BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY WEDNESDAY, DECEMBER 26, 2012 ALL TIMES ARE IN EASTERN STANDARD TIME CALM AND COOL AHEAD OF APPROACHING STORM SYSTEM After picking up just over half an inch of snow on Christmas, quiet conditions returned to the summit today. Temperatures have been quite cool, and our low temperature of 20F this morning is our coldest of the season so far by 5 degrees. We are on track for our first below normal day since December 12 as the month continues to run 6 degrees above normal. These cool temperatures have allowed much of yesterday's light snow to remain on the ground. The temperature has climbed but so far we remain well below our normal of 37F. Winds were unusually calm yesterday, and that has continued into today with a peak wind gust of just 16mph recorded so far since 7AM this morning. Winds are expected to increase this afternoon and tonight as a powerful storm prepares to bring heavy rain, high winds, and heavy snow farther inland. The barometer has started dropping and this should continue into tonight. Today's observations: 7 A.M. Weather: Clear, cumulus and stratocumulus along and offshore distant NE-SSE, altocumulus and altocumulus lenticularis distant SE-SSW, cirrus distant ENE- SE-SSW Temperature: 20F; Dew Point: 13F; Wind: N at 9 kts Sea-level pressure: 30.26 ins. Hg, decreasing then increasing Visibility: 40 miles, distant haze 6-hour min. temp: 20F 24-hour precip: 0.02 inch 24-hour snowfall: 0.4 inch Snow on ground: Trace BHO SA 1155 CLR 40 248/20/13/3609/026/ CU/SC ALG/OFFSHR DSNT NE-SSE AC/ACSL DSNT SE-SSW CI DSNT ENE-SE-SSW TOTAL NEW SNW PST 24 HRS 0.4 IN/ 8/841 4/001 55003 MANUAL 70002 ASOS 70003 10024 20020 10 A.M. Weather: Clear, few cumulus and stratocumulus along and offshore ENE-ESE, few altocumulus lenticularis distant SW-WSW, cirrus E-S-W, cirrus and cirrostratus layer Temperature: 27F; Dew Point: 16F; Wind: NNW at 4 kts Wind: Light Sea-level pressure: 30.31 ins. Hg, increasing Visibility: 45 miles, distant haze BHO SA 1455 CLR 300 –SCT 45 264/27/16/3304/031/FEW CU/SC ALNG/OFFSHR ENE-ESE FEW ACSL DSNT SW-WSW CI E-S-W CI/CS LYR DSNT S-WSW INVDNG THN K LYR ABV HRZN W-WNW ALG HRZN NW-NE DSNT HZ WND LGT/ 8/845 51016 1 P.M. Weather: Broken stratocumulus, overcast dense cirrostratus, few altocumulus lenticularis NNW-N, break in overcast distant N-E Temperature: 32F; Dew Point: 26F; Wind: NE at 9 kts Wind: Direction variable N-E Sea-level pressure: 30.24 ins Hg, falling then falling more slowly Visibiity: 40 miles, distant haze 6-hour max: 32F 6-hour min: 20F BHO SA 1755 E20 BKN 220 OVC 40 242/32/26/0409/024 FEW ACSL DSNT NNW-N BINOVC DSNT N-E WND 36V09/ 8/547 56022 10032 20020 WEATHER SUMMARY FOR TUESDAY, DECEMBER 25 CHRISTMAS DAY TEMPERATURE (DEGREES F) MAX.....33 NORMAL.....36 MIN.....25 NORMAL.....21 MEAN....29 NORMAL.....28 DEPARTURE FROM 30-YEAR NORMAL......................+1 TOTAL DEPARTURE FOR THE MONTH....................+156 [+6.0 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............36 DEPARTURE.........-1 TOTAL HEATING UNITS FOR THE MONTH...........660 DEPARTURE.......-158 TOTAL HEATING UNITS FOR THE SEASON.........1810 DEPARTURE.......-270 TOTAL HEATING UNITS LAST SEASON TO DATE....1573 DIFFERENCE......