Wednesday, September 23, 2015

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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, SEPTEMBER 23, 2015
ALL TIMES ARE IN EASTERN STANDARD TIME

OVERNIGHT TEMPS DIP TO 50F DURING ARRIVAL OF FALL

**BLUE HILL OBSERVATORY KICKSTARTER CAMPAIGN NEARLY
HALFWAY TO RAISING FUNDS TO REPLACE OUR BELFORT AEROVANE
ANEMOMETER. PLEASE MAKE A TAX-DEDUCTIBLE DONATION
TODAY SO WE CAN MAKE THIS CRITICAL INSTRUMENT PURCHASE:**

The autumnal equinox arrived at 4:21 AM EDT this morning,
and with it, tying the coolest temperatures we have seen
so far this month, with an overnight low of 50F. Skies were
mostly this morning as well, with visibility observed at
a rare station maximum of 90 miles during this morning’s
7:00 AM EST.

By the 1:00 PM EST observation skies had remained mostly clear
with only a few small cumulus and cirrus distant to mostly
our SE. Temperatures had climbed to a maximum of 71F while
dew points had dropped into the lowers 40s. Relatively humidity
reflected this large spread at 34 percent. Visibility was
80 miles in all directions.
Today’s Observations:

7 A.M.
Weather: Clear, few cumulus distant offshore ENE-S,
few cirrus distant E-SW
Temperature: 53F; Dew Point: 51F; Wind: N at 9 kts,
Sea-level pressure: 30.27 ins. Hg, rising slightly
Visibility: 35 miles, except 90 miles WSW-N, thin fog NNE-SW
6-hr Max temp: 54F
6-hr Min temp: 50F
24-hr precip: none
BHO SA 1155 CLR 35 252/53/51/3609/027/ VSBY WSW-N 90 MI FEW CU
DSNT OFFSHR ENE-S FEW CI DSNT E-SW THN FG DSNT NNE-SW/ 8/101
50002 10054 20050

10 A.M.
Weather: Clear, few cumulus distant ESE-SSE, few cirrus
distant ENE-SW
Temperature: 67F; Dew Point 45F; Wind: estimated ENE at 5 kts,
Wind Speed: Light
Sea-level pressure: 30.29 ins. Hg, rising, then falling but higher still
Visibility: 80 miles
BHO SA 1455 CLR 80 257/67/45/E0705/029/ FEW CU DSNT ESE-SSE
FEW CI DSNT ENE-SW WND LGT/ 8/101 50005

1 P.M.
Weather: Clear, few small cumulus distant ESE-SSE,
few cirrus distant ENE-SSW
Temperature: 71F; Dew Point: 42F; Wind: estimated NE 4 kts
Wind Speed and Direction: Light and Variable
Sea-level pressure: 30.26 ins. Hg, falling, then more slowly
Visibility: 80 miles
6-hr Max: 71F
6-hr Min: 53F
BHO SA 1755 CLR 80 248/71/42/E0504/026/ FEW SML CU DSNT ESE-SSE
FEW CI DSNT ENE-SSW WND LGT AND VRB/ 8/101 56009 10071 20053
SUMMARY FOR TUESDAY, SEPTEMBER 22, 2015

TEMPERATURE (DEGREES F)
MAX…..67   NORMAL…..69
MIN…..55   NORMAL…..52
MEAN….61   NORMAL…..61

DEPARTURE FROM 30-YEAR NORMAL……………………+0
TOTAL DEPARTURE FOR THE MONTH………………….+123  [+5.4 DEGREES/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY……………0   DEPARTURE……….-1
TOTAL COOLING UNITS FOR THE MONTH………….131   DEPARTURE………+78
TOTAL COOLING UNITS FOR THE SEASON…………797   DEPARTURE……..+207
TOTAL COOLING UNITS LAST SEASON TO DATE…….571   DIFFERENCE…….+226

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………4   DEPARTURE……….-1
TOTAL HEATING UNITS FOR THE MONTH…………..16   DEPARTURE………-46
TOTAL HEATING UNITS FOR THE SEASON………….17   DEPARTURE………-70
TOTAL HEATING UNITS LAST SEASON TO DATE……..68   DIFFERENCE……..-51

