BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, MAY 18, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME PARLY SUNNY TODAY WITH BUILDING CLOUDS... A nearly clear sky early this morning is filling with cumulus clouds as of early afternoon with the heating from the sun. It was a chilly start in the surrounding low elevation areas with a low temperature of 38F at nearby Norwood Airport this morning, though the low on the summit was 47F. The summit dew point has dropped from the low 40s to the middle 30s during the day and the relative humidity has dropped in to the 20s this afternoon. Visibility has been excellent near 75 miles. The monthly precipitation deficit has increased to more than one inch. Today's observations: 7 A.M. Weather: Scattered thin cirrus, few altocumulus distant SW-WSW, few altocumulus WSW-NW, few lower dense cirrus distant S-SW, thin smoke layer along horizon NW-NNW Temperature: 56F; Dew Point: 41F; Wind: NNW at 6 kts, Wind: Light Sea-level pressure: 30.30 ins. Hg, rising Visibility: 75 miles 6-hour min. temp: 47F BHO SA 1155 250 –SCT 75 262/56/41/3306/030/ FEW AC DSNT SW-WSW FEW AC WSW-NW FEW LWR DNS CI DSNT S-SW THN K LYR ALG HRZN NW-NNW WND LGT/ 8/031 53017 10056 20047 10 A.M. Weather: Scattered cumulus, broken altocumulus, broken cirrus, few moderate cumulus, few lower dense cirrus SE-S Temperature: 66F; Dew Point: 37F; Wind: WNW at 4 kts, Wind: Light and variable Sea-level pressure: 30.32 ins. Hg, rising slightly Visibility: 75 miles BHO SA 1455 40 SCT 65 SCT E90 BKN 250 BKN 75 266/66/37/2904/032/ FEW MDT CU FEW LWR DNS CI DSNT SE-S WND LGT AND VRB/ 8/231 50004 1 P.M. Weather: Scattered stratocumulus, broken altocumulus, overcast cirrostratus fibratus and cirrus, few lower cumulus, few moderate cumulus, breaks in overcast NW-ESE, solar halo Temperature: 69F; Dew Point: 35F; Wind: W at 9 kts Sea-level pressure: 30.28 ins. Hg, falling Visibility: 75 miles 6-hour max temp: 71F BHO SA 1755 65 SCT E95 BKN 250 OVC 75 254/69/35/2709/028/ FEW LWR CU FEW MDT CU BINOVC NW-ESE SOLAR HALO/ 8/578 56012 10071 20056 WEATHER SUMMARY FOR FRIDAY, MAY 17, 2013 TEMPERATURE (DEGREES F) MAX.....69 NORMAL.....67 MIN.....50 NORMAL.....48 MEAN....60 NORMAL.....57 DEPARTURE FROM 30-YEAR NORMAL....................+3 TOTAL DEPARTURE FOR THE MONTH...................+29 [+1.5 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............5 DEPARTURE..........-3 TOTAL HEATING UNITS FOR THE MONTH...........141 DEPARTURE.........-36 TOTAL HEATING UNITS FOR THE SEASON.........5663 DEPARTURE........-549 TOTAL HEATING UNITS LAST SEASON TO DATE....4867 DIFFERENCE.......+796 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............24 NW AT 6:50 A.M. AERO....................28 NW AT 6:50 A.M. ASOS....................29 N AT 3:04 P.M. DAVIS...................26 NW AT 12:30 P.M. RMY: 27 FASTEST MILE FOR YESTERDAY.................20 NW AT 6:57 A.M. * MAXIMUM 2-MINUTE ASOS AVERAGE..............20 NNW AT 6:59 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............17 NW AT 6:56 A.M. AVERAGE WIND SPEED AND DIRECTION.........10.9 NNW ASOS..................10.4 DAVIS..................9.0 NNW [334 deg] * Last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M... 0.00 DEPARTURE...........-0.13 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........0.96 DEPARTURE...........-1.12 ASOS..............0.90 TOTAL PRECIPITATION FOR THE YEAR..........17.34 DEPARTURE...........-3.29 ASOS..............N/A* *ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals 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.............0.0 TOTAL SNOWFALL FOR THE SEASON.............99.0 DEPARTURE...........+36.3 PRELIMINARY CLIMATE SUMMARY FOR MAY 2013 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust 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 67/45/56/+3/0.00/845/100 18 E AERO 16 MPH E RMY 17 5/2 75/43/59/+6/T/669/79 29 NE AERO 26 MPH NE RMY 29 5/3 54/42/48/-5/0.00/706/83 24 NE AERO 25 MPH NE RMY 28 5/4 55/40/48/-6/0.00/843/99 21 NE AERO 23 MPH NE RMY 23 5/5 58/37/48/-6/0.00/752/88 17 ENE AERO 17 MPH ENE RMY 20 5/6 66/40/53/-1/0.00/600/70 17 S AERO 18 MPH S RMY 20 5/7 77/50/64/+9/0.00/807/94 21 S AERO 23 MPH S RMY 25 5/8 71/55/63/+8/0.42/112/13 31 SSE AERO 35 MPH SSE RMY 35 TSTM 5/9 66/56/61/+6/0.41/078/09 16 NE AERO 16 MPH NE RMY 18 TSTM 5/10 79/54/66/+11/T/333/63 18 S AERO 21 MPH S RMY N/A 5/11 70/56/63/+7/0.06/026/03 43 SSW AERO 44 MPH SSW RMY 46 5/12 71/47/59/+3/0.05/339/39 30 W AERO 32 MPH W RMY 32 5/13 60/41/51/-5/0.00/821/94 25 WSW AERO 28 MPH WSW RMY 30 5/14 58/38/48/-9/T/385/44 22 W AERO 24 MPH W RMY 25 5/15 65/41/53/-4/0.02/.../.. 35 S AERO 38 MPH S RMY 40 5/16 80/51/66/+9/0.00/.../.. 40 W AERO 45 MPH W RMY 42 5/17 69/50/60/+3/0.00/.../.. 24 NW AERO 28 MPH NW RMY 27 5/18 morning low temp: 47F; the normal low is now 48F DAILY RECORDS FOR MAY 2013 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 18 HIGH 88F IN 1906, 1936, 1986 LOW 35F IN 2002 PRECIP 1.93 INS IN 2007 SNOW TRACE IN 2002 (Ice pellets) PEAK GUST 64 MPH SSW IN 2000 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 TODAY'S REPORT PREPARED BY: Mike Iacono