Monday, September 23, 2013

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

DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, SEPTEMBER 23, 2013
ALL TIMES ARE IN EASTERN STANDARD TIME

RAIN SHOWERS PRECEDE COLD FRONTAL PASSAGE SUNDAY MORNING
GUSTY S-SSW WINDS REACH SPEEDS NEAR 40 MPH
AUTUMNAL EQUINOX OCCURRED YESTERDAY AT 4:44 P.M. EDT
MUCH DRIER AND COOLER AIR MASS FOLLOWS IN WAKE OF FRONT
SPECTACULAR 90 MILES VISIBILITY THIS MORNING

Several hours of mostly light rain showers preceded the
arrival of much drier and cooler air which began arriving
yesterday afternoon.
Gusty S-SSW winds up to close to 40 MPH preceded the cold
front and winds decreased and gradually veered to west
from south-southwest between 5 and 8 A.M. EDT  Rain
ended shortly after 8 A.M. The final total rainfall was
0.39 inch.

The autumnal equinox (beginning of fall) occurred late
yesterday afternoon (4:44 P.M. EDT) as a much more seasonal
fall type and actually cooler than average air mass was arriving.
Dew points fell from the mid 60’s early yesterday morning to
the mid 40’s by late last night.
Temperatures dropped from 70 degrees early yesterday after-
noon to near 50 by midnight and then on down to a fall-like
low of 43 degrees early today. Normal high and low temperatures
for this first day of fall are 69 and 52F.

This morning’s visibility was spectacular from the summit and
we reported 90 miles, our highest reportable value.
This spectacular visibility continued into this afternoon.
Meanwhile Mount Washington continues in freezing fog, has
zero visibility, 24 degrees and one inch of snow on the
ground early this afternoon.

Today’s Observations:

7 A.M.
Weather: Clear, few stratocumulus along horizon distant NW-NNW,
cumulus distant offshore along horizon NE=SE
Temperature: 47F; Dew Point: 39F; Wind: NW at 9 kts
Sea-level pressure: 29.93 ins. Hg, rising steadily
Visibility: 90 miles
6-hr min. temp: 43F
24-hr precip: 0.01 inch
BHO SA 1155 CLR 90 134/47/39/3109/993/ FEW SC ALG HRZN DSNT NW-NNW
CU ALG HRZN DSNT OFFSHR NE-SE/ 8/800 53018 ASOS 70002 MANUAL 70001
10048 20043

10 A.M.
Weather: Clear, few occasional cumulus fractus forming vicinity
to the SW-W, few stratocumulus distant WSW-N, cumulus distant offshore
along horizon ESE-SSE
Temperature: 55F; Dew Point: 39F; Wind: WNW at 10 kts,
Wind: Direction variable W-NNW
Sea-level pressure: 29.92 ins. Hg, falling slightly
Visibility: 90 miles
BHO SA 1455 CLR 90 132/55/39/3010/992/ OCNL SC FRMG VC SW-W AND
SC DSNT WSW-N CU DSNT OFFSHR ALG HRZN DSNT ESE-SSE WND 27V34/
8/800 58002

1 P.M.
Weather: Clear, few small cumulus fractus, cumulus and
stratocumulus mostly distant S-W-NNE
Temperature: 61F; Dew Point: 42F; Wind: NW at 11 kts,
Wind: Direction variable W-NNW
Sea-level pressure: 29.91 ins. Hg, falling slightly
Visibility: 90 miles
6-hr max. temp: 62F
BHO SA 1755 CLR 90 130/61/42/3111/991/ FEW SML CUFRA/CU/SC MSTLY
DSNT S-W-NNE WND 27V34/ 8/800 58002 10062 20047

WEATHER SUMMARY FOR SUNDAY, SEPTEMBER 22, 2013
(AUTUMNAL EQUINOX AT 4:44 P.M. EDT)

TEMPERATURE (DEGREES F)
MAX…..70    NORMAL…..69
MIN…..49    NORMAL…..52
MEAN….60    NORMAL…..61

DEPARTURE FROM 30-YEAR NORMAL…………………-1
TOTAL DEPARTURE FOR THE MONTH…………………-6 [-0.5 DEGREE/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………..0   DEPARTURE………-1
TOTAL COOLING UNITS FOR THE MONTH………….56   DEPARTURE………+3
TOTAL COOLING UNITS FOR THE SEASON………..696   DEPARTURE…….+106
TOTAL COOLING UNITS LAST SEASON TO DATE……765   DIFFERENCE…….-69

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………..0   DEPARTURE……….0
TOTAL HEATING UNITS FOR THE MONTH………….69   DEPARTURE………+7
TOTAL HEATING UNITS FOR THE SEASON…………81   DEPARTURE………-6
TOTAL HEATING UNITS LAST SEASON TO DATE…….44   DIFFERENCE…….+37

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………38 S   AT 4:20 A.M.
AERO…………………..39 S   AT 4:20 A.M. *
ASOS…………………..43 S   AT 4:21 A.M.
DAVIS………………….40 S   AT 4:20 A.M. RMY 42
FASTEST MILE FOR YESTERDAY………………..27 S   AT 4:17 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………..26 SSW AT 4:53 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….27 S   AT 4:18 A.M..
AVERAGE WIND SPEED AND DIRECTION………….13.7 W
ASOS………………….12.3
DAVIS…………………12.3 WSW [250 degrees] * last of several occurrences…

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.01   DEPARTURE………….-0.14
ASOS…………..0.02
TOTAL PRECIPITATION FOR THE MONTH……….3.91   DEPARTURE………….+1.02
ASOS…………..4.04
TOTAL PRECIPITATION FOR THE YEAR……….41.92   DEPARTURE………….+4.01
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 78/54/66/+4/0.00/…/..         18 SSW AERO 18 MPH SSW RMY 23
9/21 74/57/66/+4/0.00/…/..         35 S   AERO 40 MPH S   RMY N/A
9/22 70/49/60/-1/0.39/…/..         38 S   AERO 39 MPH S   RMY 42

9/23 morning low temp: 43F; the normal low is now 52F

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 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: Robert Skilling