BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, SEPTEMBER 28, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME COOL, CLOUDY, AND DAMP; LIGHT SHOWERS BRING 0.16 INCH OF RAINFALL Yesterday, early in the evening, the wind shifted from the NW to a predominantly E direction. The temperature quickly responded to the arrival of a cool, maritime air mass brought in by the E wind. From 4 PM to shortly after 6 PM, the temperature dropped nearly 10 degrees, and has remained relatively steady since. With the E wind persisting today, the temperature on the summit has hovered around 53-54F. The cool temperatures today and those that are expected over the next couple of days may eliminate the current positive temperature departure for the month of September. A weak low pressure system to our south has been providing plenty of clouds and light rain today. Rainfall that began early this morning has reached a total of 0.16 inch through 2 PM EST. Today's observations: 7 A.M. Weather: Light rain, broken stratocumulus, overcast altostratus, thin fog all quadrants, stratus drifting below summit all quadrants, stratocumulus lenticularis all quadrants, sun dimly visible, light rain continued from previous hour Temperature: 53F; Dew Point: 53F; Wind: E at 6 kts. Sea-level pressure: 30.23 ins. Hg, rising then falling Visibility: 10 miles, light rain 6-hour precip: 0.06 inch 24-hour precip: 0.06 inch 6-hour min. temp: 53F BHO SA 1155 E30 BKN 90 OVC 10R- 237/53/53/1006/023/ THN FG ALQDS STRA DRFTNG BLO SMT ALQDS SCSL ALQDS SUN DMLY VSBL R-CTD/ 8/57/ 50000 MANUAL 60006 ASOS 60005 MANUAL 70006 ASOS 70005 10054 20053 10 A.M. Weather: Light rain shower, broken stratocumulus, overcast altostratus, low stratus layer distant WSW-N, few cumulus/cumulus fractus NNW-E and distant SSE-Sw, few bright spots in overcast distant E-SSW, rain shower distant ESE and SSE and S and SW-W moving ENE, light rain continued from previous hour and ended at 9:39 AM EST, very light and intermittent rain shower began at unknown time and ended at 9:59 AM EST Temperature: 54F; Dew Point: 53F; Wind: E at 8 kts. Sea-level pressure: 30.21 ins. Hg, falling Visibility: 30 miles, ENE-SSW 40 miles, SW-WNW 25 miles, NW-NNE 20 miles, light rain shower 3-hour precip: 0.02 inch BHO SA 1455 E30 BKN 90 OVC 30RW- 230/54/53/0908/021/ LOW STRA LYR DSNT WSW-N FEW CU/CUFRA NNW-E AND DSNT SSE-SW FEW BRGHT SPTS INOVC DSNT E-SSW VSBY ENE-SSW 40 SW-WNW 25 NW-NNE 20 SHRA DSNT ESE AND SSE AND S AND SW-W MOVG ENE R-E39 RW-BUKN VRY LGT AND INTMT RW-E59/ 8/87/ 58007 MANUAL 60002 ASOS 60003 1 P.M. Weather: Light rain, scattered cumulus, broken stratocumulus, overcast nimbostratus, thin fog all quadrants, few stratus fractus drifting below summit, light rain continued from previous hour, briefly light drizzle Temperature: 54F; Dew Point: 54F; Wind: E at 13 kts. Sea-level pressure: 30.14 ins. Hg, falling Visibility: 12 miles, ENE-ESE and W 15 miles, light rain, thin fog all quadrants 6-hour precip: 0.10 inch 6-hour max. temp: 55F BHO SA 1755 15 SCT E35 BKN 50 OVC 12R- 207/54/54/1013/014/ THN FG ALQDS FEW STFRA DRFTNG BLO SMT VSBY ENE-ESE AND W 15 R- CTD BRFLY L-/ 8/8// 58023 MANUAL 60010 ASOS 60010 10055 20053 WEATHER SUMMARY FOR THURSDAY, SEPTEMBER 27 TEMPERATURE (DEGREES F) MAX.....70 NORMAL.....67 MIN.....53 NORMAL.....50 MEAN....62 NORMAL.....59 DEPARTURE FROM 30-YEAR NORMAL.....................