BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
SATURDAY, MAY 2, 2009 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
PARTLY SUNNY THIS AFTERNOON AFTER EARLY MORNING SHOWERS...
APRIL 2009 TIES FOR FOURTH WARMEST ON RECORD...
Rain showers early this morning brought a total of 0.05
inch of precipitation, which ended just before 8 AM EDT.
It remained cloudy through most of the morning, though
the sun has made an appearance as of early afternoon.
The corrected mean temperature for April of 48.9 ties
for the fourth warmest on record with 2005. The three
warmer Aprils include 51.0 in 1976, 49.4 in 1945, and
49.0 in 1994.
 
April 2009 Summary
Temp Max: 59.4 deg F [+3.9]
Temp Min: 39.4 deg F [+2.3]
Temp Mean: 49.4 deg F [+3.1]
Temp Mean (corrected to 24 hours): 48.9 deg F
Precipitation: 4.53 inches [+0.21]
Snowfall: 0.2 inch [-2.9]
HDD: 478 [-84]
CDD: 18 [+15]
Wind Speed (corrected): 13.8 mph
Prevailing Wind Direction: W (16%)
Vapor Pressure: 7.5 mb
Thunderstorm Days: 3 [3rd, 6th, and 29th]
 
Today's observations:
 
7 A.M.  
Weather: Overcast stratocumulus, higher clouds visible
Temperature: 53F, Dew point: 51F, Wind: W at 10 kts
Sea-level pressure: 29.83 inches Hg, rising
Visibility: 55 miles, visibility W-NW 75, E-SE 35
6-hour minimum temp: 53F
6-hour precipitation: 0.05 inch
24-hour precipitation: 0.05 inch
BHO SA 1155 E50 OVC 55 102/53/51/2610/983/ HIR CLDS VSBL
W-NNE FEW LWR SC DSNT SW-N VSBY W-NW 75 E-SE 35 RE50/ 8/57/
51020 6005/ 70005 10059 20053
 
10 A.M.  
Weather: Scattered stratocumulus, overcast altocumulus,
higher clouds visible, thin spots in overcast, sun
dimly visible
Temperature: 60F, Dew point: 44F, Wind: W at 6 kts,
Wind: Light and variable
Sea-level pressure: 29.85 inches Hg, rising
Visibility: 60 miles, visibility W-NW 75
BHO SA 1455 55 SCT 120 OVC 60 107/60/44/2806/985/ HIR CLDS
VSBL THN SPTS IOVC OVHD SUN DMLY VSBL VSBY W-NW 75 WND LGT
AND VRB/ 8/571 53005
 
1 P.M.  
Weather: Scattered stratocumulus, scattered altocumulus,
broken dense cirrus, overcast cirrus, few altocumulus
lenticularis SE-S, few lower cumulus distant NNW-NE,
sun dimly visible
Temperature: 62F, Dew point: 34F, Wind: SW at 6 kts
Wind: Light and variable
Sea-level pressure: 29.83 inches Hg, falling
Visibility: 70 miles
6-hour maximum temp: 63F 
BHO SA 1755 60 SCT 120 SCT E200 BKN 250 OVC 70 103/62/34/
2306/983/ FEW ACSL SE-S FEW LWR CU DSNT NNW-NE SUN DMLY
VSBL WND LGT AND VRB/ 8/571 56004 10063 20053
 
 
WEATHER SUMMARY FOR FRIDAY, MAY 1
 
TEMPERATURE (DEGREES F)
MAX.....64    NORMAL.....62
MIN.....53    NORMAL.....42
MEAN....59    NORMAL.....52
 
DEPARTURE FROM 30-YEAR NORMAL...........+7
TOTAL DEPARTURE FOR THE MONTH...........+7 [+6.8 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............6  DEPARTURE.......-7
TOTAL HEATING UNITS FOR THE MONTH.............6  DEPARTURE.......-7
TOTAL HEATING UNITS FOR THE SEASON.........5902  DEPARTURE.....-137
TOTAL HEATING UNITS LAST SEASON TO DATE....5628  DIFFERENCE....+274
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY............37 SSW AT  8:23 A.M. *
                   AEROVANE.............37 SSW AT  7:48 A.M.
                   ASOS.................38 SSW AT  8:23 A.M.
                   DAVIS................40 S   AT  6:32 A.M.
FASTEST MILE FOR YESTERDAY..............30 SSW AT  6:03 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...........28 SSW AT  8:20 A.M. 
MAXIMUM 2-MINUTE DAVIS AVERAGE..........30 SSW AT  6:04 A.M.
AVERAGE WIND SPEED AND DIRECTION......20.0 SSW
                   ASOS...............19.3
                   DAVIS..............19.6 SSW [193 DEG]
* Last of several occurrences.
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.05  DEPARTURE....-0.08
                         ASOS..............0.05
TOTAL PRECIPITATION FOR THE MONTH..........0.05  DEPARTURE....-0.08
                         ASOS..............0.05 
TOTAL PRECIPITATION FOR THE YEAR..........14.66  DEPARTURE....-3.42
                         ASOS.............15.73  
 
