BLUE HILL OBSERVATORY MILTON, MA
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, SEPTEMBER 21, 2010
ALL TIMES ARE IN EASTERN STANDARD TIME
COOL START TO THE DAY,
TEMPERATURES REBOUNDING NICELY
ANNIVERSARY OF GREAT NEW ENGLAND HURRICANE OF 1938
Mostly clear skies and relatively calm winds provided optimum
conditions for radiational cooling overnight. The low temperature
on the summit this morning was 46F, while lower elevations near
the summit were in the mid 30s. Temperatures have warmed up
nicely this afternoon, approaching 70F.
Moisture content in the air is low, and that has been reflected
in the low dew point temperatures and high visibility today.
Dew point temperatures have been in the low 40s with visibility
an incredible 80-85 miles.
Today marks the anniversary of the Great New England Hurricane of
1938. The hurricane brought a peak gust of 186 mph to the summit,
the station record. This is also the record for the strongest
hurricane wind gust recorded anywhere in the United States.
Fall begins tomorrow at 11:09 PM EDT with the autumnal equinox.
Tomorrow also marks the earliest freeze (< or = 32F) recorded on
the summit. This occurred in 1904. The average date of the first
freeze is October 19. The latest freeze was November 15, 1938.
Listed below are the dates of the first freeze for the past 5 years:
2009 Oct 14
2008 Oct 23
2007 Oct 29
2006 Oct 27
2005 Oct 29
Today's observations:
7 A.M.
Weather: Scattered thin cirrus, few small cumulus distant
east-southeast, cirrus distant northwest thru south, few patches
dense cirrus northwest thru northeast, thin smoke layer along
horizon north thru northeast and south-southeast thru
south-southwest
Temperature: 49F, Dew point: 41F; Wind: W at 9 kts,
Sea-level pressure: 30.17 inches Hg, rising
Visibility: 85 miles
6-hour minimum temp: 46F
BHO SA 1155 250 –SCT 85 218/49/41/2809/017/ FEW SML CU DSNT
ESE CI DSNT NW-S FEW PTCHS DNS CI NW-NE THN K LYR ALG HRZN
N-NE AND SSE-SSW/ 8/102 52020 10050 20046
10 A.M.
Weather: Scattered thin cirrus, cirrus distant west thru north
thru south-southeast, patches of dense cirrus distant north and
northeast thru east and northwest
Temperature: 61F, Dew point: 41F; Wind: W at 5 kts,
Wind: Light and variable
Sea-level pressure: 30.19 inches Hg, rising
Visibility: 80 miles
BHO SA 1455 250 –SCT 80 225/61/41/2605/019/ CI DSNT W-N-SSE
PTCHS DNS CI DSNT N AND NE-E AND NW WND LGT AND VRB/ 8/002 51007
1 P.M.
Weather: Scattered cirrus, few altocumulus lenticularis distant
west-northwest thru north-northeast, cirrus all quadrants except
distant east-southeast thru south, patches of dense cirrus all
quadrants except northeast thru east
Temperature: 68F, Dew point: 42F; Wind: SW at 9 kts,
Wind: Direction variable S to W
Sea-level pressure: 30.13 inches Hg, falling
Visibility: 80 miles
6-hourly max. temp: 68F
BHO SA 1755 220 SCT 80 204/68/42/2309/013/ FEW ACSL DSNT WNW-NNE
CI ALQDS XCPT DSNT ESE-S PTCHS DNS CI ALQDS XCPT NE-E WND 18V28/
8/042 58021 10068 20049
WEATHER SUMMARY FOR MONDAY, SEPTEMBER 20
TEMPERATURE (DEGREES F)
MAX.....69 NORMAL.....70
MIN.....50 NORMAL.....52
MEAN....60 NORMAL.....61
DEPARTURE FROM 30-YEAR NORMAL..............-1
TOTAL DEPARTURE FOR THE MONTH.............+41 [+1.9 DEGREES/DAY]
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY.............5 DEPARTURE.........0
TOTAL HEATING UNITS FOR THE MONTH............50 DEPARTURE.......-18
TOTAL HEATING UNITS FOR THE SEASON...........63 DEPARTURE.......-36
TOTAL HEATING UNITS LAST SEASON TO DATE.....108 DIFFERENCE......-45
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............29 NW AT 2:30 P.M. *
AEROVANE..............33 NW AT 2:17 P.M. *
ASOS..................31 N AT 2:26 P.M.
DAVIS.................32 WNW AT 2:29 P.M.
THE FASTEST MILE FOR YESTERDAY...........23 NW AT 2:29 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE............22 NNW AT 2:30 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE...........23 WNW AT 2:30 P.M.
AVERAGE WIND SPEED AND DIRECTION.......12.6 NW
ASOS................12.7
DAVIS...............12.4 NW [318 DEG]
*Last of several occurrences
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M...Trace DEPARTURE........-0.14
ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........1.08 DEPARTURE........-1.65
ASOS..............1.05
TOTAL PRECIPITATION FOR THE YEAR..........47.11 DEPARTURE.......+10.91
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 69/50/60/-1/T/.../.. 29 NW AERO 33 MPH NW
9/21 our morning low temp: 46F; the normal low is now 51F.
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 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: Sean Fankhauser
