NATIONAL STORM SUMMARY

 

JULY 2017

 

2-8: Rainfall across the Midwest was generally light, but a band of heavier rain (locally 2 to 4 inches or more) stretched from the southeastern Plains into the Mid-Atlantic States.  Early- to mid-week downpours soaked portions of the southeastern Plains, where McAlester, OK, received 3.66 inches of rain during the first 5 days of July.  Similarly, Texarkana, AR, netted 3.69 inches from July 1-6.  Just to the north, Vichy-Rolla, MO, reported a daily-record total of 2.86 inches on July 5.  Later, heavy showers spread across the Tennessee Valley into the central Appalachians and the Mid-Atlantic States, where record-setting totals for July 6 reached 2.18 inches in Morgantown, WV, and 1.54 inches in Baltimore, MD.  Dayton, OH, also reported a daily-record total (2.22 inches) for July 6.  In the New York City area, record-setting totals for July 7 reached 2.14 inches at LaGuardia Airport and 1.92 inches at JFK Airport.  In contrast, little or no rain fell from the Pacific Coast to the Rockies and northern Plains.  In Glasgow, MT, the driest January-June period on record was followed by completely dry weather from July 1-10.

 

9-15: The Southwestern rainfall, which triggered local flooding, was largely due to the seasonal establishment of the monsoon circulation.  Elsewhere, separate areas of widespread showers affected the eastern half of the nation.  In particular, heavy showers occurred in the Deep South and from the Great Lakes region into the Northeast, sparking local flooding.  Cooler-than-normal conditions were limited to scattered areas in the Great Lakes and Northeastern States. For much of the week, the heaviest showers were concentrated in the Great Lakes States and across the South.  Recordsetting rainfall totals for July 9 included 2.99 inches in Naples, FL, and 2.44 inches in Florence, SC.  The following day in the Midwest, daily-record amounts for July 10 reached 2.15 inches in Peoria, IL, and 1.89 inches in Fort Wayne, IN.  Elsewhere in Indiana, Indianapolis netted a daily-record total (3.78 inches) for July 11.  Locally heavy showers also clipped the eastern edge of the northern Plains’ drought area on July 11, when Watertown, SD, collected a daily-record sum of 1.59 inches.  Locally heavy showers continued to pepper various parts of the country on July 12, resulting in daily-record totals in Florida locations such as Miami (5.49 inches) and Melbourne (2.60 inches).  Also on the 12th, Northeastern daily-record amounts totaled 1.33 inches in Boston, MA, and 1.09 inches in Watertown, NY.  A day later, Buffalo, NY, measured a record-setting sum (2.29 inches) for July 13.  In southeastern Wisconsin and northeastern Illinois, pounding rainfall (locally 10 inches or more) during the first half of July led to record flooding along portions of the Fox and Des Plaines Rivers.  Specifically, the Fox River achieved record crests on July 12-13 in Wisconsin locations such as Burlington and New Munster, topping high-water marks from June 15, 2008, by 2.3 to 2.6 feet.  Meanwhile in Illinois, the Des Plaines River crested on July 14-15 more than 5 feet above flood stage in Russell and Gurnee.  Previous crest records—set on May 23, 2004, in Russell and September 27, 1986, in Gurnee—were eclipsed by 1.06 and 0.14 foot, respectively.  Late-week rainfall was generally heaviest across the southern U.S., where daily-record totals were established on July 14 in New Orleans, LA (3.50 inches), and Jackson, MS (2.35 inches).  Farther west, a deadly flash flood struck near Payson, AZ, on July 15, when ten members of an extended family were swept away as runoff from a nearby thunderstorm in the Ellison Creek watershed rushed downstream.  In Tucson, AZ, where the July 10-15 rainfall totaled 2.49 inches, no measurable rain had fallen during the preceding 61-day period from May 10 to July 9.  In fact, Tucson’s rainfall from February 1 – July 9 had totaled just 0.43 inch, 16 percent of normal.

