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

DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, APRIL 21, 2015    
ALL TIMES ARE IN EASTERN STANDARD TIME

THUNDERSTORMS ROLL THROUGH EARLY THIS MORNING, 1.41
INCHES OF NEW RAINFALL OVER 24-HR SPAN

Yesterday's strong easterly winds kept temperatures
largely in the 40s until heavier rain swept through
between 5:00-7:00 PM EST. Rain likely totaled around 
1 inch yesterday, with an additional 0.40 inches falling
during a thunderstorm early this morning. 

Thick fog at this morning's 7:00 AM EST observation
kept visibility down to just 1/16 of a mile and approximately
200 feet of vertical visibility. Fog cleared out by the
10:00 AM EST observation, with dew points still high
in the 50s.

By the 1:00 PM EST observation visibility had improved to
70 miles in all directions, with clouds lifting and somewhat
dissipating. Dew points remained above 50F, keeping a humid
feel to the air. The maximum reading by this time was 67F.


Today's Observations:

7 A.M.
Weather: Thick fog   
Temperature: 56F; Dew Point: 56F; Wind: S at 12 kts,
Sea-level pressure: 29.55 ins. Hg, decreasing, then more slowly
Visibility: 1/16 of a mile, obscured by thick fog
6-hr Max temp: 56F
6-hr Min temp: 54F
24-hr precip: 1.41 inches
BHO SA 1155 W2 X 1/16F 007/56/56/1812/955/ 8//// 56013 
ASOS 60042 70148 MANUAL 600// 70141 10056 20054

10 A.M. 
Weather: Scattered stratocumulus, broken altocumulus,
broken cirrus
Temperature: 62F; Dew Point: 57F; Wind: SW at 13 kts, 
Sea-level pressure: 29.57 ins. Hg, increasing, then more quickly 
Visibility: 20 miles, thin fog
3-hr precip: trace
BHO SA 1455 12 SCT E90 BKN 250 BKN 20 014/62/57/2213/957/ 
THN FG ALQDS/ 8/431 53007 MANUAL 6000/
  
1 P.M.
Weather: Scattered stratocumulus, few cumulus in all directions    
Temperature: 62F; Dew Point: 52F; Wind: W at 16G22 kts,
Sea-level pressure: 29.59 ins. Hg, increasing, then more quickly
Visibility: 70 miles
6-hr Max temp: 67F
6-hr Min temp: 56F
6-hr precip: trace 
BHO SA 1755 42 BKN 70 019/62/52/2716G22/959/ FEW CU ALQDS/ 
8/800 53005 MANUAL 6000/ 10067 20056


SUMMARY FOR MONDAY, APRIL 20, 2015 PATRIOT'S DAY
  
TEMPERATURE (DEGREES F)
MAX.....55   NORMAL.....58
MIN.....38   NORMAL.....40
MEAN....47   NORMAL.....49

DEPARTURE FROM 30-YEAR NORMAL.......................-2
TOTAL DEPARTURE FOR THE MONTH......................+35 [+1.6 DEGREES/DAY] 
 
HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............18  DEPARTURE...........+1
TOTAL HEATING UNITS FOR THE MONTH.............369  DEPARTURE..........-36     
TOTAL HEATING UNITS FOR THE SEASON...........6112  DEPARTURE.........+223
TOTAL HEATING UNITS LAST SEASON TO DATE......5989  DIFFERENCE........+123

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY..................36 SE    AT   9:47 P.M.*      
                   ASOS.......................38 SE    AT   8:13 P.M.      
                   DAVIS......................39 SE    AT   8:03 P.M. RMY 40 
FASTEST MILE FOR YESTERDAY....................28 SE    AT   9:47 P.M.     
MAXIMUM 2-MINUTE ASOS AVERAGE.................28 SE    AT   9:47 P.M.        
MAXIMUM 2-MINUTE DAVIS AVERAGE................28 SE    AT   9:47 P.M.      
AVERAGE WIND SPEED AND DIRECTION.............17.1 ESE
                   ASOS......................15.6     
                   DAVIS.....................14.8 ESE [118 degrees] 
* Last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.....1.41  DEPARTURE.....+1.27
                         ASOS...............1.48
TOTAL PRECIPITATION FOR THE MONTH...........3.05  DEPARTURE.....-0.16  
                         ASOS...............3.02 
TOTAL PRECIPITATION FOR THE YEAR...........17.64  DEPARTURE.....+0.56
                         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.....-2.7  
TOTAL SNOWFALL FOR THE SEASON..............150.8  DEPARTURE....+88.4 


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 55/38/47/-2/..../0.0/000/00              36 SE  RMY 40

4/21 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 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

RECORDS FOR APRIL 22
HIGH 85 IN 1977, 2001
LOW 26 IN 1981
PRECIP 1.85 IN. IN 2000
SNOWFALL 3.0 IN. IN 1940
PEAK GUST 68e MPH NW IN 1945

TODAY'S REPORT PREPARED BY:  Brian Fitzgerald