Friday, September 13, 2013

BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

DAILY DISCUSSION AND CLIMATE SUMMARY
FRIDAY, SEPTEMBER 13, 2013
ALL TIMES ARE IN EASTERN STANDARD TIME

THURSDAY LATE P.M. T-STORM, FRIDAY A.M. SHOWERS BRING 0.64 INCH OF RAIN;
COOLER AND MUCH CALMER TODAY

A thunderstorm began between the 10 & 11 o’clock hours EDT Thursday evening,
producing a peak wind gust on the summit of 32 mph and rainfall of 0.47
inch. Additional light rain showers this morning added another 0.17 inch
or precipitation.

The summit began the day in the fog, with visibility down to 1/4 mile at
times. Soon after the 8 A.M. EDT observation, the fog began dissipating and
the cloud base began to lift as an area of light rain exited eastern MA.
This afternoon, visibility has improved to a hazy 45 miles. There have been
periods of sunshine this afternoon, too, which has helped develop some
towering cumulus and even a few downpours across the area.

Winds have been rather light today, even calm at times. We seem to be in a
lull awaiting a cold front that should finally move through later today,
bringing with it a cooler and much drier air mass for the weekend.

Today’s Observations:

7 A.M.
Weather: Sky obscured by light rain and dense fog, stratus drifting over
summit, light rain continued with occasional moderate rain
Temperature: 66F; Dew Point: 66F; Wind: NW at 7 kts,
Wind: Direction gradually veering over the past hour
Sea-level pressure: 29.65 ins. Hg, rising then steady
Visibility: 3/8 mile, variable 1/4 to 1/2 mile, increasing rapidly, light
rain and dense fog
24-hr precip: 0.59 inch
6-hr precip: 0.12 inch
6-hr min. temp: 66F
BHO SA 1155 W4 X 3/8R-F 042/66/66/3107/965/ STRA DRFTNG OVR SMT VSBY
1/4V1/2 INCRSNG RPDLY WND GRDLY VEERING PST HR R- CTD OCNL R/ 8//// 51010
MANUAL 70059 ASOS 70057 MANUAL 60012 ASOS 60011 10067 20066

10 A.M.
Weather: Scattered cumulus/cumulus fractus/stratus fractus, scattered
stratocumulus, broken altocumulus (2 levels), few stratus fractus below
summit ENE-S-W, few moderate cumulus tops visible distant W-N, few
altocumulus lenticularis all quadrants, thin smoke layer distant N-NE, hazy
Temperature: 69F; Dew Point: 68F; Wind: Estimated W at 1 kt,
Wind: Light and variable
Sea-level pressure: 29.64 ins. Hg, falling slightly
Visibility: 30 miles, hazy
3-hr precip: 0.05 inch
BHO SA 1455 5 SCT 25 SCT E70 BKN 100 BKN 30 038/69/68/E2701/964/ FEW STFRA
BLO SMT ENE-S-W FEW MDT CU TOPS VSBL DSNT W-N FEW ACSL ALQDS THN K LYR DSNT
N-NE HAZY WND LGT AND VRB/ 8/870 58004 MANUAL 60005 ASOS 60006

1 P.M.
Weather: Scattered cumulus, scattered altocumulus (2 levels), broken thin
cirrus, moderate cumulus all quadrants, few towering cumulus W-NNW,
altocumulus/altocumulus lenticularis distant NNE-ESE, few cirrocumulus
SSW-SW, distant haze
Temperature: 77F; Dew Point: 65F; Wind Estimated WSW at 3 kts,
Wind: Light and variable
Sea-level pressure: 29.61 ins. Hg, falling
Visibility: 45 miles, distant haze
6-hr precip: 0.05 inch
6-hr max. temp: 77F
6-hr min. temp: 65F
BHO SA 1755 25 SCT 70 SCT 100 SCT 250 –BKN 45 026/77/65/E2403/961/ MDT CU
ALQDS FEW TCU W-NNW AC/ACSL DSNT NNE-ESE FEW CC SSW-SW DSNT HZ WND LGT AND
VRB/ 8/349 58012 MANUAL 60005 ASOS 60006 10077 20065

