BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS 02186 ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SUNDAY, JANUARY 21, 2007 ALL TIMES ARE IN EASTERN STANDARD TIME THE INVASION OF ARCTIC AIR ARRIVING YESTERDAY AFTERNOON AND OVERNIGHT BROUGHT W-WNW WINDS GUSTING OVER 50 MPH LATE YESTERDAY AFTERNOON WITH LOW TEMPERATURES OF 12 DEGREES BY MIDNIGHT AND 9 DEGREES THIS MORNING WITH WINDCHILLS -10 TO -13 EARLY TODAY The arrival of the second blast of Arctic air within five days brought west to west-northwest winds gusting past 50 mph during late yesterday afternoon. Peak gusts included: Maximum, Inc. Maestro: 62 mph Maximum, Inc. Merlin: 59 mph Aerovane: 55 mph ASOS & 420C: 51 mph The temperature dropped steadily overnight reaching 12 degrees by midnight after yesterday morning's high of 30 degrees. The low just before 6:30 a.m. today was 9 degrees accompanied by gusty winds which drove windchill temperatures down to -10 to -13 degrees at times. The low this morning was our second coldest reading of the month and season after 6 degrees was recorded on Jan. 17th. Today's observations: 7 A.M. Weather: Clear, clouds offshore NE-ESE Temperature: 10F, Dew point: -4F, Wind: W at 17G24 kts Sea-level pressure: 30.27 inches Hg, rising Visibility: 60 miles 6-hourly min. temp. 9 deg. 24-hourly precip. and snowfall: trace BHO SA 1155 CLR 60 249/10/-4/2717G24/027/ SC LYR OFFSHR DSNT NE-ESE PK WND 2729/42/ 8/500 51025 10012 20009 10 A.M. Weather: Clear, few clouds offshore and cirrus distant SW-WSW Temperature: 16F, Dew point: -2F, Wind: WNW at 15G24 kts Sea-level pressure: 30.29 inches Hg, rising Visibility: 80 miles BHO SA 1455 CLR 80 257/16/-2/2915G24/029/ SC OFFSHR DSNT NE-SE FEW CI DSNT SW-WSW ALG HRZN WND 26V32/ 8/501 WEATHER SUMMARY FOR SATURDAY, JANUARY 20 TEMPERATURE (DEGREES F) MAX.....30 NORMAL.....33 MIN.....12 NORMAL.....17 MEAN....21 NORMAL.....25 DEPARTURE FROM 30-YEAR NORMAL.........-4 TOTAL DEPARTURE FOR THE MONTH.......+200 (+9.8 DEGREES/DAY) HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY..........44 DEPARTURE.......+4 TOTAL HEATING UNITS FOR THE MONTH.........577 DEPARTURE.....-197 TOTAL HEATING UNITS FOR THE SEASON.......2450 DEPARTURE.....-653 TOTAL HEATING UNITS LAST SEASON TO DATE..2758 DIFFERENCE....-308 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY............51 W AT 4:56 P.M. * AEROVANE.............55 WNW AT 5:31 P.M. * ASOS.................51 WNW AT 5:30 P.M. DAVIS................53 W AT 4:55 P.M. FASTEST MILE FOR YESTERDAY..............38 W AT 2:03 P.M. MAXIMUM 2-MINUTE ASOS AVERAGE...........38 W AT 2:06 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE..........40 W AT 2:01 P.M. AVERAGE WIND SPEED AND DIRECTION......24.2 W ASOS..............23.5 DAVIS.............24.0 W [270 deg.] * last of several occurrences.. PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....trace DEPARTURE......-0.15 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........2.81 DEPARTURE.......-0.28 ASOS..............2.74 TOTAL PRECIPITATION FOR THE YEAR...........2.81 DEPARTURE.......-0.28 ASOS..............2.74 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........trace DEPARTURE.....-0.5 TOTAL SNOWFALL FOR THE MONTH................0.1 DEPARTURE.....-9.9 TOTAL SNOWFALL FOR THE SEASON...............3.8 DEPARTURE....-19.8 PRELIMINARY CLIMATE SUMMARY FOR JANUARY 2007......CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO GUST AERO: Aerovane recording wind system when significant TSTM: Thunderstorm day ....: Data not yet available 1/1 53/30/42/+15/0.98/0/000/00 38 SE 1/2 43/31/37/+10/0.03/0/505/92 44 W Aero 47 MPH W 1/3 49/30/40/+13/0/0/435/79 40 S 1/4 53/40/47/+20/0/0/198/36 31 SSW 1/5 61/46/54/+27/0.04/0/000/00 44 S Aero 44 MPH S 1/6 66/48/57/+31/0.03/0/161/29 48 SSW Aero 47 MPH SSW 1/7 50/38/44/+18/0/0/505/91 43 W Aero 44 MPH W 1/8 52/36/44/+18/0.69/0/000/00 45 W Aero 45 MPH W 1/9 41/29/35/+9/0/0/518/93 40 W Aero 39 MPH W 1/10 34/22/28/+2/0/0/525/94 48 W 1/11 33/17/25/-1/0/0/.../.. 36 S Aero 38 MPH S 1/12 48/32/40/+14/0/0/.../.. 38 SSW Aero 39 MPH SSW 1/13 48/36/42/+16/0.06/000/00 30 S 1/14 38/31/35/+9/0.16/0/000/00 21 NE 1/15 40/31/36/+10/0.58/0/000/00 25 NNE 1/16 38/15/27/+1/0.05/0/.../.. 40 W Aero 42 MPH W 1/17 18/6*/12/-14/0.00/0/.../.. 38 WNW Aero 43 MPH WNW 1/18 36/10/23/-3/0.13/0.1/.../.. 33 SSE 1/19 38/30/34/+9/0.06/T/.../.. 40 W Aero 41 MPH W 1/20 30/12/21/-4/T/T/.../.. 51 W Aero 55 MPH WNW 1/21 morning low temp. 9 deg; normal now 17 deg. * min. temp. corrected to 6 deg. from 7 deg on 17th; mean, dep.& heating degree day units all corrected accordingly on 1/17. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR JANUARY 21 HIGH 65F IN 1906 LOW -4F IN 1888,1893 PRECIP 2.49 INS. IN 1979 SNOWFALL 7.5 INS. IN 2001 PEAK GUST 78e MPH SE IN 1979 RECORDS FOR JANUARY 22 HIGH 59F IN 1916 LOW -8F IN 1888,1976 PRECIP 1.24 INS. IN 1891,1987 SNOWFALL 7.0 INS. IN 1986 PEAK GUST 67 MPH W IN 1976 TODAY'S REPORT By: Robert Skilling