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

FRIDAY, SEPTEMBER 18, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

NEW AIR MASS FROM CANADA ARRIVES, SMOKE DEPARTS...

A cold front swept through the area overnight bringing
several notable changes today:

First thing noted out the door this morning was the
cooler temperatures and dew points. While yesterday's
air temperature and dew point maxed out at 76 degrees
and 56 degrees respectively, we have only mustered 63
degrees and the dew point has gradually fallen to 45
degrees by 1PM.

Second, a smoke-filled sky was observed for several days
this week – in fact, it likely knocked off 1 to 2 degrees
of the maximum possible temperature. Winds are now from
the north kicking the smoke to our south. Consequently, we
have observed some very small patches of welcomed blue sky
this afternoon.

Furthermore, it has been one week since we recorded our
last measurable precipitation event. This brings us to -3.86
inches below the annual normal. While this figure is not all
too noteworthy, most other locations across the Bay State are
seeing substantial deficits. Take for instance Logan Airport.
They are currently at -8.16 inches below average on the year.
Or, take Hanscom/Bedford, which is sitting at -11.45 inches.
Chatham? They are nearing a 12 inch departure! As of yesterday,
7% of MA has escalated to an "Extreme Drought" - mainly focused along
the Attleboro, Fall River, and New Bedford corridor. The rest
of the state finds itself in a "Moderate" to "Severe" drought.
The state drought monitor is updated every Thursday- it can be
found here).

Taking a quick peek at the upcoming weekend reveals much cooler
daytime and nighttime temperatures. It is worth noting that the 
lowest maximum temperature for both Saturday (19th) and Sunday
(20th) at Blue Hill is 55 degrees. The forecast calls for 60 
degrees or so both days...worth watching!

The high so far today is 63F, 8 degrees below the daily
normal max of 71F. The low since midnight is 55F, which
is 1 degree above the normal low of 54F.


Today's Observations:

7 A.M.
Weather: Overcast Stratus Fractus
Temperature: 55F; Dew Point: 49F; Relative Humidity: 79%
Wind: NNE at 13G17 kts 
Sea-level pressure: 29.99 ins. Hg: falling, then falling more slowly
Visibility: 35 miles (thin fog)
6-hr Max temp: 58F
6-hr Min temp: 55F
24-hr Precip: 0.00 ins.
BHO SA 1155 E35 OVC 35 157/55/49/0313G17/999/ THN F ALQDS
8/6// 51017 10058 20055

10 A.M.
Weather: Overcast Stratocumulus (few cumulus E-SE AND SW-N)
Temperature: 59F; Dew Point: 45F; Relative Humidity: 58%
Wind: NNE at 12G19 kts
Sea-level pressure: 30.00 ins. Hg: rising, then falling
Visibility: 40 miles (hazy)
3-hr Precip: 0.00 ins.
BHO SA 1455 E38 OVC 40 160/59/45/0212G19/000/
FEW CU E-SE AND SW-N HAZY/ 8/4// 50003

1 P.M.
Weather: (Thin) Overcast Altostratus/Altocumulus (few cumulus
all quadrants, sun occasionally dimly visible)
Temperature: 63F; Dew Point: 46F; Relative Humidity: 52%
Wind: N at 9G17 kts
Sea-level pressure: 29.98 ins. Hg: falling unsteadily
Visibility: 45 miles (hazy)
6-hr Max temp: 63F
6-hr Min temp: 55F
6-hr Precip: 0.00 ins.
BHO SA 1755 E50 -OVC 45 152/63/46/3609G17/998/ FEW CU ALQDS
SUN OCLY DMLY VSBL HAZY/ 8/17/ 57008 10063 20055 


