NATIONAL WEATHER SUMMARY

 

SEPTEMBER 2015

 

1-5: Late-season heat across the Plains and Midwest. Weekly temperatures averaged at least 5 to 10F above normal in a broad area covering much of the northern and central Plains and the Midwest. In contrast, sharply cooler weather arrived in the Northwest, accompanied by beneficial showers. The cool, showery weather aided wildfire containment efforts and boosted topsoil moisture in advance of Northwestern winter wheat planting. Across the remainder of the West, dry but cooler weather prevailed in California and the Great Basin, while monsoon-related showers dotted portions of the Four Corners States. Farther east, dry weather dominated the central and southern Plains, while mid- to late-week rainfall affected the nation’s northern tier as far east as Michigan. The warm, dry weather regime also extended into much of the mid-South and Northeast, increasing stress on pastures. Elsewhere, warm, humid weather dominated the South, although showers were mostly confined to the southern Atlantic States and areas along and near the

Gulf Coast.

Early in the week, windy weather in the vicinity of a cold front was initially a concern with respect to Northwestern wildfire expansion, but cooler, wetter conditions eventually aided containment efforts. Lewiston, ID, clocked a wind gust to 73 mph on August 30. In advance of the Northwestern front, high temperatures soared to daily-record levels on August 30 in East Rapid City, SD (101F), and Sidney, NE (99F). Later, enough cool air settled into the

Northwest to result in several daily-record lows. By September 4, record-setting lows dipped to 25F in Meacham, OR; 27F in Baker City, OR; and 28F in Alturas, CA. The following day, record-setting lows in Oregon for September 5 included 29F in Klamath Falls and 39F in Eugene. In contrast, mid- to late-week heat intensified across the central and eastern U.S. On September 2, Miles City, MT, posted a daily-record high of 102F. The following day, record-setting highs on the northern Plains for September 3 reached 101F in Bismarck, ND, and 99F in Mobridge, SD. Farther east, late-week, daily-record highs included 98F (on September 4) in Peoria, IL, and 95F (on September 3) in Atlantic City, NJ. Charleston, WV, reached or exceeded 90F on each of the first 8 days of September, following an August without 90-degree heat. Meanwhile, Chicago, IL, reported an average temperature of 79.6F during the first 7 days of the month, representing its warmest September 1-7 period since

1960 (83.6°F).

 

6-12: Near- to above-normal temperatures dominated the U.S., helping to push summer crops toward maturity. Warmth was especially notable in California and the Northeast; weekly temperatures averaged at least 10F above normal in parts of coastal southern California and interior New England. Dry weather accompanied the late season warmth across much of the western U.S. Some light rain grazed the Pacific Northwest and northern Rockies, while monsoon-related showers dotted the Southwest. In northern California, hot, dry weather was conducive to wildfire development. The Butte fire, near Mokelumne Hill, started on September 9 and by week’s end had charred more than 70,000 acres of vegetation and destroyed more than 150 homes. The Valley fire, near Glenbrook, began on September 12 and quickly consumed at least 60,000 acres, including well over 500 residences.

Farther east, dry weather across the northwestern half of the Plains favored late-season spring wheat harvesting and other fieldwork. Late in the week, much cooler air arrived across the northern Plains and upper Midwest, offsetting earlier warmth. Weekly temperatures averaged as much as 2 to 4F below normal on the northern Plains.

Prior to the arrival of cooler air, temperatures soared to 100F or higher, mainly from September 6-8, across parts of the central and southern Plains. In the East, highs topped 90°F as far north as New England from September 7-9.

