Thursday, May 18, 2023

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

THURSDAY, MAY 18, 2023
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0420E
SUNSET:  1902E

RECORD COLD START TO THE DAY, BUT SUNNY AND MILD THIS AFTERNOON…

The temperature dropped to 34F early this morning, setting a new
record low for the date, beating the previous record of 35F set
in 2002. As a matter of fact, this is the 2nd latest temperature
below 35F on record. Here is the list as provided by our Chief
Scientist Mike Iacono.

BHO Latest Minimum Temperatures Below 35 deg F (1885-2023):

1) 34 on 19 May 2002
2) 34 on 18 May 2023
3) 34 on 17 May 1956
34 on 17 May 1957
5) 30 on 16 May 1936
33 on 16 May 1917
7) 33 on 14 May 1895
34 on 14 May 1928

Also of note was the very low dew point readings last evening. We
calculated a dew point of 13F at 7pm last evening. This is quite
low for this time of year and indicative of an arctic air mass.

Despite the crisp start, the day has turned out to be quite
delightful with plenty of sunshine and temperatures that have
rebounded to the low to mid 60s. The air remains very dry however
with the dew point in the mid 20s and relative humidity levels
around 25%.

The wind has been light most of the day, but is starting to pick
up a bit this afternoon as mixing from aloft gets maximized. The
average speed has been around 8mph for the day so far.

Visibility has been excellent all day holding at around 70 miles.

The high so far today is 63F, which is 4 degrees below our normal
maximum temperature of 67F. Our low since midnight is 34F, which
is 15 degrees below our normal low temperature of 49F.

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Today’s Observations:

7 A.M.
Weather: Clear, few cirrus distant ESE-S, thin smoke layer aloft
distant N-E
Temperature: 45F; Dew Point: 22F; Relative Humidity: 40%
Wind: NW @ 4 kts, wind light
Sea-level pressure: 1025.3 mb; 30.28 in. Hg: rising, then more slowly
Visibility: 70 miles
6-hr Max temp: 45F
6-hr Min temp: 34F
24-hr Precip:  0.00 ins.
BHO SA 1155 CLR 70 253/45/22/3204/028/ FEW CI DSNT ESE-S
THN K LYR ALF DSNT N-E WND LGT/ 8/001 51025 10045 20034

10 A.M.
Weather: Clear, few cirrus distant W-N-NNE, thin smoke layer
aloft all quadrants
Temperature: 53F; Dew Point: 22F; Relative Humidity: 29%
Wind: NNW @ 5 kts, wind light and variable
Sea-level pressure: 1026.6 mb; 30.32 in. Hg: rising unsteadily
Visibility: 70 miles
3-hr Precip:  0.00 ins.
BHO SA 1455 CLR 70 266/53/22/3405/032/ FEW CI DSNT W-N-NNE
THN K LYR ALF ALQDS WND L/V/ 8/001 52013

1 P.M.
Weather: Clear, few cirrus all quadrants, thin smoke layer
aloft all quadrants
Temperature: 60F; Dew Point: 24F; Relative Humidity: 24%
Wind: W @ 6 kts, wind light and variable
Sea-level pressure: 1026.2mb; 30.30 in. Hg: falling, then more rapidly
Visibility: 70 miles
6-hr Max temp: 62F
6-hr Min temp: 45F
6-hr Precip:  0.00 ins.
BHO SA 1755 CLR 70 262/60/24/2606/030/ FEW CI ALQDS THN K LYR
ALF ALQDS WND L/V/ 8/001 58004 10062 20045

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SUMMARY FOR WEDNESDAY, MAY 17, 2023

TEMPERATURE (DEGREES F)
MAX…….62   NORMAL…..67
MIN…….37   NORMAL…..48
MEAN……50   NORMAL…..58

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL………-8
TOTAL DEPARTURE FOR THE MONTH………………..+43 [+2.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2022 THRU JUN 2023)
TOTAL HEATING UNITS FOR YESTERDAY……………15  DEPARTURE……..+7
TOTAL HEATING UNITS FOR THE MONTH…………..121  DEPARTURE…….-47
TOTAL HEATING UNITS FOR THE SEASON…………5092  DEPARTURE……-963
TOTAL HEATING UNITS LAST SEASON TO DATE…….5529  DEPARTURE……-437

COOLING DEGREE DAYS (SEASON: JAN 2023 THRU DEC 2023)
TOTAL COOLING UNITS FOR YESTERDAY…………….0  DEPARTURE……..-1
TOTAL COOLING UNITS FOR THE MONTH……………16  DEPARTURE……..+7
TOTAL COOLING UNITS FOR THE SEASON…………..25  DEPARTURE…….+13
TOTAL COOLING UNITS LAST SEASON TO DATE………24  DEPARTURE……..+1

