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NATIONAL STORM SUMMARY
1-5: Minimal Tropical Storm Emily reached Florida’s Gulf coast near Tampa Bay on July 31, contributing to heavy showers but otherwise having few impacts. Emily, which made landfall with maximum sustained winds near 45 mph, was quickly downgraded to a tropical depression while crossing Florida’s peninsula and later dissipated over the western Atlantic Ocean. However, showers lingered for much of the week along and near the Gulf Coast. In particular, late-week downpours in New Orleans, LA, sparked flash flooding when the city’s pumps were unable to keep up with runoff and inflow. As Tropical Storm Emily approached and crossed Florida, selected daily-record totals included 2.33 inches (on July 30) in Tampa and 2.12 inches (on July 31) in Naples. Another daily-record rainfall (2.19 inches) was reported in Naples on August 1. Meanwhile, locally heavy showers in the southern Rockies and adjacent High Plains led to record-setting rainfall totals in locations such as Clayton, NM (1.52 inches in July 30); Midland, TX (1.44 inches on August 1); Lubbock, TX (1.16 inches on July 31); and Roswell, NM (1.03 inches on July 31). Monsoon-related showers extended into the Southwest, where Alpine, CA (1.52 inches) and Prescott, AZ (0.63 inch), netted daily-record totals for August 1. During the mid- to late-week period, showers swept across the Great Lakes and Northeastern States, resulting in daily-record totals that exceeded 2 inches in locations such as Traverse City, MI (3.02 inches on August 3); Williamsport, PA (2.46 inches on August 2); and Rochester, MN (2.01 inches on August 3). Toward week’s end, local downpours affected the Gulf Coast region, where Pensacola, FL, tallied a daily-record sum of 5.34 inches on August 4. The following day, at least 4 to 8 inches of rain inundated portions of the New Orleans metropolitan area. Elsewhere, an EF-2 tornado cut a 7-mile swath through Tulsa, OK, and neighboring areas from 1:19 to 1:25 am CDT on Sunday, August 6, packing winds as high as 120 to 130 mph and injuring more than two dozen people.
6-12: Rainfall expanded and intensified from the central and southern Plains eastward into the middle and southern Atlantic States, providing abundant to locally excessive moisture for pastures and immature summer crops. Flash flooding struck several areas, including portions of the southeastern Plains, where late-week rainfall locally totaled 4 to 8 inches or more. During the first 8 days of the month, rainfall in Houston, TX, totaled 7.58 inches—aided by a 3.61-inch sum on August 8. Houston’s previous rainfall record for August 1-8 was 5.80 inches in 1914. Other parts of Texas also received an early-week deluge. For example, daily-record totals in Texas for August 7 included 3.31 inches in San Antonio, 2.87 inches in Austin, and 2.62 inches in College Station. Downpours also struck from the central Gulf Coast States into the Mid-Atlantic region on August 7, when totals reached 4.16 inches in Meridian, MS; 3.35 inches in New Iberia, LA; and 3.23 inches on Wallops Island, VA. Three days later, on the 10th, a total of 5.73 inches in Montgomery, AL, represented the wettest August day in that location since August 16, 1939, when 6.97 inches fell. Earlier this year, however, Montgomery was pounded by 8.15 inches of rain on May 20. Another round of torrential rainfall struck the southern Mid-Atlantic States on August 12, when Salisbury, MD, experienced its fifth-wettest day on record with a total of 6.56 inches. It was Salisbury’s wettest day since September 1, 2006, when 6.80 inches fell. During the week, many other locations across the South—including Fort Lauderdale, FL (3.43
inches on August 10); Augusta, GA (2.45 inches on August 9); Shreveport, LA (2.42 inches on August 7); Amarillo, TX (2.41 inches on August 10); Tuscaloosa, AL (2.21 inches on August 8); London, KY (2.20 inches on August 7); and Knoxville, TN (2.00 inches on August 12)—reported daily-record totals of at least 2 inches. Hattiesburg, MS, collected 6.12 inches of rain from August 6-11. In contrast, no measurable rain fell in Helena, MT, during the 35-day period from July 10 – August 13. The last time Helena experienced at least 5 weeks without measurable precipitation was 2012, when there was a 36-day dry spell from August 28 – October 2. From June 1 – August 13, 2017, Helena’s rainfall totaled just 1.44 inches (39 percent of normal). Similarly, Seattle, WA, experienced a record-breaking spell without measurable precipitation—55 days from June 18 – August 11. Seattle’s streak, which eclipsed the former record of 51 days set from July 7 – August 26, 1951, ended with a 0.02-inch rainfall on August 12. Just a few months ago, Seattle completed its wettest October-April period on record, with the 45.00-inch total (146 percent of normal) surpassing the 2015-16 mark of 44.52 inches.
