BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA   DAILY DISCUSSION AND CLIMATE SUMMARY TUESDAY, NOVEMBER 20, 2007 ALL TIMES ARE IN EASTERN STANDARD TIME   ADDITIONAL SNOWFALL TODAY AMOUNTS TO 0.7 INCH THRU 1 P.M.   FIRST MEASURABLE SNOWFALL OF THE SEASON YESTERDAY WAS EXACTLY ON THE AVERAGE DATE FOR FIRST MEASURABLE SNOWFALL FOR THE PERIOD 1891-2000!   Light snow began at 9:45 A.M. and had amounted to 0.7 inch on the snow boards while pavement and rocky surfaces remained just wet as of 1 P.M.    A total of 0.1 inch of snowfall occurred early last evening between 6 and 7 p.m. here at the summit. It was our first measurable snowfall this season after several hours with traces of light snow grains had occurred during the day. Coincidentally our first measurable snowfall this season came right on the average date for same, November 19. This average date is based on the period 1891-2000.     Last year the first measurable snowfall did not occur until 3.2 inches was recorded on December 4, 2006. Not even a trace was observed during October or November.   The long term average snowfall (1891-2000) for November is 2.7 inches.   Today's observations:   7 A.M.   Weather: Broken altotratus, overcast cirrostratus, break in overcast distant NE-SE, patches thin fog below inversion     Temperature: 32F, Dew point: 25F, Wind: ESE at 08 kts Sea-level pressure: 30.25 inches Hg, falling Visibility: 25 miles, NE 30 miles 6-hour min temp: 29F 24-hour precip: 0.01 in.; snowfall 0.1 in. BHO SA 1155 E150 BKN 220 OVC 25 243/32/25/1208/025/ SC DSNT N-ESE BINOVC/CLR SKY BND DSNT NE-SE PTCHY THN F BLO INVSN TOTAL NEW SNW PST 24 HRS 0.1 IN/ 8/016 56014 MANUAL 70001 ASOS 70001 10032 20029   10 A.M.   Weather: Overcast nimbostratus and with break in overcast distant E-ESE; very light snow began at 9:45 A.M.   Temperature: 34F, Dew point: 27F, Wind: SSE at 09 kts Sea-level pressure: 30.20 inches Hg, rising Visibility: 20 miles, 10 miles SW-NW, 40 miles NE-SE 3-hourly precip: trace, and trace of snow BHO SA 1455 E40 OVC 20S- 228/34/27/1609/020/ FEW SC DSNT NE-ESE BINOVC/HIER CLD VSB DSNT E-ESE VSBY SW-NW 10 AND LWRG PCPN/SNW ADVCNG VSBY NE-SE 40 THN K LYR N-NE WND GRDLY VEERING SB45 PCPN VRY LGT/ 8/52/ 55015 MANUAL 6000/    1 P.M.   Weather: Sky obscured with light snow and heavy fog Temperature: 32F, Dew point: 32F, Wind: SE at 10 kts Sea-level pressure: 30.12 inches Hg, falling  Visibility: 1/16 mile, light snow and heavy fog 6-hourly precip: n/a; ASOS 0.09; snowfall 0.7 inch 6-hourly max. temp. 34F BHO SA 1755 W2 X 1/16S-F 201/32/32/1310/012/ TOTAL NEW SNW PST 6 HRS 0.7 IN/ 8//// 56027 ASOS 60009 MANUAL 6XXX/ 10034 20032   WEATHER SUMMARY FOR MONDAY, NOVEMBER 19   TEMPERATURE (DEGREES F) MAX.....36    NORMAL.....48 MIN.....30    NORMAL.....33 MEAN....33    NORMAL.....41 DEPARTURE FROM 30-YEAR NORMAL...........-8 TOTAL DEPARTURE FOR THE MONTH..........-43 [-2.5 DEGREES/DAY]   HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............32  DEPARTURE.......