BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY THURSDAY, JANUARY 17, 2013 ALL TIMES ARE IN EASTERN STANDARD TIME GLAZE AND SOME VERY LIGHT RIME ICE THIS MORNING; SNOW CHANGED TO FREEZING RAIN AND SOME FREEZING DRIZZLE BY NOON YESTERDAY AND BEFORE PRECIPITATION ENDED AT MID-AFTERNOON THERE WAS 1/8 INS. WITH MORE ON THE TOWER WIRES ON THE ROOF; ICE ON PONDS PARTIALLY MELTED Freezing rain and drizzle occurred yesterday after the snow ended by mid-morning. By the time freezing precipitation ended at mid-afternoon a coating of glaze had formed. Several of our wind systems froze up including a 7 hour outage on our hourly contacting wind system. Back-up data was obtained from the 420C gust recorder which kept tracing. The Davis wind cups and vanes were also affected, causing a noticeable decrease in the day's average speed. This data is starred in the listing below. Wind speeds were unsually low yesterday, about as low as we see them in snow events. The average speed for the day was only around 7 MPH. Snow and ice were melting off trees and other surfaces by noon as temperatures warmed to a high of 39 degrees. Ponkapoag Pond was less than half covered by ice early this afternoon while Houghtons was more like 8/10 ice covered. Today's observations: 7 A.M. Weather: Scattered altocumulus and altocumulus lenticularis, scattered cirrus, thin fog and haze, thin glaze and thin rime ice, up to 1/4 inch radii glaze on wires on tower, total new snow past 24 hours 1.0 inch Temperature: 30F; Dew Point: 29F; Wind: WSW at 8 kts Sea-level pressure: 29.90 ins. Hg, rising then more rapidly Visibility: 25 miles, thin fog and hazy 24-hour precip: 0.21 in. 24-hour snowfall: 1.0 inch Snow depth on ground: 2 inches 6-hour min temp: 30F BHO SA 1155 75 SCT 220 SCT 25 124/30/29/2408/990/ FEW ACSL ALQDS THN FH THN GLZ/RIME XCPT 1/4 IN RADII GLZ ON TWR WIRES TOTAL NEW SNW PST 24 HRS 1.0 IN/ 8/041 4/002 53011 ASOS 70022 MANUAL 70021 10032 20030 10 A.M. Weather: Scattered cirrus, thin overcast cirrus, altocumulus to the mostly distant ESE-SW, numerous breaks in overcast Temperature: 33F; Dew Point: 29F; Wind: W at 10 kts Sea-level pressure: 30.01 ins. Hg, rising Visibility: 30 miles, hazy BHO SA 1455 220 SCT 250 –OVC 30 151/33/29/2610/998/ AC MSTLY DSNT ESE-SW NMRS BINOVC HAZY/ 8/031 51027 1 P.M. Weather: Scattered altocumulus, few castellanus and floccus east through south, scattered dense ci/trails snow virga E-ESE, layer dns cirrus SW-NW-NE, thin higher cirrus layer, cumulus fractus/cumulus forming few moderate cumulus north Temperature: 38F; Dew Point: 29F; Wind: WNW at 12G25 kts, Wind: Direction variable W-NW Sea-level pressure: 29.96 ins. Hg, falling slightly Visibility: 35 miles, distant haze 6-hour max. temp: 39F BHO SA 1755 150 SCT 220 SCT 250 BKN 35 147/38/29/2912G25/996/ CUFRA/CU FRMG ALQDS FEW MDT CU N FEW ACC E-S PTCHS DNS CI FEW TRLS SNW VIRGA E-ESE LYR DNS CI SW-NE-NE HIER CI THN WND 26V32 DSNT HZ/ 8/282 58004 10039 20030 WEATHER SUMMARY FOR WEDNESDAY, JANUARY 16 TEMPERATURE (DEGREES F) MAX.....33 NORMAL.....33 MIN.....29 NORMAL.....17 MEAN....31 NORMAL.....25 DEPARTURE FROM 30-YEAR NORMAL.......................