13-19: Showers and thunderstorms continued to pepper much of the central and eastern U.S., with some of the heaviest rain occurring across the southeastern Plains, mid-South, and upper Midwest. However, rain largely bypassed a few areas, namely the western Gulf Coast region and a broad section of the central and eastern Corn Belt. Meanwhile, drought-easing rain continued to fall across parts of the northern Plains, helping to revive rangeland and pastures and aiding later-planted summer crops. Precipitation was especially heavy in parts of Nebraska, where rainfall locally totaled 4 to 6 inches or more. Little rain fell, however, in Montana, where pasture and crop conditions continued to deteriorate and several large wildfires remained active. Pockets of intense rainfall caused flash flooding in scattered locations. On August 16-17, rainfall in Redwood Falls, MN, totaled 9.50 inches. During the 5-day period ending August 16, rainfall in Nebraska reached 13.80 inches in Anselmo and 7.65 inches in Broken Bow. Similarly, Russellville, AR, netted 5.21 inches from August 11-17. In fact, the week began with a heavy rainfall event in progress in parts of Texas, where 24-hour rainfall totals on August 12-13 ranged from 6 to 10 inches in portions of Collin, Fannin, Grayson, Commerce, and Hunt Counties. Monticello, AR, netted a daily-record rainfall total of 2.55 inches on August 14. The following day, record-setting totals for August 15 included 2.37 inches in Grand Island, NE; 2.24 inches in Bristol, TN; and 2.22 inches in Mobridge, SD. And, on August 17, daily-record totals topped 2 inches in locations such as Sault Sainte Marie, MI (2.83 inches); Tyler, TX (2.79 inches); and Louisville, KY (2.56 inches). Meanwhile, Northwestern wildfires helped the nation’s year-to-date total to 6.4 million acres of vegetation burned, with more than half of that amount— about 3.6 million acres—occurring since July 1.
20-26: Unprecedented rainfall from the remnants of Hurricane Harvey deluged the Houston metropolitan area and many surrounding counties, sparking historic and catastrophic flooding across a large area. Through Sunday, August 27, widespread 10- to 30-inch rainfall totals stretched northeastward from near the hurricane’s point of landfall near Rockport, TX, into southwestern Louisiana. Although Harvey’s winds also caused varying degrees of damage in the western Gulf Coast region, major impacts were mostly limited to areas along the middle Texas coast. Elsewhere, pockets of heavy rain were mostly limited to southern sections of the Rockies and Plains; the southern Atlantic region; and the western Corn Belt. Prior to Harvey’s arrival, rainfall highlights were limited to a few small areas. On August 21, heavy rain in the western Corn Belt and neighboring areas led to daily-record totals in locations such as Kansas City, MO (4.08 inches), and Topeka, KS (3.83 inches). The following day, McAlester, OK, netted a dailyr ecord sum (2.16 inches) for August 22. In contrast, Helena, MT, observed at least 50 consecutive days (July 10 – August 28) without measurable rain—the longest such warm-season streak on record in that location. The previous warm-season record of 38 days was established from September 1 – October 8, 1880. Helena’s longest spell without measurable precipitation—60 days—occurred from December 15, 1986 – February 12, 1987. Late in the week, heavy rain developed across southern Florida and in the western Gulf Coast region. From August 23-27, rainfall totals in Florida included 16.56 inches in Sarasota Bradenton, 13.88 inches in Fort Myers, and 7.67 inches in Naples. Nearly half (8.12 inches) of the 5-day total in Sarasota Bradenton fell on August 26. And, Fort Myers netted daily record totals (5.44 and 5.63 inches, respectively) on August 25 and 27. Meanwhile, Category 4 Hurricane Harvey moved ashore around 10 pm CDT on August 25 along the Texas coast between Port Aransas and Port O’Connor, with maximum sustained winds near 130 mph. Harvey was the first hurricane to strike the Texas coast since Ike in September 2008; the first major hurricane (Category 3 or higher) to cross the U.S. coastline since Wilma traversed southern Florida in October 2005; and the first Category 4 storm to pummel the Texas coast since Carla in September 1961. The highest verified gust associated with Harvey was 132 mph, clocked near Port Aransas at 9:42 pm CDT on August 25. However, as Harvey moved inland and stalled, the focus turned to heavy rain. During the weekend of August 26-27, Houston recorded its fifth-wettest and wettest calendar days on record, with respective totals of 8.37 and 16.07 inches. In fact, Houston’s daily total on the 27th demolished its former August rainfall record of 15.43 inches set in 1915. Only once before, on June 26, 1989, during Tropical Storm Allison, had Houston ever received more than 10 inches of rain in a calendar day; the total that day was 10.34 inches. More details on records Setting rainfall and subsequent flooding related to Harvey will appear next week.
