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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, APRIL 20, 2018  
ALL TIMES ARE IN EASTERN STANDARD TIME

DRY AIR AND SUN RETURN AFTER AN OVERALL 
RAINY WEEK ON TOP OF GREAT BLUE HILL....

Today we observed partly sunny skies with scattered
clouds at each observation. We also observed wind 
speed pick up overnight and we had moderate wind 
today from the WNW/NW. We have had frequent gust 
today over 24 kts (28 MPH) and a peak gust so far 
of 30 kts (35 MPH). Temperatures quickly rose today 
but are still below seasonable. Since midnight we 
observed an overnight low of 31F, which is 9 degrees 
below the daily normal of 40F. Yesterday remained 
well below seasonable with a high of 41F, 16 degrees 
below the daily normal of 57F. Although still below 
seasonable we reached a max today of 51F, this is 
still 7 degrees below the daily normal of 58F. 
Visibility increased as humidity lowered today and 
we could see an excellent 80 miles by 1:00 P.M. 
Overall we measured 0.22 ins. of liquid precipitation 
and a trace of frozen precip. during yesterday's
wintry showers.

Today's Observations:

7 A.M.
Weather: Scattered cumulus, scattered altocumulus 
Temperature: 35F; Dew Point: 25F; Wind: WNW at 17G28 kts,
Peak wind: 28 kts (32 MPH) at 6:51 A.M.
Sea-level pressure: 29.94 ins. Hg, rising, then more slowly     
Visibility: 70 miles
6-hr Max temp: 35F
6-hr Min temp: 31F
24-hr precip: 0.14 ins. 
24-hr snowfall: Trace  
Snow depth: 0 ins. 
BHO SA 1155 25 SCT 85 SCT 70 140/35/25/3017G28/994/ 
NEW SNW PST 24 HRS TRACE PK WND 3028/51/ 8/130 51023 
MANUAL 70014 ASOS 70017 10035 20031

10 A.M.
Weather: Scattered cumulus, scattered altocumulus, scattered cirrus
Temperature: 45F; Dew Point: 24F; Wind: NW at 18G29 kts,
Peak wind: 30 kts (35 MPH) at 9:19 A.M.
Sea-level pressure: 30.00 ins. Hg, rising then, more slowly 
Visibility: 75 miles
3-hr precip: 0.00 ins. 
3-hr snowfall: 0.0 ins. 
BHO SA 1455 45 SCT 70 SCT 250 SCT 75 158/45/24/3118G29/000/ 
PK WND 3130/19/ 8/131 51018 

1 P.M.
Weather: Scattered cumulus, scattered cirrostratus
Temperature: 50F; Dew Point: 26F; Wind: NW at 18G27 kts,
Peak wind: 30 kts (35 MPH) at 12:38 P.M.
Sea-level pressure: 30.03 ins. Hg, rising, then more rapidly 
Visibility: 80 miles 
6-hr Max temp: 51F
6-hr Min temp: 35F
6-hr precip: 0.00 ins. 
6-hr snowfall: 0.00 ins.   
Snow depth: 0 ins.
BHO SA 1755 50 SCT 250 SCT 80 169/50/26/3218G27/003/ 
PK WND 3230/38/ 8/100 53011 10051 20035       

SUMMARY FOR THURSDAY, APRIL 19, 2018

TEMPERATURE (DEGREES F)
MAX.....41   NORMAL.....57
MIN.....34   NORMAL.....39
MEAN....38   NORMAL.....48

DEPARTURE FROM 30-YEAR NORMAL..........................-10
TOTAL DEPARTURE FOR THE MONTH..........................-86 [-4.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY.............27   DEPARTURE.........+10
TOTAL HEATING UNITS FOR THE MONTH............474   DEPARTURE.........+85
TOTAL HEATING UNITS FOR THE SEASON..........5532   DEPARTURE........-340
TOTAL HEATING UNITS LAST SEASON TO DATE.....5201   DIFFERENCE.......+331

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.....................17 WNW AT 11:53 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE..................17 WNW AT 11:55 P.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE.................17 M   AT 11:06 P.M.**
AVERAGE WIND SPEED AND DIRECTION..............7.7 WNW
                   ASOS.......................7.8
                   DAVIS......................7.4 M**
** Davis direction malfunctioning 

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.14  DEPARTURE......+0.01
                         ASOS..............0.17
TOTAL PRECIPITATION FOR THE MONTH..........4.32  DEPARTURE......+1.25
                         ASOS..............4.48  
TOTAL PRECIPITATION FOR THE YEAR..........23.12  DEPARTURE......+6.23
                         ASOS.............24.72

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........+0.0
TOTAL SNOWFALL FOR THE SEASON..............92.8  DEPARTURE.......+30.4

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
*   : 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/+2/0.03/0.0/.../..   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 41/34/38/-10/0.22/T/.../..    28 WNW AERO 25 WNW RMY N/A 

4/20 Low temp since midnight is 31F; normal low is now 40F

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: K.Geagan