 

16-22: “Ring of fire” thunderstorms prevailed around the periphery of the ridge, as moisture associated with the Southwestern monsoon circulation became entangled with Northern cold fronts.  However, excessive rainfall (4 inches or more) caused local flooding in parts of southern Wisconsin, northern Illinois, northeastern Iowa, and southeastern Minnesota.  Widespread showers also dotted the remainder of the northern Plains.  Heavy showers fell early in the week in the East, where daily record amounts for July 17 included 3.09 inches in Orlando, FL, and 2.26 inches in Williamsport, PA.  A day later, record setting totals for July 18 reached 3.50 inches in Florence, SC, and 1.66 inches at Virginia’s Dulles Airport.  Later, heavy rain developed across the upper Midwest.  On July 19, daily-record totals included 2.85 inches in La Crosse, WI, and 1.18 inches in Mobridge, SD.  Rockford, IL, netted a daily-record sum (2.45 inches) for July 20.  Another round of heavy showers struck the upper Midwest on July 21, resulting in daily-record totals in locations such as Dubuque, IA (2.52 inches), and Watertown, SD (0.94 inch).  With 3.11 inches, Moline, IL, reported a record-setting sum for July 22.  Mid- to late-week showers also continued across the Deep South, including Florida, where daily-record totals reached 2.79 inches (on July 22) in Jacksonville and 2.68 inches (on July 20) in Gainesville.  In fact, Gainesville collected at least an inch of rain on July 17, 1920, and 22-23, boosting its month-to-date total to 13.83 inches (300 percent of normal).  Elsewhere, locally heavy showers peppered the Four Corners States, with daily-record amounts totaling 0.85 inch (on July 19) in Prescott, AZ, and 0.41 inch (on July 22) in Alamosa, CO. 

 

23-29: Rain fell in many parts of the country, with the greatest concentration of showers arcing across the Plains from the Southwest into the Southeast.  However, significant rain bypassed the south-central U.S., where mostly dry weather was accompanied by late-week heat. Another late-week development was the arrival of heavy rain across the northern Mid-Atlantic region, where totals of 2 to 6 inches were common.  Substantial showers also dotted the Southwest and neighboring areas, largely due to robust monsoon showers.  In contrast, little or no rain fell in the Pacific Coast States and across the nation’s northern tier as far east as the upper Great Lakes region.  Heavy showers peppered the East early in the week and again in late July.  Daily-record rainfall totals for July 23 reached 4.71 inches in Harrisburg, PA, and 2.33 inches in Fayetteville, NC.  Some of the early-week rain reached into the lower Great Lakes States, where record-setting totals for the 23rd included 2.50 inches in Evansville, IN, and 1.69 inches in Sault Sainte Marie, MI.  Eastern downpours lingered through July 24, when daily-record amounts totaled 3.64 inches in Birmingham, AL, and 2.46 inches in Philadelphia, PA.  By mid-week, patches of heavy rain erupted across the nation’s mid-section.  Mitchell, SD, netted a dailyrecord sum (1.14 inches) for July 25.  The following day, recordsetting amounts for July 26 included 2.94 inches in Kansas City, MO; 1.90 inches in Springfield, IL; and 1.66 inches in Colorado Springs, CO.  Farther west, an active monsoon circulation contributed to heavy showers.  In Arizona, daily-record amounts reached 1.79 inches (on July 23) in Flagstaff; 0.96 inch (on July 28) in Prescott; and 0.83 inch (on July 29) in Kingman.  Clayton, NM,

netted a daily-record sum of 1.58 inches on July 27.  In Utah, Zion National Park received 1.05 inches in a 24-hour period on July 2425.  Showers occasionally reached into the Northwest, where dailyrecord totals included 1.06 inches (on July 26) in Idaho Falls, ID, and 0.98 inch (on July 24) in Klamath Falls, OR.  Toward week’s end, the development of a low-pressure system over the MidAtlantic region helped to focus heavy rain.  Record-setting totals for July 28 climbed to 3.31 inches in Washington, DC, and 2.58 inches in Baltimore, MD.  Atlantic City, NJ, received 5.41 inches of rain on July 29, representing its wettest day since August 20, 1997, when 11.10 inches fell.  As the month drew to a close, it became the wettest July on record in Gainesville, FL (16.70 inches; previously, 16.65 inches in 2013), and Tucson, AZ (6.80 inches; previously, 6.24 inches in 1921), as well as the second-wettest July in Clarksburg, WV (10.34 inches; behind only 10.92 inches in 2003).

 

Jim G. Munley, jr.
http://www.jimmunleywx.com