BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, SEPTEMBER 26, 2009 ALL TIMES ARE IN EASTERN STANDARD TIME SUNNY AND DRY WEATHER CONTINUES...COOLEST TEMPERATURE OF THE SEASON TO DATE THIS MORNING... After a much cooler day on Friday, the low temperature this morning dropped to a season low so far of 43 on the summit. This was much warmer than in the surrounding valleys. The low at Norwood airport was 32 degrees this morning at the base of the inversion early today. The inversion caused some looming (mirage effects) of the hills and mountains to the NW-N as can happen occasionally in these conditions. There has been very little wind and only a few clouds today, as the weather transitions into a return to wetter conditions tomorrow. Today's observations: 7 A.M. Weather: Clear, few stratocumulus NNE-S, few cirrus distant NE, looming of mountains and hills NW-NNE Temperature: 49F, Dew point: 40F, Wind: NE at 7 kts Sea-level pressure: 30.39 inches Hg, falling Visibility: 70 miles 6-hour minimum temp: 43F 24-hour precipitation: 0.00 inches BHO SA 1155 CLR 70 292/49/40/0407/039/ FEW SC NNE-S FEW CI DSNT NE LOOMING ALG HRZN NW-NNE WND LGT/ 8/501 50000 10050 20043 10 A.M. Weather: Scattered cumulus, few cirrus distant S-SW Temperature: 56F, Dew point: 38F, Wind: NE at 5 kts Wind: Light and variable Sea-level pressure: 30.37 inches Hg, falling Visibility: 70 miles BHO SA 1455 30 SCT 70 286/56/38/0405/037/ FEW CI DSNT S-SW WND LGT AND VRB/ 8/101 58006 1 P.M. Weather: Scattered cumulus, few cirrus distant S-SW Temperature: 62F, Dew point: 39F, Wind: S at 7 kts Wind: Light and variable Sea-level pressure: 30.29 inches Hg, falling Visibility: 70 miles 6-hourly max. temp: 62F BHO SA 1755 35 SCT 70 256/62/39/1907/029/ FEW CI DSNT S-SW WND LGT AND VRB/ 8/101 56030 10062 20049 WEATHER SUMMARY FOR FRIDAY, SEPTEMBER 25 TEMPERATURE (DEGREES F) MAX.....63 NORMAL.....68 MIN.....50 NORMAL.....50 MEAN....57 NORMAL.....59 DEPARTURE FROM 30-YEAR AVERAGE...........-2 TOTAL DEPARTURE FOR THE MONTH...........-10 [-0.6 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY.............8 DEPARTURE.......+1 TOTAL HEATING UNITS FOR THE MONTH............84 DEPARTURE......-16 TOTAL HEATING UNITS FOR THE SEASON..........118 DEPARTURE......-13 TOTAL HEATING UNITS LAST SEASON TO DATE.....107 DIFFERENCE.....+11 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY.............33 NW AT 7:32 A.M. AEROVANE..............30 NW AT 7:32 A.M. ASOS..................31 NNW AT 7:32 A.M. DAVIS.................36 NW AT 7;31 A.M. FASTEST MILE FOR YESTERDAY...............21 NW AT 7:02 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE............21 NNW AT 7:03 A.M. MAXIMUM 2-MINUTE DAVIS AVERAGE...........23 WNW AT 7:03 A.M. AVERAGE WIND SPEED AND DIRECTION.......12.8 NW ASOS................12.2 DAVIS...............12.8 NNW [339 DEG] * last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE....-0.14 ASOS..............0.00 TOTAL PRECIPITATION FOR MONTH..............2.29 DEPARTURE....-1.14 ASOS..............2.33 TOTAL PRECIPITATION FOR THE YEAR..........37.06 DEPARTURE....+0.16 ASOS.............38.25 PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 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 9/1 71/51/61/-6/0/773/98 17 NW 9/2 76/54/65/-1/0/786/100 22 S 9/3 77/56/67/+1/0/587/75 19 SW 9/4 77/60/69/+3/0/764/98 18 NE 9/5 81/59/70/+5/0/591/76 25 NNW 9/6 64/53/59/-6/0/743/96 31 NNE 9/7 70/52/61/-4/0/709/92 20 WSW 9/8 75/56/66/+1/0/369/48 18 WSW 9/9 68/55/62/-2/0/352/46 36 NNE AERO 33 MPH NNE 9/10 65/53/59/-5/0/603/79 31 ENE 9/11 61/54/58/-6/0.49/000/00 30 NE 9/12 63/60/62/-1/1.74/000/00 30 NNE 9/13 76/58/67/+4/0.06/393/52 28 NW 9/14 74/55/65/+2/0/699/93 22 WSW 9/15 75/56/66/+4/0/682/91 22 WNW 9/16 61/53/57/-5/T/060/08 31 NNE AERO 29 MPH NNE 9/17 60/49/55/-7/0/022/03 27 N 9/18 71/47/59/-2/T/571/77 35 WSW AERO 30 MPH WSW 9/19 65/45/55/-6/0/716/97 30 NW AERO 28 MPH WNW 9/20 71/45/58/-3/0/721/98 22 SW 9/21 76/50/63/+3/0/703/96 20 S 9/22 74/55/65/+5/0/124/17 27 SSW 9/23 78/61/70/+10/0/145/20 35 SSW 9/24 77/57/67/+8/0/348/48 25 SW 9/25 63/50/57/-2/0/.../.. 33 NW 9/26 morning low temp: 43F; the normal low is now 50F NEW DAILY RECORDS FOR SEPTEMBER 2009 TO DATE... None. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR SEPTEMBER 26 HIGH 91F IN 2007 LOW 36F IN 1905,1922,1978 PRECIP 3.84 INCHES IN 1888 PEAK GUST 54e MPH S IN 1977 RECORDS FOR SEPTEMBER 27 HIGH 84F IN 1998 LOW 32F IN 1947 PRECIP 2.26 INCHES IN 1962 PEAK GUST 100 MPH SSE IN 1985 (HURRICANE GLORIA) TODAY'S REPORT PREPARED BY: Mike Iacono