BLUE HILL OBSERVATORY MILTON, MA MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, OCTOBER 22, 2010 ALL TIMES ARE IN EASTERN STANDARD TIME FIRST SNOWFALL OF THE SEASON! A trace of snow fell this morning as a mixture of snow particles and mostly melted snowflakes. There was no accumulation, but the trace amount equals the record amount of snowfall for today's date which occurred in 1969. A cold front passed through yesterday afternoon just after 3:30 PM EDT, bringing a wind gust of 55 MPH from the west, as recorded on our official 420C recorder. Several other wind systems recorded the gust over 60 MPH. The temperature dropped 7 degrees between 3:30 and 4:00 PM. The passage of the front brought brief light rain showers and mammatus clouds were observed in the vicinity of the Observatory. Today is a windy day on Great Blue Hill with frequent gusts over 40MPH, and a peak gust so far of 51 MPH which occurred shortly after 2PM EDT. Visibility has been between 70 and 80 miles for much of the day, although either virga or snowfall is currently obscuring our view of Grand Monadnock in Southern New Hampshire. Today's observations: 7 A.M. Weather: Scattered stratocumulus, few lower cumulus, virga SE Temperature: 36F, Dew point: 31F; Wind: W at 12G20 kts Wind: Peak gust 29 kts W at 6:42 A.M. Sea-level pressure: 29.83 inches Hg, rising Visibility: 70 miles 6-hour minimum temp: 34F 6-hour precipitation: 0.01 in. 24-hour precipitation: 0.08 in. 6-hour snowfall: Trace 24-hour snowfall: Trace BHO SA 1155 55 SCT 70 100/36/31/2612G20/983/ FEW LWR CU PK WND 2729/42 SW-SPW-BUKNE50 VIRGA ESE/ 8/500 53023 MANUAL 6001/ ASOS 70007 MANUAL 60008 10056 20034 10 A.M. Weather: Scattered stratocumulus scattered altocumulus Temperature: 44F, Dew point: 25F; Wind: W at 12G29 kts, Wind: Peak gust 29 kts W at 9:35 A.M. Wind: Direction variable SSW to NW Sea-level pressure: 29.86 inches Hg, rising Visibility: 80 miles BHO SA 1455 50 SCT 70 SCT 80 112/44/25/2712G29/986/ WND 21V31 PK WND 2629/35/ 8/530 51012 1 P.M. Weather: Broken altocumulus, virga distant W-NW Temperature: 46F, Dew point: 24F; Wind: W at 18G36 kts, Wind: Peak gust 37 kts W at 12:11 P.M. Wind: Direction variable SW to NNW Sea-level pressure: 29.84 inches Hg, falling Visibility: 75 miles, mountains to the northwest obscured in snow/virga 6-hour max. temp: 56F 6-hourly precip: 0.07 in. BHO SA 1755 E65 BKN 75 106/46/24/2618G36/984/ WND 22V34 PK WND 2637/11 VIRGA DSNT W-NW/ 8/500 58006 10047 20036 WEATHER SUMMARY FOR THURSDAY, OCTOBER 21 TEMPERATURE (DEGREES F) MAX.....56 NORMAL.....58 MIN.....39 NORMAL.....41 MEAN....48 NORMAL.....50 DEPARTURE FROM 30-YEAR NORMAL..............-2 TOTAL DEPARTURE FOR THE MONTH.............-16 [-1.0 DEGREE/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............17 DEPARTURE........+2 TOTAL HEATING UNITS FOR THE MONTH...........266 DEPARTURE.......+14 TOTAL HEATING UNITS FOR THE SEASON..........345 DEPARTURE.......-76 TOTAL HEATING UNITS LAST SEASON TO DATE.....485 DIFFERENCE.....-140 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............55 W AT 2:32 P.M. AEROVANE..............62 W AT 2:32 P.M. ASOS..................58 W AT 2:32 P.M. DAVIS.................61 W AT 2:32 P.M. THE FASTEST MILE FOR YESTERDAY...........41 W AT 2:31 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............38 W AT 2:32 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........40 W AT 2:33 P.M. AVERAGE WIND SPEED AND DIRECTION.......14.7 W ASOS................14.6 DAVIS...............13.4 SW [220 DEG] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M... 0.08 DEPARTURE........-0.06 ASOS..............0.07 TOTAL PRECIPITATION FOR THE MONTH..........5.58 DEPARTURE........+2.64 ASOS..............5.60 TOTAL PRECIPITATION FOR THE YEAR..........53.60 DEPARTURE.......+13.06 ASOS.............53.44** ** ASOS missing rainfall due to system failure on 6/24-25 PRELIMINARY CLIMATE SUMMARY FOR OCTOBER 2010 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/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 10/1 80/55/68/+11/0.56/035/05 55 SSE AERO 63 MPH SSE 10/2 65/46/56/0/0.00/688/98 28 WNW AERO 31 MPH WNW 10/3 55/43/49/-7/T/133/19 35 NNE AERO 39 MPH NNE 10/4 54/48/51/-5/0.78/000/00 39 NNE AERO 43 MPH NNE 10/5 57/51/54/-1/0.40/000/00 37 NE AERO 39 MPH NNE 10/6 57/49/53/-2/1.63/000/00 47 NE AERO 51 MPH NE 10/7 62/47/55/0/0.00/275/40 37 W AERO 40 MPH W 10/8 70/47/59/+5/0.00/610/89 35 WSW AERO 37 MPH WSW 10/9 62/43/53/-1/0.00/675/99 33 WNW AERO 37 MPH WNW 10/10 64/38/51/-3/0.00/679/100 25 SW AERO 29 MPH SSW 10/11 68/47/58/+5/0.00/542/80 28 W 10/12 61/43/52/-1/0.01/297/44 24 ENE 10/13 61/38/50/-2/0.00/663/99 18 NW 10/14 59/45/52/0/0.41/294/44 29 ENE 10/15 51/39/45/-7/1.71/033/05 48 WSW AERO 50 MPH WSW TSTM * 10/16 55/39/47/-4/0.00/544/82 47 WNW AERO 54 MPH WNW 10/17 63/38/51/0/0.00/581/88 43 W AERO 47 MPH W 10/18 57/41/49/-2/0.00/519/79 32 W AERO 35 MPH W 10/19 57/38/48/-3/0.00/497/76 21 W 10/20 61/44/53/+3/T/.../.. 21 S 10/21 56/39/48/-2/0.07/.../.. 55 W AERO 62 MPH W 10/22 our morning low temp: 34F; the normal low is now 41F NEW DAILY RECORDS FOR OCTOBER 2010 10/22: Daily snowfall: Trace; equals record set in 1969. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR OCTOBER 22 HIGH 85 IN 1979 LOW 22 IN 1940 PRECIP 1.37 INCHES IN 1898 SNOWFALL TRACE IN 1969 PEAK GUST 67 MPH ESE IN 1988 RECORDS FOR OCTOBER 23 HIGH 82 IN 1947 LOW 24 IN 1969 PRECIP 2.18 INCHES IN 1956 SNOWFALL 3.0 INCHES IN 1891 PEAK GUST 78e MPH NW IN 1941 TODAY'S REPORT PREPARED BY: Stephanie Radner