Wednesday, April 11, 2018

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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, APRIL 11, 2018
ALL TIMES ARE IN EASTERN STANDARD TIME

AN INCREASING CLOUD DAY BEGINS WITH COMPLETE
UNDERCAST CONDITIONS…

We observed complete undercast fog conditions limiting
visibility to 3/4 of a mile. Above the fog the sky was
clear without any clouds. The fog dissipated midday
and visibility increased to 70 miles by 10:00 A.M.
With the visibility increase we also observed a dramatic
drop in relative humidity from 97% at 7:00 A.M. down to
54% by 1:00 P.M.
Temperatures continue to be below seasonable today with
an overnight low of 29F, which is 7 degrees below the
daily normal of 36F. Yesterday max of 39F was 14 degrees
below the daily normal of 53F. Temperatures although
still below seasonable have increased today with a high
of 48F by 1:00 P.M., which is 6 degrees below the daily
normal of 54F. Wind continued to be light and variable
today, slightly picking up in the afternoon.
We observed an increase in cloud cover from clear skies
at 7:00 A.M. to broken skies by 1:00 P.M. This was due
to a midday drop in pressure.

Today’s Observations:

7 A.M.
Weather: Sky clear, complete undercast fog conditions
present in all directions
Temperature: 32F; Dew Point: 31F; Wind: Calm
Sea-level pressure: 30.19 ins. Hg, rising, then more slowly
Visibility: 3/4 mile
6-hr Max temp: 32F
6-hr Min temp: 29F
24-hr precip: Trace
24-hr snowfall: Trace
Snow depth: 0 ins.
BHO SA 1155 CLR 3/4F 224/32/31/0000/019/ SKC NEW SNW
PST 24 HRS TRACE COMPLETE UNDERCAST CDN BLO SMT ALQDS
WND CALM/ 51006 10032 20029

10 A.M.
Weather: Scattered cumulus
Temperature: 41F; Dew Point: 28F; Wind: WSW at 3 kts,
Wind: Light and variable, direction estimated
Sea-level pressure: 30.18 ins. Hg, rising then falling
Visibility: 70 miles
3-hr precip: 0.00 ins.
3-hr snowfall: 0.0 ins.
BHO SA 1455 15 SCT 70 220/41/28/E2403/018/ WND L/V/
8/100 50004

1 P.M.
Weather: Broken stratocumulus
Temperature: 43F; Dew Point: 28F; Wind: SE at 6 kts,
Wind: Light
Sea-level pressure: 30.10 ins. Hg, falling, then more slowly
Visibility: 70 miles
6-hr Max temp: 48F
6-hr Min temp: 32F
6-hr precip: 0.00 ins.
6-hr snowfall: 0.0 ins.
Snow depth: 0 ins.
BHO SA 1755 E60 BKN 70 193/43/28/1406/010/ WND LGT/
8/400 56027 10048 20032

SUMMARY FOR TUESDAY, APRIL 10, 2018

TEMPERATURE (DEGREES F)
MAX…..45   NORMAL…..53
MIN…..24   NORMAL…..36
MEAN….35   NORMAL…..45

DEPARTURE FROM 30-YEAR NORMAL……………………..-10
TOTAL DEPARTURE FOR THE MONTH……………………..-53 [-5.5 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY………….30   DEPARTURE………+10
TOTAL HEATING UNITS FOR THE MONTH…………275   DEPARTURE………+53
TOTAL HEATING UNITS FOR THE SEASON……….5333   DEPARTURE……..-373
TOTAL HEATING UNITS LAST SEASON TO DATE…..5108   DIFFERENCE…….+225

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….14 SSW AT 8:07 A.M.
AERO……………………13 SSW AT 8:08 A.M.
ASOS……………………14 SW  AT 8:07 A.M.
DAVIS…………………..12 M   AT 8:06 A.M ** RMY N/A
FASTEST MILE FOR YESTERDAY………………….8 SSW AT 8:27 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………10 S   AT 8:36 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………9 M   AT 8:08 A.M.**
AVERAGE WIND SPEED AND DIRECTION…………..3.0 SSE
ASOS…………………..2.8
DAVIS………………….2.8 M**
** Davis direction malfunctioning

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.00  DEPARTURE……-0.18
ASOS…………..0.00
TOTAL PRECIPITATION FOR THE MONTH……….1.13  DEPARTURE……-0.57
ASOS…………..0.97
TOTAL PRECIPITATION FOR THE YEAR……….19.93  DEPARTURE……+4.41
ASOS………….21.06

SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M……….0.0  DEPARTURE……..-0.1
TOTAL SNOWFALL FOR THE MONTH…………….2.6  DEPARTURE……..+1.0
TOTAL SNOWFALL FOR THE SEASON…………..92.8  DEPARTURE…….+31.4

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

4/01 58/33/46/+5/…./0.0/…/..   45 SSW AERO 43 SSW RMY N/A
4/02 38/30/34/-7/…./1.6/…/..   20 SSW AERO 15 SSW RMY 17
4/03 48/30/39/-3/…./0.0/…/..   28 SSE AERO 25 SSE RMY 25
4/04 54/36/45/+3/…./0.0/…/..   56 WNW AERO 56 WNW RMY 54
4/05 40/27/34/-9/0.00/0.0/…/..   53 WNW AERO 53 WNW RMY 52
4/06 41/25/33/-10/0.25/1.0/…/..  37 S   AERO 36 S   RMY 38
4/07 46/32/35/-4/0.00/0.0/…/..   32 WNW AERO 35 WNW RMY 34
4/08 41/29/35/-9/0.00/0.0/…/..   35 WNW*AERO 31 WNW RMY 34
4/09 45/24/35/-9/0.00/0.0/…/..   28 WNW*AERO 25 WNW RMY 29
4/10 39/31/35/-10/T/T/…/..       14 SSW AERO 13 SSW RMY N/A

4/11 Low temp since midnight is 29F; normal low is now 36F

*Estimated

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

RECORDS FOR APRIL 11
HIGH 85 IN 2017
LOW 19 IN 1909
PRECIP 1.72 IN. IN 2003
SNOWFALL 9.5 IN. IN 1958
PEAK GUST 65 MPH NW IN 1963

RECORDS FOR APRIL 12
HIGH 82 IN 1945
LOW 17 IN 1926
PRECIP 1.51 IN. IN 1993
SNOWFALL 12.0 IN. IN 1894
PEAK GUST 65e MPH W IN 1978

TODAY’S REPORT PREPARED BY: K.A. Geagan