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WEATHER OVER THE WEEKEND -- A potent storm system accompanied by an assortment of weather events traveled from the lee slopes of the southern Rockies to the Eastern United States over the weekend. Severe thunderstorms including high winds, large hail and tornadoes were found in the warm air on the south side of the storm system, while in the cold air to the north of the storm, heavy snow fell.
On Friday morning, a low pressure system was located over the southern Rockies of Colorado and New Mexico. A large area of precipitation had expanded across the southern Plains to the east of the developing storm system. Snow fell in the colder air across western Kansas and Nebraska, as well as in the Rockies of northern Colorado and southern Wyoming. Some freezing rain was reported in the Texas and Oklahoma Panhandles. On Friday daily record rainfall totals were recorded at Oklahoma City, OK with 1.81 inches and at Wichita Falls, TX with 3.12 inches. The heavy rains also produced flooding across north Texas and Oklahoma into Louisiana. The precipitation was enhanced by the easterly flow of air near the surface that was being carried upslope on the eastern slopes of the Rockies. Numerous thunderstorms developed in the warm and humid air to the south and east of the warm front associated with the storm system. On Friday afternoon, two confirmed tornadoes were spotted in central Texas, with some damage. Numerous reports of large hail and wind damage were found across the Lone Star State. To the north of Del Rio, a hail storm that lasted 20 minutes produced one and three quarter inch diameter hail.
By evening the main center of the storm system had moved to the Rio Grande Valley of south Texas. The precipitation shield stretched from eastern Colorado to the lower Mississippi Valley. Heavy snow continued across southwestern Kansas, where some locations near Dodge City received more than a foot of snow. Because of the snow 115 miles of I-70 were closed in western Kansas on Friday night, stranding numerous motorists. Ten storm related traffic fatalities were recorded in Oklahoma and Colorado. Severe thunderstorms caused wind damage and flood-producing rains were found across east Texas and portions of Arkansas and Louisiana.
On Saturday morning, a distinct storm system had developed along the Texas Gulf Coast. A warm front extended eastward across Louisiana, while a cold front trailed southwestward into Mexico. The focus of the severe weather shifted eastward as thunderstorms developed in the warm sector to the south and east of the storm. A squall line moved eastward across Louisiana and southern Mississippi during the morning hours. To the north, the precipitation shield continued to expand eastward into the mid-Mississippi Valley. The region of heaviest snow moved eastward across northern Oklahoma and southern Kansas.
By Saturday night the low pressure center was located over southern Mississippi, with a broad area of precipitation that stretched across the South, from the Appalachians west to the southern Plains and from the Gulf Coast northward to the Ohio Valley. Heavy thunderstorms were found in the warm sector from Mobile Bay eastward into the Florida Panhandle. Numerous reports of wind damage were made from southern Alabama, to include that of a possible tornado. Snow continued across the Ozarks of southwest Missouri and northwest Arkansas. By Sunday morning, more than 18 inches of snow had fallen, closing I-44 near Springfield, MO. Lesser amounts of snow were found across the Ohio Valley. As of Sunday morning, an observer at Medford in northern Oklahoma had reported 19 inches of snow from the storm system, the fourth largest snowfall total from any snowstorm in Oklahoma since complete snowfall records commenced in 1951.
Over Saturday night, the storm system began to show signs of reaching the occluding stages of its life cycle. An occluded front began to form as the cold front caught and merged with the warm front. By Sunday morning the primary low pressure center was located over northern Mississippi with an occluded front that stretched southeastward to a secondary low that had formed over central Alabama. A warm front extended eastward toward the Carolinas and a cold front continued southward, crossing the western Florida Panhandle. Severe thunderstorms produced large hail in South Carolina, and damaging winds across the Florida Peninsula. The band of heavy snow continued toward the northeast. A daily record snowfall of 8.3 inches fell at Harrisburg, PA on Sunday
A large cold high pressure system located over Great Lakes not only kept relatively cool and pleasant weather across the Midwest, but also helped feed sufficient cold air into the storm system to the south so as to produce the heavy snow from southwest Kansas to southern Missouri and then to the Ohio Valley. On Saturday morning, the overnight low temperature at Elkins, WV fell to a record-tying 2 degrees above zero under clear skies. In the wake of the southern storm system, the ridge of high pressure pushed southwestward across the Plains. With clear skies and a fresh snow cover, record low temperatures were set on Sunday morning at Liberal and Garden City in southwest Kansas, with 7 degrees and 5 degrees, respectively.
In the Northeast, the start of the weekend was marked by light snow that was associated with a storm system that remained offshore. To the east of a relatively stationary front, warm, moist air was carried around the north side of this storm system into Downeast Maine. Cooler air was found to the southwest across southern New England. The front and most of the precipitation finally dissipated by Saturday night.