SUMMARY FOR THURSDAY, SEPTEMBER 17, 2020 

TEMPERATURE (DEGREES F)
MAX.....76   NORMAL.....71
MIN.....57   NORMAL.....54
MEAN....67   NORMAL.....63

DEPARTURE FROM 30-YEAR NORMAL................. +4
TOTAL DEPARTURE FOR THE MONTH.................+14 [+0.6 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY..............0  DEPARTURE......-4
TOTAL HEATING UNITS FOR THE MONTH.............26  DEPARTURE.....-13
TOTAL HEATING UNITS FOR THE SEASON............29  DEPARTURE.....-35
TOTAL HEATING UNITS LAST SEASON TO DATE.......55  DEPARTURE.....-26

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY............  2  DEPARTURE...... 0                   
TOTAL COOLING UNITS FOR THE MONTH............ 50  DEPARTURE..... +4
TOTAL COOLING UNITS FOR THE SEASON...........807  DEPARTURE....+224
TOTAL COOLING UNITS LAST SEASON TO DATE......647  DEPARTURE....+160

PEAK WIND GUST FOR YESTERDAY (MPH) 
                   420C/Official................26 WSW AT 10:19 A.M.  
                   AERO.........................28 W   AT 11:50 A.M. 
                   ASOS.........................27 SSW AT 12:15 A.M.
                   DAVIS........................27 WSW AT  8:39 A.M.
                   RMY N/A  MERLIN N/A
FASTEST MILE FOR YESTERDAY......................20 SW  AT 12:30 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE...................20 SSW AT 12:10 A.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE..................19 W   AT 11:52 A.M.
AVERAGE WIND SPEED AND DIRECTION..............11.4 WSW (273 total miles)        
                   ASOS.......................11.3
                   DAVIS......................11.5 WSW [252 deg.]

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..........0.51  DEPARTURE....-1.65
                         ASOS..............0.51
TOTAL PRECIPITATION FOR THE YEAR..........33.32  DEPARTURE....-3.86
                         ASOS.............34.09

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

09/01  76/59/68/0/0.00/.../..              22 SSE  AERO 21 SE   RMY 20
09/02  69/59/64/-4/.../.../..              23 SSE  AERO 23 SSE  RMY 24
09/03  75/66/71/+4/.../.../..              22 SSW  AERO 21 SSW  RMY N/A
09/04  82/62/72/+5/0.00/.../..             26 WNW  AERO 26 WNW  RMY 25
09/05  76/55/66/-1/0.00/.../..             25 W    AERO 25 W    RMY 24
09/06  78/58/68/+1/0.00/.../..             24 W    AERO 24 W    RMY N/A
09/07  79/61/70/+4/0.00/.../..             27 SSE  AERO 30 SSE  RMY 28
09/08  82/61/72/+6/0.00/.../..             17 S    AERO 16 S    RMY 17
09/09  80/62/71/+5/0.00/.../..             16 S    AERO 15 S    RMY 16
09/10  81/69/75/+10/0.28/.../..            21 SSW  AERO 21 SSW  RMY N/A
09/11  72/55/64/-1/0.01/.../..             25 N    AERO 25 N    RMY N/A
09/12  68/51/60/-5/0.00/.../..             21 ENE  AERO 21 ENE  RMY 21
09/13  74/53/64/0/0.00/.../..              26 SSW  AERO 26 SSW  RMY 26
09/14  74/50/62/-2/0.00/.../..             29 NNW  AERO 33 NNW  RMY 30
09/15  64/44/54/-10/0.00/.../..            18 S    AERO 18 S    RMY N/A
09/16  72/49/61/-2/0.00/.../..             31 SSW  AERO 31 SSW  RMY 31
09/17  76/57/67/+4/0.00/.../..             26 WSW  AERO 28 W    RMY N/A

09/18 The low since midnight is 55F, the daily normal low is 54F


DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):  

RECORDS FOR SEPTEMBER 18
HIGH 88F IN 1906
LOW 36F IN 1919
PRECIP 4.25 INCHES IN 1996
PEAK GUST 77e MPH WNW IN 1948

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 

TODAY'S REPORT PREPARED BY: Andrew Swanson