+6 TOTAL DEPARTURE FOR THE MONTH.....................+130 [+7.9 DEGREES/DAY] HEATING DEGREE DAYS TOTAL HEATING UNITS FOR YESTERDAY............34 DEPARTURE..........-6 TOTAL HEATING UNITS FOR THE MONTH...........499 DEPARTURE........-129 TOTAL HEATING UNITS FOR THE SEASON.........2527 DEPARTURE........-405 TOTAL HEATING UNITS LAST SEASON TO DATE....2299 DIFFERENCE.......+228 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...............16 NNE AT 12:05 A.M. AERO....................14 N AT 11:17 A.M. ASOS....................16 W AT 10:54 P.M. DAVIS...................14 NNE AT 12:05 A.M. RMY N/A THE FASTEST MILE FOR YESTERDAY.............11 N AT 11:16 A.M. MAXIMUM 2-MINUTE ASOS AVERAGE..............13 NNW AT 4:03 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.............11 N AT 11:15 A.M. AVERAGE WIND SPEED AND DIRECTION......... 6.8 N ASOS.................. 7.6 DAVIS..................4.7 N ** [010 deg.] ** Davis anemometer slowed by glaze accumulation CONTACTING SPEED MILES STOPPED RECORDING FOR 6 HOURS PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M... 0.21 DEPARTURE..........+0.07 ASOS..............0.22 TOTAL PRECIPITATION FOR THE MONTH..........0.63 DEPARTURE..........-1.65 ASOS..............0.60 TOTAL PRECIPITATION FOR THE YEAR...........0.63 DEPARTURE..........-1.65 ASOS..............0.60 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M.........1.0 DEPARTURE............+0.5 TOTAL SNOWFALL FOR THE MONTH...............3.6 DEPARTURE............-5.4 TOTAL SNOWFALL FOR THE SEASON.............19.0 DEPARTURE............-6.0 PRELIMINARY CLIMATE SUMMARY FOR JANUARY 2013 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 1/1 35/18/27/0/0.00/0.0/313/57 44 WNW AERO 44 MPH WNW RMY 45 1/2 29/11/20/-7/0.00/0.0/457/83 35 WNW AERO 35 MPH WNW RMY 33 1/3 23/2/13/-13/0.00/0.0/529/96 24 WNW AERO 23 MPH WNW RMY 23 1/4 38/19/29/+3/0.00/0.0/320/58 35 W AERO 36 MPH W RMY 36 1/5 40/27/34/+8/0.00/0.0/536/97 36 WNW AERO 37 MPH WNW RMY 38 1/6 42/27/35/+9/T/0.1/471/85 29 SW AERO 29 MPH SW RMY 29 1/7 38/27/33/+7/0.00/0.0/538/97 29 NW AERO 27 MPH NW RMY N/A 1/8 45/27/36/+10/0.00/0.0/428/77 39 SW AERO 42 MPH SW RMY 41 1/9 42/31/37/+11/T/0.0/033/06 40 W AERO 39 MPH W RMY N/A 1/10 45/32/39/+14/0.00/0.0/.../.. 47 WNW AERO 48 MPH WNW RMY 50 1/11 38/29/34/+9/0.15/0.0/.../.. 23 SE AERO 21 MPH SE RMY 23 1/12 43/35/40/+15/0.02/0.0/000/00 21 SE AERO 18 MPH SE RMY 15 1/13 50/41/46/+21/0.01/0.0/000/00 30 SW AERO 30 MPH SW N/A 1/14 59/40/50/+25/T/0.0/.../.. 36 S AERO 37 MPH S RMY 39 1/15 40/33/37/+12/T/0.0/.../.. 17 N AERO 16 MPH NNW RMY 17 1/16 33/29/31/+6/0.45/3.5/000/00 16 NNE AERO 14 MPH N RMY 15 1/17 morning low temp: 30F; the normal low is now 17F DAILY RECORDS FOR JANUARY 2013 None so far. DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR JANUARY 17 HIGH 55F IN 1973,1995 LOW -8F IN 1907,1982 PRECIP 1.43 INS. IN 1956 SNOWFALL 13.4 INS. IN 1956 PEAK GUST 62 MPH S IN 1994 RECORDS FOR JANUARY 18 HIGH 62F IN 1973,1990 LOW -10F IN 1982 PRECIP 1.68 INS. IN 1915 SNOWFALL 13.0 INS. IN 1948 PEAK GUST 85 MPH SSE IN 2006 TODAY'S REPORT PREPARED BY: Robert Skilling