BLUE HILL OBSERVATORY MILTON, MA
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, SEPTEMBER 20, 2010
ALL TIMES ARE IN EASTERN STANDARD TIME
 
A layer of dense high cirrus clouds appeared this morning
to the distant east-northeast through south-southeast.  The
clouds are on the northwest fringes of Hurricane Igor, a
minimal hurricane with sustain winds of 75 MPH at 2 PM EDT.
Igor was accelerating toward the northeast at 26 MPH and
located 350 miles north-northeast of Bermuda.  The center
passed just to the west of Bermuda last night with minimal
sustained hurricane force winds gusting to about 80 to
90 MPH. At 2 PM today the minimum barometric pressure was
28.50 inches. 
 
Sunshine and rather gusty NNW winds prevailed here today
with temperatures in the upper 60's and dew points in the
low to middle 40's and 80 miles visibility early this
afternoon.
 
Today's observations: 
 
7 A.M.
Weather: Clear, few altocumulus and altocumulus lenticularis
Temperature: 57F, Dew point: 49F; Wind: NNW at 8 kts,
Wind: Direction variable NW to N
Sea-level pressure: 29.99 inches Hg, rising 
Visibility: 75 miles
6-hour minimum temp: 55F
BHO SA 1155 CLR 75 157/57/49/3408/999/ PTCHS AC FEW ACSL WND 31V01/ 
8/040 51009 10060 20055 
 
10 A.M.
Weather: Clear, small cumulus forming distant W-N,
dense cirrus layer extending distant ENE-SSE  
Temperature: 65F, Dew point: 44F; Wind: NNW at 13G20 kts,
Wind: Direction variable NW to NNE 
Sea-level pressure: 29.98 inches Hg, falling
Visibility: 80 miles
BHO SA 1455 CLR 80 152/65/44/3413G20/998/ SML CU FRMG DSNT W-N 
DNS CI LYR XTDNG ENE-SSE WND 31V03/ 8/102 56005
 
1 P.M. 
Weather: Scattered cu fractus, cumulus, stratocumulus generated by
cumulus, dense cirrus layer distant ENE-SSE
cumulus W, dense cirrus SW-NNE, virga NNW, clear sky overhead
Temperature: 67F, Dew point: 43F; Wind: NNW at 10G21 kts,
Wind: Direction variable W to NNE
Sea-level pressure: 29.91 inches Hg, falling
Visibility: 80 miles
6-hourly max. temp: 68F
BHO SA 1755 55 SCT 220 SCT 80 130/67/43/3310G21/991/ CU/CUSC DNS CI 
LYR XTDNG DSNT ENE-SSE WND 28V02/ 8/402 58022 10068 20057
 
WEATHER SUMMARY FOR SUNDAY, SEPTEMBER 19
 
TEMPERATURE (DEGREES F)
MAX.....76     NORMAL.....70
MIN.....54     NORMAL.....52
MEAN....65     NORMAL.....61       
DEPARTURE FROM 30-YEAR NORMAL..............+4
TOTAL DEPARTURE FOR THE MONTH.............+42 [+2.0 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............0    DEPARTURE........-5
TOTAL HEATING UNITS FOR THE MONTH…………45    DEPARTURE.......-18
TOTAL HEATING UNITS FOR THE SEASON...........58    DEPARTURE.......-36
TOTAL HEATING UNITS LAST SEASON TO DATE.....101    DIFFERENCE......-43
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............17 SW  AT  2:38 A.M.
                   AEROVANE..............22 SW  AT  1:58 A.M.
                   ASOS..................18 SW  AT  1:58 A.M.   
                   DAVIS.................19 SSW AT  1:56 A.M.  
THE FASTEST MILE FOR YESTERDAY...........14 SW  AT  4:31 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE............14 SW  AT  4:32 A.M.  
MAXIMUM 2-MINUTE DAVIS AVERAGE...........15 SW  AT  2:21 A.M. 
AVERAGE WIND SPEED AND DIRECTION........6.8 SW
                   ASOS.................6.3
                   DAVIS................6.6 SSW [210 DEG]
 
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 THE MONTH..........1.08  DEPARTURE........-1.51
                         ASOS..............1.05
TOTAL PRECIPITATION FOR THE YEAR..........47.11  DEPARTURE.......+11.05
                         ASOS.............46.89 **
** ASOS missing rainfall due to system failure on 6/24-25
 
PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2010 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  93/73/83/+16/0.00/765/97  18 SW
9/2  93/72/83/+17/0.00/740/94  25 SSW
9/3  83/69/76/+10/0.47/039/05  25 NNE
9/4  79/62/71/+5/0.00/672/86   37 WSW  AERO 39 MPH WSW
9/5  73/55/64/-1/0.00/778/100  28 SW   AERO 32 MPH SW
9/6  76/54/65/0/T/768/99       22 SSW
9/7  84/62/73/+8/0.00/440/57   30 SSW  AERO 32 MPH S 
9/8  80/59/70/+5/0.08/300/39   35 W    AERO 40 MPH W
9/9  72/55/64/0/T/352/46       28 W
9/10 67/55/61/-3/0.00/260/34   26 WNW
9/11 68/53/61/-3/0.00/723/95   18 NE
9/12 63/54/59/-4/T/045/06      22 ENE  AERO 24 MPH NE
9/13 67/54/61/-2/0.02/091/12   22 S
9/14 74/53/64/+1/T/489/65      31 WSW  AERO 32 MPH WSW
9/15 67/49/58/-4/0.00/.../..   28 W    AERO 31 MPH W
9/16 70/46/58/-4/.../.../..    43 S
9/17 68/53/61/-1/.../.../..    45 S
9/18 65/53/59/-2/0.00/.../..   15 SE
9/19 76/54/65/+4/0.00/.../..   17 SW   AERO 22 MPH SW  
 
9/20 our morning low temp: 55F; the normal low is now 52F. 
 
NEW DAILY RECORDS FOR SEPTEMBER 2010
9/1 - High maximum temperature of 93F equals the previous
record of 93F set in 1969
9/1 - High minimum temperature of 73F surpasses the previous
record of 71F in 1898, 1959
9/2 - High minimum temperature of 72F surpasses the previous
record of 71F in 1959
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR SEPTEMBER 20
HIGH 90 IN 1983
LOW 34 IN 1979
PRE 4.57 INS IN 1899
WIND 44 MPH NE IN 1972
 
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)
 
TODAY'S REPORT PREPARED BY: Robert Skilling