NATIONAL WEATHER SUMMARY

 

DECEMBER 2012

 

1^st-8^th…Pacific storms brought some additional rain and snow to California and the Northwest, culminating a period of unsettled weather that began in late November.

As the week progressed, dry weather returned to California, while a few showers lingered across the Northwest. Farther east, mild, dry weather prevailed for much of the week on the Plains. Toward week’s end, however, snow began to overspread the northern Plains. Meanwhile, frequent showers occurred from the western half of the Gulf Coast northeastward into the lower Great Lakes region. Some of the heaviest rain, locally 2 to 4 inches, fell along the central Gulf Coast and in the middle Ohio Valley. In contrast, mostly dry weather persisted through week’s end in the Southeast, except for a few showers in southern and eastern Florida. During the first full week of December, late-season warmth prevailed nearly from coast to coast. Warm conditions were especially prevalent between the Rockies and Appalachians. In fact, weekly temperatures averaged more than 15F above normal in a broad area centered on the Mid-South. During the first half of the week, record-setting warmth blanketed much of the South, East, and Midwest. On December 3, monthly record highs were established in locations such as Quincy, IL (74F; previously, 71F on December 9, 1940, and December 3, 1970); Rockford, IL (69F; previously, 67F on December 5, 2001); Muskegon, MI (66F; previously, 64°F on December 2, 1982); and Madison, WI (65°F; previously, 64°F on December 5, 2001). In addition, monthly record highs were tied on December 3 in Kansas City, MO (74F); Springfield, IL (74F); Ottumwa, IA (71F); and Traverse City, MI (64F). Peoria, IL (70F on December 3), reached the 70-degree mark in December for the first time since December 28, 1984. Farther south, highs soared to daily-record levels on December 2 in Texas locations such as Corpus Christi (87F), Victoria (85F), Houston (84F), and Dallas-Ft. Worth (83F). Highs reached 70F on December 2 as far north as Kennebec, SD, where a daily-record high was tied. In

Texas, warmth continued through December 4, when Brownsville (87F) and Houston (83F) posted daily-record highs. Meanwhile in the East, selected daily-record highs for December 4 included 74F in Danville, VA, and 70F in Syracuse, NY. By mid-week, warmth briefly shifted into the West, where Phoenix, AZ (82F), collected a daily-record high. However, warmth quickly returned to the south-central U.S., where both Midland and San Angelo, TX, posted daily-record highs of 81F on December 6. Two days later, on December 8, additional daily-record highs in Texas included 83F in Houston and 85F in both Corpus Christi and Victoria.

 

A cold, mostly dry weather pattern remained locked in across the Alaskan mainland, where temperatures averaged more than 20F below normal in some locations. However, the cold air began to erode at week’s end, when the temperature in Fairbanks climbed to -2F on December 8—up from -40F on December 3.

 

9^th-15^th…An active weather pattern led to widespread precipitation and limited drought relief in several regions, including the central and southern Plains, Midwest, Southeast, and Southwest. Some of the heaviest rain, locally 2 to 4 inches, fell early in the week across the interior Southeast. Parts of Florida’s peninsula also received substantial rainfall, slowing fieldwork but reducing irrigation demands for citrus and winter crops. Farther north, widespread precipitation fell across the Midwest early in the week and again at week’s end. The first round of precipitation included heavy snow (locally more than a foot) in the upper Midwest, while the majority of the latter event fell as rain. Elsewhere, unsettled weather finally shifted into the Southwest, where the winter wet season had started poorly. mid-December precipitation totals locally topped 2 inches in the Four Corners States. Periodic rain and snow showers also affected the Northwest, although precipitation was generally light. Despite an early- to mid-week cold snap, near to above normal temperatures covered the majority of the nation. In fact, weekly readings averaged as much as 10F above normal in parts of the Plains and Midwest. The coldest conditions, relative to normal, were observed in the southern Rockies and the far upper Midwest.

