July 2015 Gaithersburg 2 WNW Maryland – Summary statistics, descriptive climatology by Observer/NJWO member Kevin Shaw

JULY 2015 – GAITHERSBURG 2 WNW MARYLAND
BRIEF SUMMARY STATISTICS FOR WEATHER SHELTER
by Kevin Shaw, Observer in charge

Average high temperature 85.1° (- 1.7°)
Average low temperature 67.8° (+ 2.1°)
Mean temperature 76.4° (+ 0.2°)
Precipitation 2.10″ (- 1.64″)
Greatest daily amount 0.89″ (4)
Year to date precipitation 27.20″ (+ 0.92″)
High temperature for the month (date) 95° (19)
Low temperature for the month (date) 60° (16,24)
Highest barometric pressure (date) 30.15″ (5)
Lowest barometric pressure (date) 29.52″ (14)
Peak wind gust (date/direction): 20 (21/WSW)
Heating degree days for the month: 0
Cooling degree days for the month: 355
Greatest diurnal range (date): 26.2° (24)
Least diurnal range (date) 7.1° (2)

Fog days: 0
Thunder days: 2
Sunny/clear days: 7 Partly Cloudy days: 19 Cloudy days: 5

Days with measurable precipitation (=>.01″) = 10
Days with maximum temperatures of 90 or more = 4
Days with minimum temperatures of 70 or more = 14

JULY 2015 MONTHLY SUMMARY – GAITHERSBURG 2 WNW MARYLAND
by Kevin Shaw, observer in charge

July 2015 was not very noteworthy, particularly statistically with regard to temperature. Slightly above normal low temperatures were just about balanced out by slightly below normal high temperatures, resulting in a mean temperature within + 0.2° of normal. Precipitation was significantly below normal after a wet June, as the 2.10″ total was the eighth driest July in my 36 year period of record (POR). No record high or low temperatures were set, nor any daily precipitation records. The only records set were a daily low max temperature of 73° on July 2, and a daily high min temperature of 76° on the 20th, on the day after the hottest temperature of the month occurred (95° on the 19th). The lowest temperature of the month was set both on the 16th and 24th with a 60° reading. Precipitation, while meager, was spread out over 10 days with measurable albeit small amounts, but just a day below the long term POR average. There was only 2 thunder days for the entire month, tying 2002 and 2006 for the least amount ever during my POR (some years are missing – 30 year POR).

The average maximum temperature for the month was 85.1° (-1.7°), the average minimum temperature was 67.8°(+2.1°). The resultant mean average temperature for the month was 76.4° (+ 0.2°). Nothing really notably statistically as to record extremes on any of those temperature statistics. As in June we had a modest 4 days with max temperatures at or above 90°, considerably below the long term normal of 10.6. There were an above normal amount of days with minimum temperatures of 70° or more with 14, normal is probably around half that amount. Unfortunately I don’t have a long-term average amount for that statistic.

The month’s total precipitation amount of 2.10″ was 1.64″ below the normal July amount of 3.74″. The 10 days of measurable precipitation during the month was just a bit below the long term average of 11 days. The year to date (YTD) precipitation total of 27.20″ now puts us at 0.92″ above the normal YTD average amount for this time of year of 26.28″.

The monthly barometric pressure extremes were a very modest 30.15″ on the 5th at the end of our coolest period of the month with the 29.52″ lowest pressure value being recorded on the 14th, during one of our 2 day rainfall periods from a more active system than took place at other times during the month. Average barometric pressure for the month was 29.92″, within .005″ if you averaged the two extreme values (29.99″ and 29.86″). So far with five months study under my belt, this relationship has shown up as the same in March, 0.06″ difference in April, and 0.02″ in May and June, and now 0.005″ in July. These values look very promising for developing some sort of relationship there. Further study needed at least through the rest of the year.

The distribution of 7 sunny, 19 partly cloudy and 5 cloudy days coincided with the significantly below normal monthly precipitation 2.10″ amount.

There was 0 heating degree days and 355 cooling degree days. There were no days with fog observed, but with being retired now, I have been sleeping late and missing the prime time for observing fog, so we must take this very low reading with a grain of salt, especially when I had 17 days during the month when I had peak daily relative humidity percentages of 95 or greater. The peak wind gust during July was a modest 20 MPH (WSW) during a brief shower associated with a FROPA on the evening of the 21st.

My maximum temperature frequencies included 4 days at or above 90°, 23 days between 80° and 89°, and 4 days between 70°and 79°, On the minimum temperature frequency side of things, there were 17 days between 60°-69° and 14 days with minimums of 70° or greater.

The diurnal range average was a bit below normal (17.2° vs the normal 21.1°). The max daily range of 26.2° occurred on the 24th during a cooler, drier air mass we were fortunate to be under at the time. The lowest daily temperature range of 7.1° occurred on the 2nd during our coolest day of the month with lots of clouds but surprisingly no rain. We had a total of only 2 days during the month with a diurnal range less than 10° while there were a considerable 10 days with ranges of 20° or more, most of which occurred during the last half of the month.

The month of July 2015 had generally cooler temperatures during the first half of the month, with generally warmer temperatures during the last half of the month. As has been the case the past few years, warm nights persisted with many muggy nights most of the month. Once again, we failed to hit low temperatures in the 50s this July, I have done that 5 times now since I started recording temperatures back in 1979, and 3 of those 5 months occurred in 2011 and later. Three July months recorded mins in the 40s, but that has not occurred at all since 1988. Precipitation was fairly evenly dispersed during the month. So far in August we have started out a bit cooler and drier than normal. I don’t have any feeling one way or the other as far as that pattern maintaining the rest of the month. Details for August coming next, in a few short weeks.