+237 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............21 NNW AT 9:14 P.M. AERO....................21 NNW AT 9:14 P.M. ASOS....................20 NNW AT 11:47 P.M. DAVIS...................18 NNW AT 9:14 P.M. RMY: 19 THE FASTEST MILE FOR YESTERDAY.............16 NW AT 11:57 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE..............16 NNW AT 11:59 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............14 NW AT 11:59 P.M. AVERAGE WIND SPEED AND DIRECTION.........8.8 NNW ASOS..................9.2 DAVIS.................8.1 NNW [342 deg.] *...last of several occurences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.02 DEPARTURE..........-0.14 ASOS..............0.03 TOTAL PRECIPITATION FOR THE MONTH..........3.56 DEPARTURE..........-0.46 ASOS..............3.60 TOTAL PRECIPITATION FOR THE YEAR..........38.44 DEPARTURE.........-14.11 ASOS.............38.49 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........0.4 DEPARTURE..........-0.1 TOTAL SNOWFALL FOR THE MONTH...............1.7 DEPARTURE..........-8.5 TOTAL SNOWFALL FOR THE SEASON..............7.7 DEPARTURE..........-5.1 PRELIMINARY CLIMATE SUMMARY FOR DECEMBER 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 12/1 34/25/30/-7/0.08/0.8/000/00 16 E AERO 14 MPH E RMY 16 12/2 52/32/42/+6/0.00/0.0/006/01 32 SSW AERO 32 MPH SSW RMY 34 12/3 57/43/50/+14/0.00/0.0/523/94 31 NW AERO 30 MPH NW RMY 32 12/4 56/40/48/+13/0.03/0.0/000/00 37 S AERO 39 MPH S RMY 38 12/5 56/31/44/+9/0.03/0.0/310/56 38 WNW AERO 37 MPH WNW RMY 40 12/6 38/25/32/-3/0.00/0.0/519/94 31 NW AERO 30 MPH NW RMY N/A 12/7 42/30/36/+2/0.02/0.0/000/00 18 SSW AERO 16 MPH SSW RMY 18 12/8 45/41/43/+9/0.35/0.0/000/00 21 ENE AERO 18 MPH ENE RMY N/A 12/9 45/38/42/+8/0.10/0.0/181/33 24 NNW AERO 24 MPH NNW RMY 25 12/10 59/39/49/+16/0.51/0.0/000/00 32 SSW AERO 33 MPH SSW RMY 35 12/11 54/30/42/+9/0.01/0.0/351/64 25 W AERO 25 MPH W RMY 23 12/12 38/26/32/-1/0.00/0.0/126/23 20 NW AERO 18 MPH NW RMY N/A 12/13 42/29/36/+4/0.00/0.0/416/76 18 NW AERO 15 MPH NW RMY N/A 12/14 47/29/38/+6/0.00/0.0/535/98 28 W AERO 25 MPH W RMY 27 12/15 40/31/36/+4/0.00/0.0/530/97 24 NNW AERO 22 MPH NNW RMY 21 12/16 36/31/34/+3/0.25/0.1/000/00 25 E AERO 22 MPH E RMY N/A 12/17 44/36/40/+9/0.65/0.0/000/00 31 ENE AERO 29 MPH ENE RMY 30 12/18 50/40/45/+14/0.61/0.0/000/00 28 E AERO 24 MPH E RMY N/A 12/19 44/35/40/+10/T/0.0/087/16 42 WNW AERO 40 MPN WNW RMY 43 12/20 42/30/36/+6/T/0.0/262/48 25 NNW AERO 23 MPH NNW RMY N/A 12/21 53/35/44/+14/0.00/0.0/000/00 58 E AERO 53 MPH E RMY 57 12/22 37/26/32/+3/T/T/136/25 47 W AERO 47 MPH W RMY 43 12/23 37/25/31/+2/0.00/0.0/305/56 44 WNW AERO 44 MPH WNW RMY N/A 12/24 39/28/34/+5/0.01/0.2/452/83 25 W AERO 23 MPH W RMY 22 12/25 33/25/29/+1/0.02/0.4/000/00 21 NNW AERO 21 MPH NNW RMY 19 12/26 morning low temp: 20F; the normal low is now 2OF DAILY RECORDS FOR DECEMBER 2012 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR DECEMBER 26 HIGH 58 IN 1973,1982 LOW -12 IN 1980 PRECIP 3.64 INS. IN 1969 SNOWFALL 17.5 INS. IN 1909 PEAK GUST 84 MPH SSE IN 1957 RECORDS FOR DECEMBER 27 HIGH 57 IN 1895,1949 LOW -4 IN 1903 PRECIP 2.43 INS. IN 1969 SNOWFALL 11.2 INS. IN 1947 PEAK GUST 73 S IN 2011 TODAY'S REPORT PREPARED BY: Robert Skilling, Jonathan O'Brien