Early in the week, the first significant snow storm of the season blanketed the upper Midwest. December 9-10 snowfall totals ranged from 10 to 16 inches in several locations, including Eau Claire, WI (14.7 inches), and Minneapolis-St. Paul, MN (10.6 inches). Snow started earlier on the northern Plains, where December 7-10 amounts in South Dakota reached 10.8 inches in Aberdeen and 9.9 inches in Huron. The vast majority of the upper Midwestern snow fell on December 9, when daily-record totals included 12.5 inches in Eau Claire and 10.5 inches in Minneapolis-St. Paul. Meanwhile, heavy rain and locally severe thunderstorms swept across the South. Record-setting rainfall amounts for December 9 reached 1.85 inches in College Station, TX; 1.83 inches in Hot Springs, AR; and 1.49 inches in Jackson, KY. The following day, record-setting totals for December 10 climbed to 3.56 inches in Gainesville, FL, and 2.65 inches in Vicksburg, MS. By mid-week, a second round of rain overspread the lower Southeast, where Melbourne, FL (0.91 inch on

December 12) received a daily-record amount. During the second half of the week, heavy precipitation developed in the Southwest. San Diego, CA (1.56 inches), collected a record-setting rainfall total for December 13. In Nevada, Las Vegas netted consecutive daily record amounts on December 13-14, totaling 0.49 inch. On December 13, Las Vegas experienced its 25th day with thunder in 2012, just a day shy of its all-time record (26 days in 1938). Elsewhere, record-setting snowfall totals for December 14 included 3.0 inches in Alamosa, CO, and 2.8 inches in Ely, NV. Flagstaff, AZ, was buried by 20.3 inches of snow on December 14-15, including a daily-record total of 11.7 inches on the latter date. Toward week’s end, beneficial precipitation, mostly rain, overspread the Plains and Midwest. Daily-record precipitation totals were established in locations such as Garden City, KS (0.53 inch on December 14), and Sioux City, IA (0.96 inch on December

15). By the end of the week, Chicago, IL, set a record for its longest period without measurable snow (286 days from March 5 - December 15; previously, 280 days from March 1 - December 5, 1994), and approached a record for its latest measurable snowfall (previously, December 16, 1965). Elsewhere in Illinois, Rockford tied a record for its longest stretch without measurable snow (previously, 286 days from March 3 - December 13, 1922). Warmth prevailed early in the week across the lower Southeast, where record-setting highs for December 10 reached 86°F in Vero Beach FL, and 80°F in Mobile, AL. The following day, additional records in Florida included 86°F in West Palm Beach and 85°F in

Miami. In contrast, cold air settled across the Rockies and Plains. Record-breaking lows for December 10 plunged to -24F in Alamosa, CO, and -3F in Santa Fe, NM. The next day,

McAlester, OK (13°), tallied a record-tying low for December 11. Cool conditions lingered through mid-week, when Waco, TX (18F on December 12), posted a daily-record low. By week’s end, warmth returned to the Deep South. In Texas, daily-record highs for December 15 soared to 85°F in Brownsville and 83F in Victoria.

 

16^th-22^nd…The major winter storm system of the West began to move from the Rockies into the Plains on Wednesday with significant snow and strong winds. Heavy snow showers continued to blanket parts of eastern Colorado as the system trekked eastward across the state during the morning, while a mix of rain and heavy snow with strong winds developed ahead of an associated cold front extending from the low southwestward through New Mexico. Snow accumulations of up to 10 inches were anticipated across the Central and Southern Rockies, while up to 20 inches were possible in the eastern Sawatch Range above 9,000 feet, the western Mosquito Ranges above 11,000 feet, and the eastern San Juan and La Garita mountains above 10,000 feet. As the cold front progressed eastward, blizzard conditions became likely across northeastern Colorado and northwestern Kansas with snow accumulations of 2 to 6 inches possible through the afternoon along with northerly winds of 20 to 30 mph and gusts to 40 to 55 mph. These conditions created periods of wind driven snow and caused visibilities reduced down to below one-quarter of a mile at times. Meanwhile, the fast moving cold front also continued the threat for high south to southwest winds of 35 to 45 mph with gusts near 70 mph and widespread blowing dust across the Southern High Plains into the Rolling Plains and Panhandle of Texas. This translated into reduced visibilities of one quarter mile or less at times with possible downed power lines and power outages. As this storm headed off to the east this afternoon, cold northwest winds filling in behind this system allowed snow showers to continue across western Colorado, where snow totals from this storm have already reached up to 21 inches in various locations. As of this afternoon, some of the highest snow totals from this storm were reported near Oak Creek, CO with 21.0 inches of snow, Craig, CO with 19.0 inches, and Yampa, CO with 18.5 inches. Meanwhile, another shot of wintry weather hit the Pacific Northwest this morning as yet another Pacific storm approached the Pacific Northwest coast with strong winds and plenty of moisture. Snow amounts of 3 to 6 inches were expected in the coastal mountain ranges withe wind gusts of 50 to 65 mph sweeping across coastal areas. Snow amounts in the inland lowlands were expected to range between 1 to 3 inch by this evening, while 10 to 18 inches were possible in the Cascades. Finally in the East, snow showers continued across Maine today as a low pressure system became positioned off the Northeast coast. Snow totals of up to 4 to 12 inches were expected for much of Maine through the day.

