Friday, September 20, 2013

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

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, SEPTEMBER 20, 2013
ALL TIMES ARE IN EASTERN STANDARD TIME

ANOTHER BEAUTIFUL, WARM, DRY, CALM FALL DAY;
TOMORROW MARKS THE 75th ANNIVERSARY OF THE 1938 HURRICANE

The streak of beautiful Fall weather continues today. Temperatures have
continued a moderating trend, too, pushing a few degrees warmer today
compared to yesterday. The afternoon high is reaching the upper 70s, and
may near 80F. Today’s average temperature will likely finish about
5 degrees above the 30-year normal for the date.

The air remains relatively dry with dew point temperatures in the lower 50s.
Visibility has been quite good in the 65-75 mile range today. Some distant
haze and a layer of smoke/haze along the horizon have limited visibility
today compared to the past couple of days.

A temperature inversion was quite apparent today, with a prominent smoke/haze
layer trapped beneath it. Warm temperatures and calm winds are allowing the
“dirty” air to stagnate over the area. Pictures of this can be found on
bluehill.org in the member content area.

Tomorrow, September 21, marks the 75th anniversary of the Great New England
Hurricane of 1938. A 5-minute average wind of 121 mph occurred on the
summit, with an estimated peak gust of 186 mph. The center of the tropical
cyclone traveled well to the west of the area, bisecting Long Island before
traveling rapidly northward through western CT, western MA, and western VT.
Consequently, despite the almost unimaginable wind, only 0.13 inch of
rainfall was recorded. A portion of the hand-written records from this
day can be found on bluehill.org in the member content area.

Blue Hill is hosting a special event to commemorate the 75th anniversary of
the Hurricane of 1938 on Saturday, September 21. A number of meteorological
dignitaries will be in attendance. Details about the event can be found
at bluehill.org.

Today’s Observations:

7 A.M.
Weather: Scattered thin cirrus (2 levels), inversion present, ground fog
below inversion distant ESE-SSE, cirrus mostly WNW-NE-S, thin smoke layer
along horizon all quadrants, dark smoke layer above horizon distant SSE-SSW
and over city to the N, light distant haze, dew some surfaces
Temperature: 59F; Dew Point: 51F; Wind: NW at 7 kts.
Sea-level pressure: 30.10 ins. Hg, rising
Visibility: 70 miles, NW 75 miles, ESE-SSW lower due to smoke layer,
light distant haze
6-hr min. temp: 54F
BHO SA 1155 250 –SCT 300 –SCT 70 193/59/51/3107/010/ INVSN PRSNT GF BLO
INVSN DSNT ESE-SSE CI MSTLY WNW-NE-S THN K LYR ALG HRZN ALQDS DRK K LYR
ABV HRZN DSNT SSE-SSW AND OVR CTY N LGT DSNT HZ DEW SOME SFCS VSBY NW 75
ESE-SSW LWR/ 8/001 53017 10059 20054

10 A.M.
Weather: Scattered thin cirrus (2 levels), cirrus WNW-NE invading the sky,
cirrus distant SE-SSW receding, thin smoke layer distant all quadrants,
dark smoke layer above horizon WNW-N-ENE, light distant haze
Temperature: 71F; Dew Point: 53F; Wind: Estimated SW at 1 kt,
Wind: Light and variable
Sea-level pressure: 30.12 ins. Hg, rising
Visibility: 65 miles, NW 70 miles, N-NE lower due to smoke layer,
light distant haze
BHO SA 1455 250 –SCT 300 –SCT 65 199/71/53/E2201/012/ CI WNW-NE INVADING
CI DSNT SE-SSW RECEDING THN K LYR DSNT ALQDS DRK K LYR ABV HRZN WNW-N-ENE
LGT DSNT HZ VSBY N-NE LWR WND LGT AND VRB/ 8/004 53006

1 P.M.
Weather: Scattered thin cirrus, broken thin cirrus, cirrus invading the
sky, thin smoke layer distant all quadrants, dark smoke layer along/above
horizon NNW-ENE, light distant haze
Temperature: 78F; Dew Point: 52F; Wind: Estimated W at 1 kt.
Wind: Light and variable
Sea-level pressure: 30.08 ins. Hg, falling
Visibility: 65 miles, NW 70 miles, NNW-NE lower due to smoke layer,
light distant haze
6-hr max. temp: 78F
BHO SA 1755 250 –SCT 300 –BKN 65 185/78/52/E2701/008/ CI INVADING THN K
LYR DSNT ALQDS DRK K LYR ALG/ABV HRZN NNW-ENE VSBY NW 70 NNW-NE LWR LGT
DSNT HZ WND LGT AND VRB/ 8/004 56014 10078 20059

