Friday, September 21, 2018

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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, SEPTEMBER 21, 2018
ALL TIMES ARE IN EASTERN STANDARD TIME

A DRY, SEASONABLE DAY WITH INCREASING AFTERNOON
CLOUDS….TODAY IS THE 80TH ANNIVERSARY OF THE
GREAT NEW ENGLAND HURRICANE OF 1938…

Today began with partly cloudy skies, becoming overcast
in the afternoon. Visibility was 70 miles throughout the
day. Relative humidity decreased from 83 percent at 7 A.M.
to 60 percent at 10 A.M. The high so far today is
70F, which is the daily normal maximum temperature.
The low since midnight is 55F, 2 degrees above the daily
normal minimum of 53F.

During the afternoon and evening of September 21st, 1938,
the Great New England Hurricane came roaring ashore as a
Category 3 hurricane in transition to an extra-tropical system
with a forward speed of about 50 mph. As the storm moved
into western New England, very high winds near or exceeding
100 mph affected the south coast and eastern areas causing severe
coastal flooding and devastating wind damage. Heavy rain fell
near the storm center to the west. At the Observatory, a minimum
sea-level pressure of 29.01″ occurred at around 5:15 PM while
only 0.13 inches of rain fell during the storm. Of course, the
excessive wind was the story at Blue Hill with a recorded 5-minute
average wind speed peaking at 121 mph shortly before 6 PM, with
a calculated gust of 186 mph at that time. This was measured
with the one anemometer at the Observatory that survived the
storm. Another anemometer was destroyed by the increasing wind
during the afternoon as the storm approached.

Today’s Observations:

7 A.M.
Weather: Broken altocumulus
Temperature: 59F; Dew Point: 54F; Wind: SSE at 8 kts
Sea-level pressure: 30.32 ins. Hg, rising, then steady
Visibility: 70 miles
6-hr Max temp: 59F
6-hr Min temp: 55F
24-hr Precip: 0.00 ins.
BHO SA 1155 E100 BKN 70 267/59/54/1608/032/ 8/050 51007 10059
20055

10 A.M.
Weather: Scattered altocumulus, few cumulus in all directions
Temperature: 66F; Dew Point: 52F; Wind: S at 9G14 kts
Sea-level pressure: 30.27 ins. Hg, falling, then more rapidly
Visibility: 70 miles
3-hr Precip: 0.00 ins.
BHO SA 1455 160 SCT 70 249/66/52/1709G14/027/ FEW CU ALQDS/
8/150 58018

1 P.M.
Weather: Scattered stratocumulus, broken cirrostratus,
few cumulus in all directions
Temperature: 68F; Dew Point: 55F; Wind: S at 10G18 kts
Sea-level pressure: 30.19 ins. Hg, falling, then more rapidly
Visibility: 70 miles
6-hr Max temp: 70F
6-hr Min temp: 59F
6-hr Precip: 0.00 ins.
BHO SA 1755 70 SCT E250 BKN 70 222/68/55/1810G18/019/ FEW CU ALQDS/
8/116 58027 10070 20059

SUMMARY FOR THURSDAY, SEPTEMBER 20, 2018

TEMPERATURE (DEGREES F)
MAX…..63   NORMAL…..70
MIN…..55   NORMAL…..53
MEAN….59   NORMAL…..62

DEPARTURE FROM 30-YEAR NORMAL…………………..-3
TOTAL DEPARTURE FOR THE MONTH………………….+74 [+3.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………6   DEPARTURE………+5
TOTAL HEATING UNITS FOR THE MONTH…………..27   DEPARTURE……..-25
TOTAL HEATING UNITS FOR THE SEASON………….27   DEPARTURE……..-50
TOTAL HEATING UNITS LAST SEASON TO DATE……..60   DIFFERENCE…….-33

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY……………0  DEPARTURE……….-1
TOTAL COOLING UNITS FOR THE MONTH………….102  DEPARTURE………+51
TOTAL COOLING UNITS FOR THE SEASON…………855  DEPARTURE……..+267
TOTAL COOLING UNITS LAST SEASON TO DATE…….665  DIFFERENCE…….+190

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY…………………22 NE  AT 5:05 A.M.
AERO……………………..21 NE  AT 5:34 A.M.
ASOS……………………..22 NE  AT 5:36 A.M.
DAVIS…………………….21 ENE AT 4:53 A.M. RMY N/A
FASTEST MILE FOR YESTERDAY…………………..14 NE  AT 6:04 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE………………..15 NNE AT 9:02 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE……………….15 NE  AT 6:04 A.M.
AVERAGE WIND SPEED AND DIRECTION…………….9.0 NE
ASOS…………………….9.1
DAVIS……………………9.5 ENE

**Davis direction malfunctioning

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 THE MONTH……….6.39  DEPARTURE……+3.95
ASOS…………..6.46
TOTAL PRECIPITATION FOR THE YEAR……….44.34  DEPARTURE……+6.92
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 63/55/59/-3/…./…/..        22 NE  AERO 21 NE  RMY 19

9/21 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 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)

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: Benjamin Turner / Mike Iacono