BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
TUESDAY, MAY 19, 2009 
ALL TIMES ARE IN EASTERN STANDARD TIME
 
HIGH CLOUDS CLEAR AWAY EARLY THIS MORNING
CLEAR AND SUNNY WITH RISING TEMPERATURES
THROUGH THE 60'S BY EARLY AFTERNOON
 
A deck of high clouds remained over us last
night and early this morning preventing ex-
pected strong radiational cooling and frost
overnight. Low temperatures were generally
in the middle and upper 30's even in the
usual cold spots so there appeared to be no
late season frost. The low reading at nearby
Norwood Airport was 35F while Taunton and
Plymouth both had 38F.  Today's warmer
temperatures in the 60's included very low
humidity dropping into the 20% range.
 
Today's observations:
 
7 A.M.  
Weather: Scattered dense cirrostratus layer extending from
the east-northeast to south-southwest 
Temperature: 48F, Dew point: 36F, Wind: NW at 6 kts
Sea-level pressure: 30.43 inches Hg, rising
Visibility: 60 miles, 70 miles northwest,
thin smoke layer along horizon S-SW and W-N 
6-hour minimum temp: 42F
24-hour precipitation: 0.04 inch
BHO SA 1155 200 SCT 60 306/48/36/3106/043/ DENS CS LYR XTDNG
ENE-SSW THN K LYR ALG HRZN S-SW AND W-N VSBY NW 70/ 8/008 51021
MANUAL 70004 ASOS 70003 10048 20042
 
10 A.M.  
Weather: Clear, few stratocumulus distant ESE and
dense cirrostratus layer distant ENE-SSW  
Temperature: 58F, Dew point: 32F, Wind: WNW at 8 kts,
Wind: direction variable WSW to NNW 
Sea-level pressure: 30.42 inches Hg, falling
Visibility: 60 miles, 70 miles northwest 
BHO SA 1455 CLR 60 303/58/32/3008/042/ FEW SC DSNT ESE
DENS CS LYR DSNT ENE-SSW VSBY NW 70 WND 25V33/ 8/508 58003
 
1 P.M.  
Weather: Clear, dense cirrostratus layer distant
east thru south, few thin cirrus W-NNW
Temperature: 65F, Dew point: 30F, Wind: SSW at 8 kts,
Wind: direction variable SSE to WSW
Sea-level pressure: 30.38 inches Hg, falling
Visibility: 60 miles, 70 miles northwest
6-hour maximum temp: 66F
BHO SA 1755 CLR 60 289/65/30/2108/038/ DENS CS LYR DSNT E-S
FEW THN CI W-NNW VSBY NW 70 WND 16V25/ 8/008
58014 10066 20048
 
WEATHER SUMMARY FOR MONDAY, MAY 18
 
TEMPERATURE (DEGREES F)
MAX.....53    NORMAL.....68
MIN.....42    NORMAL.....48
MEAN....48    NORMAL.....58
 
DEPARTURE FROM 30-YEAR NORMAL..........-10
TOTAL DEPARTURE FOR THE MONTH..........+34 [+1.7 DEGREES/DAY]
 
HEATING DEGREE DAYS
TOTAL HEATING UNITS FOR YESTERDAY............17  DEPARTURE.......+9
TOTAL HEATING UNITS FOR THE MONTH...........148  DEPARTURE......-42
TOTAL HEATING UNITS FOR THE SEASON.........6044  DEPARTURE.....-172
TOTAL HEATING UNITS LAST SEASON TO DATE....5824  DIFFERENCE....+220
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY............27 NE  AT  8:57 A.M.
                   AEROVANE.............25 NE  AT  8:57 A.M. 
                   ASOS.................25 NE  AT  8:58 A.M.  
                   DAVIS................26 WNW AT 12:20 A.M. 
FASTEST MILE FOR YESTERDAY..............16 WNW AT 12:07 A.M. 
MAXIMUM 2-MINUTE ASOS AVERAGE...........16 NE  AT  8:58 A.M. 
MAXIMUM 2-MINUTE DAVIS AVERAGE..........18 WNW AT 12:11 A.M.
AVERAGE WIND SPEED AND DIRECTION....... 7.0 NE
                   ASOS.................6.6
                   DAVIS................7.2 N [000 DEG]
 
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.04  DEPARTURE....-0.08
                         ASOS..............0.03
TOTAL PRECIPITATION FOR THE MONTH..........2.38  DEPARTURE....+0.17
                         ASOS..............2.37 
TOTAL PRECIPITATION FOR THE YEAR..........16.99  DEPARTURE....-3.17
                         ASOS.............18.05 
 
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..............78.9  DEPARTURE.....18.8 
 
PRELIMINARY CLIMATE SUMMARY FOR MAY 2009 CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
AERO: Aerovane recording wind system gust when significant
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
 
5/1  64/53/59/+7/T/000/00          37 SSW   AERO 37 MPH SSW
5/2  68/52/60/+8/0.05/263/31       32 WNW
5/3  64/48/56/+3/T/068/08          25 S
5/4  64/48/56/+3/0.01/009/01       17 SSW
5/5  52/44/48/-5/0.95/000/00       43 NNE   AERO 40 MPH NNE
5/6  63/43/53/-1/0.40/189/22       24 SSE  
5/7  68/49/59/+5/0.60/009/01       29 S    
5/8  75/52/64/+10/0/690/80         28 S
5/9  71/55/63/+8/0.13/104/12       31 W     TSTM
5/10 65/46/56/+1/0/840/97          53 W     Aero 50 MPH W
5/11 63/41/52/-3/0/781/90          24 WNW
5/12 63/45/54/-2/0/696/80          22 ENE
5/13 70/45/58/+2/0/732/84          31 SSE   AERO 29 MPH SSE
5/14 62/47/55/-2/0.10/166/19       53 S     AERO 52 MPH S
5/15 76/54/65/+8/0/474/54          38 S     AERO 38 MPH S
5/16 68/54/61/+4/0/.../..          35 S     AERO 35 MPH S
5/17 61/49/55/-2/0.09/009/01       35 WNW   AERO 33 MPH WNW
5/18 53/42/48/-10/0.04/.../..      27 NE   
 
5/19 our morning low temp: 42F; the normal low is now 48F
 
NEW DAILY RECORDS FOR MAY 2009...
5/14: RECORD PEAK WIND GUST 53 MPH S;
      surpasses previous record of 50 MPH SW in 1976
 
DAILY EXTREMES
 
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
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
 
RECORDS FOR MAY 20
HIGH 91F IN 1975,1996
LOW 37F IN 1948, 2002
PRECIP 1.65 INCHES IN 1969
PEAK GUST 57 MPH S IN 1963, WNW IN 1982
 
TODAY'S REPORT PREPARED BY: Robert Skilling