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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, APRIL 19, 2018  
ALL TIMES ARE IN EASTERN STANDARD TIME

DAY CONSISTS OF LIGHT WINDS, BELOW SEASONABLE 
TEMPERATURES, AND AN ON AND OFF MIX OF WINTERY 
PRECIPITATION... 

The day began with a wintery mix of precipitation.
We observed light rain, light snow and sleet 
ending around 10:30 A.M. this morning EST. Light
rain began during the 1:00 P.M. observation and 
has continued on and off throughout the afternoon.
So far we have measured a trace of frozen 
precipitation and 0.19 ins of liquid precipitation. 
Temperature remain below seasonable with a chilly
high so far of 39F today. This is 18 degrees below
the daily normal of 57F. We reached our daily low
so far of 34F between 7 and 8 this morning. This
is 5 degrees below the daily normal of 39F. So
far April is running about 4.4 degrees below 
average for temperature.
Visibility was limited in the morning due to fog 
and light falling snow/ice. The skies opened in the 
afternoon after the snow showers passed and we could 
see 60 miles by 1:00 P.M.  

Today's Observations:

7 A.M.
Weather: Light snow and ice pellets, overcast nimbostratus  
Temperature: 35F; Dew Point: 32F; Wind: WSW at 4 kts,
Wind: Light
Sea-level pressure: 29.74 ins. Hg, falling, then more slowly     
Visibility: 15 miles, except NE-SSE 20 miles and NNW-NE and 
SSE-SSW 5 miles, distant fog in all directions 
6-hr Max temp: 38F
6-hr Min temp: 35F
24-hr precip: 0.08 ins. 
24-hr snowfall: Trace  
Snow depth: Trace
BHO SA 1155 E30 OVC 15S-IP 072/35/32/2404/974/ NEW SNW PST 24 
HRS TRACE VSBY NE-SSE 20 NNW-NE AND SSE-SSW 5 DSNT FG ALQDS 
WND LGT/ 8/6// 56005 MANUAL 70008 ASOS 70007 10038 20035

10 A.M.
Weather: Light rain, ice pellets, and fog, overcast nimbostratus 
Temperature: 35F; Dew Point: 34F; Wind: NW at 6 kts,
Wind: Light
Sea-level pressure: 29.72 ins. Hg, falling then rising 
Visibility: 3/4 mile, except NE-SSE 3 miles. 
3-hr precip: 0.11 ins. 
3-hr snowfall: Trace 
BHO SA 1455 E11 OVC 3/4L-IPF 065/35/34/3106/972/ NEW SNW PST 3 
HRS TRACE VSBY NE-SSE 3 WND LGT/ 8/6// MANUAL 6011// 
ASOS 60014 55007 

1 P.M.
Weather: Very light drizzle, broken stratus fractus, 
overcast stratus  
Temperature: 39F; Dew Point: 35F; Wind: WNW at 4 kts,
Wind: Light
Sea-level pressure: 29.68 ins. Hg, falling then rising
Visibility: 60 miles, distant fog in all directions  
6-hr Max temp: 39F
6-hr Min temp: 34F
6-hr precip: 0.11 ins. 
6-hr snowfall: Trace  
Snow depth: Trace
BHO SA 1755 E11 BKN E60 OVC 60L- 051/39/35/3004/968/ NEW 
SNW PST 6 HRS TRACE PCPN VRY LGT L-B55 DSNT FG ALQDS WND 
LGT/ 8/6// MANUAL 6011// ASOS 60014 55014 10039 20034       

SUMMARY FOR WEDNESDAY, APRIL 18, 2018

TEMPERATURE (DEGREES F)
MAX.....53   NORMAL.....57
MIN.....32   NORMAL.....39
MEAN....43   NORMAL.....48

DEPARTURE FROM 30-YEAR NORMAL...........................-5
TOTAL DEPARTURE FOR THE MONTH..........................-76 [-4.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY.............22   DEPARTURE..........+5
TOTAL HEATING UNITS FOR THE MONTH............447   DEPARTURE.........+75
TOTAL HEATING UNITS FOR THE SEASON..........5505   DEPARTURE........-350
TOTAL HEATING UNITS LAST SEASON TO DATE.....5180   DIFFERENCE.......+325

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY...................35 W AT  2:16 P.M.  
                   AERO........................31 W AT  2:17 P.M.
                   ASOS........................34 W AT  2:17 P.M.
                   DAVIS.......................36 W AT 10:28 A.M ** RMY 37
FASTEST MILE FOR YESTERDAY.....................25 W AT  2:15 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................25 W AT  2:41 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE.................25 M AT  2:41 P.M.**
AVERAGE WIND SPEED AND DIRECTION.............14.9 W
                   ASOS......................14.4
                   DAVIS.....................13.5 M**
** Davis direction malfunctioning 

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.08  DEPARTURE......-0.06
                         ASOS..............0.07
TOTAL PRECIPITATION FOR THE MONTH..........4.18  DEPARTURE......+1.24
                         ASOS..............4.31  
TOTAL PRECIPITATION FOR THE YEAR..........22.98  DEPARTURE......+6.22
                         ASOS.............24.55

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........+0.1
TOTAL SNOWFALL FOR THE SEASON..............92.8  DEPARTURE.......+30.5

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
*   : Estimated data 

4/01 58/33/46/+5/0.00/0.0/336/44   45 SSW AERO 43 SSW RMY N/A  
4/02 38/30/34/-7/0.13/1.6/077/10   20 SSW AERO 15 SSW RMY 17
4/03 48/30/39/-3/..../0.0/238/31   28 SSE AERO 25 SSE RMY 25
4/04 54/36/45/+3/..../0.0/000/00   56 WNW AERO 56 WNW RMY 54
4/05 40/27/34/-9/0.00/0.0/760/98   53 WNW AERO 53 WNW RMY 52 
4/06 41/25/33/-10/0.25/1.0/156/20  37 S   AERO 36 S   RMY 38
4/07 46/32/35/-4/0.00/0.0/312/40   32 WNW AERO 35 WNW RMY 34
4/08 41/29/35/-9/0.00/0.0/290/37   35 WNW*AERO 31 WNW RMY 34
4/09 45/24/35/-9/0.00/0.0/715/01   28 WNW*AERO 25 WNW RMY 29
4/10 39/31/35/-10/T/T/000/00       14 SSW AERO 13 SSW RMY N/A
4/11 48/29/39/-6/T/0.0/364/46      24 SSE AERO 23 SSE RMY 25 
4/12 61/33/47/+2/..../0.0/.../..   39 SSW AERO 38 SSW RMY 41 
4/13 65/47/56/+10/T/0.0/.../..     37 SSW AERO 37 SSW RMY N/A
4/14 51/36/44/-2/0.00/0.0/.../..   33 ENE AERO 31 ENE RMY N/A
4/15 36/30/33/-14/..../T/.../..    39 ENE AERO 39 ENE RMY N/A
4/16 55/32/44/-3/..../.../..       41 ENE AERO 43 ENE RMY 41
4/17 48/36/42/-5/0.00/0.0/.../..   37 W   AERO 33 W   RMY 37
4/18 53/32/43/-5/..../0.0/.../..   35 W   AERO 31 W   RMY 34

4/19 Low temp since midnight is 35F; normal low is now 39F

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

RECORDS FOR APRIL 19
HIGH 94 IN 1976 [RECORD FOR MONTH]
LOW 21 IN 1890
PRECIP 1.71 IN 1969
SNOWFALL 6.0 IN. IN 1887
PEAK GUST 66 MPH E IN 1984

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

TODAY'S REPORT PREPARED BY: K.Geagan