+8 TOTAL HEATING UNITS FOR THE MONTH...........416  DEPARTURE......+42 TOTAL HEATING UNITS FOR THE SEASON..........794  DEPARTURE.....-203 TOTAL HEATING UNITS LAST SEASON TO DATE.....821  DIFFERENCE.....-27   PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY............28 N   AT 10:03 A.M.                        AEROVANE.............26 N   AT 10:03 A.M.                        ASOS.................25 N   AT 10:03 A.M.                        DAVIS................25 N   AT 10:30 A.M.     FASTEST MILE FOR YESTERDAY..............17 N   AT  9:07 A.M.         MAXIMUM 2-MINUTE ASOS AVERAGE...........16 N   AT 12:27 P.M.    MAXIMUM 2-MINUTE DAVIS AVERAGE..........17 N   AT 12:26 P.M.    AVERAGE WIND SPEED AND DIRECTION...... 9.1 N                    ASOS............... 9.1                     DAVIS.............. 9.4 N [350 deg]      PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.01  DEPARTURE....-0.15                          ASOS..............0.01 TOTAL PRECIPITATION FOR THE MONTH..........2.92  DEPARTURE....-0.04                          ASOS..............2.90  TOTAL PRECIPITATION FOR THE YEAR..........38.46  DEPARTURE....-6.52                          ASOS.............37.73     SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.1  DEPARTURE..... 0.0 TOTAL SNOWFALL FOR THE MONTH................0.1  DEPARTURE.....-1.5 TOTAL SNOWFALL FOR THE SEASON...............0.1  DEPARTURE.....-1.7   PRELIMINARY CLIMATE SUMMARY FOR NOVEMBER 2007...CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW*/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST   AERO: Aerovane recording wind system when significant TSTM: Thunderstorm day ....: Data not yet available   * entries beginning 19th   11/1  66/42/54/+7/0/050/08         37 S 11/2  50/37/44/-2/0/446/73         29 NE 11/3  46/40/43/-3/0.95/000/00      51 N   Aero 50 MPH NNW  11/4  54/37/46/0/0/503/82          33 W   Aero 33 MPH W    11/5  56/40/48/+3/0/483/79         29 SE 11/6  53/37/45/0/0.75/000/00       35 SSE Aero 35 MPH SSE  11/7  50/32/41/-4/0/551/91         30 W 11/8  43/28/36/-8/0/494/82         22 W 11/9  44/32/38/-6/0.09/331/55      21 NNE 11/10 39/28/34/-10/0.05/383/64     32 N 11/11 42/24/33/-10/0/590/99        23 WNW 11/12 42/27/35/-8/0.02/024/04      25 SSE 11/13 55/42/49/+6/0.33/308/52      28 S 11/14 58/41/50/+8/0/.../..         37 S 11/15 64/40/52/+10/N/A/.../..      44 SSE Aero 46 MPH SSE 11/16 44/30/37/-5/N/A/.../..       51 W   Aero 54 MPH W 11/17 40/28/34/-7/0/.../..         37 W 11/18 41/29/35/-6/0/.../..         25 ENE 11/19 36/30/33/-8/0.01/0.1/000/00  29 N   11/20 morning low temp. 29F; the normal low is now 33F        NEW DAILY RECORDS FOR NOVEMBER 2007: NONE   DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated):   RECORDS FOR NOVEMBER 20 HIGH 72 IN 1953 LOW 10 IN 1894 PRECIP 2.78 INS IN 1988 SNOWFALL 3.0 INS IN 1897 PEAK GUST 73e S IN 1950   RECORDS FOR NOVEMBER 21 HIGH 69 IN 1931 LOW 10 IN 1888 PRECIP 2.60 INCHES IN 1950 SNOWFALL 4.0 INS IN 1929 PEAK GUST 69 NW IN 1989   TODAY'S REPORT PREPARED By: Robert Skilling