WEATHER SUMMARY FOR THURSDAY, SEPTEMBER 19, 2013

TEMPERATURE (DEGREES F)
MAX…..78 NORMAL…..71
MIN…..51 NORMAL…..54
MEAN….65 NORMAL…..62

DEPARTURE FROM 30-YEAR NORMAL………………….+3
TOTAL DEPARTURE FOR THE MONTH…………………-14 [-0.9 DEGREE/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………..0 DEPARTURE………-1
TOTAL COOLING UNITS FOR THE MONTH………….54 DEPARTURE………+5
TOTAL COOLING UNITS FOR THE SEASON………..694 DEPARTURE…….+108
TOTAL COOLING UNITS LAST SEASON TO DATE……765 DIFFERENCE…….-71

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL COOLING UNITS FOR YESTERDAY…………..0 DEPARTURE………-4
TOTAL COOLING UNITS FOR THE MONTH………….64 DEPARTURE……..+17
TOTAL COOLING UNITS FOR THE SEASON…………76 DEPARTURE………+4
TOTAL COOLING UNITS LAST SEASON TO DATE…….25 DIFFERENCE…….+51

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………17 WSW AT 10:15 P.M. *
AERO…………………..16 WSW AT 10:17 P.M. *
ASOS…………………..17 WSW AT 10:50 P.M.
DAVIS………………….18 WSW AT 1-2 A.M. RMY 18
FASTEST MILE FOR YESTERDAY………………..14 WSW AT 10:13 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE……………..14 W AT 11:16 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….14 WSW AT 10-11 P.M.
AVERAGE WIND SPEED AND DIRECTION………….8.7 WSW
ASOS………………….8.1
DAVIS…………………8.0 WSW [255 degrees] * last of several occurrences…

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……….3.52 DEPARTURE………….+1.07
ASOS…………..3.63
TOTAL PRECIPITATION FOR THE YEAR……….41.53 DEPARTURE………….+4.06
ASOS…………..N/A*
*ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2013 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane wind recording system gust
RMY: 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 76/67/72/+4/2.32/008/01 33 S AERO 39 MPH S RMY 38 TSTM
9/2 79/67/73/+5/0.43/056/07 30 SSE AERO 33 MPH SSE RMY N/A TSTM
9/3 79/61/70/+3/0.00/219/28 28 S AERO 29 MPH S RMY 30 TSTM
9/4 78/57/68/+1/0.00/733/94 24 W AERO 25 MPH W RMY 25
9/5 66/51/59/-8/0.08/179/23 20 NNE AERO 20 MPH NNE RMY 21
9/6 68/46/57/-10/0.00/751/97 18 WSW AERO 17 MPH WSW RMY N/A
9/7 78/51/65/-1/0.00/594/77 20 WSW AERO 21 MPH WSW RMY 21
9/8 74/50/62/-4/0.00/646/84 31 NW AERO 33 MPH NW RMY 32
9/9 69/47/58/-8/T/529/69 23 SW AERO 23 MPH SSW RMY N/A
9/10 73/56/65/0/0.03/007/01 30 S AERO 32 MPH S RMY 33
9/11 93/68/81/+16/0.00/654/86 25 SW AERO 27 MPH SW RMY N/A
9/12 85/66/76/+11/0.47/455/60 32 S AERO 33 MPH S RMY 34 TSTM
9/13 79/58/69/+5/0.17/242/32 24 NNW AERO 25 MPH NNW RMY 23
9/14 67/52/60/-4/0.00/361/48 21 NW AERO 21 MPH NW RMY 21
9/15 70/48/59/-5/0.00/547/73 17 WSW AERO 18 MPH WSW RMY 20
9/16 66/46/56/-7/0.02/179/24 29 NNW AERO 31 MPH NNW RMY 30
9/17 60/40/50/-13/0.00/722/97 27 NNE AERO 27 MPH NNE RMY 26
9/18 73/47/60/-2/0.00/726/98 18 W AERO 18 MPH WSW RMY 20
9/19 78/51/65/+3/0.00/…/.. 17 WSW AERO 16 MPH WSW RMY 18

9/20 morning low temp: 54F; the normal low is now 53F

DAILY RECORDS FOR SEPTEMBER 2013
9/1 – NEW DAILY RECORD MAXIMUM PRECIPITATION OF 2.32 INCHES;
surpasses previous record of 1.60 inches set in 1927
9/11 – TIED DAILY RECORD MAXIMUM HIGH TEMPERATURE OF 93F;
ties record of 93F set in 1983

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
PRE 4.57 INS IN 1899
WIND 44 MPH NE IN 1972

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)

TODAY’S REPORT PREPARED BY: Sean Fankhauser