NATIONAL WEATHER SUMMARY

 

JULY 2013

 

7^th-13^th…Hot, humid, and wet conditions continued in the East on Monday, while hot and unsettled weather continued in portions of the West. In the East, an area of high pressure spanning across the Southeast into the western Atlantic Ocean maintained southerly flow from the Gulf of Mexico into the region. As moisture streamed in from the south, warm and moist conditions combined with daytime heating led to areas of continued scattered showers and thunderstorms from parts of the Gulf Coast northward into the Midwest and Northeast. A stalled frontal disturbance extending across the Upper Great Lakes and the northern tier of the Northeast also supported rain and storms through the afternoon and evening. Elsewhere in the East, daytime temperatures remained a few degrees above average from southern New England to Virginia with as highs climbed into the upper 80s and 90s. Out West, hot conditions continued for the region as an upper high remained situated over New Mexico. Chances of scattered showers and thunderstorms continued in the Four Corners through the Northern Rockies due to monsoonal moisture. Rich low level moisture and favorable instability created a slight risk of severe thunderstorm development from Montana through Iowa from this afternoon through Monday night. Damaging wind gusts and hail were possible with storms in this region.

Showers and thunderstorms continued in parts of the Eastern Seaboard on Friday, while active weather developed across the North-Central U.S. In the East, a frontal boundary lingered over the Southeast and Mid-Atlantic states with waves of low pressure through the day. Ample moisture combined with energy from this disturbance and daytime heating supported another round of widely scattered to scattered showers and thunderstorms from the Gulf of Mexico through the Carolinas and the Virginias into the southern New England coastal areas. Meanwhile, near this area, an area of unsettled weather associated with the remnants of Chantal moved northward over the Bahamas. The disturbance remained disorganized and became less likely to redevelop. To the west of this activity, a low pressure system over the Northern Rockies strengthened as it ejected eastward into the Northern Plains. Showers and thunderstorms began to pick up in the Northern Plains and the Upper Mississippi Valley through the afternoon. The Storm Prediction Center issued a slight risk of severe thunderstorms for portions of South Dakota, Minnesota, and southeastern North Dakota due to the possibility of damaging wind gusts and locally large hail.

Further west, monsoonal moisture combined with daytime heating created chances of rain showers and afternoon thunderstorms in the Four Corners and the Central and Southern Rockies.

 

14^th-20^th…Cool and rainy weather continued for the Southern Plains on Monday as an upper low trekked across the region. This system, combined with moist, favorable environmental conditions, kicked up moderate to heavy rainfall and slow moving thunderstorms, especially in parts of north-central and central Texas. Excessive rainfall in already well saturated areas of north-central Texas led to another 1 to 3 inches of additional rain through the afternoon with isolated locally higher amounts of up to 5 inches. A Flash Flood Watch was issued for the region in anticipation of Monday's precipitation. Meanwhile, to the north, showers and thunderstorms remained focused along a nearly stationary frontal boundary that extended across Nebraska, the Northern Plains and parts of Minnesota. In the East, deep moisture and waves of energy over the Southeast supported scattered showers and chances of thunderstorms through the the day. Limited shower activity continued to the north, while hot and humid conditions persist-especially along the southern New England coast. Various Heat Advisories and Excessive Heat Warnings were issued for areas from southeastern New Hampshire through northern Delaware. Finally, out West, monsoonal moisture streaming across the Four Corners will triggered areas of showers and thunderstorms. Flash Flood Watches were issued for the region in anticipation of today\'s precipitation.

 

21^st-27^th…Mostly dry weather returned to Texas and persisted in the Plains, resulting in varying degrees of stress to summer crops. Most of Texas had received substantial rain the previous week, but portions of the western Plains was dry during the last 4 to 6 weeks. In contrast, heavy showers soaked much of Kansas and Oklahoma, as well as the eastern one-third of the U.S. Some of the heaviest rain, 4 inches or more, fell on the southeastern Plains and the southern Appalachians. Elsewhere, locally heavy monsoon showers continued to dot the Southwest, but hot, dry weather dominated the Northwest. The Southwestern showers provided drought relief but triggered local flooding. Weekly temperatures ranged from more than 5F above normal in portions of the Northwest to more than 5F below normal in much of the Upper Midwest. As the week progressed, cool air settled across the Plains, Midwest, and Mid-South. Lingering warmth across the Midwest and Northeast was quickly replaced by cooler conditions. In Philadelphia, PA, the temperature fell below 70F on July 24 for the first time since June 23. Philadelphia’s nighttime warm spell, which lasted 30 days, eclipsed its record of 26 consecutive days (July 12 – August 6, 1995) with lows of 70F or higher. Scattered daily-record lows were set during the first cool surge, which was followed by a stronger push late in the week. Rhinelander, WI, notched a daily-record low (41F) on July 24, followed by next day in Springfield, IL, by a record-tying low (54F) for July 25. Later, Upper Midwestern temperatures plunged at week’s end, resulting in daily-record lows on July 27 in locations such as Bismarck, ND (39F); Aberdeen, SD (41F); Eau Claire, WI (46F); and Sioux City, IA (47F). High temperatures remained below the 60-degree mark on July 27 in Minnesota locations such as Duluth (56F) and International Falls (59F). With a high of 62F on July 27,

