by Kevin Shaw, Observer in charge

Average high temperature 65.7° (- 0.5°)
Average low temperature 43.1° (+ 1.4°)
Mean temperature 54.4° (+ 0.4°)
Precipitation 7.66″ (+4.00″)
Greatest daily amount 4.15″ (30)
Greatest storm amount 5.67″ (28-30)
Year to date precipitation 19.95 ” (+6.27″)
Snowfall (Sleet) T (-0.4″)
Greatest daily amount T (15)
2013-2014 Season snowfall 56.6″
High temperature for the month (date) 85° (13)
Low temperature for the month (date) 31° (16)

Highest barometric pressure (date) 30.67″ (17)
Lowest barometric pressure (date) 29.47″ (8)
Peak wind gust (date/direction): 25 (15/N)

Heating degree days for the month: 335
Cooling degree days for the month: 16
Greatest diurnal range (date): 36.6° (21)
Least diurnal range (date) 3.3° (29)

Fog days: 7
Sleet/Freezing Rain days: 1/0
Snow days : 0
Thunder days: 2
Sunny/clear days: 11 Partly Cloudy days: 11 Cloudy days: 8

Days with measurable precipitation (=>.01″) = 8
Days with minimum temperatures of 32 or less = 3
Days with maximum temperatures of 80 or more = 2
Days with minimum temperatures below 40 = 10

April 2014 Station Highlights – Gaithersburg 2 WNW Maryland

April 2014 was relatively dry and seasonable for the first 27 days of the month (1.99″),
but the last 3 days changed that in a big way with long-time monthly and daily records
falling by the wayside. The 4.15″ of rain that fell on the last day of the month not only
set a daily record for the 30th, but also set an all-time daily April record for any day,
surpassing the old record of 4.08″ set back on April 22, 2006. On the day before, the
1.32″ that fell also set a daily record for the 29th. Combined with the 0.20″ that fell
on the 28th and 0.18″ on the 1st of May, the four day total of 5.85″ was also an event
record breaker for April (5.67″ for Apr 28-30). This late “rally” put my monthly
total well above normal, and in fact set a new April monthly record of 7.66″, surpassing
the old monthly record of 7.50″ set back in 1983. Flooding was quite widespread for
several days in the region, but my neighborhood was spared any water damage that I
know of. A few daily temperature records were set, nothing as spectacular as the
precipitation records though. The 85 high temperature on the 13th set a daily record,
the 50 maximum temperature on the rainy 29th set a low maximum temperature
record for the date, and the 64 minimum temperature on the 14th set a high minimum
temperature daily record. A trace of sleet at the end of the storm (15th) also set a
daily record for snow/sleet on the date (Sleet and snow are considered the same for

Notable April 2014 weather was confined to mostly precipitation events. Temperatures
were quite seasonable, as the average maximum temperature for the month of 65.7° was
only 0.5° below the normal value of 66.2°. The average minimum temperature was a bit
warmer than normal, coming in at 43.1° which was 1.4° above the long-term average of
41.7°. The resulting mean average temperature for the month of 54.4° computes out to
just 0.4° above normal for the April mean. was quite a month. Three total minimum
temperature days of 32 or less was below the long term average of about 5.
Notable extremes of temperature were not to be found in April after having quite a
few during the first three months of 2014.

The monthly precipitation total of 7.66″ was 4.00″ above the normal amount of 3.66″.
The monthly snowfall total of a T was 0.4″ below the normal amount of 0.4″. My seasonal
snowfall total now stands at 56.6″, which ranks 4th greatest all-time.

Barometer readings varied significantly, though not as wild as March. The 30.61″ highest
reading on the 17th at the outset of our longest dry spell of the month (6 days – from
April 16 through April 21) followed the lowest reading of 29.47″ low reading on the 8th,
during our first significant rainfall of the month. . On the mid-month rainstorm of over
an inch, I hit my rather meager peak wind gust for the month of 25 MPH from the north.
Thankfully no power outages during that storm and peak wind, nor none the rest of the month.

The distribution of 11 sunny, 11 partly cloudy and 8 cloudy days was not necessarily in
concert with the number of measurable precipitation days (8), and above normal monthly
precipitation values, which were skewed due to the large dump on the 30th.

There was 1 day with at least a trace of snow, 4 days with fog, 1 day with sleet (in
concert with the snow day as sleet and snow are considered in the same statistic),
2 days with thunder and but no days with glaze. There was 16 cooling degree days
and 335 heating degree days.

My maximum temperature frequencies included 2 days of 80 or above, 7 days of 70-79,
13 days from 60-69, 7 days from 50-59, and 1 day from 40-49. On the minimum
temperature frequency side of things, there were 3 days of 32 or less, 7 days between
33-39, 14 days between 40-49, 4 days between 50-59, and 2 days between 60-69.

The diurnal range average was a bit below normal (22.6° vs the normal 24.5°). The max
daily range of 36.6° on the 8th occurred in the middle of our longest dry spell of the
month, and also the day of the lowest humidity value for the month (18%) while the 3.3°
lowest daily temperature range on the 29th occurred on our 2nd wettest day of the
month (1.32″), and when under the cool, cloudy stable air prior to the warm frontal
passage on the 30th. There were 3 days total with diurnal ranges lower than 10.0°,
two days near the beginning and this lowest value at the end of the month.
Conversely, the 6 days with ranges of 30° or more mostly occurred in the early part
of the month – all of those 6 days were on or before April 21.

After a cold and snowy winter, April reversed that trend. On April 1, the vegetation
in my immediate area looked like mid-winter after the cold March we had, but
spring warmth proliferated most of April, accelerating spring growth/tree blossom
generation. An analysis of my past 35 years of snowfall records places the winter
of 2013-2014 at 56.6″, the fourth snowiest of all time, with only the winters of
2009-2010 (80.7″), 1995-96 (63.2″) and 2003-2004 (59.0″) having more. With
ice still chiliing parts of the Great Lakes here in early May, there are thoughts by
many that this summer will be cooler than normal, especially if we can keep up
frequent frontal passages under NW flow.

Here are a few top monthly rainfall totals, in light of our most recent record rainfall
at the end of the month:

January 3.00” 1/20/2013 February 2.80” 2/14/2007 March 2.86” 3/13/1993 April 4.15” 4/30/2014

2.12” 1/14/2005 1.81” 2/29/2012 2.43” 3/23/1991 4.08” 4/22/2006

May 2.75” 5/5/1989 June 4.09” 6/25/2006 July 2.79” 7/20/1986 August 4.68” 8/11/2001

2.71” 5/18/1988 3.11” 6/18/1996 2.57” 7/27/1994 3.71” 8/6/1995

3.01” 6/19/1996 3.58” 8/19/1979

September 5.41” 9/5/1979 October 5.20” 10/29/2012 November3.03: 11/27/1993 December 2.10” 12/7/2011

5.20” 9/30/2010 3.50” 10/23/1990 2.95” 11/16/2006 2.09” 12/24/1986

4.92” 9/8/2011 3.22” 10/1/1979 2.71” 11/7/1997

4.31” 9/6/2008 3.07” 10/2/2012 2.58” 11/8/1996

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