27-31: Historic and devastating rainfall and flooding persisted early in the week across southeastern Texas and southwestern Louisiana. Final storm totals associated with Hurricane Harvey ranged from 20 to 50 inches of rain in Houston and Beaumont-Port Arthur, as well as all areas in between. In the wake of Harvey’s departure, dry weather favored recovery efforts as floodwaters began to recede. The remnants of Harvey eventually accelerated northeastward, with the circulation decaying over the middle Ohio Valley in early September. Local rainfall totals in excess of 4 inches, along with pockets of flash flooding, were observed from eastern Arkansas into central Kentucky. A separate disturbance resulted in some early-week downpours along the middle and southern Atlantic Coast. Outside of Harvey’s sphere of influence, little or no rain fell. August 27 was the wettest day on record in Houston, TX, where the 16.07-inch daily total shattered the Tropical Storm Allison-fueled total of 10.34 inches on June 26, 1989. In fact, 5-day rainfall records were demolished throughout southeastern Texas, with totals reaching 37.01 inches at Hobby Airport in Houston; 31.26 inches at Bush Intercontinental Airport in Houston; and 22.84 inches in Galveston. Former records in Houston had been set during another Tropical Storm Allison from June 5-9, 2001, when totals reached 20.69 inches at Hobby Airport and 16.48 inches at the official Intercontinental Airport site. Galveston’s former standard was 16.06 inches, set from July 1216, 1900. As a tropical storm, Harvey made its final landfall before dawn on August 30, just west of Cameron, LA, with maximum sustained winds near 45 mph. In advance of landfall, August 29 was by far the wettest day on record in Beaumont-Port Arthur (BPT), TX, where 26.03 inches of rain fell. That total more than doubled BPT’s former calendar-day record of 12.76 inches, set on May 19, 1923. By the time monthly totals were tallied, August 2017 became the wettest month on record in a vast number of locations in southeastern Texas, including BPT (54.74 inches; previously, 22.74 inches in November 1902); Houston (39.11 inches; previously, 19.21 inches in June 2001); Orange (37.94 inches; previously, 28.96 inches in October 1970); Huntsville (21.35 inches; previously, 19.00 inches in May 1929); and College Station (21.02 inches; previously, 18.77 inches in October 1994). It was the wettest August on record in Lake Charles, LA, where 23.57 inches fell (previously, 17.36 inches in 1962). However, the wettest month in Lake Charles remains 25.33 inches in June 1989. A U.S. tropical cyclone rainfall record was established in Texas along Cedar Bayou, where the 51.88-inch storm total surpassed the record of 48.00 inches set in Medina, TX, during Tropical Storm Amelia in July-August 1978. Harvey’s remnants eventually sparked heavy rain in the mid-South, where record-setting totals for August 31 in Tennessee included 4.04 inches in Memphis and 3.76 inches in Jackson. In Kentucky, September 1 featured daily-record amounts in Bowling Green (4.93 inches) and Louisville (3.51 inches). Farther east, an early-week coastal storm led to daily-record totals for August 29 in Virginia locations such as Norfolk (3.93 inches) and Wallops Island (3.68 inches). A few showers also dotted the Great Lakes States, resulting in record-breaking amounts for August 29 in Fort Wayne, IN (2.06 inches), and Dayton, OH (1.32 inches). Meanwhile in southern California, spotty showers led to record-setting totals for August 31 in Sandberg (0.59 inch) and Elsinore (0.54 inch). And in Florida, late-week downpours produced a record-setting sum for September 2 in Melbourne, where 4.62 inches fell. In contrast, Helena, MT, observed at least 55 consecutive days (July 10 – September 2) without measurable rain—the longest such warm-season streak on record in that location. The previous warm-season record of 38 days was established from September 1 – October 8, 1880. Helena’s longest spell without measurable precipitation—60 days—occurred from December 15, 1986 – February 12, 1987.
Jim G. Munley, jr.
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