Wednesday, May 13, 2015

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

DAILY DISCUSSION AND CLIMATE SUMMARY
WEDNESDAY, MAY 13, 2015
ALL TIMES ARE IN EASTERN STANDARD TIME

THUNDERSTORM FORMS QUICKLY IN VICINITY LAST EVENING
LITTLE RAINFALL (0.10) LAST EVENING AT THE SUMMIT
DOWNPOUR ESPECIALLY 10 MI EAST OF THE OBSERVATORY
OVER 1/2 INCH RAIN IN 10-15 MINS. IN HINGHAM AREA

After some thunderstorms had passed eastward north of
Boston late yesterday afternoon, suddenly, and without
much warning a thunderstorm formed to the west of
Blue Hill just before 7 P.M. EDT and soon became a red
blip on the radar.  A cloud type of cumulonimbus mammatus
was observed to our east over Hingham as the storm was
forming and thunder and lightning and an intense downpour
soon followed hitting in north Hingham just after 7 p.m.
Pea size hail was observed and the downpour deposited 0.57
inch in only about 10 minutes from 7:10 to 7:20 P.M.
before quickly moving away to the east by 7:30 P.M.

A beautiful mid-May today with temperatures much more
seasonable than yesterday. Highs are in the 60’s instead
of the 80’s of yesterday, and dew points are down in the 40’s
compared to the summer-like 60’s of 24 hours ago.
Winds today have been gusty from the NW to WNW up to 25
to 35 MPH.

Today’s Observations:

7 A.M.
Weather: Scattered stratocumulus, broken altocumulus, mostly
clear sky south, few cumulus, few altocumulus lenticularis past hour
Temperature: 57F; Dew Point: 42F; Wind: WNW at 14G24 kts
Sea-level pressure: 29.89 ins. Hg, rising then more rapidly
Visibility: 50 miles, distant haze
6-hr Max temp: 57F
6-hr Min temp: 52F
24-hr precip: 0.10 inch
BHO SA 1155 40 SCT E70 BKN 50 121/57/42/3014G24/989/
MSTLY CLR SKY S FEW CU FEW ACSL PST HR/ 8/830 53019
ASOS 70009 MANUAL 70010 10057 20052

10 A.M.
Weather: Scattered cumulus, broken stratocumulus, mostly clear
sky distant E
Temperature: 65F; Dew Point: 43F; Wind: NW at 14G22 kts
Wind Speed: Light
Sea-level pressure: 29.95 ins. Hg, rising then more slowly
Visibility: 60 miles, distant haze, mountain 70 NW in cloud
BHO SA 1455 40 SCT E55 BKN 60 141/65/43/3214G22/995/
CLR SKY DSNT E FEW LWR CU MTN INCLD 70 NW LGT DSNT HZ/
8/800 51020

1 P.M.
Weather: Scattered cumulus, stratocumulus generated by
cumulus and stratocumulus
Temperature: 65F; Dew Point: 41F; Wind: NW at 17G23 kts,
Wind: Peak wind from NW at 26 kts at 12:14 P.M.
Sea-level pressure: 29.97 ins. Hg, rising then more slowly
Visibility: 70 miles, distant haze
6-Hr Max temp: 67F
6-Hr Min temp: 57F
BHO SA 1755 50 SCT 70 149/65/41/3117G23/997/ CU/SC/SCCG
FEW MDT TOPS ALQDS PK WND 3226/14/ 8/800 51008 10067 20057

SUMMARY FOR TUESDAY, MAY 12, 2015

TEMPERATURE (DEGREES F)
MAX…..84   NORMAL…..65
MIN…..47   NORMAL…..47
MEAN….66   NORMAL…..56

DEPARTURE FROM 30-YEAR NORMAL………………….+10
TOTAL DEPARTURE FOR THE MONTH………………….+90 [+7.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL TO JUN)
TOTAL HEATING UNITS FOR YESTERDAY……………0  DEPARTURE……….-10
TOTAL HEATING UNITS FOR THE MONTH…………..53  DEPARTURE……….-80
TOTAL HEATING UNITS FOR THE SEASON………..6324  DEPARTURE………+157
TOTAL HEATING UNITS LAST SEASON TO DATE……6255  DIFFERENCE………+69

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY…………..1   DEPARTURE……….+1
TOTAL COOLING UNITS FOR THE MONTH………….16   DEPARTURE………+12
TOTAL COOLING UNITS FOR THE SEASON…………16   DEPARTURE………+10
TOTAL COOLING UNITS LAST SEASON TO DATE……..9   DIFFERENCE………+7

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………33 WNW   AT   9:56 P.M.
ASOS…………………..42 WNW   AT   9:56 P.M.
DAVIS………………….35 SSW   AT   4:09 P.M.  RMY 37
FASTEST MILE FOR YESTERDAY………………..26 WNW   AT   9:55 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE……………..26 WNW   AT   9:57 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….24 SW    AT   4:09 P.M.
AVERAGE WIND SPEED AND DIRECTION………….11.2 WSW
ASOS………………….11.1
DAVIS………………….9.5 W [270 deg.] * Last of several occurrences…

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…..0.10  DEPARTURE…..-0.03
ASOS……………0.09
TOTAL PRECIPITATION FOR THE MONTH………..0.27  DEPARTURE…..-1.20
ASOS……………0.26
TOTAL PRECIPITATION FOR THE YEAR………..18.19  DEPARTURE…..-1.70
ASOS…………….N/A ***
*** ASOS annual totals not available due to erroneous readings

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…………..150.8  DEPARTURE….+88.1

PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/SUN(MIN.)/SUN(%)/ PEAK GUST/RMY 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

5/1  52/37/45/-8/0.00/0.0/…/..               21 NE  RMY 20
5/2  63/35/49/-4/0.00/0.0/…/..               20 S   RMY 20
5/3  74/44/59/+6/0.00/0.0/…/..               22 S   RMY 22
5/4  83/47/65/+11/0.00/0.0/…/..              39 SSW RMY 45
5/5  77/56/67/+13/0.03/0.0/…/..              29 SW  RMY N/A
5/6  74/54/64/+10/0.00/0.0/…/..              24 SSW RMY 25
5/7  84/52/68/+13/0.00/0.0/…/..              29 S   RMY 32
5/8  74/44/59/+4/0.00/0.0/…/..               27 NNE RMY 26
5/9  77/44/61/+6/0.00/0.0/…/..               30 S   RMY 32
5/10 88/60/74/+19/0.00/0.0/…/..              28 SSW RMY 30
5/11 84/48/66/+10/0.00/0.0/…/..              30 NE  RMY 31
5/12 84/47/66/+10/0.24/0.0/…/..              33 WNW RMY 37

5/13 low since midnight is 52F; normal low now 47F

DAILY RECORDS FOR MAY 2015

NONE SO FAR

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

RECORDS FOR MAY 13
HIGH 85F IN 1947
LOW 35F IN 1914, 2005
PRECIP 2.39 INCHES IN 2006
PEAK GUST 49 MPH NNW IN 1965

RECORDS FOR MAY 14
HIGH 85F IN 1961
LOW 33F IN 1895
PRECIP 1.93 INCHES IN 2006
PEAK GUST 53 MPH S IN 2009

TODAY’S REPORT PREPARED BY: Robert Skilling