BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS 02186
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
 
DAILY DISCUSSION AND CLIMATE SUMMARY
MONDAY, JULY 9, 2007   
ALL TIMES ARE IN EASTERN STANDARD TIME
 
HOT WITH LOW TO MODERATE HUMIDITY ON SUNDAY
BACK-DOOR COLD FRONT BROUGHT RAPID TEMPERATURE DROP
COOL MARITIME AIR REPLACED BY BY WARM, HUMID TODAY
 
A back-door type cold front quickly put an end to the
very warm to hot weather yesterday after the temperature 
briefly touched 90 degrees. Humidity was low to moderate 
with dewpoints in the upper 50's. The late afternoon 
frontal passage sent the thermometer skidding down up to
17 degrees per hour bottoming out at 62 degrees during 
last evening with east winds prevailing. 
 
Thunder and rain showers accompanied the frontal passage 
with 0.41 inch of rainfall through midnight.
 
The frontal system returned moving back north of us this
morning with temperatures rising back to 80 degrees. The 
humidity increased dramatically with the dewpoint up to  
the low 70's by early this afternoon. 
 
Today's observations:
 
7 A.M.   
Weather: High overcast dense cirrus   
Temperature: 64F, Dew point: 62F, Wind: ENE at 07 kts 
Sea-level pressure: 29.96 inches Hg, rising
Visibility: 2 miles in fog, ESE-WSW 7 miles    
6-hour min temp: 62F     
24-hour rainfall: 0.54 inch 
BHO SA 1155 130 SCT E200 OVC 2F 147/64/62/0707/996/ 
STRA LYR XTDNG W-N-E BASES BLO SMT FEW ACC 
DENSE CI OVC SUN DMLY VSB VSBY W-N-E 2 ESE-WSW 7 
THN F/ 8/087 53017 ASOS 60012 MANUAL 6014/ 
ASOS 70051 MANUAL 70054 10064 20062
 
1 P.M. 
Weather: High thin broken clouds, hazy  
Temperature: 78F, Dew point: 70F, Wind: S at 07 kts 
Sea-level pressure: 29.91 inches Hg, falling 
Visibility: 7 miles, 8 miles SW, hazy 
6-hourly rainfall: 0.07 inch     
BHO SA 1755 220 SCT 250 –BKN 7 128/78/70/1707/991/ FEW SC NE
FEW AC N-NE FEW LWR DENSE CI N-NE VSBY SW 8 HAZY ALQDS/ 8/542 
58004 ASOS 60006 MANUAL 6007/ 10078 20064
 
WEATHER SUMMARY FOR SUNDAY, JULY 8
 
TEMPERATURE (DEGREES F)
MAX.....90    NORMAL.....81 
MIN.....62    NORMAL.....61
MEAN....76    NORMAL.....71
DEPARTURE FROM 30-YEAR NORMAL........+5
TOTAL DEPARTURE FOR THE MONTH.......-18  (-2.5 DEGREES/DAY)
 
PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY..............36 NW AT 3:55 P.M.     
                   AEROVANE...............33 NW AT 3:55 P.M.   
                   ASOS...................N/A  #
                   DAVIS..................33 NW AT 3:55 P.M.        
FASTEST MILE FOR YESTERDAY................25 NW AT 3:57 P.M.      
MAXIMUM 2-MINUTE ASOS AVERAGE.............N/A  # 
MAXIMUM 2-MINUTE DAVIS AVERAGE............25 NW AT 3:57 P.M.          
AVERAGE WIND SPEED AND DIRECTION........13.3 SW 
                   ASOS...................N/A  #
                   DAVIS................13.4 SW [220 deg]  
 
# ASOS WINDS SWITCHED OFF BY NWS 6/6, IT IS NOT KNOWN WHEN 
THAT DATA WILL RESUME
 
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.54  DEPARTURE.....+0.42
                         ASOS..............0.51  
TOTAL PRECIPITATION FOR JULY...............0.91  DEPARTURE.....-0.07 
                         ASOS..............0.84    
TOTAL PRECIPITATION FOR THE YEAR..........27.89  DEPARTURE.....+1.24 
                   ASOS FOR YEAR..........27.25    
 
PRELIMINARY CLIMATE SUMMARY FOR JULY 2007......CALENDAR DAY DATA
DATA REPORTED:
DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST
 
AERO: Aerovane recording wind system when significant
TSTM: Thunderstorm day
....: Data not yet available
 
7/1  70/52/61/-9/0.02/649/71/28 W      
7/2  73/50/62/-8/0/841/92/   29 WNW 
7/3  75/53/64/-6/0/839/92/   23 NW 
7/4  78/58/68/-2/0.09/465/51/45 SSE 
7/5  80/61/71/ 0/0.24/383/42/38 SSE
7/6  83/62/73/+2/0.01/.../../46 WNW
7/7  81/60/71/0/0/.../../    32 WSW
7/8  90/62/76/+5/0.41/.../../36 NW Aero 33 MPH TSTM
 
7/9  morning low temp. 62 deg; normal low now 61 deg. 
     early morning rainfall: 0.13; 0.07 after 7 a.m. 
     early morning TSTM; total rainfall since midnight
     is 0.20 inch.
 
NEW DAILY RECORDS FOR JULY 2007: 
 
None to date
 
DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):
 
RECORDS FOR JULY 9
HIGH 98F IN 1912
LOW 47F IN 1909
PRECIP 3.74 INCHES IN 1921
WIND 46 MPH NW IN 1992
 
RECORDS FOR JULY 10
HIGH 99F IN 1911
LOW 46F IN 1890
PRECIP 1.68 INS IN 1933
WIND 75 MPH W IN 1985
 
TODAY'S REPORT PREPARED By: Robert Skilling