BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, SEPTEMBER 21, 2009 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
WARMING TREND FOLLOWS VERY SUNNY COOL WEEKEND
TODAY WILL MAKE THIRD VERY SUNNY DAY IN A ROW
SEPTEMBER'S COOL TEMPERATURES HAVE
BEEN PART OF A DRY WEATHER PATTERN
 
Temperatures have begun to recover today into
the mid-70's ending a 5-day cool spell with high
readings between 60 and 71F and with the daily
means averaging 5 degree cooler than normal.
Low temperatures of 45F both Saturday and Sunday
morning were the lowest since 41F on 1 June.  
Strong radiational cooling allowed temperatures
to drop to 31F and 35F at nearby Norwood Airport
on Sunday morning and this morning respectively. 
 
While rainfall is only slightly below normal this
month all of the 2.29 inches (down one half inch
from the average) can be accounted for on just
three days with measurable rain.  Sunshine has
continued to run above normal for September and
will wind up at 68% after a third very sunny day
today with over 95% of the possible sunshine.  
Average for the month is 55%. 
 
Today's observations:
 
7 A.M.  
Weather: Clear, cirrus, dense cirrus distant south
through west-southwest, inversion, patchy thin ground
fog with few dense patches dissipating past hour  
Temperature: 53F, Dew point: 49F, Wind: W at 8 kts,
Wind: direction gradually veering
Sea-level pressure: 30.32 inches Hg, rising
Visibility: 70 miles, northwest 90 miles
6-hour minimum temp: 50F
24-hour precipitation: 0.00
BHO SA 1155 CLR 70 266/53/49/2808/032/ CI/DENS CI DSNT S-WSW 
INVSN VSBY NW 90 PTCHY THN GF FEW DENS PTCHS ESE-S-W-N
DSSPTG PST HR WND GRDL VEERING/ 8/002 51012 10053 20050
 
10 A.M.
Weather: Clear, cirrus distant south thru west-northwest 
Temperature: 67F, Dew point: 50F, Wind: W at 2 kts (estimated)
Sea-level pressure: 30.32 inches Hg, falling
Visibility: 70 miles, NW 80, NNE-NE 30, thin smoke
along horizon southwest thru north thru east 
BHO SA 1455 CLR 70 268/67/50/E2702/032/ CI DSNT S-WNW 
THN K LYR ALG HRZN SW-N-E VSBY NW 80 NNE-NE 30/ 8/001 50002
 
1 P.M. 
Weather: Clear, cirrus south thru west-northwest  
Temperature: 75F, Dew point: 47F, Wind: S at 5 kts
Sea-level pressure: 30.31 inches Hg, falling
Visibility: 75 miles
BHO SA 1755 CLR 75 263/75/47/1705/031/ CI DSNT S-WNW/
8/001 58005 10075 20053
 
WEATHER SUMMARY FOR SUNDAY, SEPTEMBER 20
 
TEMPERATURE (DEGREES F)
MAX.....71    NORMAL.....70
MIN.....45    NORMAL.....52
MEAN....58    NORMAL.....61
 
DEPARTURE FROM 30-YEAR AVERAGE...........-3
TOTAL DEPARTURE FOR THE MONTH...........-34 [-1.9 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............7  DEPARTURE.......+5
TOTAL HEATING UNITS FOR THE MONTH............74  DEPARTURE.......+6
TOTAL HEATING UNITS FOR THE SEASON..........108  DEPARTURE.......+9
TOTAL HEATING UNITS LAST SEASON TO DATE......69  DIFFERENCE.....+39
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............22 SW   AT 11:31 P.M. 
                   AEROVANE..............17 SW   AT 11:31 P.M. *
                   ASOS..................20 SW   AT 11:31 P.M.  
                   DAVIS................ 21 SSW  AT  3:34 P.M. 
FASTEST MILE FOR YESTERDAY...............16 SW  AT 11:22 P.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE............15 SW  AT 11:37 P.M. 
MAXIMUM 2-MINUTE DAVIS AVERAGE...........17 SW  AT  3:36 P.M.  
AVERAGE WIND SPEED AND DIRECTION....... 8.9 SW
                   ASOS.................8.9
                   DAVIS................8.9 WSW [240 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..............2.29   DEPARTURE....-0.44
                         ASOS..............2.33
TOTAL PRECIPITATION FOR THE YEAR..........37.06   DEPARTURE....+0.86
                         ASOS.............38.25
 
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
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 our morning low temp: 50F; the normal low is now 51F
 
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 21
HIGH 91 IN 1895
LOW 35 IN 1929, 1956, 1962
PRE 5.58 INS IN 1961 (HURRICANE ESTHER; RETURNED AS TS SEPT 25-26TH) 
WIND 186 MPH S IN 1938 (GREAT NEW ENGLAND HURRICANE; CALCULATED GUST, STATION RECORD)
 
RECORDS FOR SEPTEMBER 22
HIGH 90F IN 1895, 1914
LOW 30F IN 1904 (Earliest freeze)
PRECIP 1.16 INCHES IN 2001
PEAK GUST 60 MPH SSW IN 1989
 
TODAY'S REPORT PREPARED BY: Robert Skilling