BLUE HILL METEOROLOGICAL OBSERVATORY  MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY FRIDAY, MAY 8, 2015     ALL TIMES ARE IN EASTERN STANDARD TIME MAXIMUM OF 74F REACHED BY EARLY MORNING, WINDS SHIFT, BACK DOOR FRONT ROLLS THROUGH Friday morning's temperature began to climb similar to previous days, until a back door cold front moved through around 8:30 AM EST. Hazy conditions at the 7:00 AM EST observation coupled with the thin fog that moved in off the ocean reduced visibility from 40 miles at time to 12 miles during the morning. By the 1:00 PM EST observation visibility had been reduced further to 10 miles in all directions with obscuring haze and fog coming in from off the ocean. Temperatures had dropped from a maximum of 74F by the time of the wind shift to a day time minimum of 56F only a little more than an hour later. PRELIMINARY STATS FOR APRIL 2015 TEMPERATURE, Deg. F Avg. Max. 55.9 [+0.2] Avg. Min. 38.4 [+0.7] Mean      47.2 [+0.5] Corrected mean: 46.7  Max. for month: 69 on 4/13 Min. for month: 26 on 4/1 HEATING DEGREE DAYS  Total heating units: 528 [-23]     Total for the season: 6271 [+236] Total for last season: 6171 PRECIPITATION, Inches Total: 3.33 [-1.22] Greatest in 24 hrs: N/A SNOWFALL, Inches Total: Trace [-3.0] Greatest in 24 hrs: Trace on 4/8 WIND, mph Avg. uncorrected wind speed: 12.6 Avg. corrected wind speed: 13.0 Prevailing wind direction: NW @ 16% Peak gust and direction: 54 NW on the 4th SUNSHINE: Astronomical total minutes:   12386 / 24083 or 51% Campbell-Stokes card minutes: 11946 / 23250 or 51% Today's Observations: 7 A.M. Weather: Clear, few cirrus distant WNW-SE Temperature: 64F; Dew Point: 44F; Wind: W at 7 kts, Sea-level pressure: 30.14 ins. Hg, rising steadily Visibility: 40 miles, hazy 6-hr Max temp: 64F 6-hr Min temp: 57F 24-hr precip: none BHO SA 1155 CLR 40 205/64/44/2607/014/ FEW CI DSNT WNW-SE HAZY/  8/001 52010 10064 20057   10 A.M.  Weather: Thin scattered cirrus Temperature: 59F; Dew Point: 45F; Wind: ENE at 13 kts, Sea-level pressure: 30.18 ins. Hg, rising, then more quickly Visibility: 20 miles, except 15 miles NW-NE, thin fog and hazy BHO SA 1455 250 -SCT 20 220/59/45/0613/018/ VSBY NW-NE 15 MI THN FG ALQDS HAZY/ 8/001 53015 1 P.M.  Weather: Think broken cirrus Temperature: 57F; Dew Point: 44F; Wind: ENE at 13G20 kts, Sea-level pressure: 30.21 ins. Hg, rising, then more slowly Visibility: 10 miles, hazy and thin fog 6-Hr Max temp: 74F 6-Hr Min temp: 56F BHO SA 1755 E250 -BKN 10 229/57/44/0613G20/021/ THN FG ALQDS HAZY/ 8/001 51009 10074 20056 SUMMARY FOR THURSDAY, MAY 7, 2015     TEMPERATURE (DEGREES F) MAX.....84   NORMAL.....64 MIN.....52   NORMAL.....45 MEAN....68   NORMAL.....55 DEPARTURE FROM 30-YEAR NORMAL......................+13 TOTAL DEPARTURE FOR THE MONTH......................+41 [+5.7 DEGREES/DAY]    HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY...............0  DEPARTURE..........-11 TOTAL HEATING UNITS FOR THE MONTH..............43  DEPARTURE..........-39     TOTAL HEATING UNITS FOR THE SEASON...........6314  DEPARTURE.........+197 TOTAL HEATING UNITS LAST SEASON TO DATE......6238  DIFFERENCE.........+76 PEAK GUST AND AVERAGE WIND SPEED (MPH)  PEAK WIND GUST FOR YESTERDAY..................29 S     AT   4:53 P.M.                          ASOS.......................32 S     AT   4:53 P.M.                           DAVIS......................31 S     AT   4:53 P.M. RMY 32  FASTEST MILE FOR YESTERDAY....................24 S     AT   4:51 P.M.*   MAXIMUM 2-MINUTE ASOS AVERAGE.................24 S     AT   4:53 P.M.          MAXIMUM 2-MINUTE DAVIS AVERAGE................22 S     AT   4:43 P.M.    AVERAGE WIND SPEED AND DIRECTION............12.0 SW                    ASOS.....................12.3                         DAVIS....................10.9 SW [225 degrees]  * Last of several occurrences...   PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.....0.00  DEPARTURE.....