Thursday, September 19, 2013

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

DAILY DISCUSSION AND CLIMATE SUMMARY
THURSDAY, SEPTEMBER 19, 2013
ALL TIMES ARE IN EASTERN STANDARD TIME

CLEAR  AND CALM BEAUTIFUL WEATHER CONTINUES!!
A SECOND DAY OF PERFECTLY CLEAR SKY

This morning had no clouds and perfectly clear. The visibility was high around 80 miles
in all directions. Pollution was visible over the city of Boston during the early morning
hours and into the afternoon. This would indicate that there was a pretty strong inversion,
which is helping with the clear skies. Another indication of the inversion is that the
Hingham station was 46, Taunton was 40, and Norwood was 38. The low temperature here
was 51F. Temperatures were increasing with height, Worcester, was also 51 degrees.

With bright sunshine we were able to warm up to 76F. This would continue the trend of
running below to near normal. Yesterday was the 5th day in a row of being cooler.
The month as of right now is running about a degree below normal.

An interesting note is how calm our winds are today. We had a gust of 17 mph at around 4am
this morning. Winds have weaken since then. We are averaging only around 5 mph this
afternoon. This is most likely due to a strong high pressure system that has been
dominating our weather. We had our highest pressure on Tuesday at 30.44 inches of Hg.
This was the highest pressure recorded since May! However we have since dropped since then
but still running at 30.11 inches of Hg.

Its rare to have two consecutive perfectly clear sky days in the observations
from Blue Hill.  There was a tiny bit of cirrus or cirrostratus in the distant
SE-SSE sky yesterday.

Today’s Observations:

7 A.M.
Weather: Sky, Clear, perfectly clear, SKC
Temperature: 55F; Dew Point: 45F; Wind: WNW at 8 kts,
Sea-level pressure: 30.14 ins. Hg, rising slightly
Visibility: 75 miles, light distant haze
6-hr min. temp: 51F
BHO SA 1155 CLR 75 205/55/45/3008/014/ SKC PTCH THN GF 4 SW
THN K LYR ALG HRZN NNE-ENE AND S-SW/ 52003 10055 20051

10 A.M.
Weather: Sky clear, perfectly clear, SKC
Temperature: 69F; Dew Point: 52F; Wind: W at 2 kts (estimated),
Wind: Light
Sea-level pressure: 30.14 ins. Hg, falling slightly
Visibility: 75 miles, light distant haze
BHO SA 1455 CLR 75 206/69/52/E2702/014/ SKC THN K LYR BLO INVSN ESTMTD
TOP 15 HND N-NE WND LGT/ 50001

1 P.M.
Weather: Sky perfectly clear, SKC,
Temperature: 76F; Dew Point: 48F; Wind: NW at 4 kts,
Wind: Light
Sea-level pressure: 30.11 ins. Hg, falling then more rapidly
Visibility: 75 miles, light distant haze smoke layer NE-E, Dark smoke layer E
6-hr max. temp: 76F
BHO SA 1755 CLR 75 195/76/48/3204/011/ SKC THN K LYR ALG/ABV HRZN NE
DRK K LYR ABV HRZN E LGT DSNT HZ WND LGT/ 58011 10076 20055

WEATHER SUMMARY FOR WEDNESDAY, SEPTEMBER 18, 2013

TEMPERATURE (DEGREES F)
MAX…..73    NORMAL…..71
MIN…..47    NORMAL…..54
MEAN….60    NORMAL…..62

DEPARTURE FROM 30-YEAR NORMAL………………….-2
TOTAL DEPARTURE FOR THE MONTH…………………-17 [-1.1 DEGREE/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………..0   DEPARTURE………-2
TOTAL COOLING UNITS FOR THE MONTH………….54   DEPARTURE………+6
TOTAL COOLING UNITS FOR THE SEASON………..694   DEPARTURE…….+109
TOTAL COOLING UNITS LAST SEASON TO DATE……765   DIFFERENCE…….-71

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………18 W   AT  10:57 P.M.*
AERO…………………..18 WSW AT  09:35 P.M.
ASOS…………………..20 W   AT  10:57 P.M.
DAVIS………………….19 WSW AT  10:25 P.M. RMY 20
FASTEST MILE FOR YESTERDAY………………..16 W   AT  10:45 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………..15 W   AT  11:37 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….15 WSW AT  10:29 P.M.
AVERAGE WIND SPEED AND DIRECTION………… 9.5 W
ASOS………………….9.2
DAVIS…………………8.3 W [260 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………….+1.21
ASOS…………..3.63
TOTAL PRECIPITATION FOR THE YEAR……….41.53   DEPARTURE………….+4.20
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 morning low temp: 51F; the normal low is now 54F

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 19
HIGH 87F IN 1906,1983
LOW 37F IN 1929
PRECIP 3.69 INCHES IN 1936
PEAK GUST 55 MPH S IN 2012

RECORDS FOR SEPTEMBER 20
HIGH 90 IN 1983
LOW 34 IN 1979
PRE 4.57 INS IN 1899
WIND 44 MPH NE IN 1972

TODAY’S REPORT PREPARED BY: Robert Skilling and Kevin Pecora