SNOWFALL (INCHES) THROUGH THIS MORNING (EST)
TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0  DEPARTURE.....-0.1
TOTAL SNOWFALL FOR THE MONTH................0.0  DEPARTURE.....-0.1
TOTAL SNOWFALL FOR THE SEASON..............78.9  DEPARTURE.....18.8
 
 
PRELIMINARY CLIMATE SUMMARY FOR APRIL 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane recording wind system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
4/1  45/31/38/-3/0.13/0/015/02       24 SE    *
4/2  52/39/46/+4/0.02/0/000/00       20 SSE       
4/3  58/45/52/+10/0.70//000/00       39 SSE   AERO 38 MPH SSE TSTM
4/4  51/38/45/+3/0.01/0/015/02       48 WSW   AERO 48 MPH WSW 
4/5  58/37/48/+5/0/0/551/71          40 W     AERO 37 MPH W
4/6  55/38/47/+4/1.42/0/047/006      42 SE    AERO 40 MPH SE  TSTM 
4/7  50/34/42/-1/T/0/109/14          36 WSW   AERO 35 MPH WSW
4/8  45/32/39/-5/0/0/149/19          33 SW    AERO 31 MPH SW
4/9  60/34/47/+3/0/0/692/88          36 SSW   AERO 33 MPH SSW
4/10 65/41/53/+9/0.18/0/544/69       37 SSW   AERO 35 MPH SSW 
4/11 44/33/39/-6/0.77/0.2/000/00     35 N     AERO 30 MPH N
4/12 43/29/36/-9/0/0/541/68          45 NW    AERO 43 MPH WNW
4/13 52/29/41/-4/0/0/734/92          38 W     AERO 35 MPH W
4/14 58/37/48/+2/0/0/696/87          25 E     
4/15 49/36/43/-3/0/0/650/81          35 NE    AERO 31 MPH NE
4/16 50/34/42/-4/0/0/806/100         29 NNE  
4/17 69/35/52/+5/0/0/695/86          37 W     AERO 33 MPH W
4/18 64/44/54/+7/0.05/0/170/21       28 W  
4/19 52/38/45/-2/0.03/0/773/95       33 NNE   AERO 28 MPH NNE
4/20 51/36/44/-4/0.10/0/196/24       43 E     AERO 39 MPH E
4/21 58/42/50/+2/0.95/0/000/00       43 E     AERO 43 MPH S
4/22 62/45/54/+5/0.16/0/296/36       28 S    
4/23 56/40/48/-1/0.01/0/668/81       43 W
4/24 70/40/55/+6/0/0/810/98          30 W
4/25 83/49/66/+16/T/0/647/78         29 S
4/26 88/56/72/+22/0/0/574/69         33 NE
4/27 72/49/61/+11/0/0/768/92         29 S
4/28 92/57/75/+24/0/0/704/84         37 SSW   AERO 36 MPH S
4/29 63/44/54/+3/T/0/823/98          35 NW    AERO 30 MPH NW TSTM
4/30 67/41/54/+2/T/0/717/85          37 S
 
* High temperature for 1 April corrected from 43 to 45
 
PRELIMINARY CLIMATE SUMMARY FOR MAY 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane recording wind system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
5/1  64/53/59/+7/T/0/.../..          37 SSW   AERO 37 MPH SSW
 
5/2 morning low temperature 53F; our normal low is now 43F
 
 
NEW DAILY RECORDS FOR APRIL 2009...
New record high maximum temperature for April 25 of 83F
surpasses 80F in 1942.
New record high maximum temperature for April 26 of 88F
surpasses 83F in 1908.
New record high minimum temperature for April 26 of 56F
surpasses 55F in 1985.
Maximum temperature of 92F for April 28 equals record
high maximum of 92F in 1990.
Minimum temperature of 57F for April 28 equals record
high minimum of 57F in 1935. 
 
NEW DAILY RECORDS FOR MAY 2009...
NONE
 
DAILY EXTREMES
 
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR MAY 2
HIGH 92F IN 2001
LOW 29F IN 1903
PRECIP 1.36 INCHES IN 2006
SNOWFALL 1.0 INS IN 1888
PEAK GUST 58 MPH S IN 1983
 
RECORDS FOR MAY 3
HIGH 92F IN 2001
LOW 31F IN 1888
PRECIP 2.25 INS IN 1900
SNOWFALL TRACE IN 1908, 1985
PEAK GUST 71 MPH W IN 2002
 
TODAY'S REPORT PREPARED BY: Mike Iacono