BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, JULY 18, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME THUNDERSTORM EARLY SATURDAY BRINGS BRIEFLY HEAVY RAINFALL...VERY HIGH DEW POINTS TODAY... A thunderstorm this morning at about 2:30 AM EDT brought a total of 0.36 inch of rainfall in under an hour. Nearby Norwood airport reported a total of 0.85 inch during the same storm. Dense fog covered the summit this morning, and low clouds have been slow to burn off during the day. The warm, humid airmass over New England today is a noticeable change from the conditions for most of this summer. The dew point has been in the low 70s since early this morning. The temperature reached a high of 86 degrees on Friday, surpassing 80 for the first time since May 24th and the first time this summer. This is ia new record for no 80 degree days until this date in the summer. Today's observations: 7 A.M. Weather: Sky obscured in dense fog Temperature: 71F, Dew point: 71F, Wind: S at 6 kts Sea-level pressure: 29.71 inches Hg, steady Visibility: 1/4 mile 6-hour minimum temp: 69F 6-hour precipitation: 0.36 inch (with a thunderstorm) 24-hour precipitation: 0.36 inch BHO SA 1155 W3 X 1/4F 061/71/71/1806/971/ WND LGT/ 8//// 54000 6036/ 70036 10071 20069 10 A.M. Weather: Scattered stratocumulus, broken stratocumulus cumulogenitus, overcast cirrus, thin spots in overcast, few moderate cumulus, hazy Temperature: 75F, Dew point: 71F, Wind: WS at 6 kts Wind: Light and variable Sea-level pressure: 29.73 inches Hg, rising Visibility: 10 miles, hazy BHO SA 1455 E15 SCT 35 BKN 250 OVC 10 069/75/71/2406/973/ THN SPTS IOVC OVHD FEW MOD CU HAZY WND LGT AND VRB/ 8/401 51008 1 P.M. Weather: Broken cumulus, few cirrus, few moderate cumulus Temperature: 81F, Dew point: 70F, Wind: SW at 9 kts Wind: Direction variable SSW to W Sea-level pressure: 29.72 inches hg, falling Visibility: 25 miles, hazy 6-hourly max. temp. 81F BHO SA 1755 E30 BKN 25 066/81/70/2409/972/ FEW CI FEW MOD CU HAZY WND 21V27/ 8/201 53003 10081 20071 WEATHER SUMMARY FOR FRIDAY, JULY 17 TEMPERATURE (DEGREES F) MAX.....86 NORMAL.....82 MIN.....65 NORMAL.....62 MEAN....76 NORMAL.....72 DEPARTURE FROM 30-YEAR NORMAL...........+4 TOTAL DEPARTURE FOR THE MONTH..........-87 [-5.3 DEGREES/DAY] HEATING DEGREE DATA WILL RESUME IN SEPTEMBER PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............24 ESE AT 9:39 P.M. AEROVANE..............22 ESE AT 9:39 P.M. ASOS..................22 SE AT 9:39 P.M. DAVIS.................23 ESE AT 9:38 P.M. FASTEST MILE FOR YESTERDAY...............17 E AT 9:55 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE............16 ESE AT 9:57 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........17 E AT 9:56 P.M. AVERAGE WIND SPEED AND DIRECTION........9.5 S ASOS.................8.2 DAVIS................7.8 S [191 DEG] PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.36 DEPARTURE....+0.24 ASOS..............0.37 TOTAL PRECIPITATION FOR THE MONTH..........3.45 DEPARTURE....+1.39 ASOS..............3.52 TOTAL PRECIPITATION FOR THE YEAR..........27.09 DEPARTURE....-0.64 ASOS.............28.17 PRELIMINARY CLIMATE SUMMARY FOR JULY 2009 CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane wind recording system gust when significant TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 7/1 62/57/60/-10/0.51/000/00 25 NNE TSTM 7/2 66/56/61/-9/1.00/000/00 29 SSW TSTM 7/3 75/58/67/-3/T/283/31 23 WSW 7/4 77/59/68/-2/0/838/92 43 W 7/5 78/54/66/-5/0/856/94 33 W 7/6 79/60/70/-1/0/883/97 20 SSE 7/7 66/58/62/-9/0.73/027/03 28 SE TSTM 7/8 67/56/62/-9/0.23/091/10 27 NNE TSTM 7/9 66/55/61/-10/0/689/76 23 NE 7/10 76/54/65/-6/0/896/99 21 SW 7/11 77/56/67/-5/0.29/686/76 36 S 7/12 78/60/69/-3/0.33/650/72 30 SSW TSTM 7/13 76/55/66/-6/0/802/89 32 SW 7/14 75/56/66/-6/0/567/63 25 WNW 7/15 79/55/67/-5/0/826/92 30 WSW 7/16 77/62/70/-2/T/161/18 30 S 7/17 86/65/76/+4/.../.../.. 24 ESE 7/18 morning low temp: 68F; the normal low is now 62F; thunderstorm early AM NEW DAILY RECORDS FOR JULY 2009 TO DATE... NONE DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR JULY 18 HIGH 96F IN 1991, 1999 LOW 54F IN 1892, 1956, 1971 PRECIP 1.65 INS IN 2000 WIND 43e MPH SW IN 1949 RECORDS FOR JULY 19 HIGH 96F IN 1977, 1991 LOW 50F IN 1890 PRE 1.10 INS IN 1951 WIND 63 MPH SSW IN 1982 TODAY'S REPORT PREPARED BY: Mike Iacono