BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, MAY 6, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME A LITTLE LATE AFTERNOON SUNSHINE SATURDAY LOWEST AVERAGE WIND SPEED IN RECORDS BACK TO 2000 LOW CLOUDS CLEAR BRIEFLY AFTER SUNRISE THIS MORNING The sun made its first appearance during the month of May to date late yesterday afternoon. In our long term record hourly average wind speeds are corrected up 1 MPH when speeds drop to 10 MPH or less to account for inertia (drag) on the 3-cup anemometer as has been used throughout the whole period of record here at Blue Hill. Only 94 miles (uncorrected) of wind blew passed the Observatory yesterday for an uncorrected daily average wind speed of 3.9 NE (uncorrected) as registered on our contacting wind system. This surpasses the previous low wind day of 4.0 WNW on January 22, 2007, in records checked back to 2000. (records are uncorrected for low winds) The wind average for May has now dropped to 7.3 MPH with two days so far this month averaging below 5 MPH. After brief clearing this morning low clouds moved back in within a couple of hours and we continue with what has so far been a nearly sunless month of May. Today's observations: 7 A.M. Weather: Scattered altocumulus, stratus, stratus fractus layer S-NW, stratocumulus, few stratocumulus and altocumulus castellanus distant WNW-NNE-ESE, fog S-NW, partial undercast dissipated past hour Temperature: 51F, Dew point: 49F, Wind: ENE at 5 kts Sea-level pressure: 29.98 inches Hg, rising Visibility: 12 miles, thin fog, except 6 miles fog, SW-NW, visibility NE-SE 15 miles, partial undercast dissipated past hour 24-hour precip: trace 6-hour min. temp: 45F BHO SA 1155 90 SCT 12 196/51/49/0705/011/ STRA/STFRA LYR S-NW SC/ FEW SCC AND ACC DSNT WNW-N-ESE VSBY S-NW 6 FG NE-SE 15 CLRG PST HR PARTIAL UNDRCST DSSPTD/ 8/680 51010 10051 20045 10 A.M. Weather: Scattered low cumulus, overcast stratocumulus, higher clouds visible, virga, dark cloud bases distant WNW, few bright spots in the overcast, higher clouds visible Temperature: 51F, Dew Point: 46F; Wind: NE at 8 kts, Wind: Direction variable N-E Sea-level pressure: 30.14 inches Hg, rising then more rapidly Visibility: 50 miles except 40 miles W-WNW BHO SA 1455 10 SCT E30 OVC 50 208/51/46/0408/014/ VIRGA/DRK CLD BASES DSNT WNW FEW BRGHT SPTS IOVC HIER CLDS VSB VSBY W-WNW 40 36V09/ 8/8// 53012 WEATHER SUMMARY FOR SATURDAY, MAY 5 TEMPERATURE (DEGREES F) MAX.....57 NORMAL.....63 MIN.....46 NORMAL.....45 MEAN....52 NORMAL.....54 DEPARTURE FROM 30-YEAR NORMAL.......................-2 TOTAL DEPARTURE FOR THE MONTH......................-23 [-4.8 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY..............13 DEPARTURE..........+1 TOTAL HEATING UNITS FOR THE MONTH..............81 DEPARTURE.........+18 TOTAL HEATING UNITS FOR THE SEASON...........4795 DEPARTURE.......-1294 TOTAL HEATING UNITS LAST SEASON TO DATE......5946 DIFFERENCE......-1151 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............14 NE AT 4:23 P.M. * AERO..................15 NE AT 3:37 P.M. ASOS..................15 NE AT 4:24 P.M. DAVIS.................15 NE AT 4:23 P.M. RMY 15 THE FASTEST MILE FOR YESTERDAY............9 NE AT 4:17 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............10 ENE AT 4:24 P.M. DAVIS MAXIMUM 2-MINUTE AVERAGE...........10 NE AT 3:37 P.M. AVERAGE WIND SPEED AND DIRECTION........3.9 NE ASOS.................3.2 DAVIS................3.7 NE[050 deg.] * last of several occurrences.... PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....TRACE DEPARTURE..........-0.13 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........0.83 DEPARTURE..........+0.21 ASOS..............0.81 TOTAL PRECIPITATION FOR THE YEAR..........10.44 DEPARTURE..........-8.73 ASOS.............10.54 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..............24.2 DEPARTURE.........-35.9 PRELIMINARY CLIMATE SUMMARY FOR MAY 2012 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 RMY: RMY = R.M. Young wind gust recording system added 8/9/2011 TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 5/1 47/42/45/-8/0.65/0.0/000/00 33 SE AERO 36 MPH SE RMY 37 5/2 50/43/47/-6/0.05/0.0/000/00 16 ENE AERO 16 MPH ENE RMY 17 5/3 51/44/48/-5/0.08/0.0/000/00 14 SSE AERO 16 MPH SSE RMY N/A 5/4 56/47/52/-2/.../0.0/000/00 21 SSW AERO 25 MPH SSW RMY 23 5/5 57/46/52/-2/.../0.0/.../.. 14 NE AERO 15 MPH NE RMY 15 5/6 morning low temp: 45F; the normal low is now 45F DAILY RECORDS FOR MAY 2012 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 6 HIGH 90F IN 1930 LOW 29F IN 1891 PRECIP 1.04 INCHES IN 1890 SNOWFALL TRACE IN 1917,1996 PEAK GUST 65 MPH SSE IN 1989 RECORDS FOR MAY 7 HIGH 93F IN 1930 LOW 33F IN 1970 PRECIP 1.19 INCHES IN 2005 SNOWFALL TRACE IN 1967 PEAK GUST 66e MPH WNW IN 1940 TODAY'S REPORT PREPARED BY: Robert Skilling