WEATHER SUMMARY FOR THURSDAY, SEPTEMBER 12, 2013

TEMPERATURE (DEGREES F)
MAX…..85 NORMAL…..73
MIN…..66 NORMAL…..56
MEAN….76 NORMAL…..65

DEPARTURE FROM 30-YEAR NORMAL………………….+11
TOTAL DEPARTURE FOR THE MONTH…………………..+9 [+0.6 DEGREE/DAY]

COOLING DEGREE DAYS (SEASON JAN TO DEC)
TOTAL COOLING UNITS FOR YESTERDAY………….11 DEPARTURE………+9
TOTAL COOLING UNITS FOR THE MONTH………….50 DEPARTURE……..+13
TOTAL COOLING UNITS FOR THE SEASON………..690 DEPARTURE…….+116
TOTAL COOLING UNITS LAST SEASON TO DATE……754 DIFFERENCE…….-64

PEAK GUST AND AVERAGE WIND SPEED (MPH)
PEAK WIND GUST FOR YESTERDAY………………32 S AT 9:32 P.M.
AERO…………………..33 S AT 9:32 P.M. *
ASOS…………………..33 S AT 9:33 P.M.
DAVIS………………….33 S AT 9:32 P.M. RMY 34
FASTEST MILE FOR YESTERDAY………………..26 S AT 9:33 P.M. *
MAXIMUM 2-MINUTE ASOS AVERAGE……………..25 S AT 12:59 P.M.
MAXIMUM 2-MINUTE DAVIS AVERAGE…………….25 SSW AT 12:59 P.M.
AVERAGE WIND SPEED AND DIRECTION…………14.8 S
ASOS…………………13.9
DAVIS………………..13.6 SSW [193 degrees] * last of several occurrences

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST)
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M….0.59 DEPARTURE………….+0.46
ASOS…………..0.57
TOTAL PRECIPITATION FOR THE MONTH……….3.45 DEPARTURE………….+1.96
ASOS…………..3.56
TOTAL PRECIPITATION FOR THE YEAR……….41.46 DEPARTURE………….+4.95
ASOS…………..N/A*
*ASOS malfunctioned during storm on 2/8-9, leading to erroneous totals

PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER 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

9/1 76/67/72/+4/2.32/008/01 33 S AERO 39 MPH S RMY 38 TSTM
9/2 79/67/73/+5/0.43/056/07 30 SSE AERO 33 MPH SSE RMY N/A TSTM
9/3 79/61/70/+3/0.00/219/28 28 S AERO 29 MPH S RMY 30 TSTM
9/4 78/57/68/+1/0.00/733/94 24 W AERO 25 MPH W RMY 25
9/5 66/51/59/-8/0.08/179/23 20 NNE AERO 20 MPH NNE RMY 21
9/6 68/46/57/-10/0.00/751/97 18 WSW AERO 17 MPH WSW RMY N/A
9/7 78/51/65/-1/0.00/594/77 20 WSW AERO 21 MPH WSW RMY 21
9/8 74/50/62/-4/0.00/646/84 31 NW AERO 33 MPH NW RMY 32
9/9 69/47/58/-8/T/529/69 23 SW AERO 23 MPH SSW RMY N/A
9/10 73/56/65/0/0.03/007/01 30 S AERO 32 MPH S RMY 33
9/11 93/68/81/+14/0.00/654/86 25 SW AERO 27 MPH SW RMY N/A
9/12 85/66/76/+11/0.47/…/.. 32 S AERO 33 MPH S RMY 34 TSTM

9/13 morning low temp: 66F; the normal low is now 56F

DAILY RECORDS FOR SEPTEMBER 2013
9/1 – NEW DAILY RECORD MAXIMUM PRECIPITATION OF 2.32 INCHES;
surpasses previous record of 1.60 inches set in 1927
9/11 – TIED DAILY RECORD MAXIMUM HIGH TEMPERATURE OF 93F;
ties record of 93F set in 1983

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated):

RECORDS FOR SEPTEMBER 13
HIGH 91F IN 1957
LOW 40F IN 1985
PRECIP 3.10 INCHES IN 1987
PEAK GUST 44 MPH WNW IN 1986

RECORDS FOR SEPTEMBER 14
HIGH 90F IN 1931
LOW 34F IN 1911
PRECIP 4.38 INCHES IN 1944 (Great Atlantic Hurricane in 1944)
PEAK GUST 96e MPH E IN 1944 (Great Atlantic Hurricane in 1944)

TODAY’S REPORT PREPARED BY: Sean Fankhauser