BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, SEPTEMBER 30, 2009 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
MOSTLY CLOUDY DAY WITH COOLER AIR ARRIVING
ON WEST WINDS GUSTING 20 TO 25 MPH
SEPTEMBER--SLIGHTLY COOL, AN INCH DRIER
AND ALSO SUNNIER THAN AVERAGE
 
Clouds have prevailed along with cooler
temperatures for this last day of September.  
The early afternoon high has made it only to 
60F as the dew points drop into the lower 40's 
and as a cooler and drier air mass arrives. 
September has been only very slightly cooler 
than normal but about one inch drier than average.  
The sunshine has been 64% of possible through 29 
days or well above the long-term average of 56%. 
 
Today's observations:
 
7 A.M.  
Weather: Overcast stratocumulus, lower stratocumulus with few
moderate cumuloform tops distant SE-SSE, lower stratocumulus
distant W-NW, break in overcast (clear sky band) distant
northeast thru southeast, breaks in overcast distant west thru
northwest       
Temperature: 52F, Dew point: 48F, Wind: WSW at 9 kts
Sea-level pressure: 29.71 inches Hg, rising
Visibility: 75 miles, mountain in cloud 70 miles NW 
6-hour minimum temp: 50F
24-hour precipitation: 0.00 inch
BHO SA 1155 E55 BKN 65 OVC 75 061/52/48/2409/971/
LINE LWR SC FEW MDT TOPS DSNT SE-SSE AND
LWR SC DSNT W-NW ALG HRZN BINOVC ALG HRZN DSNT W-N
AND BINOVC/CLR SKY BND DSNT NE-SSE MTN INCLD 70 NW
THN K LYR ALG HRZN N-E-SE/ 8/5// 51018 10053 20050
 
10 A.M.
Weather: Overcast stratocumulus, cumulus, lower stratocumulus
to the distant SE-SW-NW, virga distant NNE-E, patches of
higher cloud dense cirrus south thru west, mountain 70 NW
in cloud   
Temperature: 54F, Dew point: 46F, Wind: W at 9 kts.
Wind: direction gradually veering
Wind: Direction variable from WSW to WNW
Sea-level pressure: 29.74 inches Hg, rising
Visibility: 70 miles, mountain in cloud 70 NW
BHO SA 1455 E50 BKN 60 OVC 70 071/54/46/2709/974/
CU/LWR SC DSNT SE-SW-NW VIRGA DSNT NNE-E PTCHS
HIER CLD DENS CI DSNT S-W SML BINOVC DSNT SW-W MTN
INCLD 70 NW WND GRDL VEERING WND 24V30/ 8/802 51010
 
1 P.M. 
Weather: Overcast stratocumulus with few lower cumulus,
and breaks in overcast, higher altocumulus and cirrus
are visible  
Temperature: 56F, Dew point: 43F, Wind: W at 14 kts,
Wind: Direction variable SSW-WNW
Sea-level pressure: 29.73 inches Hg, falling
Visibility: 75 miles
6-hour max. temp: 60F
BHO SA 1755 E35 BKN 40 OVC 75 067/56/43/2614/973/
FEW LWR CU BINOVC HIER CLD VSB WND 20V30/ 8/831 58004 
10060 20052
 