PEAK WIND GUST (MPH):
Note: Instruments designated #1 = Main Tower, #2 = South Tower,
F420C, Contacting, Merlin, and Richards are all Main Tower.
E=Estimated

F420C (Official)……….E36 NNW @  02:09 P.M.
VECTOR #1 (1-Sec)……….37 NNW @  02:09 P.M.
VECTOR #2 (1-Sec)……….40 NNW @  02:08 P.M.
DAVIS #1……………….35 NW  @  02:09 P.M.
DAVIS #2 ………………35 NNW @  02:06 P.M.
RMY #1 (Instantaneous)…..40 NNW @  02:08 P.M.
RMY #2 (Instantaneous)…..42 NNW @  02:08 P.M.
MERLIN…………………35 N
RICHARDS (C5C) (Inst)……37     @  09:50 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………26 NNW @  02:11 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..26     @  02:10 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..25     @  02:10 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………27 NW  @  02:09 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………24 NNW @  02:10 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..26 NNW @  02:10 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..24 NNW @  02:10 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………26     @  02:10 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………14.0 NNW [336 total miles] VECTOR #1……………….13.6
VECTOR #2……………….13.9
DAVIS #1………………..13.8 NNW
DAVIS #2………………..13.9 N
RMY #1………………….13.1 NNW
RMY #2………………….12.6 NNW
RICHARDS (C5C)…………..13.7

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.12
TOTAL PRECIPITATION FOR THE MONTH…………..0.45 DEPARTURE…..-1.57
TOTAL PRECIPITATION FOR THE YEAR…………..18.65 DEPARTURE…..-2.15

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE…….0.0
TOTAL SNOWFALL FOR THE MONTH………………..0.0 DEPARTURE…….0.0
TOTAL SNOWFALL FOR THE SEASON (2022-2023)……34.9 DEPARTURE…..-34.8

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PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN)/SUN(%)/PEAK GUST/VEC1/RMY GUST
PEAK GUST: F420C (Official)
VEC1: Vector #1 1-second gust
RMY:  R.M. Young #1 wind gust recording system (Instantaneous)
TSTM: Thunderstorm day (thunder heard some time during day)
….: Data not yet available, records not finalized
M:    Missing data

5/1   63/45/54/+1/0.04/0.0/540/64         44 SSE  VEC1 46 SSE RMY 48
5/2   57/43/50/-4/0.22/0.0/144/17         33 S    VEC1 34 S   RMY 35
5/3   55/42/49/-5/0.01/0.0/093/11         25 E    VEC1 25 E   RMY 25
5/4   45/40/43/-11/0.07/0.0/009/01        29 NE   VEC1 29 NE  RMY 29
5/5   59/43/51/-4/0.07/0.0/367/43         18 NE   VEC1 19 NE  RMY 19
5/6   74/43/59/+4/0.00/0.0/847/99         25 NW   VEC1 26 NW  RMY 26
5/7   78/52/65/+10/0.01/0.0/789/92        26 WNW  VEC1 27 W   RMY 28
5/8   74/49/62/+7/0.03/0.0/800/93         32 NW   VEC1 33 NW  RMY 35
5/9   60/45/53/-3/0.00/0.0/819/95         24 NE   VEC1 25 NE  RMY 25
5/10  72/51/62/+6/0.00/0.0/830/96         25 WSW  VEC1 26 WSW RMY 26
5/11  81/53/67/+11/T/0.0/729/84           30 W    VEC1 30 W   RMY 30
5/12  84/57/71/+14/T/0.0/687/79           31 WNW  VEC1 35 WNW RMY 34
5/13  81/58/70/+13/0/0.0/715/82           28 NNW  VEC1 30 NNW RMY 35
5/14  66/47/57/0/0.00/0.0/822/94          28 NNW  VEC1 29 NNW RMY 31
5/15  72/45/59/+2/0.00/0.0/675/77         33 W    VEC1 35 W   RMY 34
5/16  80/55/68/+10/0.00/0.0/…/..        38 SW   VEC1 39 SW  RMY 41
5/17  62/37/50/-8/0.00/0.0/…/..         36 NNW  VEC1 37 NNW RMY 40

5/18 The low since midnight is 34F, the daily normal low is 49F

DAILY RECORDS

05/18/2023: NEW RECORD LOW MINIMUM TEMPERATURE OF 34F,
THIS BEATS THE OLD RECORD OF 35F SET IN 2002

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

RECORDS FOR MAY 18
HIGH 96F IN 2017(RECORD FOR MAY)
LOW 35F IN 2002
PRECIP 1.93 INS IN 2007
SNOW TRACE IN 2002 (Ice pellets)
PEAK GUST 64 MPH SSW IN 2000

RECORDS FOR MAY 19
HIGH 91F IN 1962
LOW 34F IN 2002
PRECIP 1.54 INCHES IN 1900
PEAK GUST 58 MPH NW IN 1964

TODAY’S REPORT PREPARED BY: Matt Douglas