May 2017 NJWO Blog Climate summary and report for Rockville 2.8 WNW Maryland by Kevin Shaw Observer

by Kevin Shaw, Observer in charge

Average high temperature 72.4°
Average low temperature 55.9°
Mean temperature 64.2°
Precipitation 5.65″
Greatest daily amount(date) 1.75″ (5)
Snow 0.0″
Year to date precipitation 16.21″
High temperature for the month (date) 92° (17)
Low temperature for the month (date) 42° (8)
Highest barometric pressure (date) 30.34 (21)
Lowest barometric pressure (date) 29.30 (6)
Peak wind gust (date/direction): N/A
Heating degree days for the month: 105
Cooling degree days for the month: 80
Greatest diurnal range (date): 30.4° (14)
Least diurnal range (date) 7.4° (23)
Number of days:
Fog 9
Thunder 3
Cloudy 12
Partly Cloudy 15
Sunny/Clear 4

by Kevin Shaw, observer in charge

May 2017 reversed the general trend we had earlier this year, as we
had a wet and cooler month. The biggest highlight statistic of this trend was
the 20 days of measurable precipitation, an occurrence that has only
occurred a few times in the past. Precipitation totaled 5.65″ for the month,
with the heaviest daily amount recorded on the 5th (1.75″) due to the biggest
storm of the month, which also recorded the lowest pressure reading of the
month (29.30″). The coolest temperatures of the month occurred right after
this storm passage with a 42° on the 8th. Then about a week later, temperatures
rebounded up to 92° on the 17th, the highest reading of the month and the start
of a heat wave, which is defined as 3 days in a row (or more) of 90° or greater
maximum temperatures.

May coincided with my first full month of reliable precipitation readings from
my ground-mounted 4 inch cocorahs rain gauge. Timing on the establishment
of the gauge was excellent to capture all those rainy days!

There were 105 heating degree days (HDD) and 80 cooling degree
days (CDD) during the month. These figures weren’t all that different than
the ones for April.

My maximum temperature frequencies included the 3 days of 90° or more,
4 days between 80° and 89°, 12 days between 70° and 79°, 10 days
between 60° and 69°, and 2 days between 50° and 59°. On the minimum
temperature frequency side of things, there were 8 days between 40° and
49°, 13 days between 50° and 59°, 9 days between 60° and 69°, and 1 day
of 70° or over.

The diurnal range daily monthly average was 16.5°. Though I have no normals
for this location as yet, I will exhibit generally relatively low diurnal ranges
due to my station’s elevated location above ground. The maximum daily
range of 30.4° occurred on the 14th (76.2°- 45.8°) at the beginning of our
warmest period of the month. There were 8 days total with daily ranges at
or above 20°. The lowest daily temperature range of 7.4° (66.3°- 58.9°)
which occurred on the 23rd, near the beginning of our longest wet period
of the month, when 9 out of the last 10 days of the month had measurable
precipitation. There were a total of 6 days with minimum daily temperature
ranges less than 10°.

Despite the relative coolness of May, it still appears that the 2017 year
is headed for yet another record warm year. June has been warm and humid,
and once again dry. Please ask me any questions you want at any time through
any means you can. I am still working on some backlog issues, but they are
getting resolved slowly but surely. More improvements to my station are in
the works, and will be highlighted in future monthly reports.


About dabourphoto

Professional Photographer
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