BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, MAY 11, 2010 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
COLD TEMPERATURES FOR MAY DROP TO THE
MID 30'S THREE CONSECUTIVE MORNINGS
 
After a very warm start to this month our
temperatures have turned sharply downward over
the past several days.  This morning's low of
34F was slightly colder than the 35F just 24
hours ago.  The low readings have been several
degrees away from records, but the mean temperature
of 46F yesterday was 9 degrees below normal. On
the summit a persistent light breeze prevented
maximum radiational cooling from occurring overnight.
Otherwise, one could speculate that we may have
reached 32F or lower.  Many lowland areas did
dip to the freezing mark or below with calm winds
and adequate radiational cooling overnight.
 
Today has been a sunny, but another cool day.  The
high temperature through 1PM EDT is 57F, several
degrees below average.
 
Today's observations:
 
7 A.M.
Weather: Clear, few distant cumulus/stratocumuls
east-northeast thru south, cumulus/stratocumulus
dissipating, few distant high thin cirrus south thru
southwest, thin smoke layer north thru northeast
Temperature: 42F, Dew point: 28F, Wind: WNW at 5 kts
Wind: Light and variable
Sea-level pressure: 30.42 inches Hg, rising
Visibility: 70 miles   
6-hour minimum temp: 34F
BHO SA 1155 CLR 70 300/42/28/3005/042/ FEW DSNT CU/SC ENE-S
CU/SC DSSPTNG FEW DSNT THN CI S-SW THN K LYR N-NE
WND LGT AND VRB/ 8/801 51024 10042 20034
 
10 A.M.
Weather: High thin scattered cirrus, few distant cumulus
east-southeast thru south
Temperature: 49F, Dew point: 24F, Wind: NW at 7 kts,
Wind: Direction variable W-N
Sea-level pressure: 30.41 inches Hg, falling
Visibility: 70 miles
BHO SA 1455 250 –SCT 300 –SCT 70 298/49/24/3207/041/
FEW DSNT CU ESE-S WND 26V01/ 8/101 58002
 
1 P.M.
Weather: Scattered cirrostratus, broken high thin cirrus,
few distant cumulus south, few cirrocumulus north thru
southeast, cirrostratus layer southeast thru
west-northwest, partial halo
distant NNW-NE, altocumulus lenticularis distant NE-SE  
Temperature: 54F, Dew point: 23F, Wind: WNW at 7 kts,
Wind: Direction variable WSW-NNW
Sea-level pressure: 30.37 inches Hg, falling
Visibility: 70 miles
6-hourly max. temp: 57F
BHO SA 1755 250 SCT E300 BKN 70 286/54/23/3007/037/
FEW DSNT CU S FEW CC N-SE CS LYR SE-WNW PARTIAL HALO
WND 24V34/ 8/107 56012 10057 20042
 
WEATHER SUMMARY FOR MONDAY, MAY 10
 
TEMPERATURE (DEGREES F)
MAX.....57     NORMAL.....65
MIN.....35     NORMAL.....45
MEAN....46     NORMAL.....55
 
DEPARTURE FROM 30-YEAR AVERAGE...............-9
TOTAL DEPARTURE FOR THE MONTH................+79 [+7.7 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............19   DEPARTURE........+9
TOTAL HEATING UNITS FOR THE MONTH............56   DEPARTURE.......-62
TOTAL HEATING UNITS FOR THE SEASON.........5538   DEPARTURE......-606
TOTAL HEATING UNITS LAST SEASON TO DATE....5972   DIFFERENCE.....-434
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY.............31 WNW  AT   2:13 P.M. *
                   AEROVANE..............35 WNW  AT   8:40 A.M. 
                   ASOS..................32 NW   AT   8:40 A.M.       
                   DAVIS.................35 W    AT   8:39 A.M.          
THE FASTEST MILE FOR YESTERDAY...........23 WNW  AT   5:55 P.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE............22 WNW  AT  10:20 A.M.        
MAXIMUM 2-MINUTE DAVIS AVERAGE...........24 WNW  AT   2:14 P.M.             
AVERAGE WIND SPEED AND DIRECTION........13.8 W 
                   ASOS.................12.7
                   DAVIS................14.1 WNW [300 DEG] 
* last of several occurrences...
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00  DEPARTURE......-0.12
                         ASOS..............0.00
TOTAL PRECIPITATION FOR THE MONTH..........0.76  DEPARTURE......-0.50
                         ASOS..............0.75
TOTAL PRECIPITATION FOR THE YEAR..........31.12  DEPARTURE.....+11.91
                         ASOS.............31.20
 
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......-0.1
TOTAL SNOWFALL FOR THE SEASON..............64.4  DEPARTURE......+4.3
 
PRELIMINARY CLIMATE SUMMARY FOR MAY 2010 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane wind recording system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
5/1  81/58/70/+18/0.00/0.0/684/81   29 SE
5/2  87/56/72/+20/0.00/0.0/432/51   29 SSW
5/3  80/62/71/+18/T/0.0/170/20      41 W     AERO 50 MPH W
5/4  81/52/67/+14/0.09/0/562/66     51 WNW   AERO 58 MPH WNW TSTM
5/5  78/50/64/+11/0.00/0/845/99     28 S
5/6  76/54/65/+11/T/0/531/62        46 WNW   AERO 48 MPH WNW
5/7  72/47/60/+6/0.00/0/.../..      28 W
5/8  63/45/54/0/0.63/0/.../..       39 WSW   AERO 39 MPH WSW TSTM
5/9  53/37/45/-10/0.00/0/.../..     46 W     AERO 50 MPH W
5/10 57/35/46/-9/0.00/0/.../..      31 WNW   AERO 35 MPH WNW
 
5/11 our morning low temp: 34F; the normal low is now 45F
 
NEW DAILY RECORDS FOR MAY 2010
5/1 - minimum temp. of 58F equals record high
      minimum for the date set in 2001
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR MAY 11
HIGH 90F IN 1993
LOW 28F IN 1900
PRE 1.28 INS IN 1957
SNOW 1.0 INS IN 1907 (LATEST MEASURABLE SNOW ON RECORD)
PEAK GUST 75e MPH NW IN 1945
 
RECORDS FOR MAY 12
HIGH 88F IN 2001
LOW 29F IN 1907
PRECIP 1.49 INCHES IN 1968
PEAK GUST 76 MPH S IN 1974
 
TODAY'S REPORT PREPARED BY: Sean Fankhauser