On September 6, the temperature in Russell, KS, soared to a daily record high of 105F. The following day, Borger, TX, also collected a daily-record high (99°F on September 7). Meanwhile in New York, Poughkeepsie posted a trio of daily-record highs (95, 97, and 95F) from September 7-9. During the same period, Allentown, PA, also achieved three daily-record highs (91, 94, and 95F). Similarly, consecutive daily-record highs were noted on September 8-9 in Northeastern locations such as Boston, MA (96 and 93F), and Hartford, CT (96 and 93F). September began with 8 consecutive days of 90-degree heat in Charleston, WV—the longest such streak in that location since June 28 – July 8, 2012. Farther west, an early-week cool spell was quickly replaced by late-season heat. In Winnemucca, NV, a daily-record low of 24F on September 6 was followed by 5 consecutive days (September 9-13) with highs above 90F. Sacramento, CA, registered consecutive daily-record highs (105 and 106F, respectively) on September 9-10. Other triple-digit, daily-record highs included 100F (on September 12) in Medford, OR; 104F (on September 11) in Desert Rock, NV; and 105F (on September 10) in Paso Robles, CA. Elsewhere in California, lows of 81F (on September 10) in Burbank and 78F (on September 11) in San Diego tied all-time records for highest minimum temperature. At week’s end, warmth returned to the northern Plains. Bismarck, ND, reported its first autumn freeze (31F) on September 11. The next day, September 12, Helena, MT, notched a daily-record high of 91F.

 

13-19: A large sections of the nation, especially the central, southern, and eastern U.S., experienced dry weather, reducing topsoil moisture.  Above normal temperatures dominated the Plains and the upper Midwest. The late-season warmth also extended across the Great

Lakes region and into the Northeast. Meanwhile, cool air settled across the southeastern and northwestern U.S. for several days, helping to hold weekly temperatures more than 5F below normal in a few locations.

Cool weather lingered early in the week across the South. On September 13-14, the week opened with consecutive daily record lows in Mississippi locations such as Hattiesburg (52 and 49F, respectively) and Greenville (50F both days). Other daily record lows for September 13 included 44F in Paducah, KY, and Cape Girardeau, MO. Daily record lows for September 14 dipped to 45F in Charlotte, NC, and 49F in Macon, GA. Meanwhile, heat returned to the nation’s mid-section. From September 13-17, Dalhart, TX, noted five consecutive daily-record highs (99, 101, 97, 97, and 99F). Early-week temperatures topped the 95 degree mark as far north as North Dakota, where Bismarck notched a daily record high of 97°F on September 13. Later, triple-digit, daily record highs included 103F (on September 15) in Hill City, KS, and 101F (on September 14) in Valentine, NE. Elsewhere in Nebraska, Imperial registered consecutive daily record highs (98 and 99F, respectively) on September 14-15. Warmth extended into the Northeast, resulting in daily record highs for September 17 in Burlington, VT (86F), and Caribou, ME (84F). Burlington reached 8°F or higher on 4 consecutive days from September 16-19. From August 15 – September 20,

Bangor, ME, reported 37 days in a row without a below normal daily average temperature.

 

20-26: For the second week in a row, dry weather in many parts of the U.S. In particular, warm, dry weather in the central and eastern Plains. Mostly dry weather extended southward to the Mississippi Delta and the western Gulf Coast. In contrast, rainy weather in the Southeast boosted soil moisture.

Meanwhile, warm, dry weather dominated the western U.S., except in the Pacific Northwest and areas affected by the former tropical depression. Weekly temperatures averaged at least 10F above normal in numerous locations across the northern Plains, upper Midwest, and northern Intermountain West. Near normal temperatures were mostly limited to the eastern U.S. and the Pacific Northwest. Western warmth was especially prominent early in the week and again at week’s end. September 20-21 featured consecutive daily record highs in California locations such as Sacramento (99 and 102F) and Stockton (101 and

102F). In southern California, record-setting highs for September 20 included 106F in Riverside; 105F in Paso Robles; and 100F in Long Beach. In Nevada, Ely posted a trio of daily record highs (85, 86, and 85F) from September 20-22. Late-season warmth also reached the Plains, where record setting highs in Nebraska climbed to 97F (on September 22) in McCook and 95F (on September 21) in Imperial. Late in the week, warmth further intensified across the western and central U.S. On September 24-25, Needles, CA, collected consecutive daily record highs of 110°F. From September 24-26, Sheridan, WY, noted three consecutive daily record highs (90, 94, and 97F), including its latest ever reading above the 95-degree mark (previously, 97F on September 15, 1948). Similarly, a high of 90F on

September 26 in Lander, WY, represented the latest 90 degree heat in that location (previously, 90F on September 22, 1958). In Montana, Miles City closed the week on

September 25-26 with consecutive daily-record highs (97 and 95F, respectively). Other record-setting highs for September 25 included 95F in Boise, ID; 93F in Salt Lake City, UT; and 92°F in Elko, NV.

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