Thursday, September 20, 2018

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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, SEPTEMBER 20, 2018
ALL TIMES ARE IN EASTERN STANDARD TIME

A COOL FALL DAY ATOP GREAT BLUE HILL….

Today began mostly cloudy, becoming overcast in the
afternoon. Winds at or below 10 mph have persisted
from the NNE. Visibility increased from 40 miles this
morning to 70 miles by 10 A.M. The high so far today is
63F, 7 degrees below the daily normal of 70F. The low
since midnight is 55F, 2 degrees above the normal
minimum of 53F.

Today’s Observations:

7 A.M.
Weather: Broken stratocumulus with few lower cumulus,
virga NE-S
Temperature: 58F; Dew Point: 56F; Wind: NNE at 8G17 kts
Sea-level pressure: 30.20 ins. Hg, rising, then more slowly
Visibility: 40 miles
6-hr Max temp: 58F
6-hr Min temp: 55F
24-hr Precip: 0.04 ins.
BHO SA 1155 E30 BKN 40 226/58/56/0308G17/020/ FEW LWR CU VIRGA
NE-S/ 8/800 70004 53023 10058 20055

10 A.M.
Weather: Broken stratocumulus with a few lower cumulus
Temperature: 61F; Dew Point: 56F; Wind: NNE at 10G18 kts
Sea-level pressure: 30.26 ins. Hg, rising steadily
Visibility: 70 miles, except 30 miles NE-S (distant haze)
3-hr Precip: 0.00 ins.
BHO SA 1455 E30 BKN 70 247/61/56/0310G18/026/ FEW LWR CU VSBY
30 NE-S DSNT HZ NE-S/ 8/800 51021

1 P.M.
Weather: Overcast stratocumulus with breaks E-SW
Temperature: 62F; Dew Point: 56F; Wind: ENE at 8G16 kts
Sea-level pressure: 30.25 ins. Hg, falling steadily
Visibility: 70 miles
6-hr Max temp: 63F
6-hr Min temp: 57F
6-hr Precip: 0.00 ins.
BHO SA 1755 E45 OVC 70 245/62/56/0608G16/025/ BINOVC E-SW/
8/400 58002 10063 20057

SUMMARY FOR WEDNESDAY, SEPTEMBER 19, 2018

TEMPERATURE (DEGREES F)
MAX…..66   NORMAL…..71
MIN…..57   NORMAL…..54
MEAN….62   NORMAL…..62

DEPARTURE FROM 30-YEAR NORMAL……………………0
TOTAL DEPARTURE FOR THE MONTH………………….+77 [+3.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………3   DEPARTURE………-1
TOTAL HEATING UNITS FOR THE MONTH…………..21   DEPARTURE……..-26
TOTAL HEATING UNITS FOR THE SEASON………….21   DEPARTURE……..-51
TOTAL HEATING UNITS LAST SEASON TO DATE……..60   DIFFERENCE…….-39

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY……………0  DEPARTURE……….-1
TOTAL COOLING UNITS FOR THE MONTH………….102  DEPARTURE………+53
TOTAL COOLING UNITS FOR THE SEASON…………855  DEPARTURE……..+269
TOTAL COOLING UNITS LAST SEASON TO DATE…….665  DIFFERENCE…….+190

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY…………………28 NE  AT 6:07 A.M.
AERO……………………..25 NE  AT 6:07 A.M.
ASOS……………………..29 NE  AT 6:07 A.M.
DAVIS…………………….27 M   AT 6:06 A.M.** RMY 26
FASTEST MILE FOR YESTERDAY…………………..18 NE  AT 6:26 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………..20 NE  AT 6:22 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………….20 M   AT 6:07 A.M.**
AVERAGE WIND SPEED AND DIRECTION…………….11.5 NE
ASOS…………………….11.9
DAVIS……………………11.6 **

**Davis direction malfunctioning

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.04  DEPARTURE……-0.10
ASOS…………..0.05
TOTAL PRECIPITATION FOR THE MONTH……….6.39  DEPARTURE……+3.95
ASOS…………..6.46
TOTAL PRECIPITATION FOR THE YEAR……….44.34  DEPARTURE……+7.06
ASOS………….45.98

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST
AERO: Aerovane wind recording system 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
M:    Missing data

9/01 75/58/67/-1/0.00/521/66        17 NE  AERO 15 NE  RMY 16
9/02 83/61/72/+4/0.00/684/87        20 SSW AERO 18 SSW RMY N/A
9/03 92/68/80/+13/0.00/650/83       24 WSW AERO 22 WSW RMY 25
9/04 88/70/79/+12/0.00/695/89       17 W   AERO 16 W   RMY 17
9/05 89/67/78/+11/0.00/638/82       23 SSW AERO 23 SSW RMY 25
9/06 92/70/81/+14/0.56/488/63       29 NNW AERO 29 NNW RMY N/A TSTM
9/07 70/63/67/+1/0.01/000/00        24 NE  AERO 22 NE  RMY N/A
9/08 68/54/61/-5/0.00/031/04        22 NE  AERO 18 NE  RMY 21
9/09 61/53/57/-9/0.00/000/00        23 NE  AERO 21 NE  RMY N/A
9/10 62/56/59/-6/…./…/..        30 E   AERO 28 E   RMY 28
9/11 75/61/68/+3/…./…/..        23 E   AERO 21 E   RMY N/A TSTM
9/12 69/63/66/+1/…./…/..        21 ENE AERO 21 ENE RMY 21  TSTM
9/13 68/62/65/+1/…./…/..        21 NE  AERO 21 NE  RMY N/A TSTM
9/14 75/61/68/+4/…./…/..        13 NE  AERO 12 ENE RMY 12
9/15 76/62/69/+5/0.01/…/..        14 SW  AERO 13 SW  RMY 13
9/16 84/61/73/+10/…./…/..       15 S   AERO 14 S   RMY N/A
9/17 82/64/73/+10/…./…/..       22 SSW AERO 22 SSW RMY N/A
9/18 74/67/71/+9/…./…/..        31 SSW AERO 30 SSW RMY N/A TSTM
9/19 66/57/62/0/…./…/..         28 NE  AERO 25 NE  RMY 26

9/20 Low temp since midnight is 55F; normal low is now 53F

DAILY RECORDS FOR SEPTEMBER

09/04/18: DAILY RECORD HIGH MINIMUM TEMPERATURE OF 70F,
BREAKS PREVIOUS RECORD OF 68F SET IN 1937 AND 1959

09/06/18: DAILY RECORD HIGH MAXIMUM TEMPERATURE OF 92F,
TIES PREVIOUS RECORD OF 92F SET IN 1900

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
PRECIP 4.57 INS IN 1899
PEAK GUST 44 MPH NE IN 1972

RECORDS FOR SEPTEMBER 21
HIGH 91 IN 1895
LOW 35 IN 1929, 1956, 1962
PRECIP 5.58 INS IN 1961 (HURRICANE ESTHER; RETURNED AS TS SEPT 25-26TH)
PEAK GUST 186 MPH S IN 1938 (GREAT NEW ENGLAND HURRICANE; CALCULATED GUST, STATION RECORD)

TODAY’S REPORT PREPARED BY: Benjamin Turner