July 2015: Rainfall Variability!

Posted: August 4, 2015, 8:32 pm by cspeciale

 

Shelf Cloud in Rhode Island July 2015. Photo Credit: Perry Russom

 

After enduring one of the wettest Junes on record, Mother Nature took it down a notch during July 2015. The rainfall variability across the Northeast was impressive as most of the month’s rain fell from typical garden variety thunderstorms as opposed to the organized systems seen in June. While the mid-Atlantic encountered more frequent severe weather days that included heavy downpours, North Jersey and New England missed much of action. Temperature wise, many from New York City to D.C recorded the first textbook heat wave of the year. Let’s take a look back at the month.

The active pattern from late June continued for the first half of July. On the 1st, severe storms rolled into the Washington D.C area producing a 74 mph gust before pushing north into New Jersey. Storms led to widespread rainfall west of I – 95 and a 51 mph gust at Newark Airport. Then, after hit and miss showers and storms on the 2nd and a quiet 3rd, Mother Nature brought cool temperatures and more wet weather for the Fourth. A large area of showers traversed Baltimore to Boston during the morning and early afternoon, keeping temperatures in the 70s. Luckily, it cleared in time for evening fireworks and a gorgeous day followed on July 5th.

Then, training storms from a warm front dumped nearly 3 inches around Baltimore on the 6th before pushing north and stalling in southern New England on the 7th. Temperatures spiked to near 90 south of New York City but heavy rain from storms in Fairfield County, CT raised flash flooding concerns. The associated cold front stalled over the mid-Atlantic on the 9th, setting the stage for severe weather. An organized area of severe storms rolled through the Philly metro area and not only produced numerous wind related damage, but an EF-0 tornado was confirmed in New Castle County, DE.

Warm and humid air returned for the 10th to the 13th with a few topping 90 degrees before storms fired again in the mid-Atlantic heading into the 14th. As a boundary stalled, training storms dumped over 3 inches in less than 2 hours in Salem and Cumberland County, NJ! Mother Nature didn’t stop here as an unusually strong system for July arrived on the 15th. While hit and miss storms impacted the Hudson Valley and North Jersey, heavy rain again targeted South Jersey. In fact, Little Egg Harbor, NJ received 4 inches in under 2 hours! Such a rainfall event is quite rare, occurring only once every 200 years.

Quieter weather then took shape from July 16th to the 23rd, but temperatures turned hot and humid. After a brief cool down from the 16th  - 17th (Boston, MA cooled to 68 degrees!), temperatures spiked into the 90s for the 19th and 20th. Add in the humidity and heat indices jumped to near 100 degrees. After hit and miss storms on the 21st, Canadian air relieved the Northeast from the heat for the 22nd - 23rd.

 

By the last week of the month, severe weather hit northern areas before Mother Nature turned up the heat, leading to the first true heat wave of the season for some spots. A back door cold front on the 26th brought severe storms to parts of New England and the Hudson Valley. Storms even reached Sussex County, NJ on the 27th, dumping nearly 5 inches of rain! Temperatures then turned hot for the final days of month, ranging from the upper 80s to mid 90s. The I – 95 corridor from New York City to Philadelphia even met the definition of a heat wave as temperatures remained at or above 90 degrees for 3 or more days. Of course, the humidity added insult to injury and the National Weather Service issued an Excessive Heat Warning during this time for some. By the 30th, a line of storms traversed the Northeast, finally bringing a widespread rainfall. The month then finished out a hot yet less humid note on the 31st.

 

 

The month of July 2015 did not break notable records in either the precipitation or temperature department but as seen in the image above, there were some drastic precipitation differences over short distances. Although this is typical for summer months as thunderstorms may dump heavy rain in one spot but fizzle before reaching another, some of the differences this July were impressive. Atlantic City, NJ, for instance, had a monthly rainfall surplus of nearly 3 inches while nearby Philadelphia, PA had a deficit of almost 1.50 inches. Of course, southern New England once again finished drier than normal, which kept the moderate drought in place since May untouched.

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