BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, SEPTEMBER 16, 2009 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
BACK DOOR COLD FRONTAL PASSAGE LATE TUESDAY
LOW CLOUDS AND MUCH COOLER WEATHER TODAY
NNE-NE WINDS GUSTING TO NEAR 30 MPH 
 
A back door cold frontal passage at 6:05 P.M. EDT
late yesterday brought a wind shift from northwest
to northeast with only light wind speeds, but the
temperature dropped 6 degrees in one hour.  Low
clouds and gusty NNE-NE winds prevailed today with
temperatures struggling up to 61F.
 
Today's observations:
 
7 A.M.  
Weather: Broken stratus, overcast stratocumulus, bright spots in
the overcast distant NE-SE, virga distant ENE-SE
Temperature: 58F, Dew point: 55F, Wind: NNE at 14G23 kts,
Wind: peak gust to 26 kts NE at 6:23 a.m.,
Wind: direction variable NNW to ENE 
Sea-level pressure: 30.22 inches Hg, rising
Visibility: 30 miles, 25 miles W-NW and 35 miles northeast,
light haze 
6-hour minimum temp: 56F
24-hour precipitation: 0.00 
BHO SA 1155 E10 BKN 20 OVC 30 232/58/55/0314G23/022/
VIRGA DSNT ENE-SE BRGHT SPTS IOVC DSNT NE-SE
LGT HZ PK WND 0426/23/ WND 34V06/ 8/6// 53026
10059 20056
 
10 A.M.
Weather: Overcast two layers of stratocumulus,
the ceiling is ragged  
Temperature: 57F, Dew point: 53F, Wind: NNE at 17G27 kts,
Wind: peak gust to 27 kts NNE at 9:50 a.m.,
Wind: direction variable NNW to ENE
Sea-level pressure: 30.28 inches Hg, rising
Visibility: 35 miles 
BHO SA 1455 E12 BKN 17 OVC 35 253/57/53/0317G27/028/
CIG RGD PK WND 0327/50/ WND 34V07/ 8/5// 51021
 
1 P.M.
Weather: Overcast with several layers of stratocumulus,
breaks in overcast 
Temperature: 59F, Dew point: 52F, Wind: NNE at 12G23 kts,
Wind: direction variable NNW to ENE 
Sea-level pressure: 30.32 inches Hg, rising
Visibility: 40 miles, NW 55 miles, NE-SE 25 miles,
light haze 
6-hour max. temp: 61F
BHO SA 1755 18 SCT E25 BKN 40 OVC 40 268/59/52/0312G23/032/
BINOVC VSBY NW 55 NE-SE 25 LGT HZ WND 34V07/
8/5// 51010 10061 20057
 
WEATHER SUMMARY FOR TUESDAY, SEPTEMBER 15
 
TEMPERATURE (DEGREES F)
MAX.....75    NORMAL.....71
MIN.....56    NORMAL.....54
MEAN....66    NORMAL.....62
 
DEPARTURE FROM 30-YEAR AVERAGE...........+4
TOTAL DEPARTURE FOR THE MONTH...........-11 [-0.9 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............0  DEPARTURE.......-4
TOTAL HEATING UNITS FOR THE MONTH............33  DEPARTURE......-11
TOTAL HEATING UNITS FOR THE SEASON...........67  DEPARTURE.......-8
TOTAL HEATING UNITS LAST SEASON TO DATE......30  DIFFERENCE.....+37
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............22 WNW  AT 11:17 A.M.    
                   AEROVANE..............23 WNW  AT 11:17 A.M.    
                   ASOS..................23 WNW  AT 11:18 A.M.    
                   DAVIS................ 24 WNW  AT  9:41 A.M.     
FASTEST MILE FOR YESTERDAY...............15 WSW  AT  5:35 A.M.  * 
MAXIMUM 2-MINUTE ASOS AVERAGE............16 WNW  AT  9:41 A.M.      
MAXIMUM 2-MINUTE DAVIS AVERAGE...........18 WNW  AT  9:43 A.M.     
AVERAGE WIND SPEED AND DIRECTION.......10.5 WNW
                   ASOS................10.1 
                   DAVIS...............10.6 W [260 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....+0.26
                         ASOS..............2.33
TOTAL PRECIPITATION FOR THE YEAR..........37.06   DEPARTURE....+1.70
                         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 63/60/61/-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/.../..     22 WNW
 
9/16 our morning low temp: 56F; the normal low is now 53F
 
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 16
HIGH 91F IN 1939,1941
LOW 39F IN 1984
PRECIP 5.12 INCHES IN 1933 (Hurricane)
PEAK GUST 59 MPH SSE IN 1999
 
RECORDS FOR SEPTEMBER 17
HIGH 86F IN 1915,1941,1991
LOW 38F IN 1959
PRECIP 2.73 INCHES IN 1933
PEAK GUST 60 MPH WNW IN 1999
 
TODAY'S REPORT PREPARED BY: Robert Skilling