-0.13                          ASOS...............0.00 TOTAL PRECIPITATION FOR THE MONTH...........0.03  DEPARTURE.....-0.84                            ASOS...............0.03  TOTAL PRECIPITATION FOR THE YEAR...........17.95  DEPARTURE.....-1.34                          ASOS................N/A ***  *** ASOS annual totals not available due to erroneous readings SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M...........0.0  DEPARTURE......0.0 TOTAL SNOWFALL FOR THE MONTH.................0.0  DEPARTURE......0.0   TOTAL SNOWFALL FOR THE SEASON..............150.8  DEPARTURE....+88.1  PRELIMINARY CLIMATE SUMMARY FOR APRIL CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/SUN(MIN.)/SUN(%)/ PEAK GUST/RMY GUST RMY:  R.M. Young wind gust recording system  TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 4/1  44/26/35/-6/0.00/0.0/748/98              30 WNW RMY 31  4/2  59/29/44/+3/T/0.0/375/49                 39 SSW RMY 43  4/3  56/47/52/+10/0.02/0.0/000/00             36 SW  RMY N/A 4/4  49/32/41/-1/0.32/0.0/501/65              54 NW  RMY 64  TSTM 4/5  47/30/39/-4/T/0.0/464/60                 40 W   RMY 45 4/6  48/33/41/-2/0/00/0.0/544/70              18 NE  RMY N/A   4/7  39/34/37/-6/0.13/0.0/000/00              21 NE  RMY N/A 4/8  41/32/37/-7/0.51/T/000/00                30 ENE RMY 32 4/9  35/32/34/-10/0.38/0.0/000/00             31 ENE RMY 32 4/10 53/35/44/-1/0.07/0.0/000/00              31 SW  RMY N/A 4/11 56/38/46/+1/0.00/0.0/744/94              39 WNW RMY 48 4/12 68/35/52/+7/0.00/0.0/762/96              23 WNW RMY 23   4/13 69/47/58/+12/0.00/0.0/764/96             35 SSW RMY N/A 4/14 65/51/58/+12/0.05/0.0/072/09             37 SSW RMY N/A 4/15 67/45/56/+9/0.00/0.0/786/98              32 NW  RMY 33 4/16 64/42/53/+6/0.00/0.0/765/95              31 S   RMY 21 4/17 64/45/55/+8/0.05/0.0/065/08              31 SSW RMY 32 4/18 64/43/54/+6/0.00/0.0/770/95              31 N   RMY 36  4/19 55/39/47/-1/0.00/0.0/724/89              25 NNW RMY N/A 4/20 55/38/47/-2/1.00/0.0/000/00              36 SE  RMY 40 4/21 67/51/59/+10/0.44/0.0/417/51             30 SSE RMY N/A TSTM 4/22 67/45/56/+7/0.03/0.0/632/77              44 SSW RMY 52 4/23 49/34/42/-8/0.00/0/0/362/44              32 W   RMY N/A  4/24 50/32/41/-9/0.00/0.0/562/68              32 NW  RMY 36   4/25 56/30/43/-7/0.00/0.0/638/77              26 NW  RMY 29 4/26 54/39/47/-4/0.00/0.0/258/31              17 NW  RMY N/A 4/27 56/42/49/-2/0.15/0.0/125/15              30 NW  RMY N/A 4/28 63/39/51/-1/0.10/0.0/527/63              32 NW  RMY 35  4/29 58/46/52/+0/T/0.0/461/55                 24 ENE RMY 22 4/30 60/42/51/-1/0.00/0.0/320/38              21 NE  RMY N/A PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA DATA REPORTED: DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOWFALL/SUN(MIN.)/SUN(%)/ PEAK GUST/RMY GUST RMY:  R.M. Young wind gust recording system  TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 5/1 52/37/45/-8/0.00/0.0/.../..               21 NE  RMY 20 5/2 63/35/49/-4/0.00/0.0/.../..               20 S   RMY 20   5/3 74/44/59/+6/0.00/0.0/.../..               22 S   RMY 22 5/4 83/47/65/+11/0.00/0.0/.../..              39 SSW RMY 45 5/5 77/56/67/+13/0.03/0.0/.../..              29 SW  RMY N/A 5/6 74/54/64/+10/0.00/0.0/.../..              24 SSW RMY 25 5/7 84/52/68/+13/0.00/0.0/.../..              29 S   RMY 32 5/8 Low since midnight is 57F; normal low now 45F DAILY RECORDS FOR MAY 2015 NONE SO FAR  DAILY EXTREMES  Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated):   RECORDS FOR MAY 8 HIGH 89F IN 2000 LOW 29F IN 1956 PRECIP 1.48 INCHES IN 1886 SNOWFALL TRACE IN 1898, 1947 PEAK GUST 68e MPH NNW IN 1943 RECORDS FOR MAY 9 HIGH 93F IN 2000 LOW 31F IN 1947 PRECIP 2.72 INCHES IN 1954 SNOWFALL 5.0 INS IN 1977 (RECORD FOR MAY) PEAK GUST 70e MPH NE IN 1977 TODAY'S REPORT PREPARED BY: Brian Fitzgerald