Monday, April 20, 2015

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

DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, APRIL 20, 2015 PATRIOT’S DAY
ALL TIMES ARE IN EASTERN STANDARD TIME

EASTERLY WINDS HOLD TEMPS IN THE 40S AS RAIN
MOVES INTO THE REGION

After a cool and comfortable Sunday, temperatures dipped
overnight to a low of 38F on the summit of Great Blue Hill.
By the 7:00 AM EST observation an approaching band of rain
was seen, along with virga from SSW to WNW nearly over
the Hopkinton area at the start of this morning’s Boston Marathon.

A brief shower moved through after the 7:00 AM EST observation,
as winds began to increase from the east. At the 10:00 AM EST
observation 0.01 inches of new rain had been measured, although
no rain was falling at the time of the observation. Showers became
visible once again in the distance not long after, with heavy
rain expected for the second half of the day. Temperatures had
only reached 43F by 10:00 AM EST.
Today’s Observations:

7 A.M.
Weather: Broken cumulus/stratus fractus, broken stratus,
overcast altostratus, showers distant SSW-WNW, virga SW
Temperature: 40F; Dew Point: 39F; Wind: E at 11 kts,
Sea-level pressure: 30.18 ins. Hg, increasing, then decreasing
Visibility: 30 miles, except 25 miles SSW-WNW, obscured by showers
6-hr Max temp: 40F
6-hr Min temp: 38F
BHO SA 1155 E3 BKN 30 BKN 140 OVC 30 219/40/39/0811/018/
VSBY SSW-WNW 25 MI SHWRS DSNT SSW-WNW VIRGA DSNT SW/ 8/62/
58004 10040 20038

10 A.M.
Weather: Overcast altostratus, few cumulus fractus in all direction,
few stratocumulus lenticularis in all directions
Temperature: 43F; Dew Point: 39F; Wind: E at 15G24 kts,
Sea-level pressure: 30.11 ins. Hg, decreasing, then more quickly
Visibility: 30 miles, except 25 miles WSW-WNW
3-hr precip: 0.01 inches
BHO SA 1455 E40 OVC 30 196/43/39/1015G24/011/
VSBY WSW-WNW 25 MI FEW CUFRA ALQDS FEW SCSL ALQDS/
8/72/ 58023 ASOS 60001 MANUAL 60001

SUMMARY FOR SUNDAY, APRIL 19, 2015

TEMPERATURE (DEGREES F)
MAX…..55   NORMAL…..57
MIN…..39   NORMAL…..39
MEAN….47   NORMAL…..48

DEPARTURE FROM 30-YEAR NORMAL…………………..-1
TOTAL DEPARTURE FOR THE MONTH………………….+37 [+1.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………..18  DEPARTURE………..+1
TOTAL HEATING UNITS FOR THE MONTH………….351  DEPARTURE……….-38
TOTAL HEATING UNITS FOR THE SEASON………..6094  DEPARTURE………+222
TOTAL HEATING UNITS LAST SEASON TO DATE……5968  DIFFERENCE……..+126

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………25 NNW   AT   2:24 A.M.
ASOS…………………..28 N     AT   2:25 A.M.
DAVIS………………….24 NNW   AT   2:25 A.M. RMY N/A
FASTEST MILE FOR YESTERDAY………………..18 NNW   AT   2:29 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………..17 NNW   AT   2:29 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….16 NNW   AT   2:26 A.M.
AVERAGE WIND SPEED AND DIRECTION………….9.6 NNW
ASOS………………….9.6
DAVIS…………………8.4 ENE [065 degrees] * Last of several occurrences…

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………..1.64  DEPARTURE…..-1.43
ASOS……………1.54
TOTAL PRECIPITATION FOR THE YEAR………..16.23  DEPARTURE…..-0.71
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…..-0.1
TOTAL SNOWFALL FOR THE MONTH……………TRACE  DEPARTURE…..-2.6
TOTAL SNOWFALL FOR THE SEASON…………..150.8  DEPARTURE….+88.5
PRELIMINARY CLIMATE SUMMARY FOR APRIL 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

4/1  44/26/35/-6/0.00/0.0/748/98              30 WNW RMY 31
4/2  59/29/44/+3/T/0.0/375/49                 39 SSW RMY 43
4/3  56/47/52/+10/0.02/0.0/000/00             36 SW  RMY N/A
4/4  49/32/41/-1/…./0.0/501/65              54 NW  RMY 64
4/5  47/30/39/-4/…./0.0/464/60              40 W   RMY 45
4/6  48/33/41/-2/0/00/0.0/544/70              18 NE  RMY N/A
4/7  39/34/37/-6/…./0.0/000/00              21 NE  RMY N/A
4/8  41/32/37/-7/…./T/000/00                30 ENE RMY 32
4/9  35/32/34/-10/…./0.0/000/00             31 ENE RMY 32
4/10 53/35/44/-1/…./0.0/000/00              31 SW  RMY N/A
4/11 56/38/46/+1/0.00/0.0/744/94              39 WNW RMY 48
4/12 68/35/52/+7/0.00/0.0/762/96              23 WNW RMY 23
4/13 69/47/58/+12/0.00/0.0/764/96             35 SSW RMY N/A
4/14 65/51/58/+12/0.05/0.0/072/09             37 SSW RMY N/A
4/15 67/45/56/+9/0.00/0.0/…/..              32 NW  RMY 33
4/16 64/42/53/+6/0.00/0.0/…/..              31 S   RMY 21
4/17 64/45/55/+8/0.05/0.0/…/..              31 SSW RMY 32
4/18 64/43/54/+6/0.00/0.0/…/..              31 N   RMY 36
4/19 55/39/47/-1/0.00/0.0/…/..              25 NNW RMY N/A

4/20 low since midnight is 38F normal low is 40F

DAILY RECORDS FOR APRIL 2015

4/3 – NEW RECORD DAILY HIGH MINIMUM TEMPERATURE: 47F
surpasses the previous record of 46F in 1892

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

RECORDS FOR APRIL 20
HIGH 88 IN 1927
LOW 18 IN 1897
PRECIP 1.14 IN 1972
SNOWFALL 2.5 IN. IN 1904, 1972
PEAK GUST 76 MPH WNW IN 1963

RECORDS FOR APRIL 21
HIGH 85 IN 1923
LOW 22 IN 1908
PRECIP 3.18 IN. IN 1991
SNOWFALL 0.8 IN. IN 1947
PEAK GUST 76e MPH NE IN 1940

TODAY’S REPORT PREPARED BY:  Brian Fitzgerald