR WEDNESDAY, MAY 20, 2020

TEMPERATURE (DEGREES F)
MAX…..63   NORMAL…..68
MIN…..43   NORMAL…..48
MEAN….53   NORMAL…..58

DEPARTURE FROM 30-YEAR NORMAL……………….-5
TOTAL DEPARTURE FOR THE MONTH………………-53 [-2.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………12  DEPARTURE……..+5
TOTAL HEATING UNITS FOR THE MONTH…………..244  DEPARTURE…….+44
TOTAL HEATING UNITS FOR THE SEASON…………5765  DEPARTURE……-470
TOTAL HEATING UNITS LAST SEASON TO DATE…….6149  DEPARTURE……-384

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………….0  DEPARTURE……..-1
TOTAL COOLING UNITS FOR THE MONTH…………….2  DEPARTURE……..-7
TOTAL COOLING UNITS FOR THE SEASON……………2  DEPARTURE……..-9
TOTAL COOLING UNITS LAST SEASON TO DATE……….4  DEPARTURE……..-2

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………..22 ESE AT  1:42 P.M.
AERO…………………….20 SE  AT  6:42 P.M.
ASOS…………………….18 S   AT 10:16 P.M.
DAVIS……………………19 E   AT  1:41 P.M. RMY 19
FASTEST MILE FOR YESTERDAY………………….13 SSE AT  9:32 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….14 S   AT 10:16 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………14 SSE AT  9:28 P.M.
AVERAGE WIND SPEED AND DIRECTION…………….7.9 ENE
ASOS…………………….8.1
DAVIS……………………8.5 ESE [107 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.00  DEPARTURE……-0.13
ASOS…………..0.00
TOTAL PRECIPITATION FOR THE MONTH……….2.55  DEPARTURE……+0.07
ASOS…………..2.54
TOTAL PRECIPITATION FOR THE YEAR……….19.59  DEPARTURE……-1.44
ASOS………….20.04

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….0.0  DEPARTURE……..0.0
TOTAL SNOWFALL FOR THE MONTH…………..Trace  DEPARTURE……..0.0
TOTAL SNOWFALL FOR THE SEASON…………..31.9  DEPARTURE……-30.8

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  64/52/58/+5/…./0.0/000/00         46 SSE  AERO 44 SSE RMY N/A
05/02  70/42/56/+3/…./0.0/729/86         41 NW   AERO 40 NW  RMY N/A
05/03  78/55/67/+14/0.00/0.0/613/72        35 SSW  AERO 35 SSW RMY 36
05/04  72/45/59/+5/T/0.0/247/29            37 NW   AERO 40 WNW RMY 39
05/05  60/40/50/-4/0.00/0.0/821/96         31 NW   AERO 32 NW  RMY N/A
05/06  57/38/48/-6/T/0.0/498/58            24 ESE  AERO 22 ENE RMY 22
05/07  63/37/50/-5/0.00/0.0/576/67         30 WSW  AERO 29 WSW RMY N/A
05/08  57/40/49/-6/…./0.0/328/38         31 W    AERO 32 W   RMY N/A
05/09  44/32/38/-17/…./T/484/56          52 W    AERO 53 W   RMY 54
05/10  59/31/45/-10/0.00/0.0/763/88        46 W    AERO 46 W   RMY 49
05/11  65/43/54/-2/0.22/0.0/…/..         39 S    AERO 43 S   RMY 41
05/12  55/37/46/-10/0.00/0.0/…/..        37 W    AERO 37 W   RMY 37
05/13  59/32/46/-10/0.00/0.0/…/..        37 WNW  AERO 37 WNW RMY 38
05/14  70/40/55/-2/0.00/0.0/…/..         29 W    AERO 26 W   RMY 27
05/15  78/50/64/+7/…./0.0/…/..         40 WSW  AERO 40 WSW RMY 43
05/16  69/47/58/+1/…./0.0/…/..         31 NW   AERO 31 NW  RMY 32
05/17  67/47/57/0/0.00/0.0/…/..          22 SSW  AERO N/A    RMY 21
05/18  60/47/54/-4/T/0.0/…/..            24 W    AERO 22 ENE RMY N/A
05/19  56/45/51/-7/0.00/0.0/…/..         35 ENE  AERO 34 ENE RMY 32
05/20  63/43/53/-5/0.00/0.0/…/..         22 ESE  AERO 20 SE  RMY 19

05/21 The low since midnight is 42F, the daily normal low is 49F

DAILY RECORDS FOR MAY 2020

5/13/2020: NEW RECORD LOW OF 32F, REPLACING 35F SET IN
1914 AND 2005

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

RECORDS FOR MAY 21
HIGH 92F IN 1921
LOW 35F IN 1907
PRECIP 1.61 INS IN 1954
PEAK GUST 74 MPH WSW IN 2006

RECORDS FOR MAY 22
HIGH 93F IN 1911
LOW 35F IN 1907
PRECIP 3.75 INCHES IN 1920
PEAK GUST 49e MPH SSW IN 1947

TODAY’S REPORT PREPARED BY: Benjamin Turner