Tuesday, April 27, 2021

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

TUESDAY, APRIL 27, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0445E
SUNSET:  1840E

CLOUDS DOMINATED INTO EARLY AFTERNOON, STARTING TO
BREAK UP FINALLY….

Mid level clouds moved in early this morning and hung around
into early this afternoon. This has of course limited solar
insolation today and has kept temperatures on the cool side
through the morning hours. Readings were mainly in the 40s
to low 50s. However as we progress into the afternoon, the
clouds are eroding and an increase in sunshine is occuring.
This is allowing the temperature to finally respond with
readings into the upper 50s at the 1 P.M. observation.

The air has been exceptionally dry for this time of year with
dew point readings in the upper teens to around 20.

Despite the dry air, we did have a very brief sprinkle this
morning between 10-11 A.M., thus giving us a trace of rain
for today.

The dry air has allowed for really exceptional visibility this
morning with a maximum distance of 80 miles, it has however
slipped a bit early this afternoon to around 70 miles.

The high so far today is 58F, this is 2 degrees below the
normal high of 60F. The low since midnight is 38F, which
is 4 degrees below the daily normal low of 42F.

Today’s Observations:

7 A.M.
Weather: Broken altocumulus, overcast cirrostratus, few breaks
in overcast distant NW-NE-SSE
Temperature: 43F; Dew Point: 20F; Relative Humidity: 39%
Wind: WNW at 9 kts
Sea-level pressure: 30.04 in Hg, rising, then steady
Visibility: 80 miles
6-hr Max temp: 43F
6-hr Min temp: 38F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0.0 ins.
BHO SA 1155 E120 BKN 170 OVC 80 174/43/20/2909/004/
FEW BINOVC DSNT NW-NE-SSE/ 8/077 51008 10043 20038

10 A.M.
Weather: Broken altocumulus, overcast cirrostratus, few breaks
in overcast distant WNW-N-ESE, virga all quadrants
Temperature: 47F; Dew Point: 21F; Relative Humidity: 35%
Wind: WSW @ 7 kts
Sea-level pressure: 30.03 in Hg; rising, then falling
Visibility: 70 miles
3-hr Precip: 0.00 ins.
3-hr Snow: 0.00 ins.
BHO SA 1455 E100 BKN 180 OVC 70 168/47/21/2507/003/
FEW BINOVC DSNT WNW-N-ESE VIRGA ALQDS SUN OCLY DMLY VSBL/
8/077 58006

1 P.M.
Weather: Broken altocumulus, broken cirrostratus,
thin overcast cirrus, few altocumulus lenticularis NNW-E
Temperature: 56F, Dew point: 17F; Relative Humidity: 21%
Wind: W @ 10G19 kts
Sea-level pressure: 29.97 in Hg; falling, then more slowly
Visibility: 70 miles
6-hr Max temp: 58F
6-hr Min temp: 43F
6-hr Precip: Trace
6-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1755 E110 BKN 200 BKN 250 -BKN 70 150/56/17/2810G19/997/
FEW ACSL NNW-E/ 8/046 56018 6000/ 10058 20043

SUMMARY FOR MONDAY, APRIL 26, 2021

TEMPERATURE (DEGREES F)
MAX…….55     NORMAL…..60
MIN…….40     NORMAL…..42
MEAN……48     NORMAL…..51

DEPARTURE FROM 30-YEAR (1981-2010) NORMAL……. -3
TOTAL DEPARTURE FOR THE MONTH……………….+28 [+0.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………17  DEPARTURE…….+3
TOTAL HEATING UNITS FOR THE MONTH…………..467  DEPARTURE……-30
TOTAL HEATING UNITS FOR THE SEASON…………5289  DEPARTURE…..-692
TOTAL HEATING UNITS LAST SEASON TO DATE…….5432  DEPARTURE…..-143

PEAK WIND GUST (MPH):
                     420C/Official…………..39 NW  @  3:10 P.M.
                     AEROVANE (south tower)…..40 NW  @  3:10 P.M
                     ASOS…………………..39 NW  @  3:10 P.M
                     DAVIS #1……………….38 WNW @  9:22 A.M
                     DAVIS #2 (south tower)…..37 WNW @ 11:57 A.M
                     RMY……………………43     @  2:29 P.M
                     VECTOR…………………45     @  1:52 P.M
                     MERLIN…………………46

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………28 WNW @ 11:58 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….28 WNW @ 11:57 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………29 WNW @ 11:57 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………30 WNW @ 11:59 A.M.
MAXIMUM 2-MINUTE RMY AVERAGE………………..27 NNW @  3:10 P.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE……………..27     @  3:09 P.M.

