BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, JULY 12, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME BRIEF, HEAVY DOWNPOUR ACCOMPANIES FRONTAL PASSAGE THURSDAY EVENING; COOL, CLOUDY, AND BREEZY TODAY, BUT DRIER A frontal passage Thursday evening between 8 and 9 P.M. EDT brought a drastic change in wind direction from SSW to NW, a brief ~20 minute heavy downpour of 0.62 inch of rain, and a much drier air mass. Dew point temperatures are 10-15 degrees cooler today compared to yesterday, providing relief from the recent bout of very humid conditions. This morning, the wind direction has gradually veered to NE. It has been a fairly breezy day, with winds of 10-20 mph with occasional gusts of 25-30 mph. Mostly cloudy conditions have prevailed today, with a persistent deck of stratocumulus. That, combined with the NE flow has kept temperatures in check. While the morning low of 64F started the day very close to the 30-year normal for the date, the afternoon high has struggled to reach 70F (~10 degrees below the 30-year normal). Today's Observations: 7 A.M. Weather: Scattered stratocumulus and cumulus, broken altocumulus (2 levels), broken cirrus, stratocumulus/cumulus W-N-ESE, few altocumulus lenticularis all quadrants, few altocumulus castellanus distant NE-E, higher cirrus layer partly thin, light distant haze Temperature: 66F; Dew Point: 59F; Wind: NE at 12G19 kts, Wind: Direction variable N-ENE Sea-level pressure: 30.08 ins. Hg, rising Visibility: 65 miles, E-S lower, NW 70 miles, light distant haze 24-hr precip: 0.62 inch 6-hr min. temp: 64F BHO SA 1155 40 SCT E70 BKN 120 BKN 250 BKN 65 185/66/59/0412G19/008/ SC/CU W-N-ESE FEW ACSL ALQDS FEW ACC DSNT NE-E HIER CI LYR PRTLY THN LGT DSNT HZ VSBY E-S LWR NW 70 WND 36V07/ 8/581 53027 ASOS 70063 MANUAL 70062 10069 20064 10 A.M. Weather: Broken stratocumulus, broken altocumulus, few lower cumulus/ cumulus fractus distant E-ESE, light distant haze Temperature: 69F; Dew Point: 60F; Wind: NE at 13G23 kts, Wind: Direction variable N-E Sea-level pressure: 30.13 ins. Hg, rising Visibility: 55 miles, E-S lower, NW 65 miles, light distant haze BHO SA 1455 E15 BKN 120 BKN 55 203/69/60/0413G23/013/ FEW LWR CU/CUFRA DSNT E-ESE LGT DSNT HZ VSBY E-S LWR NW 65 WND 36V08/ 8/830 53018 1 P.M. Weather: Broken stratocumulus, broken stratus, broken altocumulus, few cumulus distant NW-N few lower ragged stratocumulus bases all quadrants, altocumulus visible distant NNW-NNE, sun occasionally visible, rain shower/virga distant WSW and distant WNW-NNW moving SW, hazy Temperature: 66F; Dew Point: 58F; Wind: NE at 12G19 kts, Wind: Direction variable N-E Sea-level pressure: 30.14 ins. Hg, rising slightly Visibility: 40 miles, ENE-SSW 30 miles, WNW 50 miles, hazy 6-hour max. temp: 70F BHO SA 1755 E15 BKN 20 BKN 120 BKN 40 206/66/58/0412G19/014/ FEW CU DSNT NW-N FEW LWR RGGD SC BASES ALQDS AC VSBL DSNT NNW-NNE SUN OCNLY VSBL SHRA/VIRGA DSNT WSW AND DSNT WNW-NNW MOVG SW HAZY VSBY ENE-SSW 30 WNW 50 WND 36V08/ 8/530 50003 10070 20066 WEATHER SUMMARY FOR THURSDAY, JULY 11, 2013 TEMPERATURE (DEGREES F) MAX.....79 NORMAL.....81 MIN.....69 NORMAL.....63 MEAN....74 NORMAL.....72 DEPARTURE FROM 30-YEAR NORMAL.....................+2 TOTAL DEPARTURE FOR THE MONTH....................+58 [+5.1 DEGREES/DAY] PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY................23 W AT 8:54 A.M. AERO.....................23 W AT 8:54 A.M. ASOS.....................25 W AT 8:55 A.M. DAVIS....................24 WSW AT 8:54 A.M. RMY N/A FASTEST MILE FOR YESTERDAY..................18 W AT 8:56 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE...............18 W AT 8:55 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..............17 WSW AT 8:55 A.M. AVERAGE WIND SPEED AND DIRECTION...........8.5 SSW ASOS....................8.5 DAVIS...................8.1 SW [220 deg] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.62 DEPARTURE............+0.49 ASOS..............0.63 TOTAL PRECIPITATION FOR THE MONTH..........0.93 DEPARTURE............-0.32 ASOS..............0.93 TOTAL PRECIPITATION FOR THE YEAR..........33.13 DEPARTURE............+4.91 ASOS..............N/A* *ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals PRELIMINARY CLIMATE SUMMARY FOR JULY 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 7/1 82/69/76/+6/0.05/247/27 29 S AERO 31 MPH SSW RMY 32 7/2 82/61/72/+2/T/100/11 23 SSW AERO 23 MPH SSW RMY 25 7/3 87/62/75/+4/T/556/61 28 SW AERO 30 MPH SW RMY 30 7/4 90/71/81/+10/0.00/811/89 25 WSW AERO 26 MPH SW RMY 28 7/5 92/73/83/+12/0.00/874/96 24 W AERO 25 MPH WSW RMY 25 7/6 90/73/82/+11/0.00/836/92 25 WNW AERO 25 MPH WNW RMY 26 7/7 91/72/82/+11/0.21/508/56 38 SSW AERO 43 MPH SSW RMY 44 TSTM 7/8 82/64/73/+1/0.04/.../.. 18 NE AERO 20 MPH NE RMY 20 TSTM 7/9 72/63/68/-4/0.01/.../.. 14 ENE AERO 14 MPH ENE RMY 14 7/10 84/65/75/+3/T/.../.. 32 S AERO 36 MPH S RMY 35 7/11 79/69/74/+2/0.62/.../.. 23 W AERO 23 MPH W RMY N/A 7/12 morning low temp: 64F; the normal low is now 63F DAILY RECORDS FOR JULY 2013 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR JULY 12 HIGH 97F IN 1943 LOW 48F IN 1945 PRECIP 1.43 INS IN 1975 WIND 48e MPH SSW IN 1944 RECORDS FOR JULY 13 HIGH 95F IN 1894 LOW 52F IN 1888, 1895, 1939, 1973 PRECIP 3.54 INS IN 1996 WIND 55 MPH SE IN 1996 TODAY'S REPORT PREPARED BY: Sean Fankhauser