WEATHER SUMMARY FOR TUESDAY, SEPTEMBER 29
 
TEMPERATURE (DEGREES F)
MAX.....67    NORMAL.....66
MIN.....54    NORMAL.....49
MEAN....61    NORMAL.....58
 
DEPARTURE FROM 30-YEAR AVERAGE...........+3
TOTAL DEPARTURE FOR THE MONTH............-8 [-0.5 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............4  DEPARTURE.......-4
TOTAL HEATING UNITS FOR THE MONTH...........109  DEPARTURE......-21
TOTAL HEATING UNITS FOR THE SEASON..........143  DEPARTURE......-18
TOTAL HEATING UNITS LAST SEASON TO DATE.....112  DIFFERENCE.....+31
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............35 S   AT  1:44 P.M. * 
                   AEROVANE..............35 S   AT  1:44 P.M.  
                   ASOS..................37 S   AT  1:44 P.M.   
                   DAVIS.................35 SSW AT 12:35 P.M.   
FASTEST MILE FOR YESTERDAY...............28 SSW AT 12:35 P.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE............26 S   AT 12:48 P.M.     
MAXIMUM 2-MINUTE DAVIS AVERAGE...........28 SSW AT 12:48 P.M.      
AVERAGE WIND SPEED AND DIRECTION.......14.9 SSW 
                   ASOS................14.1
                   DAVIS...............14.5 SSW [210 DEG]
 
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00   DEPARTURE....-0.14
                         ASOS..............0.00
TOTAL PRECIPITATION FOR MONTH..............3.11   DEPARTURE....-0.88
                         ASOS..............3.14
TOTAL PRECIPITATION FOR THE YEAR..........37.88   DEPARTURE....+0.42
                         ASOS.............39.06
 
PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane wind recording system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
9/1  71/51/61/-6/0/773/98     17 NW
9/2  76/54/65/-1/0/786/100    22 S
9/3  77/56/67/+1/0/587/75     19 SW
9/4  77/60/69/+3/0/764/98     18 NE
9/5  81/59/70/+5/0/591/76     25 NNW
9/6  64/53/59/-6/0/743/96     31 NNE
9/7  70/52/61/-4/0/709/92     20 WSW
9/8  75/56/66/+1/0/369/48     18 WSW  
9/9  68/55/62/-2/0/352/46     36 NNE  AERO 33 MPH NNE
9/10 65/53/59/-5/0/603/79     31 ENE
9/11 61/54/58/-6/0.49/000/00  30 NE
9/12 63/60/62/-1/1.74/000/00  30 NNE  TSTM 
9/13 76/58/67/+4/0.06/393/52  28 NW 
9/14 74/55/65/+2/0/699/93     22 WSW
9/15 75/56/66/+4/0/682/91     22 WNW
9/16 61/53/57/-5/T/060/08     31 NNE  AERO 29 MPH NNE
9/17 60/49/55/-7/0/022/03     27 N   
9/18 71/47/59/-2/T/571/77     35 WSW  AERO 30 MPH WSW
9/19 65/45/55/-6/0/716/97     30 NW   AERO 28 MPH WNW
9/20 71/45/58/-3/0/721/98     22 SW  
9/21 76/50/63/+3/0/703/96     20 S
9/22 74/55/65/+5/0/124/17     27 SSW
9/23 78/61/70/+10/0/145/20    35 SSW
9/24 77/57/67/+8/0/348/48     25 SW
9/25 63/50/57/-2/0/671/93     33 NW
9/26 62/43/53/-6/0/689/96     24 S
9/27 65/49/57/-1/0.32/000/00  32 SE   AERO 31 MPH SE
9/28 73/55/64/+6/0.38/619/87  43 W    AERO 39 MPH W; DAVIS 45 MPH WSW TSTM 
9/29 67/54/61/+3/0.12/533/75  35 S    AERO 35 MPH S
 
9/30 our morning low temp: 50F; the normal low is now 48F
 
NEW DAILY RECORDS FOR SEPTEMBER 2009 TO DATE...
None.
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR SEPTEMBER 30
HIGH 84F IN 1986
LOW 31F IN 1992
PRECIP 1.93 INCHES IN 1946
PEAK GUST 58 MPH SSE IN 1999
 
RECORDS FOR OCTOBER 1
HIGH 85F IN 1927
LOW 30F IN 1992
PRECIP 1.44 INCHES IN 1984
PEAK GUST 68e MPH SSE IN 1977
 
TODAY'S REPORT PREPARED BY: Robert Skilling