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY……………….21  E   AT  1:36 P.M.
ASOS……………………22  ENE AT  1:19 P.M.
DAVIS…………………..20  E   AT  1:18 P.M. RMY 21
FASTEST MILE FOR YESTERDAY…………………13  E   AT  1:18 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………15  ENE AT  1:34 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………..14  E   AT  1:20 P.M.
AVERAGE WIND SPEED AND DIRECTION…………..9.3 ENE
ASOS…………………..9.5
DAVIS………………….8.5 ENE [058 DEG]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…..0.00  DEPARTURE…..-0.15
ASOS……………0.00
TOTAL PRECIPITATION FOR THE MONTH………..1.35  DEPARTURE…..-1.53
ASOS……………1.33
TOTAL PRECIPITATION FOR THE YEAR………..31.60  DEPARTURE…..-6.29
ASOS…………….N/A ***
*** ASOS annual total not available due to erroneous readings

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/RMY GUST
RMY:  R.M. Young wind gust recording system
TSTM: Thunderstorm day (thunder heard some time during day)
….: Data not yet available, records not finalized

9/1  81/65/73/+5/0.00/766/97               20 SSW RMY 20
9/2  89/64/77/+9/0.00/732/93               20 SW  RMY 21
9/3  85/66/76/+9/T/612/78                  17 E   RMY N/A TSTM
9/4  72/58/65/0/0.00/297/38                31 ENE RMY N/A
9/5  77/55/66/-1/0.00/748/96               14 SW  RMY 18
9/6  87/57/72/+5/0.00/753/97               21 SSW RMY 22
9/7  92/63/78/+12/0.00/727/94              23 WSW RMY 24
9/8  97/70/84/+18/0.00/693/90              22 WSW RMY 24
9/9  92/70/81/+15/0.00/683/89              30 SSW RMY 33
9/10 73/62/68/+3/…./000/00               29 NE  RMY N/A
9/11 70/59/65/0/…./084/11                33 NE  RMY N/A
9/12 75/58/67/2/…./380/50                18 SSE RMY 25
9/13 66/60/63/-1/…./000/00               25 E   RMY N/A
9/14 70/53/62/-2/0.00/550/73               33 W   RMY 35
9/15 82/56/69/+5/0.00/736/98               23 W   RMY N/A
9/16 84/62/73/+10/0.00/711/95              17 NW  RMY N/A
9/17 87/64/76/+13/0.00/723/97              17 SW  RMY 16
9/18 86/64/75/+13/0.00/712/96              21 SSW RMY 21
9/19 80/62/71/+9/0.00/…/..               22 S   RMY N/A
9/20 74/55/65/+3/T/…./…                24 S   RMY N/A
9/21 65/50/58/-3/0.00/…/..               29 ENE RMY 30
9/22 67/55/61/+0/0.00/…/..               21 E   RMY 21

9/23 low since midnight is 50F; normal low is now 52F

DAILY RECORDS FOR SEPTEMBER 2015

**9/7 DAILY RECORD MAXIMUM TEMPERATURE OF 92F
TIES PREVIOUS RECORD SET IN 2007**

**9/8 DAILY RECORD MAXIMUM TEMPERATURE OF 97F
BREAKS PREVIOUS RECORD OF 93F SET IN 2007**

**9/8 DAILY RECORD HIGH MINIMUM TEMPERATURE OF 70F
BREAKS PREVIOUS RECORD OF 69F SET IN 1999**

**9/9 DAILY RECORD MAXIMUM TEMPERATURE OF 92F
BREAKS PREVIOUS RECORD OF 91F SET IN 2002**

**9/9 DAILY RECORD HIGH MINIMUM TEMPERATURE OF 70F
BREAKS PREVIOUS RECORD OF 69F SET IN 1999**

**9/17 DAILY RECORD MAXIMUM TEMPERATURE OF 87F
BREAKS PREVIOUS RECORD OF 86F SET IN 1915, 1941, AND 1991**

**9/18 DAILY RECORD HIGH MINIMUM TEMPERATURE OF 64F
TIES PREVIOUS RECORD SET IN 1992**

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):

RECORDS FOR SEPTEMBER 23
HIGH 93F IN 1895,1914
LOW 33F IN 1904
PRECIP 2.67 INCHES IN 1994
PEAK GUST 62 MPH SSW IN 1989

RECORDS FOR SEPTEMBER 24
HIGH 87F IN 1959
LOW 33F IN 1885,1950,1963
PRECIP 1.19 INCHES IN 1955
PEAK GUST 54e MPH SW IN 1940

TODAY’S REPORT PREPARED BY: Brian Fitzgerald