Wednesday, September 30, 2020

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

WEDNESDAY, SEPTEMBER 30, 2020
ALL TIMES ARE IN EASTERN STANDARD TIME

QUITE STORMY THIS MORNING WITH COLD FRONTAL PASSAGE, MUCH
NICER AFTERNOON….

The big story today is of course the big wind gusts we
observed this morning. The official gust on our F420C wind
system is 71 mph from the S at 6:48 A.M. This also sets a
new record wind gust for the date beating the old record
of 58 mph SSE in 1999. Our various wind systems were in
pretty good respective agreement in relation to which
tower they were on. Here is the listing…

Observatory tower:
F420C (official): 71 mph
ASOS…………: 72 mph
Davis #1……..: 71 mph
RM Young……..: 71 mph
Merlin……….: 71 mph

South Auxiliary tower:
Aerovane……..: 88 mph
Davis #2……..: 89 mph

It should be noted the instrumentation on the south tower
is at the same height as the instrumentation on the
Observatory.

The wind was associated with a strong cold front moving
through the region helping to push the warm and humid air
mass out. The dew point, which was in the low 70s early
this morning has returned to much more comfortable levels
in the low 50s this afternoon.

The front also brought much needed rain to the region this
morning with 1.01″ storm total being measured here on the
summit.

Despite the rainfall, we are still under the influence of
a severe drought, with some parts of the region in extreme
drought. The rainfall total for the month is up to 1.61″,
but this is still more than 2 inches below normal. For the
year to date, we are still more than 4.50″ below normal.

The high so far today is 72F, 6 degrees above the daily
normal max of 66F. The low since midnight is 61F, which
is 12 degrees above the normal low of 49F.

Today’s Observations:

7 A.M.
Weather: Broken stratus fractus, overcast nimbostratus,
light rain shower
Temperature: 71F; Dew Point: 69F; Relative Humidity: 94%
Wind: S at 39G62 kts, peak wind S 62 kts at 6:48 A.M.
Sea-level pressure: 29.45 ins. Hg: falling, then more rapidly
Visibility: 6 miles, 4 miles S, 10 miles N-NE
6-hr Max temp: 72F
6-hr Min temp: 70F
24-hr Precip: 0.91 ins.
BHO SA 1155 E10 BKN 22 OVC 6RW-F 974/71/69/1839G62/945/
VSBY 4 S 10 N-NE PK WND 1862/48/ 8/7// 58028 6090 70091
10072 20070

10 A.M.
Weather: Overcast Stratus, moderate rain shower
Temperature: 61F; Dew Point: 61F; Relative Humidity: 100%
Wind: W at 20G33 kts, wind shift, peak wind SSW 39 kts at 9:07 A.M.
Sea-level pressure: 29.55 ins. Hg: rising, then more slowly
Visibility: 2 miles, fog
3-hr Precip: 0.10 ins.
BHO SA 1455 E10 OVC 2RWF 006/61/61/2620G33/955/ RWB48
WSHFT 45 PK WND 2039/07/ 8/6// 51032 6010

1 P.M.
Weather: Broken cumulus/stratocumulus, broken altocumulus,
thin broken cirrus, cumulonimbus distant NNE
Temperature: 69F; Dew Point: 53F; Relative Humidity: 56%
Wind: WSW at 22G33 kts, peak wind W 39 kts at 12:32 P.M.
Sea-level pressure: 29.60 ins. Hg: rising, then more rapidly
Visibility: 70 miles
6-hr Max temp: 71F
6-hr Min temp: 61F
6-hr Precip: 0.11 ins.
BHO SA 1755 E35 BKN 140 BKN 250 -BKN 70 023/69/53/2422G33/960/
SML CB DSNT NNE RW DSNT NNE MVG E PK WND 2639/32/ 8/332 53017
6011 10071 20061

SUMMARY FOR TUESDAY, SEPTEMBER 29, 2020

TEMPERATURE (DEGREES F)
MAX…..76 NORMAL…..67
MIN…..62 NORMAL…..49
MEAN….69 NORMAL…..58

DEPARTURE FROM 30-YEAR NORMAL…………….+11
TOTAL DEPARTURE FOR THE MONTH…………….+27 [+0.7 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY…………. 0 DEPARTURE….. -8
TOTAL HEATING UNITS FOR THE MONTH………….94 DEPARTURE…..-15
TOTAL HEATING UNITS FOR THE SEASON…………97 DEPARTURE…..-37
TOTAL HEATING UNITS LAST SEASON TO DATE…….84 DEPARTURE…..+13