In the Pacific Northwest, a cold front reached the Washington State Coast by Saturday morning. Generally light precipitation fell along coastal areas for nearly 24 hours preceding the arrival of the cold front. The front slowed and remained relatively stationary across western Washington State and Oregon through Saturday and into Sunday. A 24 hour precipitation record was broken on Saturday at Quillayute, WA when 1.81 inches fell. By Sunday morning, precipitation had extended southward into northern California.
Record high temperatures were set on Sunday afternoon in Wyoming at Worland (71 degrees), Saratoga (59 degrees), Rock Springs (58 degrees) and Laramie (58 degrees). In Arizona, Winslow had a record high temperature of 76 degrees.
The afternoon high temperature at Lake Charles, LA only reached 49 degrees, establishing a new record low high temperature for the date.
WEATHER FOR STARTING THE NEW WEEK --The storm system that had moved across the northern Gulf Coast states over the weekend had begun to spread snow into the Middle Atlantic states late Sunday night. A complex storm system with several low pressure centers was located over the Carolinas as of late Sunday night. A warm front extended to the northeast into Chesapeake Bay, while a cold front trailed southward, across south Florida near Miami. Heavy snow continued to fall across portions of the Appalachians into the cities of the Northeast. Most of the thunderstorms had exited the Carolinas earlier on Sunday afternoon. However, some thunderstorms continued over south Florida.
One of the eastern low pressure centers is forecast to move offshore and proceed northeastward on Monday morning, reaching a point off the Delmarva Peninsula at sunrise. A band of heavy snow is expected to fall in a region just inland from the coast, stretching from the Blue Ridge of Virginia northeastward through the New York metropolitan area to southern Maine. A variety of snow advisories and winter storm warnings were posted for the region. Some areas could receive more than a foot of new snow.
A ridge of high pressure extended from Lake Superior to Texas. This ridge is expected to remain in the same area over the next day.
Along the West Coast, a large, elongated region of precipitation that extended over Central California was situated to the west of a cold front. This cold front extended southwestward from a storm system on the lee slopes of the Canadian Rockies in Alberta to southern California near Los Angeles.
The northern low should continue eastward into the Prairie Provinces. The southern portion of the cold front may break with a low pressure cell developing over Nevada. Heavy snow is expected in the Sierras, with as much as 12 inches possible over the Santa Anas and other mountain ranges near the Los Angeles basin.
TEMPERATURE EXTREMES IN THE COTERMINOUS U.S. -- The lowest temperature on Sunday was 4 degrees at West Yellowstone, MT, while Sunday's highest temperature was 87 degrees at Coolidge, AZ.
ALASKAN WEATHER --A large storm system located over the northern Gulf of Alaska near the Kenai Peninsula spread clouds and light precipitation along a front that stretched eastward along the Gulf coast to Yakutat. Another storm system situated over Bristol Bay, was responsible for clouds across western Alaska and the Bering Sea, with another band of clouds along a cold front that trailed southwestward along the Alaska Peninsula and the Aleutians. A third low pressure cell was located near Nome, with clouds along a frontal band that stretched across the interior. A variety of snow advisories and winter storm warnings were continued through Sunday for many areas of the state. Strong northerly winds across the Bering Sea necessitated blizzard and wind-chill warnings. Wind-chill equivalent temperatures were expected to fall to 80 degrees below zero in the Bering Strait.
On Sunday afternoon, a downslope chinook wind crossed the Alaska Range and descended into the Tanana Valley, causing the temperatures to soar to the mid 30s, breaking the prolonged spell of below freezing weather. Fairbanks had 139 consecutive days (since last 25 October) when the temperature did not reach 32 degrees Fahrenheit, tying for the fourth longest subfreezing stretch since 1904; the longest was 157 days, set during the winter of 1971-72.
The overnight lowest temperature in the state as of Sunday was 29 degrees below zero at Umiat. The midafternoon highest temperature was 43 degrees at Birchwood, Elmendorf AFB, Annette and Klawock.
HAWAIIAN WEATHER -- A shear line with clouds and showers passed over the islands at the beginning of the weekend. Otherwise, fair weather with cloud-free skies predominated. Trade winds increased in speed on Saturday as a high pressure cell moved eastward, passing to the north of Hawaii. Another shear line to the north of Hawaii on Saturday night moved southward, producing light showers across the windward sections of the islands on Sunday evening. A large high pressure system situated over the Pacific approximately 1000 miles to the north-northeast of Honolulu was responsible for the northeast trade winds that had wind speeds reaching 25 mph. Some strengthening of the trades is expected by Tuesday, when a new high pressure cell arrives. Small craft advisories were in effect for state waters.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
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Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 1999, The American Meteorological Society.