+3 TOTAL DEPARTURE FOR THE MONTH....................+20 [+0.5 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............3 DEPARTURE........-4 TOTAL HEATING UNITS FOR THE MONTH............67 DEPARTURE.......-27 TOTAL HEATING UNITS FOR THE SEASON...........67 DEPARTURE.......-52 TOTAL HEATING UNITS LAST SEASON TO DATE......75 DIFFERENCE.......-8 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............24 NNW AT 9:01 A.M. * AERO..................23 NNW AT 8:58 A.M. ASOS..................23 NNW AT 9:01 A.M. DAVIS.................22 NW AT 8:58 A.M. RMY 23 THE FASTEST MILE FOR YESTERDAY...........16 NNW AT 8:58 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............16 NNW AT 9:02 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........15 NW AT 8:59 A.M. AVERAGE WIND SPEED AND DIRECTION........8.9 NW ASOS.................8.5 DAVIS................8.3 NW [304 deg] * Last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.06 DEPARTURE...........-0.09 ASOS..............0.05 TOTAL PRECIPITATION FOR THE MONTH..........2.34 DEPARTURE...........-1.28 ASOS..............2.35 TOTAL PRECIPITATION FOR THE YEAR..........27.69 DEPARTURE..........-10.95 ASOS.............27.61 PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 2012 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 9/1 75/60/68/0/0.00/637/81 27 ENE AERO 25 MPH ENE RMY 23 9/2 80/60/70/+2/0.00/455/58 21 ENE AERO 20 MPH ENE RMY 20 9/3 76/57/67/0/0.00/485/62 20 SE AERO 20 MPH S RMY 21 9/4 72/62/67/0/0.40/000/00 25 S AERO 23 MPH S RMY N/A 9/5 79/64/72/+5/0.31/171/22 33 SSW AERO 35 MPH SSW RMY 33 9/6 77/62/70/+3/0.00/279/36 20 SSW AERO 20 MPH SSW RMY 19 9/7 85/66/76/+10/0.00/463/60 22 SSW AERO 20 MPH SSW RMY N/A TSTM 9/8 81/62/72/+6/0.38/453/59 45 S AERO 45 MPH S RMY 45 9/9 72/58/65/-1/0.02/283/37 25 WNW AERO 23 MPH WNW RMY N/A 9/10 66/50/58/-7/0.00/313/41 33 NW AERO 32 MPH NW RMY 34 9/11 71/47/59/-6/0.00/714/94 23 NW AERO 21 MPH WNW RMY N/A 9/12 77/53/65/0/0.00/719/95 20 S AERO 18 MPH S RMY 18 9/13 81/59/70/+6/0.00/731/97 21 S AERO 18 MPH S RMY 19 9/14 81/59/70/+6/0.00/706/94 25 S AERO 23 MPH S RMY 23 9/15 72/54/63/-1/0.07/441/59 28 NW AERO 27 MPH WNW RMY 27 9/16 70/49/60/-3/0.00/731/98 23 W AERO 20 MPH W RMY 21 9/17 74/51/63/0/0.00/698/94 20 S AERO 17 MPH S RMY N/A 9/18 74/58/66/+4/0.13/044/06 60 S AERO 62 MPH S RMY 63 9/19 70/53/62/0/0.90/472/64 55 S AERO 56 MPH S RMY N/A 9/20 63/50/57/-5/0.00/539/87 24 NE AERO 21 MPH NE RMY 21 9/21 63/48/56/-5/0.01/241/33 18 E AERO 16 MPH E RMY 16 9/22 70/55/63/+2/0.04/306/42 28 S AERO 25 MPH S RMY 27 9/23 69/50/60/0/0.02/653/90 27 WNW AERO 24 MPH WNW RMY 27 9/24 66/45/56/-4/0.00/694/96 23 WSW AERO 21 MPH WSW RMY 22 9/25 72/48/60/0/0.00/691/96 35 SSW AERP 35 MPH SW RMY 36 9/26 70/57/64/+5/T/050/07 31 S AERO 32 MPH S RMY 32 9/27 70/53/62/+3/0.00/.../.. 24 NNW AERO 23 MPH NNW RMY 23 9/28 morning low temp: 53F; the normal low is now 50F DAILY RECORDS FOR SEPTEMBER 2012 9/19 - NEW RECORD PEAK WIND GUST OF 55 MPH S; surpasses previous record of 49 MPH NE IN 1972 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR SEPTEMBER 28 HIGH 82F IN 1959 LOW 33F IN 1897,1947 PRECIP 2.46 INCHES IN 2004 PEAK GUST 69 MPH NE IN 1962 RECORDS FOR SEPTEMBER 29 HIGH 85F IN 1952 LOW 28F IN 1914 (SEPTEMBER MINIMUM RECORD) PRECIP 2.61 INCHES IN 1907 PEAK GUST 62 MPH S IN 2005 TODAY'S REPORT PREPARED BY: Sean Fankhauser