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL……16.8 WNW [404 total miles]                     ASOS…………………15.5
                     DAVIS #1……………..16.7 NW
                     DAVIS #2……………..17.3 NW
                     RMY………………….15.2 NW
                     VECTOR……………….16.3

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………….4.21  DEPARTURE….+0.19
                             ASOS………….4.12
TOTAL PRECIPITATION FOR THE YEAR………….14.38  DEPARTURE….-3.63
                              ASOS………..14.63

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HOURS ENDING 7 A.M………..0.0  DEPARTURE….. 0.0
TOTAL SNOWFALL FOR THE MONTH ………………3.6  DEPARTURE…..+0.7
TOTAL SNOWFALL FOR THE SEASON……………..76.2  DEPARTURE….+14.1

PRELIMINARY CLIMATE SUMMARY FOR APRIL 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

04/01   56/30/43/+2/0.89/T/000/00        44 NW   AERO 51 NW   RMY 49
04/02   37/24/31/-10/0.00/0.0/614/80     28 NW   AERO 32 NNW  RMY 30
04/03   48/23/36/-6/0.00/0.0/755/98      24 NW   AERO 25 NW   RMY 26
04/04   58/33/46/+4/0.00/0.0/734/95      38 NNW  AERO 41 NNW  RMY 41
04/05   57/41/49/+6/T/T/031/04           41 NNW  AERO 48 NNW  RMY 50
04/06   61/40/51/+8/0.00/0.0/412/53      26 NNW  AERO 25 NNW  RMY 31
04/07   57/41/49/+6/0.00/0.0/391/50      23 ENE  AERO 21 ENE  RMY 22
04/08   59/43/51/+7/0.00/0.0/745/95      22 ENE  AERO 22 ENE  RMY 24
04/09   69/42/56/+12/0.00/0.0/707/90     24 S    AERO  M   M  RMY 26
04/10   75/43/59/+14/0.00/0.0/576/73     26 SSW  AERO 28 SSW  RMY 30
04/11   53/40/47/+2/T/0.0/000/00         33 ENE  AERO 33 ENE  RMY 34
04/12   46/37/42/-3/0.05/0.0/000/00      36 ENE  AERO 37 ENE  RMY 41
04/13   56/37/47/+1/T/0.0/415/52         31 NE   AERO 30 NE   RMY 33
04/14   56/42/49/+3/0.00/0.0/729/91      22 ESE  AERO 23 ESE  RMY 22
04/15   51/37/44/-3/0.30/0.0/016/02      26 ESE  AERO 25 ESE  RMY 28
04/16   39/31/35/-12/2.22/3.6/000/00     48 NNW  AERO 58 NNW  RMY 58
04/17   45/34/40/-7/0.07/T/040/05        27 NNW  AERO 30 NNW  RMY 29
04/18   60/38/49/+1/0.00/0.0/666/82      28 NW   AERO 28 NW   RMY 31
04/19   66/44/55/+7/T/0.0/…/..         22 SSW  AERO 25 SSW  RMY 28
04/20   72/45/59/+10/0.00/0.0/…/..     38 SW   AERO 37 WSW  RMY 40
04/21   68/32/50/+1/0.48/*T/…/..       45 S    AERO 51 S    RMY 51 TSTM
04/22   44/28/36/-13/T/T/…/..          54 W    AERO 55 W    RMY 59
04/23   58/32/45/-5/0.00/0.0/…/..      47 W    AERO 48 W    RMY 52
04/24   70/44/57/+7/0.00/0.0/…/..      33 WNW  AERO 37 WNW  RMY 55
04/25   54/44/49/-1/0.20/0.0/…/..      23 NNE  AERO 20 SSW  RMY 24
04/26   55/40/48/-3/0.00/0.0/…/..      39 NW   AERO 40 NW   RMY 43

04/27   The low since midnight is 38F, the daily normal low is 42F

*Trace of frozen on 04/21 was hail, 1/8″ diameter, this does not
count as snowfall.

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

RECORDS FOR APRIL 27
HIGH 93 IN 1990
LOW 28 IN 1919
PRECIP 1.89 IN 1979
SNOWFALL 2.7 IN. IN 1993
PEAK GUST 65e MPH N IN 1941

RECORDS FOR APRIL 28
HIGH 92 IN 1990, 2009
LOW 26 IN 1947
PRECIP 2.41 IN 1904
SNOWFALL 10.0 IN. IN 1987
PEAK GUST 69 MPH NE 1967

TODAY’S REPORT PREPARED BY: Matt Douglas