La Crosse, WI, noted its coldest July day since 1967, when the high reached 62F on Independence Day. The only colder July day in La Crosse occurred on July 3, 1962, when the high was 61F. Meanwhile, heat persisted for much of the week in the Northwest. Yakima, WA, reported triple-digit heat on 8 consecutive days from July 19-26, surpassing its standard of 7 days established from August 7-13, 1981. Yakima also posted a daily-record high of 102F on July 25. Other Western daily record highs included 105F (on July 21) in Reno, NV, and 100F (on July 25) in Alturas, CA. Prior to the arrival of cooler conditions across the Plains, Garden City, KS, collected a daily record high of 104F on July 22. Early in the week, heavy showers peppered the Midwest and East. Record-setting totals for July 21 reached 3.19 inches in Birmingham, AL, and 2.55 inches in Columbia, SC. The following day, record-high rainfall amounts for July 22 reached 3.70 inches in Montgomery, AL; 3.27 inches in Norfolk, VA; and 2.31 inches in Columbus, OH. During yet another day of heavy showers on July 23, daily-record totals included 3.05 inches in

Philadelphia, PA; 2.40 inches in Concord, NH; and 2.14 inches in El Dorado, AR. Through the 27th, July rainfall records had already been set in Southeastern locations such as Greenville-Spartanburg, SC (14.40 inches); Asheville, NC (13.44 inches); and

Roanoke, VA (12.59 inches). Later, the focus for heavy rain shifted to the southeastern Plains and the Southwest. Record-high amounts for July 26 totaled 3.53 inches in Oklahoma City, OK, and 2.13 inches in Wichita, KS. Scattered showers also developed

across the Midwest, where record-setting totals in Iowa for July 25 included 3.09 inches in Waterloo and 1.64 inches in Mason City. Waterloo had received rainfall totaling just 0.30 inch from July 1-21, but netted 3.73 inches from July 22-26.

 

28^th-31…Heavy rain drenched the nation’s mid-section, but little or no precipitation fell in the upper Midwest. Weekly rainfall totaled 4 inches or more in southwestern Missouri and much of the eastern half of Kansas, but minimal precipitation fell in most of Iowa, Minnesota, Wisconsin, and the eastern Dakotas. The Ohio Valley also received only a few light showers, but weekly rainfall totaled 1 to 2 inches or more in many other areas, including the northern Plains, middle Mississippi Valley, Southeast, and the Atlantic coastal plain. In contrast, generally dry weather prevailed in the Far West and from Texas to the lower Mississippi Valley, while monsoon shower activity temporarily waned in

the Southwest. Hot weather (weekly temperatures up to 5F above normal) accompanied the southern Plains’ dryness, however, unusually cool air settled across the northern Plains

and the Midwest, holding temperatures as much as 5 to 10F below normal. Early in the week, unusually cool air settled across the Midwest. With a low of 48F on July 28, Springfield, IL, tied a monthly record previously achieved on July 14, 1967; July 31, 1971; July 6, 1972; and July 13, 1975. Rochester, MN (46F on July 28), experienced its lowest July reading since July 7, 1997. With a low of 56F on July 28, St. Louis, MO, posted its first daily-record low since September 15, 2007. Elsewhere on the 28th, daily-record lows included 40F in Aberdeen, SD; 41F in Jamestown, ND; and 44F in Sioux City, IA, and Norfolk, NE. As the cool weather lingered, South Bend, IN, set a record with 9 consecutive July days with temperatures below 80F. South Bend’s streak, which lasted from July 23-31, surpassed 8-day cool spells from July 5-12, 1918, and July 20-27, 1992. Farther south, however, heat returned by mid-week. On July 31 – August 1, San Antonio, TX, logged consecutive daily-record highs of 103F. As the  month came to a close, July 2013 became the hottest month on record in locations such as Salt Lake City, UT (average temperature of 84.1F); Bridgeport, CT (78.5F); and Elko, NV (76.8F). In late July, heavy showers peppered the central Plains and northern Mid-Atlantic region. In Kansas, daily-record totals included 1.75 inches (on July 28) in Salina and 1.34 inches (on July 29) in Topeka. Meanwhile, Philadelphia, PA (8.02 inches on July 28), experienced its wettest calendar day on record, surpassing the 6.63-inch total associated with the remnants of Hurricane Floyd on September 16, 1999. As July came to a close, locally heavy showers continued across the nation’s mid-section and shifted into the Southeast. Springfield, MO, was pelted by 2.26 inches of rain on July 30, helping to surpass its 2012 precipitation total of 30.94 inches. Elsewhere, daily-record totals reached 3.55 inches (on July 31) in Gainesville, FL, and 2.18 inches (on July 30) in Valentine, NE. Gainesville’s deluge contributed to a record-high July rainfall total of 16.65 inches, surpassing the 1909 standard of 16.41 inches. July rainfall records were also established in locations such as Miami Beach, FL (18.47 inches); Greenville-Spartanburg, SC (14.45 inches); Asheville, NC (13.69 inches); and Roanoke, VA (12.73 inches). The new month began as July had ended in the East, with a daily-record total of 5.32 inches on August 1 in Salisbury, MD.

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