BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, MAY 17, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME TEMPERATURE REACHED 80F ON THURSDAY; COOLER, CALMER CONDITIONS TODAY Yesterday, the temperature atop the summit finally reached 80F for the first time this season. This was the first 80F since September 14, 2012. Conditions today are about 10 degrees cooler, and temperatures are running very close to the 30-year normals. A front passed through the region late last night, shifting the wind direction to NNW and eventually NW, and ushering in the cooler air mass. The air remains, like yesterday, relatively dry with dew point temperatures near 40F. The relatively dry air is providing for excellent visibility today in the 70-80 mile range. Winds are noticeably less than yesterday's strong W winds. From late morning through early evening on Thursday, the wind speed averaged more than 20 mph. While breezy at times with gusts in the 20-30 mph range, there have been short periods of a calm wind today. Today's observations: 7 A.M. Weather: Scattered thin cirrus, few small cumulus/cumulus fractus distant ESE and distant WSW-NNE, few altocumulus lenticularis distant NE-E, light distant haze Temperature: 53F; Dew Point: 39F; Wind: NW at 16G21 kts, Wind: Direction variable W-N Sea-level pressure: 29.97 ins. Hg, rising then more slowly Visibility: 75 miles, light distant haze 6-hour min. temp: 50F BHO SA 1155 250 –SCT 75 150/53/39/3216G21/997/ FEW SML CU/CUFRA DSNT ESE AND DSNT WSW-NNE FEW ACSL DSNT NE-E LGT DSNT HZ WND 28V36/ 8/141 51027 10057 20050 10 A.M. Weather: Scattered cumulus/stratocumulus, scattered altocumulus, scattered cirrostratus, scattered cirrus, cumulus all quadrants except distant ENE, stratocumulus distant NNW-NNE, few altocumulus lenticularis distant E, cirrostratus SE-SW-W invading the sky, higher cirrus layer partly thin, light distant haze Temperature: 61F; Dew Point: 40F; Wind: NW at 7G13 kts, Wind: Direction variable W-N Sea-level pressure: 30.03 ins. Hg, rising then more quickly Visibility: 80 miles, light distant haze BHO SA 1455 40 SCT 100 SCT 200 SCT 250 BKN 80 168/61/40/3207G13/003/ CU ALQDS XCPT DSNT ENE SC DSNT NNW-NNE FEW ACSL DSNT E CS SE-SW-W INVADING HIER CI LYR PRTLY THN LGT DSNT HZ WND 27V01/ 8/545 53018 1 P.M. Weather: Scattered cumulus/stratocumulus, scattered cirrostratus, scattered thin cirrus, few moderate cumulus all quadrants, stratocumulus distant NE-E, cirrostratus SE-SW-W, light distant haze Temperature: 65F; Dew Point: 41F; Wind: NW at 9G19 kts, Wind: Direction variable W-N Sea-level pressure: 30.03 ins. Hg, steady then rising slightly Visibility: 75 miles, light distant haze 6-hour max temp: 68F BHO SA 1755 50 SCT 200 SCT 250 –SCT 75 171/65/41/3209G19/003/ FEW MDT CU ALQDS SC DSNT N-E CS SE-SW-W LGT DSNT HZ WND 27V36/ 8/507 53003 10068 20053 WEATHER SUMMARY FOR THURSDAY, MAY 16, 2013 TEMPERATURE (DEGREES F) MAX.....80 NORMAL.....66 MIN.....51 NORMAL.....48 MEAN....66 NORMAL.....57 DEPARTURE FROM 30-YEAR NORMAL....................+9 TOTAL DEPARTURE FOR THE MONTH...................+26 [+1.4 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............0 DEPARTURE..........-9 TOTAL HEATING UNITS FOR THE MONTH...........136 DEPARTURE.........-33 TOTAL HEATING UNITS FOR THE SEASON.........5658 DEPARTURE........-545 TOTAL HEATING UNITS LAST SEASON TO DATE....4862 DIFFERENCE.......+796 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............40 W AT 2:50 P.M. AERO....................45 W AT 2:50 P.M. ASOS....................43 W AT 2:51 P.M. DAVIS...................41 W AT 2:49 P.M. RMY: 42 FASTEST MILE FOR YESTERDAY.................29 W AT 4:33 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE..............29 WNW AT 4:33 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............28 W AT 2:52 P.M. AVERAGE WIND SPEED AND DIRECTION.........15.6 W ASOS..................15.2 DAVIS.................13.5 W [269 deg] * last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M... 0.00 DEPARTURE...........-0.12 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........0.96 DEPARTURE...........-0.99 ASOS..............0.90 TOTAL PRECIPITATION FOR THE YEAR..........17.34 DEPARTURE...........-3.16 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 morning low temp: 50F; 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 17 HIGH 88F IN 1974, 1977 LOW 34F IN 1956, 1957 PRECIP 2.07 INS IN 1916 PEAK GUST 52 MPH SW IN 1967, W IN 1974 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 TODAY'S REPORT PREPARED BY: Sean Fankhauser