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………. 4 DEPARTURE….. +3
TOTAL COOLING UNITS FOR THE MONTH………… 73 DEPARTURE…..+14
TOTAL COOLING UNITS FOR THE SEASON………..830 DEPARTURE….+234
TOTAL COOLING UNITS LAST SEASON TO DATE……680 DEPARTURE….+150

PEAK WIND GUST FOR YESTERDAY (MPH)
420C/Official…………….30 S AT 11:41 P.M.
AERO…………………….30 S AT 11:59 P.M.
ASOS…………………….31 S AT 11:41 P.M.
DAVIS……………………32 S AT 11:53 P.M.
RMY N/A MERLIN N/A
FASTEST MILE FOR YESTERDAY………………….22 S AT 11:58 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………….21 S AT 11:56 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE………………22 S AT 11:41 P.M.
AVERAGE WIND SPEED AND DIRECTION…………..11.2 S (269 total miles)
ASOS…………………..11.2
DAVIS………………….10.6 S [191 deg.]

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.91 DEPARTURE….+0.76
ASOS…………..0.98
TOTAL PRECIPITATION FOR THE MONTH……….1.50 DEPARTURE….-2.42
ASOS…………..1.54
TOTAL PRECIPITATION FOR THE YEAR……….34.31 DEPARTURE….-4.63
ASOS………….35.12

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 76/59/68/0/0.00/698/88 22 SSE AERO 21 SE RMY 20
09/02 69/59/64/-4/0.18/102/13 23 SSE AERO 23 SSE RMY 24
09/03 75/66/71/+4/0.04/000/00 22 SSW AERO 21 SSW RMY N/A
09/04 82/62/72/+5/0.00/763/98 26 WNW AERO 26 WNW RMY 25
09/05 76/55/66/-1/0.00/760/98 25 W AERO 25 W RMY 24
09/06 78/58/68/+1/0.00/356/46 24 W AERO 24 W RMY N/A
09/07 79/61/70/+4/0.00/632/82 27 SSE AERO 30 SSE RMY 28
09/08 82/61/72/+6/0.00/545/71 17 S AERO 16 S RMY 17
09/09 80/62/71/+5/0.00/214/28 16 S AERO 15 S RMY 16
09/10 81/69/75/+10/0.28/015/02 21 SSW AERO 21 SSW RMY N/A
09/11 72/55/64/-1/0.01/152/20 25 N AERO 25 N RMY N/A
09/12 68/51/60/-5/0.00/666/88 21 ENE AERO 21 ENE RMY 21
09/13 74/53/64/0/0.00/611/81 26 SSW AERO 26 SSW RMY 26
09/14 74/50/62/-2/0.00/511/68 29 NNW AERO 33 NNW RMY 30
09/15 64/44/54/-10/0.00/583/78 18 S AERO 18 S RMY N/A
09/16 72/49/61/-2/0.00/603/81 31 SSW AERO 31 SSW RMY 31
09/17 76/57/67/+4/0.00/453/61 26 WSW AERO 28 W RMY N/A
09/18 64/48/56/-6/0.00/163/22 28 NE AERO 30 NNW RMY N/A
09/19 59/42/51/-11/0.00/722/98 23 N AERO 23 N RMY N/A
09/20 58/40/49/-13/0.00/602/82 25 NE AERO 25 NE RMY 27
09/21 61/41/51/-10/0.00/…/.. 29 NE AERO 27 NE RMY 29
09/22 63/39/51/-10/0.00/…/.. 28 NNW AERO 30 NNW RMY 29
09/23 78/50/64/+4/0.00/…/.. 31 NW AERO 32 WNW RMY 32
09/24 76/57/67/+7/0.00/…/.. 20 SW AERO 18 WSW RMY 19
09/25 77/57/67/+7/0.00/…/.. 18 ENE AERO 18 WSW RMY N/A
09/26 77/57/67/+8/0.00/…/.. 21 S AERO 21 S RMY 21
09/27 79/64/72/+13/0.01/…/.. 24 S AERO 25 S RMY 24
09/28 78/64/71/+13/0.07/…/.. 24 SSE AERO 24 S RMY 25
09/29 76/62/69/+11/0.01/…/.. 30 S AERO 30 S RMY N/A