 

23^rd-31^st…Active weather continued in the West, as well as the South, East, and lower Midwest. However, significant storminess bypassed the nation’s mid-section, including the drought-stricken hard red winter wheat belt. A rapid-fire series of three storms delivered wintry precipitation from the mid-South into the Northeast. The strongest winter storm, the middle of the three weather systems, resulted in significant travel disruptions from December 25-27. Of particular note were historic, Christmas Day snow accumulations across the mid-South and a severe weather outbreak on the same date that spawned several dozen tornadoes from eastern Texas to Alabama. Elsewhere, drought-easing rainfall soaked much of the Southeast, although Florida’s peninsula remained mostly dry. Farther west, patchy, light precipitation on the Plains provided a few areas with beneficial moisture. However, the precipitation had little effect on the region’s long-running drought, which has adversely affected establishment of the 2013 hard red winter wheat crop. Elsewhere, cold but generally unsettled weather prevailed in the West. The heaviest precipitation fell across the northern Intermountain West and the Pacific Coast States. In addition to the cold weather in the West, some of the coldest air of the season across the Plains held weekly temperatures at least 5 to 15F below normal in most locations.

Widespread readings below -10F were noted from Montana to Minnesota, starting December 24. Cold air made its strongest southward push on December 26, when sub-zero readings were common and a few readings below -10°F were noted as far south as the central High Plains. Record-setting warmth was generally confined to a few locations across the Deep South. For example, Galveston, TX, posted consecutive daily record highs (76 and 75F, respectively) on December 24 and 25. Elsewhere in Texas, Brownsville (88°F on December 25) also posted a daily-record high. Farther east, Vero Beach, FL (85°F), ended the week with a record-setting high for December 29. In contrast, much of the nation was blanketed by cold air in the wake of a sprawling, mid-week storm. In Kansas, Goodland achieved a record-setting low (-9F) for December 25 late in the day, followed by another daily-record low (-10F) on December 26. At the time, Goodland had a 4-inch snow depth, helping to insulate winter wheat. Elsewhere on the 26th, daily-record lows included -15°F in Alliance, NE, and 7°F in Borger, TX. Late in the week, cold air also spilled across the West, where South Lake Tahoe, CA, collected a daily-record low of -5F on December 28.

Multiple storms maintained unsettled conditions across a broad swath of the nation. Early in the week, snow developed across the Intermountain West and spread onto the northern High Plains. Record-setting snowfall totals for December 24 included 4.4 inches in Ely, NV, and 4.0 inches in Havre, MT. Elsewhere in Montana, Billings (3.4 inches) not only measured a record-setting total for Christmas Eve, but also experienced its first measurable snowfall on December 24 since 1996. Light snow also dusted the southern Plains, where record breaking December 25 totals in Texas included 2.5 inches in Wichita Falls and 1.0 inch in Dalhart. Meanwhile, severe thunderstorms ripped across the Deep South, while wintry precipitation spread from the Ohio Valley into the Northeast. Preliminary reports indicated that there were more than 50 tornadoes on December 25 in the Gulf Coast States, including an EF-3 twister (estimated winds near 140 mph) with a 61-mile path length through five counties in southern Mississippi. High winds accompanied and trailed the Eastern storms; for example, Nantucket, MA, clocked wind gusts to 61 mph on December 27 and 58 mph on December 29. Farther west, isolated locations in northern California received in excess of 10 inches of rain from December 20-24, while more than 5 feet of snow fell in parts of the Sierra Nevada. According to the California Department of Water Resources, the average water content of the high-elevation Sierra Nevada snow pack climbed to 14 inches (150 percent of normal) by December 27, up from just 6 inches in mid-December. Additional Western snow fell during the second half of the week; up to 2 feet fell in Utah’s Wasatch Range from December 26-28, with 23 inches reported in Alta and 6.2 inches noted in the valley at Salt Lake City. Elsewhere, Elko, NV, received measurable snow on 6 consecutive days from December 22-27, totaling 15.8 inches.

Markedly milder air arrived in Alaska, boosting weekly temperatures more than 5F above normal in some northern locations. Chilly conditions lingered, however, in parts of east-central and southeastern Alaska. For example, Valdez posted a high of 9F on December 23, failing to reach the 10-degree mark on that date for the first time on record. Kodiak (3°F on December 25) noted its lowest reading since January 27, when temperature dipped to -5F. Alaskan precipitation was generally light, except for some locally heavier amounts across the southern tier of the state.

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