This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
JULY 2015 – GAITHERSBURG 2 WNW MARYLAND BRIEF SUMMARY STATISTICS FOR WEATHER SHELTER
by Kevin Shaw, Observer in charge

Average high temperature 85.1 (- 1.7) Average low temperature 67.8 (+ 2.1) Mean temperature 76.4 (+ 0.2) Precipitation 2.10″ (- 1.64″) Greatest daily amount 0.89″ (4) Year to date precipitation 27.20″ (+ 0.92″) High temperature for the month (date) 95 (19) Low temperature for the month (date) 60 (16,24) Highest barometric pressure (date) 30.15″ (5) Lowest barometric pressure (date) 29.52″ (14) Peak wind gust (date/direction): 20 (21/WSW) Heating degree days for the month: 0
Cooling degree days for the month: 355
Greatest diurnal range (date): 26.2 (24) Least diurnal range (date) 7.1 (2)

Fog days: 0 Thunder days: 2
Sunny/clear days: 7 Partly Cloudy days: 19 Cloudy days: 5

Days with measurable precipitation (=>.01″) = 10 Days with maximum temperatures of 90 or more = 4
Days with minimum temperatures of 70 or more = 14

JULY 2015 MONTHLY SUMMARY – GAITHERSBURG 2 WNW MARYLAND
by Kevin Shaw, observer in charge

July 2015 was not very noteworthy, particularly statistically with regard to temperature. Slightly above normal low temperatures were just about balanced out by slightly below normal high temperatures, resulting in a mean temperature within + 0.2 of normal. Precipitation was significantly below normal after a wet June, as the 2.10″ total was the eighth driest July in my 36 year period of record (POR). No record high or low temperatures were set, nor any daily precipitation records. The only records set were a daily low max temperature of 73 on July 2, and a daily high min temperature of 76 on the 20th, on the day after the hottest temperature of the month occurred (95 on the 19th). The lowest temperature of the month was set both on the 16th and 24th with a 60 reading. Precipitation, while meager, was spread out over 10 days with measurable albeit small amounts, but just a day below the long term POR average. There was only 2 thunder days for the entire month, tying 2002 and 2006 for the least amount ever during my POR (some years are missing – 30 year POR).

The average maximum temperature for the month was 85.1 (-1.7), the average minimum temperature was 67.8(+2.1). The resultant mean average temperature for the month was 76.4 (+ 0.2). Nothing really notably statistically as to record extremes on any of those temperature statistics. As in June we had a modest 4 days with max temperatures at or above 90, considerably below the long term normal of 10.6. There were an above normal amount of days with minimum temperatures of 70 or more with 14, normal is probably around half that amount. Unfortunately I don’t have a long-term average amount for that statistic.

The month’s total precipitation amount of 2.10″ was 1.64″ below the normal July amount of 3.74″. The 10 days of measurable precipitation during the month was just a bit below the long term average of 11 days. The year to date (YTD) precipitation total of 27.20″ now puts us at 0.92″ above the normal YTD average amount for this time of year of 26.28″.

The monthly barometric pressure extremes were a very modest 30.15″ on the 5th at the end of our coolest period of the month with the 29.52″ lowest pressure value being recorded on the 14th, during one of our 2 day rainfall periods from a more active system than took place at other times during the month. Average barometric pressure for the month was 29.92″, within .005″ if you averaged the two extreme values (29.99″ and 29.86″). So far with five months study under my belt, this relationship has shown up as the same in March, 0.06″ difference in April, and 0.02″ in May and June, and now 0.005″ in July. These values look very promising for developing some sort of relationship there. Further study needed at least through the rest of the year.

The distribution of 7 sunny, 19 partly cloudy and 5 cloudy days coincided with the significantly below normal monthly precipitation 2.10″ amount.
There was 0 heating degree days and 355 cooling degree days. There were no days with fog observed, but with being retired now, I have been sleeping late and missing the prime time for observing fog, so we must take this very low reading with a grain of salt, especially when I had 17 days during the month when I had peak daily relative humidity percentages of 95 or greater. The peak wind gust during July was a modest 20 MPH (WSW) during a brief shower associated with a FROPA on the evening of the 21st.

My maximum temperature frequencies included 4 days at or above 90, 23 days between 80 and 89, and 4 days between 70and 79, On the minimum temperature frequency side of things, there were 17 days between 60-69 and 14 days with minimums of 70 or greater.

The diurnal range average was a bit below normal (17.2 vs the normal 21.1). The max daily range of 26.2 occurred on the 24th during a cooler, drier air mass we were fortunate to be under at the time. The lowest daily temperature range of 7.1 occurred on the 2nd during our coolest day of the month with lots of clouds but suprisingly no rain. We had a total of only 2 days during the month with a diurnal range less than 10 while there were a considerable 10 days with ranges of 20 or more, most of which occurred during the last half of the month.

The month of July 2015 had generally cooler temperatures during the first half of the month, with generally warmer temperatures during the last half of the month. As has been the case the past few years, warm nights persisted with many muggy nights most of the month. Once again, we failed to hit low temperatures in the 50s this July, I have done that 5 times now since I started recording temperatures back in 1979, and 3 of those 5 months occurred in 2011 and later. Three July months recorded mins in the 40s, but that has not occurred at all since 1988. Precipitation was fairly evenly dispersed during the month. So far in August we have started out a bit cooler and drier than normal. I don’t have any feeling one way or the other as far as that pattern maintaining the rest of the month. Details for August coming next, in a few short weeks.

Advertisements
This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s