BLUE HILL METEOROLOGICAL OBSERVATORY  
MILTON, MASSACHUSETTS 
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, SEPTEMBER 16, 2011
ALL TIMES ARE IN EASTERN STANDARD TIME
  
MUCH COOLER AND DRIER;
PLENTY OF SUN 

Yesterday's cold front passage has brought a big change to the air.
Temperatures cooled 37 degrees between yesterday's high of 80F and
this morning's chilly low of 43F.  In fact, our low was only 4 degrees
off of the record for the date of 39F set in 1984.  Our high has
managed to break 60F early this afternoon.  With this cool air mass,
temperatures are averaging about 10 degree below normal today.

A few light rain showers late yesterday evening behind the cold front
brought 0.04 inch of rainfall to the summit.

Skies have been mostly sunny today, with only widely scattered small
cumulus clouds and some thin cirrus slowly advancing toward our area
from the west and southwest.

The air mass is also much drier, with dew point temperatures near 40F.
The fresh, dry air mass is providing for great visibility in the
80-85 mile range.

Below is the current record low temperature for Saturday morning. 

CURRENT BLUE HILL RECORD LOW TEMPERATURE:
Sept. 17  38F in 1959

Today's observations: 

7 A.M.   
Weather: Clear, few cumulus distant NE-SE and distant S and distant
WSW, few cumulus/stratocumulus distant NW-N, few thin cirrus distant
S-SW
Temperature: 47F, Dew point: 39F; Wind: WNW at 9G16 kts,
Wind: Direction variable W-NW 
Sea-level pressure: 30.17 inches Hg, rising   
Visibility: 85 miles, mountain 65 miles NW in cloud
24-hour precip: 0.04 inch
6-hour min. temp: 43F
BHO SA 1155 CLR 85 217/47/39/2909G16/017/ FEW CU DSNT NE-SE AND
DSNT S AND DSNT WSW FEW CU/SC DSNT NW-N FEW THN CI DSNT S-SW MTN
INCLD 65 NW WND 26V32/ 8/501 51027 MANUAL 70004 ASOS 70003
10047 20043

10 A.M. 
Weather: Scattered cumulus, scattered thin cirrus, small cumulus/
cumulus fractus all quadrants, few thin cirrus distant SSW-WSW
Temperature: 56F, Dew Point: 40F; Wind: W at 12G19 kts,
Wind: Direction variable WSW-NNW
Sea-level pressure: 30.22 inches Hg, rising 
Visibility: 80 miles 
BHO SA 1455 40 SCT 250 –SCT 80 234/56/40/2812G19/022/ SML CU/CUFRA
ALQDS FEW THN CI DSNT SSW-WSW WND 24V33/ 8/101 51017

1 P.M. 
Weather: Scattered cumulus, scattered thin cirrus, small cumulus/
cumulus fractus all quadrants, cirrus SSE-WSW and W-NNW invading
the sky
Temperature: 60F, Dew Point: 40F; Wind: W at 10G15 kts,
Wind: Direction variable SW-NNW
Sea-level pressure: 30.22 inches Hg, steady (rising then falling)
Visibility: 80 miles  
6-hour max: 61F  
BHO SA 1755 45 SCT 250 –SCT 80 234/60/40/2610G15/022/ SML CU/CUFRA
ALQDS CI SSE-WSW AND W-NNW INVADING WND 22V33/ 8/104 50000 10061 20047

WEATHER SUMMARY FOR THURSDAY, SEPTEMBER 15

TEMPERATURE (DEGREES F)
MAX.....80    NORMAL.....71
MIN.....49    NORMAL.....54
MEAN....65    NORMAL.....62

DEPARTURE FROM 30-YEAR NORMAL.....................+3
TOTAL DEPARTURE FOR THE MONTH....................+34 [+2.1 DEGREES/DAY]

PEAK GUST AND AVERAGE WIND SPEED (MPH) 
PEAK WIND GUST FOR YESTERDAY..............38 WNW AT  8:55 P.M.
                   AEROVANE...............47 WNW AT  8:53 P.M.
                   ASOS...................41 NW  AT  8:55 P.M.
                   DAVIS..................41 WNW AT  8:53 P.M. RMY 42
THE FASTEST MILE FOR YESTERDAY............30 WNW AT  8:54 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE.............29 NW  AT  8:55 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE............27 WNW AT  8:54 P.M.
AVERAGE WIND SPEED AND DIRECTION........12.3 WNW
                   ASOS.................12.0
                   DAVIS................11.0 SW [236 deg.) 
  
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.04  DEPARTURE.........-0.10
                         ASOS..............0.03
TOTAL PRECIPITATION FOR THE MONTH..........3.29  DEPARTURE.........+1.26
                         ASOS..............3.22
TOTAL PRECIPITATION FOR THE YEAR..........41.33  DEPARTURE.........+5.83
                        ASOS..............41.78**
**ASOS data is in error due to system failure on 1/12-13

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2011 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
RMY:  R.M. Young wind gust recording system added 8/9/2011 
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized

9/1  76/58/67/0/0.00/441/56     17 NE  AERO 22 MPH RMY 17 MPH
9/2  71/57/64/-2/0.00/708/90    15 NE  AERO 20 MPH RMY N/A
9/3  83/57/70/+4/0.00/619/79    21 SSW AERO 27 MPH RMY 22 MPH
9/4  81/65/73/+7/0.00/266/34    34 S   AERO 35 MPH RMY 31 MPH
9/5  83/65/74/+9/0.00/467/60    37 S   AERO 44 MPH RMY 40 MPH
9/6  70/56/63/-2/1.10/000/00    36 NNW AERO 45 MPH NNW RMY 40 MPH
9/7  60/56/58/-7/0.62/000/00    29 NE  AERO 32 MPH NE  RMY 28 MPH
9/8  60/56/58/-7/1.51/000/00    29 ENE AERO 31 MPH ENE RMY 27 MPH
9/9  76/58/67/+3/0.00/506/66    18 NNW AERO 26 MPH NNW RMY 21 MPH
9/10 72/56/64/0/0.00/718/94     18 NNE AERO 25 MPH N   RMY 22 MPH
9/11 74/54/64/0/0.00/632/83     18 S   AERO 25 MPH S   RMY 21 MPH
9/12 80/57/69/+6/0.00/668/88    20 SW  AERO 27 MPH SSW RMY 22 MPH
9/13 81/63/72/+9/0.00/627/83    27 S   AERO 32 MPH S   RMY 26 MPH 
9/14 83/65/74/+11/0.02/.../..   24 WSW AERO 31 MPH S   RMY 26 MPH TSTM
9/15 80/49/65/+3/0.04/.../..    38 WNW AERO 47 MPH RMY 42 MPH TSTM

9/16 our morning low temp: 43F; the normal low is now 53F
 
DAILY RECORDS FOR SEPTEMBER 2011
9/8 - RECORD DAILY PRECIPITATION OF 1.51 inches;
surpasses the previous record of 0.79 inch set in 2004  

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: Sean Fankhauser